[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"$fxLN3MUwXCdr5RPjwZYIDpOj8CHyjOmngWTgoKXPtZbg":3,"$fLpN5olSZcVj5sV61zsnTHUby7u9hhML7nD1XHuH1RlQ":36,"$f3Ft0rKFJHppdzE-vuveecxx1BUcg9iOlMLtyzf_MJDg":358,"$fucxFBm2ZjZfGSdmdRaSNGBI_F0jJme4f0GTvzUhQfL8":423},[4,8,12,16,20,24,28,32],{"title":5,"slug":6,"path":7},"About Microbeonline.com","about-microbeonline-com","\u002Fabout-microbeonline-com\u002F",{"title":9,"slug":10,"path":11},"About Me","about-me","\u002Fabout-microbeonline-com\u002Fabout-me\u002F",{"title":13,"slug":14,"path":15},"Advertise with Us","advertise-us","\u002Fadvertise-us\u002F",{"title":17,"slug":18,"path":19},"Privacy Policy","privacy-policy","\u002Fprivacy-policy\u002F",{"title":21,"slug":22,"path":23},"Authors","authors","\u002Fauthors\u002F",{"title":25,"slug":26,"path":27},"Microbes","microbes","\u002Fmicrobes\u002F",{"title":29,"slug":30,"path":31},"Books","recommended-books","\u002Frecommended-books\u002F",{"title":33,"slug":34,"path":35},"Tags","tags","\u002Ftags\u002F",{"type":37,"data":38},"blog",{"slug":39,"title":40,"description":41,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":44,"lastUpdatedDate":44,"draft":45,"category":46,"image":42,"body":47,"faq":48,"commentsClosed":45,"tags":64,"related":66,"comments":354},"pus-cells-in-a-gram-stain-report","Pus Cells in a Gram Stain Report: What They Actually Mean","\u003Cp>What \"pus cells\" mean on a Gram stain report, how neutrophils are graded, and how to read phrases like \"moderate pus cells, no organisms seen\" correctly.\u003C\u002Fp>",null,"Acharya Tankeshwar","2026-09-15",false,"bacteriology","A laboratory report that says \"many pus cells seen\" or \"moderate pus cells, no organisms seen\" is not describing a bacterium at all. Pus cells are host cells, and they carry some of the most useful information on the whole report.\n\nReading them well is what separates \"the culture grew something\" from \"this is the infection.\" This article explains what a pus cell is, how the laboratory grades them, and how to read them together with the organisms, including the report phrases that confuse people most.\n\n## What a pus cell is\n\nA pus cell is a neutrophil, the most common type of white blood cell and the body's first responder to bacterial infection. On a report you will also see them called polymorphonuclear cells, PMNs, polymorphs, or neutrophils. All four terms mean the same cell.\n\nThey are called polymorphonuclear because the nucleus is divided into several connected lobes, which is how they are recognized on a stained smear: a cell roughly 12 to 15 micrometers across with a multi-lobed nucleus and a pale, granular cytoplasm.\n\nThe key idea is simple. Bacteria are the possible cause of infection. Pus cells are the body's response to it. A smear shows you both, and the two are read together.\n\n## Why the laboratory counts them\n\nNeutrophils leave the bloodstream and pour into tissue when there is an infection there. So the number of pus cells on a smear is a direct readout of whether the body is mounting a response at the sampled site. This does two jobs at once.\n\nFirst, it tells you whether there is a host response, which supports true infection rather than passing colonization. Second, together with epithelial cells, it tells you whether the specimen actually came from the site of infection or was contaminated on the way out. Both jobs come from counting cells, which is why the laboratory reports them before, or alongside, the organisms.\n\n## How pus cells are graded\n\nPus cells are reported semiquantitatively, meaning by rough category rather than an exact count. The laboratory estimates how many neutrophils are present per field, averaged over several fields, and reports a grade.\n\nThe magnification depends on the job. When the point is to judge specimen quality, such as deciding whether a sputum is a genuine lower-airway sample or just saliva, the laboratory scans at low power (the 10x objective, about 100x total), because a wide field is needed to weigh neutrophils against squamous epithelial cells across the smear.\n\nWhen the point is to read the organisms and the cells on an accepted direct smear, such as pus, a wound, or cerebrospinal fluid, the neutrophils are counted under the oil-immersion lens (the 100x objective, about 1000x total) in the same fields where the bacteria are examined. So the same \"pus cells\" grade can come from a different lens depending on what the smear is for.\n\n| Report term | Rough meaning |\n| --- | --- |\n| No pus cells \u002F none seen | None in the fields examined |\n| Occasional \u002F scant \u002F few | A small number, not in every field |\n| Moderate (1+ to 2+) | Present in most fields, several per field |\n| Many \u002F numerous (3+ to 4+) | Heavy, filling the fields |\n\nThe exact numeric bands vary between laboratories, and the specific cutoffs and magnification used to accept, reject, or read a specimen are set per specimen type (a sputum has different rules from a wound). What travels everywhere is the direction: more pus cells means a stronger host response at the sampled site.\n\n## The reading that matters: pus cells and organisms together\n\nNo single line on a smear report should be read alone. The useful signal is the combination of how many pus cells are present and how many kinds of organisms are seen. Four combinations cover most reports.\n\n\u003Cfigure>\n\u003Cimg src=\"https:\u002F\u002Fassets.microbeonline.com\u002Fblogs\u002Fpus-cells-with-gram-positive-cocci.png\" alt=\"Microscopy field showing many neutrophils (pus cells) surrounding gram-positive cocci in clusters, illustrating a host response with a predominant organism.\" width=\"1604\" height=\"981\" draggable=\"false\" contenteditable=\"false\">\u003Cfigcaption>Figure: \"Pus cells\" on a report are neutrophils. Read with a single predominant organism and abundant host cells like this, they support true infection.\u003C\u002Ffigcaption>\n\u003C\u002Ffigure>\n\n**Many pus cells with a single predominant organism.** This is the classic picture of infection: a strong host response and one organism dominating. This combination gives the culture that follows real weight, because the organism you grow is very likely the true pathogen.\n\n**Few or no pus cells with many different organisms (and often squamous epithelial cells).** This points away from infection at the sampled site. A mixture of organisms with little host response usually means the swab or sample caught a colonized surface, not an infected depth. Squamous epithelial cells are the giveaway that the sample includes skin or mucosal surface, so it is contaminated with surface flora.\n\n**Many pus cells but no organisms seen.** A real host response with nothing to explain it. There are three common reasons: the patient was already started on antibiotics, so the organisms are damaged or cleared but the inflammation remains; the organism does not take up Gram stain well or does not grow on routine media (think anaerobes, mycobacteria, *Actinomyces*, or *Chlamydia*); or the smear simply missed organisms that the culture will still recover. It does not mean \"no infection.\" It means \"look harder, and reconsider the methods.\"\n\n**Few pus cells and no organisms.** The least eventful result. It fits a specimen from a site without active infection, or a very early or already-resolved process. Read against the clinical picture.\n\n## Squamous epithelial cells: the quality flag\n\nSquamous epithelial cells are large, flat surface cells from skin or mucous membranes. They do not belong in a sample that should come from a deep or sterile site, so their presence is a warning that the specimen is contaminated with surface material.\n\nIn practice, abundant squamous epithelial cells with few pus cells is the signature of a poorly collected sample, most famously a \"sputum\" that is really saliva. The laboratory uses this cell mix to decide whether a specimen is good enough to culture at all. For how those accept-or-reject rules are applied to a respiratory sample, see the [sputum and lower respiratory tract article](https:\u002F\u002Fmicrobeonline.com\u002Fkey-points-laboratory-diagnosis-lower-respiratory-tract-infections\u002F).\n\n## The same logic across different specimens\n\nThe principle \"count the host cells, then the organisms\" is used on every Gram-stained smear, but the specific cutoffs and what counts as contamination change with the specimen. Each specimen article owns its own numbers; this is the shared idea behind all of them.\n\n| Specimen | What pus cells tell you | Where the cutoffs live |\n| --- | --- | --- |\n| Sputum | Screened at low power (10x): many pus cells with few squamous epithelial cells means a genuine lower-airway sample; the reverse means saliva | [Sputum \u002F LRTI article](https:\u002F\u002Fmicrobeonline.com\u002Fkey-points-laboratory-diagnosis-lower-respiratory-tract-infections\u002F) |\n| Pus \u002F abscess | Many pus cells with one organism supports infection; few cells with mixed flora suggests a surface sample | [Pus sample article](https:\u002F\u002Fmicrobeonline.com\u002Fpus-sample-collection-staining-culture\u002F) |\n| Wound swab | Abundant pus cells with a predominant organism supports infection; scanty cells with mixed flora and squamous cells suggests colonization | [Wound swab article](https:\u002F\u002Fmicrobeonline.com\u002Fwound-swab-collection-transport-lab-diagnosis\u002F) |\n| Urine | Pus cells support urinary tract infection and are read with the colony count; squamous cells suggest perineal contamination | [Urine \u002F UTI article](https:\u002F\u002Fmicrobeonline.com\u002Fspecimen-collection-diagnosis-urinary-tract-infection\u002F) |\n| Cerebrospinal fluid | Any organisms with many neutrophils is an urgent finding; the normal count is very low, so even modest numbers matter | [CSF \u002F CNS infection article](https:\u002F\u002Fmicrobeonline.com\u002Fkey-points-for-the-laboratory-diagnosis-of-central-nervous-system-infections\u002F) |\n| Genital (endocervical, urethral) | Many pus cells with intracellular gram-negative diplococci supports gonococcal infection in the right patient and site | [Genital and STI article](https:\u002F\u002Fmicrobeonline.com\u002Fgenital-and-sti-specimens-collection-transport-lab-diagnosis\u002F) |\n\nThe staining itself, the steps that make bacteria and cells visible in the first place, is covered in the [Gram staining procedure article](https:\u002F\u002Fmicrobeonline.com\u002Fgram-staining-principle-procedure-results\u002F).\n\n## Reading real report phrases\n\n**\"Moderate pus cells, no organisms seen.\"** A clear host response, but nothing stained. Most often prior antibiotics, or an organism that does not show on a routine Gram film. Not a green light to stop; it is a prompt to check what antibiotics were given and whether a special culture is needed.\n\n**\"Few pus cells, no organisms seen.\"** Little host response and nothing to see. Often a site without active infection, or a very good sample from a treated one. Interpret with the clinical picture.\n\n**\"Many pus cells, gram-negative bacilli seen.\"** A strong host response with a likely pathogen already visible. The culture that follows carries weight. In pus or wound samples this points toward organisms such as *Escherichia coli*, *Klebsiella*, *Pseudomonas*, or *Proteus*.\n\n**\"Occasional pus cells, mixed organisms, squamous epithelial cells present.\"** The contamination pattern. Little host response, several organisms, and surface cells together say the sample caught a colonized surface. Treatment aimed at this \"growth\" would often be treating flora, not infection.\n\n## How to Remember\n\n**Pus cells are the body, bacteria are the enemy.** The smear shows both. Read them together, never one alone.\n\n**Poly, PMN, neutrophil, pus cell: one cell, four names.** All mean the multi-lobed white cell that floods an infected site.\n\n**Host cells high plus one organism equals infection.** Host cells low plus many organisms, with squamous cells, equals a surface sample.\n\n**Pus cells but no bugs? Ask two questions.** Were antibiotics started, and could this be an organism that will not stain or grow routinely?\n\n**Squamous cells are the spit flag.** Flat surface cells where they do not belong mean the sample is contaminated, classically saliva sent as sputum.\n\n## Key exam facts\n\n| Point | Fact |\n| --- | --- |\n| Pus cell identity | Neutrophil (polymorphonuclear cell, PMN, polymorph) |\n| Recognized by | Multi-lobed nucleus, \\~12 to 15 micrometers, granular cytoplasm |\n| What they signal | Host response at the sampled site; supports infection |\n| How reported | Semiquantitatively (none, few, moderate, many; or 1+ to 4+) |\n| Magnification | Specimen quality screen (e.g. sputum) at low power (10x); organism reading on an accepted smear at oil immersion (100x) |\n| Read with | The organisms present, never alone |\n| Many PMNs + one organism | Supports true infection |\n| Few PMNs + mixed organisms + squamous cells | Surface contamination or colonization |\n| Many PMNs + no organisms | Prior antibiotics; or non-staining\u002Ffastidious organism; or missed on smear |\n| Squamous epithelial cells | Surface\u002Fskin\u002Fmucosal contamination flag (classically saliva as sputum) |\n| Cutoffs | Set per specimen type; owned by each specimen article |\n\n## Where Students Get Confused\n\n**\"Pus cells means there is pus, so it must be a severe infection.\"** Not quite. Pus cells are neutrophils, and they appear wherever the body responds to infection, not only in visible pus. Their number grades the host response; severity is judged clinically, not by the word \"pus\" on the report.\n\n**\"No organisms seen means no infection.\"** No. If pus cells are present, there is a host response, and \"no organisms\" often means prior antibiotics or an organism that does not stain or grow on routine media. The smear is one window, not the whole diagnosis.\n\n**\"The report listed several organisms, so it is a mixed infection.\"** Usually the opposite. Several organisms with few pus cells and squamous epithelial cells is the classic contamination pattern: the sample caught a colonized surface. A true mixed infection still shows a host response.\n\n**\"Polymorphs, PMNs, neutrophils, and pus cells must be different things.\"** They are all the same cell. Different reports and textbooks use different names for the multi-lobed white blood cell that responds to bacterial infection.\n\n**\"Squamous epithelial cells are just skin, so they do not matter.\"** They matter a great deal. In a sample that should come from a deep or sterile site, surface cells mean the specimen is contaminated, and the laboratory may reject it or read the culture with caution.\n\n## References\n\n1. Tille PM (2022). Bailey & Scott's Diagnostic Microbiology. 15th edn. Elsevier. pp. 74-90.\n2. Procop GW, Church DL, Hall GS, Janda WM, Koneman EW, Schreckenberger PC, Woods GL (2017). Koneman's Color Atlas and Textbook of Diagnostic Microbiology. 7th edn. Wolters Kluwer. pp. 89-104.\n3. Leber AL (ed) (2016). Clinical Microbiology Procedures Handbook. 4th edn. ASM Press. DOI 10.1128\u002F9781683670438.CMPH",[49,52,55,58,61],{"question":50,"answer":51},"\u003Cp>What are pus cells in a Gram stain report?\u003C\u002Fp>","\u003Cp>Pus cells are neutrophils, the white blood cells the body sends to fight bacterial infection. On a report they may also be called polymorphonuclear cells, PMNs, or polymorphs. Their number shows how strongly the body is responding at the sampled site, and they are read together with the organisms seen, not on their own.\u003C\u002Fp>",{"question":53,"answer":54},"\u003Cp>What does \"moderate pus cells, no organisms seen\" mean?\u003C\u002Fp>","\u003Cp>It means there is a clear host response but nothing stained on the smear. The common reasons are that antibiotics were already started, that the organism does not stain or grow on routine media (such as anaerobes, mycobacteria, or \u003Cem>Actinomyces\u003C\u002Fem>), or that the smear missed organisms the culture will still grow. It does not by itself mean there is no infection.\u003C\u002Fp>",{"question":56,"answer":57},"\u003Cp>Is a high pus cell count always bad?\u003C\u002Fp>","\u003Cp>A high count means a strong host response, which supports true infection at the sampled site, but it does not by itself measure how severe the illness is. Severity is judged from the clinical picture. The pus cell count is most useful when read together with the organisms and the type of specimen.\u003C\u002Fp>",{"question":59,"answer":60},"\u003Cp>What is the difference between pus cells and squamous epithelial cells?\u003C\u002Fp>","\u003Cp>Pus cells (neutrophils) are the host response to infection. Squamous epithelial cells are large flat surface cells from skin or mucous membranes. Many pus cells suggest infection at the site, while many squamous epithelial cells suggest the sample was contaminated with surface material, classically saliva collected instead of sputum.\u003C\u002Fp>",{"question":62,"answer":63},"\u003Cp>Why would there be pus cells but no bacteria on the Gram stain?\u003C\u002Fp>","\u003Cp>Because the Gram stain is only one window. Prior antibiotics can clear or damage organisms while the inflammation remains, some organisms do not take up Gram stain or grow on ordinary media, and a thin smear can miss organisms that the culture recovers. The finding calls for checking recent antibiotics and considering special cultures.\u003C\u002Fp>",[65],"bacterial-staining-technique",[67,112,146,175,221,267,314,340],{"slug":68,"title":69,"description":70,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":71,"lastUpdatedDate":72,"draft":45,"category":46,"image":42,"faq":73,"tags":110},"key-points-laboratory-diagnosis-lower-respiratory-tract-infections","Sputum Sample: Collection, Transport, Staining, and Culture","\u003Cp>How to collect a good sputum sample, the cell criteria that decide accept or reject, how to read the culture against mouth flora, and what a 3+ growth means.\u003C\u002Fp>","2013-09-04","2026-09-09",[74,77,80,83,86,89,92,95,98,101,104,107],{"question":75,"answer":76},"\u003Cp>Why is the first morning sputum sample preferred?\u003C\u002Fp>","\u003Cp>Secretions pool in the lower airways overnight, so the first deep cough of the day gives the most concentrated lower-airway material. For tuberculosis this raises the bacillary yield.\u003C\u002Fp>",{"question":78,"answer":79},"\u003Cp>How does the laboratory decide a sputum sample is really sputum and not saliva?\u003C\u002Fp>","\u003Cp>It screens a Gram-stained smear under low power. A good expectorated sample has more than 25 neutrophils and fewer than 10 squamous epithelial cells per low power field. Many squamous cells indicate saliva, and the sample is rejected. This screen applies to expectorated sputum only.\u003C\u002Fp>",{"question":81,"answer":82},"\u003Cp>Why is induced sputum sometimes rejected even though it is a valid sample?\u003C\u002Fp>","\u003Cp>Induced sputum is watery and cell-poor, so it fails the squamous-cell screen that is designed for expectorated samples. If it is labeled as induced, the lab bypasses that screen and processes it. Unlabeled, it can be wrongly rejected.\u003C\u002Fp>",{"question":84,"answer":85},"\u003Cp>What sample is used when a patient cannot cough up sputum?\u003C\u002Fp>","\u003Cp>Step up the invasiveness only as far as needed: induced sputum first, then endotracheal or tracheostomy aspirate in intubated patients, then bronchoscopy with BAL for immunocompromised or non-resolving cases. In young children, gastric aspirate (for TB) or bronchoscopy is often used because children swallow their sputum.\u003C\u002Fp>",{"question":87,"answer":88},"\u003Cp>How quickly must sputum reach the laboratory, and can it be refrigerated?\u003C\u002Fp>","\u003Cp>Process within 1 to 2 hours at room temperature. If delayed, refrigerate at 2 to 8 degrees C for up to 24 hours, except when a fastidious organism such as pneumococcus or \u003Cem>Haemophilus influenzae\u003C\u002Fem> is suspected, since cold lowers their recovery.\u003C\u002Fp>",{"question":90,"answer":91},"\u003Cp>Why might a hospitalized patient's gram-negative growth be ignored?\u003C\u002Fp>","\u003Cp>Intubated and hospitalized patients are colonized by gram-negative and nosocomial flora within days. A few colonies without matching clinical signs usually mean colonization, not infection, so identification and susceptibility testing would not change treatment.\u003C\u002Fp>",{"question":93,"answer":94},"\u003Cp>What concentration of saline is used for sputum induction?\u003C\u002Fp>","\u003Cp>Nebulized hypertonic saline, 3% to 7% NaCl. Normal saline (0.9%) is too dilute to irritate the airway and trigger a productive cough.\u003C\u002Fp>",{"question":96,"answer":97},"\u003Cp>How do you tell a pathogen from normal flora in a sputum culture?\u003C\u002Fp>","\u003Cp>Look for one organism predominating, growing heavily, and matching what the Gram stain showed among the pus cells. Normal flora is a mix of several organisms (viridans streptococci, \u003Cem>Neisseria\u003C\u002Fem>, diphtheroids, yeast) with none dominant. A single heavy growth that fits the clinical setting is likely the pathogen; a mixed light growth is usually colonization or mouth contamination.\u003C\u002Fp>",{"question":99,"answer":100},"\u003Cp>What does 3+ or heavy growth mean on a sputum culture report?\u003C\u002Fp>","\u003Cp>It is a semiquantitative estimate of how much of an organism grew, judged by how far colonies carried across the streaked-out plate. Growth into the third or fourth quadrant (3+ to 4+) suggests a dominant lower-airway organism, while growth only in the first quadrant (1+) is more likely a colonizer. It indicates significance, not an exact count.\u003C\u002Fp>",{"question":102,"answer":103},"\u003Cp>If the sputum culture grew only normal flora, does that rule out pneumonia?\u003C\u002Fp>","\u003Cp>No. Several causes of pneumonia do not grow on routine media, including \u003Cem>Mycoplasma pneumoniae\u003C\u002Fem>, \u003Cem>Chlamydophila pneumoniae\u003C\u002Fem>, \u003Cem>Legionella\u003C\u002Fem> species, and \u003Cem>Mycobacterium tuberculosis\u003C\u002Fem>. A routine culture showing only normal flora does not exclude these, so the clinical picture decides whether to send PCR, a \u003Cem>Legionella\u003C\u002Fem> urinary antigen, or tuberculosis testing.\u003C\u002Fp>",{"question":105,"answer":106},"\u003Cp>Which sputum organisms are most important in cystic fibrosis?\u003C\u002Fp>","\u003Cp>\u003Cem>Staphylococcus aureus\u003C\u002Fem>, \u003Cem>Pseudomonas aeruginosa\u003C\u002Fem>, \u003Cem>Haemophilus influenzae\u003C\u002Fem>, and the \u003Cem>Burkholderia cepacia\u003C\u002Fem> complex. \u003Cem>Burkholderia cepacia\u003C\u002Fem> complex matters most: it is difficult to treat and can affect transplant eligibility, so it must not be missed or misreported in a cystic fibrosis sample.\u003C\u002Fp>",{"question":108,"answer":109},"\u003Cp>What is the fastest way to diagnose tuberculosis from sputum?\u003C\u002Fp>","\u003Cp>A nucleic acid amplification test such as GeneXpert MTB\u002FRIF gives a result the same day and also reports rifampicin resistance. It does not replace microscopy and culture, because a negative test does not exclude tuberculosis, but it is much faster than waiting for culture on Lowenstein-Jensen medium.\u003C\u002Fp>",[111],"specimen-collection-transport",{"slug":113,"title":114,"description":115,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":116,"lastUpdatedDate":44,"draft":45,"category":46,"image":42,"faq":117,"tags":145},"pus-sample-collection-staining-culture","Pus Sample: Collection, Processing, Staining and Culture","\u003Cp>Why an abscess aspirate beats a swab, the fallback when you cannot, how to protect anaerobes in transport, and how the lab stains and cultures pus.\u003C\u002Fp>","2019-02-07",[118,121,124,127,130,133,136,139,142],{"question":119,"answer":120},"\u003Cp>Why is an aspirate preferred over a swab for pus?\u003C\u002Fp>","\u003Cp>An aspirate provides more sample, keeps air out so anaerobes survive, and avoids the skin surface where colonizing flora live. A swab loses on all three counts, which is why an aspirate from an undrained abscess is the ideal specimen.\u003C\u002Fp>",{"question":122,"answer":123},"\u003Cp>What do I do when I cannot get an aspirate?\u003C\u002Fp>","\u003Cp>Take two swabs from the depth of the wound after clearing superficial debris, one for culture and one for the Gram smear. If only one swab is available, inoculate the culture media first, then make the smear from the same swab.\u003C\u002Fp>",{"question":125,"answer":126},"\u003Cp>How much pus should be collected?\u003C\u002Fp>","\u003Cp>Aim for 1 to 5 mL. Larger volumes keep anaerobes viable longer and give the lab enough material for smear, culture, and any special testing.\u003C\u002Fp>",{"question":128,"answer":129},"\u003Cp>Is a swab in Amies medium enough when anaerobes are suspected?\u003C\u002Fp>","\u003Cp>No. Amies prevents the swab from drying but is not a true anaerobic transport method, so strict anaerobes still die. Use a capped syringe aspirate with the air expelled, or tissue in an anaerobic transport system.\u003C\u002Fp>",{"question":131,"answer":132},"\u003Cp>Should a pus sample be refrigerated if transport is delayed?\u003C\u002Fp>","\u003Cp>For routine aerobic culture, refrigeration is better than leaving the sample at room temperature. Do not refrigerate if anaerobes or fastidious organisms are suspected, because cold lowers their recovery. For those, transport quickly at room temperature, and remember that a capped aspirate protects anaerobes far better than any swab.\u003C\u002Fp>",{"question":134,"answer":135},"\u003Cp>How does the Gram stain distinguish colonization from infection?\u003C\u002Fp>","\u003Cp>By the number of pus cells. Few or no polymorphonuclear cells with abundant skin flora suggests colonization. Moderate to many pus cells suggests true infection.\u003C\u002Fp>",{"question":137,"answer":138},"\u003Cp>Is Cary-Blair medium used for pus samples?\u003C\u002Fp>","\u003Cp>No. Cary-Blair is for enteric (stool) specimens. If a pus swab must be held during a transport delay, Amies is the medium to use.\u003C\u002Fp>",{"question":140,"answer":141},"\u003Cp>What does \"pus cells seen\" mean on a Gram stain or culture report?\u003C\u002Fp>","\u003Cp>Pus cells are neutrophils, the white blood cells the body sends to fight infection, so seeing them means there is a host response at the site. On a pus sample they are read together with the organisms: many pus cells with a single predominant organism supports infection, while few pus cells with a mixture of organisms and squamous epithelial cells suggests the sample caught the skin surface rather than the infection. Pus cells with no organisms seen can reflect prior antibiotics or an organism that does not grow on routine media.\u003C\u002Fp>",{"question":143,"answer":144},"\u003Cp>Which organisms are expected in pus from a bite wound?\u003C\u002Fp>","\u003Cp>Animal bites (dog and cat) commonly grow \u003Cem>Pasteurella multocida\u003C\u002Fem>, which grows on blood agar but not on MacConkey agar, so it is easily missed if the laboratory is not told the specimen is from a bite. Human bites and clenched-fist injuries add \u003Cem>Eikenella corrodens\u003C\u002Fem> and mouth anaerobes. Always note a bite on the request form so the right media are used and read.\u003C\u002Fp>",[111],{"slug":147,"title":148,"description":149,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":150,"lastUpdatedDate":151,"draft":45,"category":46,"image":42,"faq":152,"tags":174},"wound-swab-collection-transport-lab-diagnosis","Wound Swab: Collection, the Levine Technique, and When Not to Swab","\u003Cp>Why an open-wound swab is only as good as the technique, how the Levine method samples deep fluid instead of surface flora, how to tell colonization from infection, and when tissue biopsy or aspirate is the right specimen instead.\u003C\u002Fp>","2026-08-14","2026-08-20",[153,156,159,162,165,168,171],{"question":154,"answer":155},"\u003Cp>When should a wound be swabbed for culture?\u003C\u002Fp>","\u003Cp>Only when it is clinically infected or chronic and failing to heal. Every open wound is colonized, so swabbing a clean, healing wound just grows colonizers and can lead to unnecessary antibiotics. Signs of infection, such as spreading redness, increasing pain, purulence, and non-healing, guide the decision.\u003C\u002Fp>",{"question":157,"answer":158},"\u003Cp>What is the Levine technique and why is it preferred?\u003C\u002Fp>","\u003Cp>The Levine technique involves rotating the swab over a 1 cm² area of clean, viable tissue with firm pressure for about 5 seconds, which expresses fluid from deep tissue. This samples the infecting organisms rather than surface flora and recovers results close to a tissue biopsy, outperforming the surface Z-technique.\u003C\u002Fp>",{"question":160,"answer":161},"\u003Cp>Why must the wound be cleaned with saline before swabbing?\u003C\u002Fp>","\u003Cp>Cleaning with sterile saline removes surface colonizers so the swab reaches the infecting organisms underneath. An antiseptic must not be used just before swabbing, because it suppresses the organisms you are trying to grow.\u003C\u002Fp>",{"question":163,"answer":164},"\u003Cp>When is a tissue biopsy or aspirate better than a swab?\u003C\u002Fp>","\u003Cp>For deep, chronic, or serious infections such as diabetic foot ulcers and osteomyelitis, and for any closed collection of pus. Tissue biopsy is the reference standard, and an aspirate protects anaerobes and avoids surface flora. A swab is the fallback when neither can be obtained.\u003C\u002Fp>",{"question":166,"answer":167},"\u003Cp>Why are anaerobes often missed on a wound swab?\u003C\u002Fp>","\u003Cp>Anaerobes survive poorly on a swab exposed to air. A tissue sample or a capped aspirate protects them much better. When anaerobes are suspected, avoid a plain swab if tissue or aspirate can be taken, or use an anaerobic transport swab.\u003C\u002Fp>",{"question":169,"answer":170},"\u003Cp>How should wound tissue for culture be transported?\u003C\u002Fp>","\u003Cp>In a sterile container with a little sterile saline to keep it moist. Never place tissue for culture in formalin, which kills all organisms; formalin is only for histopathology.\u003C\u002Fp>",{"question":172,"answer":173},"\u003Cp>Where in the wound should the sample be taken?\u003C\u002Fp>","\u003Cp>From viable infected tissue at the advancing margin or the base of the wound, not from dead slough or crust. In burns, sample several areas because organisms are unevenly distributed.\u003C\u002Fp>",[111],{"slug":176,"title":177,"description":178,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":179,"lastUpdatedDate":72,"draft":45,"category":46,"image":42,"faq":180,"tags":220},"specimen-collection-diagnosis-urinary-tract-infection","Urine Culture: Sample Collection, Transport and Lab Diagnosis ","\u003Cp>How to collect and culture urine, read colony counts to separate infection from contamination, and interpret the culture alongside pyuria, nitrite, and esterase.\u003C\u002Fp>","2026-08-12",[181,184,187,190,193,196,199,202,205,208,211,214,217],{"question":182,"answer":183},"\u003Cp>When should urine be sent for culture, and when should it not?\u003C\u002Fp>","\u003Cp>Send it only when there is real clinical suspicion of UTI: suspected pyelonephritis (loin pain and fever), UTI in men, recurrent UTI, pregnancy, or failed empiric treatment. Culturing every patient risks detecting asymptomatic bacteriuria, which usually does not need treatment.\u003C\u002Fp>",{"question":185,"answer":186},"\u003Cp>Which collection method gives the least contaminated sample?\u003C\u002Fp>","\u003Cp>Suprapubic aspiration, because the needle enters the bladder directly and bypasses the urethra. It is reserved for infants, young children, or cases where other methods fail. For routine adults, the clean-catch midstream sample is the practical standard despite its higher contamination risk.\u003C\u002Fp>",{"question":188,"answer":189},"\u003Cp>Why can urine never be cultured from a catheter drainage bag?\u003C\u002Fp>","\u003Cp>Bacteria multiply in the bag, so the count no longer reflects what is in the bladder. For a catheterized patient, clamp the tubing above the port, disinfect the port, and aspirate fresh urine through it.\u003C\u002Fp>",{"question":191,"answer":192},"\u003Cp>What does the calibrated loop actually do, and why does the angle matter so much?\u003C\u002Fp>","\u003Cp>It delivers a fixed, reproducible volume of urine (commonly 1 microlitre) so that counting colonies gives an estimate of CFU per mL. The result depends entirely on picking up that exact volume, so the loop must be held vertical and dipped only a few millimetres. A tilted or over-dipped loop delivers the wrong volume and invalidates the count.\u003C\u002Fp>",{"question":194,"answer":195},"\u003Cp>Why is \u003Cem>Staphylococcus aureus\u003C\u002Fem> in the urine treated differently from other organisms?\u003C\u002Fp>","\u003Cp>\u003Cem>S. aureus\u003C\u002Fem> usually reaches the kidney through the bloodstream rather than by ascending the urethra. So\u003Cem> S. aureus\u003C\u002Fem> in urine raises the question of a bloodstream infection, and any count from a suprapubic or catheter specimen can be significant rather than dismissed as a low count.\u003C\u002Fp>",{"question":197,"answer":198},"\u003Cp>Is \u003Cem>Staphylococcus saprophyticus\u003C\u002Fem> a contaminant like other coagulase-negative staphylococci?\u003C\u002Fp>","\u003Cp>No. Most coagulase-negative staphylococci in urine are skin contaminants, but \u003Cem>S. saprophyticus\u003C\u002Fem> is a genuine uropathogen in young women and should not be dismissed in a symptomatic patient.\u003C\u002Fp>",{"question":200,"answer":201},"\u003Cp>How quickly must urine reach the laboratory?\u003C\u002Fp>","\u003Cp>Within 1 to 2 hours at room temperature. If delayed, refrigerate at 2 to 8 degrees C for up to 24 hours, or use a boric acid preservative tube. Urine left warm overgrows and can turn a contaminant or a low count into a falsely significant result.\u003C\u002Fp>",{"question":203,"answer":204},"\u003Cp>Why is nitrofurantoin a poor choice for pyelonephritis?\u003C\u002Fp>","\u003Cp>It reaches good concentrations in the bladder urine but poor levels in the kidney tissue (renal parenchyma). That makes it effective for lower UTI (cystitis) but inadequate for a kidney infection. Fosfomycin is avoided in pyelonephritis for the same reason.\u003C\u002Fp>",{"question":206,"answer":207},"\u003Cp>Why is a urine culture read together with the urinalysis?\u003C\u002Fp>","\u003Cp>Because the culture tells you how much grew and the urinalysis tells you whether the body is reacting to it. A significant colony count with white cells in the urine (pyuria) supports a true infection, while a significant count with no pyuria and no symptoms may be harmless colonization. Reading the two together separates infection from colonization and contamination far better than the count alone.\u003C\u002Fp>",{"question":209,"answer":210},"\u003Cp>What is sterile pyuria?\u003C\u002Fp>","\u003Cp>Sterile pyuria is white cells in the urine with no significant growth on routine culture. It does not mean there is no problem. Common causes include recent antibiotic use that suppresses the culture but not the inflammation, urethritis, kidney stones, and genitourinary tuberculosis, the last of which a routine culture will not detect.\u003C\u002Fp>",{"question":212,"answer":213},"\u003Cp>What does a positive nitrite on a urine dipstick mean?\u003C\u002Fp>","\u003Cp>It means bacteria in the urine are converting nitrate into nitrite, which the Enterobacterales such as \u003Cem>Escherichia coli\u003C\u002Fem> do. So a positive nitrite points toward a Gram-negative uropathogen. A negative nitrite does not rule out a UTI, because \u003Cem>Enterococcus\u003C\u002Fem>, \u003Cem>Staphylococcus saprophyticus\u003C\u002Fem>, and \u003Cem>Pseudomonas\u003C\u002Fem> often do not produce it.\u003C\u002Fp>",{"question":215,"answer":216},"\u003Cp>Does Group B Streptococcus in the urine matter?\u003C\u002Fp>","\u003Cp>Yes, particularly in pregnancy. \u003Cem>Streptococcus agalactiae\u003C\u002Fem> (Group B strep) is a recognized uropathogen, and its presence in a pregnant patient's urine signals heavier colonization and the need for antibiotics during labor to protect the newborn, so it is reported and acted on rather than dismissed.\u003C\u002Fp>",{"question":218,"answer":219},"\u003Cp>Can urine be collected from a nephrostomy tube?\u003C\u002Fp>","\u003Cp>Yes. A nephrostomy tube drains urine directly from the kidney, so a sample aspirated aseptically from the tube reflects upper-tract urine. Like other catheter specimens, it is interpreted with the any-count caution rather than the clean-catch threshold, because it bypasses the urethra.\u003C\u002Fp>",[111],{"slug":222,"title":223,"description":224,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":225,"lastUpdatedDate":72,"draft":45,"category":46,"image":42,"faq":226,"tags":266},"key-points-for-the-laboratory-diagnosis-of-central-nervous-system-infections","CSF Sample: Collection, Processing, Staining, and Culture","\u003Cp>How to collect CSF, why microbiology never gets the first tube, why CSF is never refrigerated, and how to read the cell count, protein, and glucose to a diagnosis.\u003C\u002Fp>","2013-08-08",[227,230,233,236,239,242,245,248,251,254,257,260,263],{"question":228,"answer":229},"\u003Cp>Why must CSF never be refrigerated?\u003C\u002Fp>","\u003Cp>The common causes of bacterial meningitis (\u003Cem>Neisseria meningitidis\u003C\u002Fem>, \u003Cem>Haemophilus influenzae\u003C\u002Fem>, \u003Cem>Streptococcus pneumoniae\u003C\u002Fem>) are fastidious and cold-sensitive. Refrigeration kills them and lowers the chance of a positive culture. \u003C\u002Fp>\u003Cp>\u003C\u002Fp>\u003Cp>Hold CSF at 35°C or room temperature, and use Trans-Isolate medium if processing will be delayed beyond an hour.\u003C\u002Fp>",{"question":231,"answer":232},"\u003Cp>Which CSF tube should be sent for culture, and why?\u003C\u002Fp>","\u003Cp>Not the first tube. The first drops can carry skin and blood introduced by the needle, which contaminates a culture. The second tube is sent to microbiology. If only one tube is obtained, it goes to microbiology.\u003C\u002Fp>",{"question":234,"answer":235},"\u003Cp>If only a small volume of CSF is available, which test takes priority?\u003C\u002Fp>","\u003Cp>Microbiology. A culture cannot be repeated without another lumbar puncture, and it identifies the organism and its susceptibility. Cell count and chemistry can usually be done on very small volumes.\u003C\u002Fp>",{"question":237,"answer":238},"\u003Cp>How do the CSF findings differ between bacterial, viral, and tuberculous meningitis?\u003C\u002Fp>","\u003Cp>Bacterial shows many neutrophils, high protein, and low glucose. Viral shows mononuclear cells with normal glucose. Tuberculous and fungal show mononuclear cells with low glucose. The cell type and the glucose together separate them.\u003C\u002Fp>",{"question":240,"answer":241},"\u003Cp>How quickly must CSF reach the laboratory?\u003C\u002Fp>","\u003Cp>Within about 1 hour. Delay lowers the chance of growing the organism, lyses white cells so the count falls, and lowers the glucose through glycolysis, which can distort the result.\u003C\u002Fp>",{"question":243,"answer":244},"\u003Cp>Why is CSF Gram stain prepared using a cytocentrifuge?\u003C\u002Fp>","\u003Cp>Because CSF may contain very few organisms, as low as 10³ CFU\u002FmL. Cytocentrifugation concentrates cells and bacteria onto the slide and greatly improves the chance of seeing the organism.\u003C\u002Fp>",{"question":246,"answer":247},"\u003Cp>Is India ink enough to diagnose cryptococcal meningitis?\u003C\u002Fp>","\u003Cp>No. India ink misses many cases. The cryptococcal antigen test is more sensitive and is the preferred method, so a negative India ink does not rule out cryptococcal meningitis.\u003C\u002Fp>",{"question":249,"answer":250},"\u003Cp>How do you interpret a CSF report?\u003C\u002Fp>","\u003Cp>Read it in a fixed order: cell count and type, then protein, then glucose. A high count with neutrophils points to acute bacterial meningitis; a modest count with lymphocytes points to viral, tuberculous, or fungal. High protein means the barrier is inflamed. \u003C\u002Fp>\u003Cp>\u003C\u002Fp>\u003Cp>Low glucose means organisms or cells are consuming it, which happens in bacterial, tuberculous, and fungal meningitis but not usually in viral. When the cell type and the glucose agree, the diagnosis is usually clear.\u003C\u002Fp>",{"question":252,"answer":253},"\u003Cp>Why must CSF glucose be interpreted with a blood glucose?\u003C\u002Fp>","\u003Cp>Because CSF glucose is normally about two thirds of the blood glucose, a ratio of roughly 0.6. The raw CSF number is meaningless without the paired blood value. A CSF glucose of 45 mg\u002FdL is low if the blood glucose is 90 but normal if the patient is diabetic with a blood glucose of 300. Draw the serum glucose at the same time as the lumbar puncture.\u003C\u002Fp>",{"question":255,"answer":256},"\u003Cp>How do you tell a traumatic tap from a true subarachnoid bleed?\u003C\u002Fp>","\u003Cp>Compare the red cell count in the first and last CSF tubes. In a traumatic tap the count falls from the first tube to the last as the needle blood clears. In a true bleed the count stays roughly the same across tubes. Xanthochromia, a yellow tinge in the spun supernatant, means blood has been present for hours and points to a real bleed rather than fresh puncture blood.\u003C\u002Fp>",{"question":258,"answer":259},"\u003Cp>What is the meningitis and encephalitis PCR panel?\u003C\u002Fp>","\u003Cp>It is a rapid multiplex PCR, such as the BioFire FilmArray panel, that tests one small CSF sample for the common bacterial causes, several viruses including herpes simplex and enterovirus, and \u003Cem>Cryptococcus\u003C\u002Fem>, with a result in about an hour. It is fast and needs very little sample, but it is costly, is not available everywhere, and does not replace culture, which is still needed to grow the organism and test its antibiotic susceptibility.\u003C\u002Fp>",{"question":261,"answer":262},"\u003Cp>If coagulase-negative staphylococci grow from CSF, is it a contaminant?\u003C\u002Fp>","\u003Cp>It depends on how the CSF was collected. From a clean lumbar puncture, coagulase-negative staphylococci are usually skin contaminants. From a shunt, external drain, or Ommaya reservoir, the same organisms are usually the true cause of the infection, because these devices are colonized by skin bacteria. Always interpret the result against the specimen source.\u003C\u002Fp>",{"question":264,"answer":265},"\u003Cp>Which test is preferred for cryptococcal meningitis?\u003C\u002Fp>","\u003Cp>The cryptococcal antigen test, ideally the lateral flow assay. It is faster and more sensitive than India ink, which misses many cases, so a negative India ink does not rule out the diagnosis. In patients with HIV, cryptococcal antigen can also be tested on serum or plasma to screen before meningitis develops.\u003C\u002Fp>",[111],{"slug":268,"title":269,"description":270,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":271,"lastUpdatedDate":44,"draft":45,"category":46,"image":42,"faq":272,"tags":312},"genital-and-sti-specimens-collection-transport-lab-diagnosis","Genital and STI Specimens: Collection, Transport and Lab Diagnosis","\u003Cp>Which genital specimen for which STI, by sex and by syndrome: why gonococcus needs bedside culture and no fridge, first-void not midstream, and when to reflex to \u003Cem>M. genitalium.\u003C\u002Fem>\u003C\u002Fp>","2026-08-16",[273,276,279,282,285,288,291,294,297,300,303,306,309],{"question":274,"answer":275},"\u003Cp>Which specimen is preferred for STI screening by NAAT?\u003C\u002Fp>","\u003Cp>A vaginal swab in women and a first-void urine in men. Both are highly sensitive and acceptable to patients, and vaginal swabs can be self-collected with results equivalent to clinician collection.\u003C\u002Fp>",{"question":277,"answer":278},"\u003Cp>Why is first-void urine used for STI testing when urine culture uses midstream?\u003C\u002Fp>","\u003Cp>The two tests want opposite fractions. STI NAAT needs the first-void portion, which carries the urethral cells and organisms. A urine culture uses midstream to avoid urethral contamination. Collect the first 10 to 20 mL for STI NAAT.\u003C\u002Fp>",{"question":280,"answer":281},"\u003Cp>Why must gonococcal culture specimens not be refrigerated?\u003C\u002Fp>","\u003Cp>\u003Cem>Neisseria gonorrhoeae\u003C\u002Fem> is fragile and cold-sensitive. Refrigeration kills it. Keep the specimen at room temperature, use Amies charcoal medium if there is a delay, and ideally inoculate Modified Thayer-Martin medium at the bedside.\u003C\u002Fp>",{"question":283,"answer":284},"\u003Cp>If NAAT is the routine test, why is gonococcal culture still needed?\u003C\u002Fp>","\u003Cp>Culture is needed for antimicrobial susceptibility testing. NAAT confirms the organism is present but does not routinely report which antibiotics will work, and gonococcal resistance is a growing problem.\u003C\u002Fp>",{"question":286,"answer":287},"\u003Cp>What is the best specimen for gonococcal culture in a woman?\u003C\u002Fp>","\u003Cp>An endocervical swab collected through a speculum. A vaginal swab is preferred for NAAT but is not the optimal specimen for gonococcal culture in adult women.\u003C\u002Fp>",{"question":289,"answer":290},"\u003Cp>Can genital specimens be self-collected?\u003C\u002Fp>","\u003Cp>For NAAT, yes. Self-collected vaginal, rectal, and pharyngeal swabs perform as well as clinician-collected ones. Culture specimens such as endocervical and urethral swabs still require a trained collector.\u003C\u002Fp>",{"question":292,"answer":293},"\u003Cp>How is syphilis specimen collection different?\u003C\u002Fp>","\u003Cp>\u003Cem>Treponema pallidum\u003C\u002Fem> cannot be grown on culture media. Syphilis is diagnosed from lesion exudate by dark-field microscopy or molecular methods, or from blood by serology, not by routine swab culture.\u003C\u002Fp>",{"question":295,"answer":296},"\u003Cp>Why are two swabs collected for genital culture?\u003C\u002Fp>","\u003Cp>One is used to make the Gram-stained smear and one for culture. In a symptomatic man, intracellular gram-negative diplococci on the smear are presumptive for gonorrhea, while the culture provides the isolate and its susceptibility. If only one swab is taken, it goes to culture first.\u003C\u002Fp>",{"question":298,"answer":299},"\u003Cp>When and how are pregnant women screened for group B streptococcus?\u003C\u002Fp>","\u003Cp>Screening is done at 36 0\u002F7 to 37 6\u002F7 weeks of pregnancy using a single swab of the lower vagina and the rectum, collected without a speculum. Combining both sites raises the yield because the gut is the reservoir. In the laboratory the swab is enriched in a selective broth (Lim broth) before culture, which is what makes the screen sensitive. A molecular test is an accepted alternative. A positive result means the woman is a carrier and should receive antibiotics during labor; it is not a diagnosis of infection.\u003C\u002Fp>",{"question":301,"answer":302},"\u003Cp>How do you choose the specimen for a genital ulcer?\u003C\u002Fp>","\u003Cp>Start from whether the ulcer is painless or painful. A painless ulcer (chancre) points to syphilis, sampled from the lesion base for dark-field microscopy (genital lesions only) or diagnosed by blood serology. Painful vesicles or ulcers point to genital herpes: unroof a fresh vesicle and swab the base into viral transport medium for PCR. A painful soft ulcer with a tender, swollen inguinal lymph node points to chancroid, sampled from the ulcer or the aspirated node and grown on chocolate agar.\u003C\u002Fp>",{"question":304,"answer":305},"\u003Cp>Why can dark-field microscopy not be used on mouth or rectal syphilis lesions?\u003C\u002Fp>","\u003Cp>Because the mouth and rectum normally contain harmless spirochetes that are indistinguishable from \u003Cem>Treponema pallidum\u003C\u002Fem> under a dark-field microscope. A positive result there could be a commensal, not syphilis, so it is unreliable. Dark-field is used on genital lesions, and oral or rectal lesions are worked up by serology or specific molecular or direct fluorescent methods instead.\u003C\u002Fp>",{"question":307,"answer":308},"\u003Cp>If gonorrhea and chlamydia tests are negative but there is still discharge, what is tested next?\u003C\u002Fp>","\u003Cp>Often a nucleic acid test for \u003Cem>Mycoplasma genitalium\u003C\u002Fem>, a common cause of urethritis and cervicitis that the routine gonorrhea-and-chlamydia panel does not detect. The same specimen already collected, a swab or a first-void urine, is used. This organism has no cell wall, so it is not diagnosed by culture, and because resistance to first-line macrolide treatment is common, the test often reports a resistance marker to guide therapy.\u003C\u002Fp>",{"question":310,"answer":311},"\u003Cp>Why can a negative \u003Cem>Trichomonas\u003C\u002Fem> wet mount be wrong?\u003C\u002Fp>","\u003Cp>Because the wet-mount diagnosis depends on seeing the organism move, and that motility is lost as the sample cools or sits. A wet mount made from an old or refrigerated specimen can read falsely negative. The sample should be fresh, kept at room temperature, and examined within about an hour, or a nucleic acid test can be used instead, since it does not depend on live organisms.\u003C\u002Fp>",[111,313],"sexually-transmitted-infections-stis",{"slug":315,"title":316,"description":317,"seoTitle":318,"seoDescription":319,"author":43,"createdDate":320,"lastUpdatedDate":321,"draft":45,"category":322,"image":42,"faq":323,"tags":339},"gram-staining-principle-procedure-results","Gram Staining: Step-by-Step Procedure, Results & Interpretation Guide","Master gram staining: step-by-step procedure, results interpretation, clinical significance of each gram stain pattern, organism-specific appearances, quality control, and troubleshooting.","Gram Stain: Procedure, Results, Troubleshooting, and Interpretation","Perform Gram staining step by step, interpret common cellular patterns, troubleshoot weak or mixed results, and connect findings with organism identity.","2015-02-02","2026-09-14","staining-techniques",[324,327,330,333,336],{"question":325,"answer":326},"What does it mean if neutrophil nuclei appear blue instead of red on a Gram stain?","\u003Cp>Neutrophil nuclei staining blue\u002Fpurple instead of red\u002Fpink indicates under-decolorization: the decolorizing agent (alcohol or acetone-alcohol) was not applied for long enough, or was too dilute. \u003C\u002Fp>\u003Cp>\u003C\u002Fp>\u003Cp>In this situation, gram-negative organisms may also retain the crystal violet and appear falsely gram-positive. The entire slide must be repeated with correct decolorization technique: drop-by-drop application until the effluent runs clear, approximately 10-15 seconds.\u003C\u002Fp>",{"question":328,"answer":329},"What is the clinical significance of gram-negative intracellular diplococci in a urethral smear?","\u003Cp>Gram-negative intracellular diplococci (GNID) in a urethral or cervical smear is presumptive evidence of \u003Cem>Neisseria gonorrhoeae\u003C\u002Fem> infection and is sufficient justification to start treatment immediately, before culture confirmation. \u003C\u002Fp>\u003Cp>\u003C\u002Fp>\u003Cp>The sensitivity of this finding in symptomatic males is approximately 90-95%; sensitivity is lower in females and asymptomatic individuals. In a CSF specimen, gram-negative diplococci (intracellular within neutrophils) indicate probable \u003Cem>Neisseria meningitidis \u003C\u002Fem>meningitis, a medical emergency requiring immediate ceftriaxone.\u003C\u002Fp>",{"question":331,"answer":332},"Why do gram-positive bacteria sometimes stain gram-negative?","\u003Cp>Gram-positive bacteria can appear gram-negative due to: over-decolorization (decolorizer applied too long or too vigorously); cell wall damage from antibiotic therapy (beta-lactams damage peptidoglycan, reducing crystal violet retention); use of old or degraded iodine solution (yellow rather than dark brown); old culture age (aging cells lose cell wall integrity); or excessive heat fixation distorting the smear. When gram-positive control organisms also stain incorrectly, the reagents should be investigated first.\u003C\u002Fp>",{"question":334,"answer":335},"\u003Cp>What is the mordant in Gram staining, and what does it do?\u003C\u002Fp>","\u003Cp>The mordant is iodine. A mordant is a substance that fixes a dye in place by combining with it to form a larger, insoluble complex. In the Gram stain, iodine binds the crystal violet to form the bulky crystal violet-iodine (CV-I) complex. \u003C\u002Fp>\u003Cp>\u003C\u002Fp>\u003Cp>That complex is too large to wash out of the thick, dehydrated wall of gram-positive cells, which is what lets them stay purple while gram-negative cells lose the color. Without the mordant, the stain would rinse out of both and the test would not work.\u003C\u002Fp>",{"question":337,"answer":338},"\u003Cp>What do the colors mean in a Gram stain?\u003C\u002Fp>","\u003Cp>Purple (or blue) means gram-positive: the cell kept the crystal violet-iodine complex. Pink (or red) means gram-negative: the cell lost that complex during decolorization and then took up the pink counterstain, safranin. The color is read directly as the Gram reaction.\u003C\u002Fp>",[65],{"slug":341,"title":342,"description":343,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":344,"lastUpdatedDate":345,"draft":45,"category":322,"image":42,"faq":346,"tags":353},"capsule-stain-principle-procedure-results","Capsule Stain: Principle, Procedure, and Results","\u003Cp>Capsule staining detects bacterial capsules. Learn the India ink and Anthony's methods, clinically important capsulated organisms, and the Quellung reaction for pneumococcal identification.\u003C\u002Fp>","2016-10-15","2026-08-21",[347,350],{"question":348,"answer":349},"Why can bacterial capsules not be stained directly?","\u003Cp>Bacterial capsules are composed primarily of polysaccharides (occasionally polypeptides), which are non-ionic. Since conventional dyes are either cationic (basic dyes) or anionic (acidic dyes), they have no charged surface to bind to on the capsule. \u003Cbr>\u003Cbr>Capsule staining is therefore always indirect: the bacterial cell is stained with a basic dye and the background is stained with an acidic dye, revealing the capsule as an unstained clear halo between them.\u003C\u002Fp>",{"question":351,"answer":352},"\u003Cp>How is India ink used to diagnose Cryptococcal meningitis?\u003C\u002Fp>","\u003Cp>India ink (or nigrosin) is mixed with a drop of CSF on a microscope slide and examined under oil immersion. \u003Cem>Cryptococcus neoformans \u003C\u002Fem>appears as a yeast cell (round to oval, 4-20 μm) surrounded by a clear capsule halo against the dark ink background. The halo can be dramatically large relative to the cell body. \u003Cbr>\u003Cbr>India ink is a rapid, inexpensive bedside diagnostic test with approximately 50-80% sensitivity in cryptococcal meningitis. A negative India ink does not exclude cryptococcal meningitis; the cryptococcal antigen latex agglutination test is more sensitive and should be performed when clinical suspicion is high.\u003C\u002Fp>",[65],{"enabled":355,"threads":356,"total":357},true,[],0,[359,365,372,379,385,390,396,401,407,410,417],{"slug":360,"name":43,"description":361,"image":362,"body":363,"postCount":364},"acharya-tankeshwar","Editor-in-chief","https:\u002F\u002Fassets.microbeonline.com\u002Fauthors\u002Ftankeshwar-acharya-author-microbeonline.jpg","***Tankeshwar Acharya, MSc (Medical Microbiology)***\n\n*Tankeshwar Acharya is an Assistant Professor in the Department of Microbiology at Patan Academy of Health Sciences (PAHS), Nepal, where he has been teaching and practicing clinical microbiology for over 14 years. He is the founder of Microbe Online, one of the leading free microbiology education resources on the web, covering bacteriology, mycology, parasitology, immunology, and clinical laboratory diagnostics written from direct experience in both the classroom and the diagnostic laboratory.*",523,{"slug":366,"name":367,"description":368,"image":369,"body":370,"postCount":371},"ashma-shrestha","Ashma Shrestha","SEO Copywriter and Science Communicator\nKathmandu, Nepal","https:\u002F\u002Fassets.microbeonline.com\u002Fauthors\u002Fashma-shrestha.png","Ashma Shrestha holds a Master of Science in Medical Microbiology from the Institute of Science and Technology (IOST), Tribhuvan University, Nepal, where she developed a strong foundation in virology, molecular biology, and diagnostic microbiology.\n\nShe now works as an SEO Copywriter at Resolution Digital, where she combines her scientific training with research-driven content strategy. She is certified in Google Analytics and Google Business Profile (GBP), and brings a data-informed approach to science communication writing content that is not only accurate but structured to reach and serve the students who need it most.\n\nAt microbeonline, Ashma contributes articles primarily in virology and molecular biology, areas she finds most compelling for their mechanistic depth and their growing clinical relevance. Her writing reflects the same standard the site is built on: factual rigor, clear explanation of the *why* behind microbiology concepts, and content that helps students move from memorization to genuine understanding.\n\nShe is passionate about making complex microbiological concepts accessible without sacrificing accuracy; a skill that sits at the intersection of her scientific training and her professional work in content and SEO.",88,{"slug":373,"name":374,"description":375,"image":376,"body":377,"postCount":378},"sushmita-baniya","Sushmita Baniya","Author \u002F Contributor","https:\u002F\u002Fassets.microbeonline.com\u002Fauthors\u002Fsushmita-baniya-1.png","Sushmita Baniya holds an M.Sc. in Medical Microbiology from Tribhuvan University (National College), with a research focus in Genetics and Molecular Biology. She is actively involved in teaching and research in the field of microbiology.",26,{"slug":380,"name":381,"description":375,"image":382,"body":383,"postCount":384},"samikshya-acharya","Samikshya Acharya","https:\u002F\u002Fassets.microbeonline.com\u002Fauthors\u002Fsamikshya-acharya.jpeg","Samikshya Sharma completed her postgraduate studies in Medical Microbiology at the Central Department of Microbiology, Tribhuvan University, Nepal. She contributes to Microbeonline with the goal of making foundational and clinical microbiology concepts clear and useful for students in medical, laboratory science, and allied health programs.",20,{"slug":386,"name":387,"description":375,"image":42,"body":388,"postCount":389},"alisha-tripathi","Alisha Tripathi","Alisha Tripathi holds an M.Sc. in Medical Microbiology from National College, Tribhuvan University. With over a year of teaching experience, her academic interests span Molecular Biology, Immunology, and Genetics.",6,{"slug":391,"name":392,"description":393,"image":42,"body":394,"postCount":395},"aastha-shrestha","Aastha Shrestha"," Author \u002F Contributor","Aastha Shrestha is a Biotechnology graduate with an M.Sc. from National College, Tribhuvan University. Her academic interests center on Molecular Biology and Immunology; two fields that are increasingly converging in modern diagnostic and clinical microbiology. \n\nShe contributes to Microbeonline with the goal of making complex concepts in these areas approachable and exam-relevant for students across medical, biotechnology, and laboratory science programs.",9,{"slug":397,"name":398,"description":399,"image":42,"body":42,"postCount":400},"guest-author","Guest Author","Guest Author \u002F Contributor",1,{"slug":402,"name":403,"description":375,"image":404,"body":405,"postCount":406},"srijana-khanal","Srijana Khanal","https:\u002F\u002Fassets.microbeonline.com\u002Fauthors\u002Fsrijana-khanal-1.png","Srijana Khanal is a microbiology educator with nearly a decade of teaching experience, including her role as faculty in the Microbiology Department at National College, NIST. \n\nHer time in the classroom has given her a clear sense of where students struggle and what explanations actually work, a perspective that directly shapes how she writes.\n\nHer academic interests span Immunology, Genetics, Basic Sciences, and Research Methodology, and she brings the same rigor to her writing that she brought to teaching. Alongside academic writing, she has a passion for creative writing -- an instinct that shows in her ability to make dense scientific material readable without sacrificing accuracy.\n\nShe contributes to Microbeonline to extend her teaching reach beyond the classroom, helping medical and laboratory science students across the region build a stronger foundation in microbiology.",15,{"slug":408,"name":409,"description":399,"image":42,"body":42,"postCount":400},"dr-poonam-acharya","Dr. Poonam Acharya",{"slug":411,"name":412,"description":413,"image":414,"body":415,"postCount":416},"nisha-rijal","Nisha Rijal","Microbiologist and AMR Specialist Kathmandu, Nepal","https:\u002F\u002Fassets.microbeonline.com\u002Fauthors\u002Fnisha-rijal-1.png","Nisha Rijal is a microbiologist with nearly 15 years of frontline diagnostic and surveillance experience at the National Public Health Laboratory (NPHL), national reference laboratory under the Department of Health Services, Nepal. She currently works as an AMR Support Officer at the World Health Organization (WHO), Nepal, where her work focuses on strengthening antimicrobial resistance surveillance systems and translating AMR data into actionable public health response.\n\nHer research, published in peer-reviewed journals and cited over 220 times, spans some of the most clinically significant infectious disease challenges in Nepal and South Asia: antimicrobial resistance trends in *Vibrio cholerae* across an 11-year national surveillance dataset, sero-epidemiology of scrub typhus in patients with acute febrile illness, lower respiratory tract infections in HIV-positive patients, and gonococcal resistance surveillance. She was a contributor to Nepal's National Antimicrobial Resistance Containment Action Plan, a foundational policy document for AMR governance in Nepal. You can find list of [Nisha Rijal's article here in Google Scholar.](https:\u002F\u002Fscholar.google.com\u002Fcitations?user=N-Ruq54AAAAJ&hl=en)\n\nThis depth of experience is visible in her writing at Microbeonline. Her 53 published articles cover bacteriology, parasitology, mycology, immunology, and laboratory techniques, and are consistently among the most detailed and clinically grounded content on the site. She brings to every article the same standard that national reference laboratory work demands: methodological precision, awareness of real diagnostic constraints, and an understanding of what results actually mean for patient care in resource-limited settings.\n\nHer areas of particular expertise include antimicrobial susceptibility testing and resistance mechanism detection, quality assurance in clinical microbiology, and laboratory-based infectious disease surveillance.\n\n---\n\n*Nisha Rijal contributes to Microbeonline in a personal capacity. Her views and writing do not represent the positions of the World Health Organization or any other institution.*",55,{"slug":418,"name":419,"description":420,"image":421,"body":422,"postCount":400},"padma-shrestha","Padma Shrestha","Author","https:\u002F\u002Fassets.microbeonline.com\u002Fauthors\u002Fpadma-shrestha.png","Padma Shrestha is from Kathmandu, Nepal. She has completed Masters degree in Medical microbiology from Tribhuvan University. She has great interest in Microbiology and Molecular Biology.",[424,431,437,441,446,451,455,459,463,468,472,477,481,486,489,494,498,502,507,512,516,520,524,528,532,536,540,544,549,554,559,563,567,572,576,580,584,588,592,596,600,604,608,611,614,619,623,627,632,636,640,644,648,652,656,660,664,668,672,676,680,684,688,692,696,700,704,708,711,715,718,721,724,727,730,733,736,739,742,745,748,751,754,757,760,763,767,770,773,776],{"slug":425,"name":426,"description":427,"image":428,"body":429,"postCount":430},"gram-negative-cocci","Gram-Negative Cocci and Coccobacilli","Neisseria, Moraxella, Haemophilus and related gram-negative coccal organisms","https:\u002F\u002Fassets.microbeonline.com\u002Ftags\u002Fgram-negative-cocci.png","# Gram Negative Cocci\n\nNeisseria gonorrhoeae, Neisseria meningitides, Moraxella catarrhalis, and other Neisseria spp. are clinically relevant gram-negative cocci.\n\nN. gonorrhoeae is the leading cause of sexually transmitted disease whereas N. meningitides is a leading cause of fatal bacterial meningitis.",14,{"slug":432,"name":433,"description":434,"image":42,"body":435,"postCount":436},"microscopy","Microscopy","Microscope types, components, and microscopy techniques","These are list of blog posts related to microscopy. ",12,{"slug":438,"name":439,"description":440,"image":42,"body":42,"postCount":436},"gram-positive-cocci","Gram-Positive Cocci","Staphylococcus, Streptococcus, Enterococcus, Micrococcus — organisms, diseases, and identification tests",{"slug":442,"name":443,"description":444,"image":42,"body":42,"postCount":445},"gram-negative-rods","Gram-Negative Rods (Other than Enterobacteriaceae)","\u003Cp>Gram negative rods other than members of Enterobacteriaceae family such as  Pseudomonas, Acinetobacter and related organisms\u003C\u002Fp>",5,{"slug":447,"name":448,"description":449,"image":42,"body":42,"postCount":450},"gram-positive-rods","Gram-Positive Rods","Bacillus, Clostridium, Listeria, Corynebacterium, Actinomyces and related organisms",8,{"slug":452,"name":453,"description":454,"image":42,"body":42,"postCount":436},"mycobacteria","Mycobacteria","Mycobacterium tuberculosis, leprosy, atypical mycobacteria, and acid-fast organism diagnosis",{"slug":456,"name":457,"description":458,"image":42,"body":42,"postCount":436},"anaerobic-bacteriology","Anaerobic Bacteriology","Anaerobic organisms, anaerobic culture methods, and anaerobic infection diagnosis",{"slug":460,"name":461,"description":462,"image":42,"body":42,"postCount":436},"enterobacteriaceae","Enterobacteriaceae","Identification, differentiation, and clinical significance of Enterobacteriaceae family members",{"slug":464,"name":465,"description":466,"image":42,"body":42,"postCount":467},"spirochetes","Spirochetes","Treponema, Leptospira, Borrelia and spirochetal infections",7,{"slug":469,"name":470,"description":471,"image":42,"body":42,"postCount":430},"food-microbiology","Food Microbiology","Food-borne pathogens, food safety, spoilage, and preservation",{"slug":473,"name":474,"description":475,"image":42,"body":42,"postCount":476},"antimicrobial-susceptibility-testing","Antimicrobial Susceptibility Testing","Methods for testing antibiotic susceptibility in clinical microbiology",22,{"slug":478,"name":479,"description":480,"image":42,"body":42,"postCount":430},"antimicrobials-moa-amr","Antimicrobials (MOA & AMR)","Mechanisms, detection, and clinical significance of antimicrobial resistance",{"slug":482,"name":483,"description":484,"image":42,"body":42,"postCount":485},"sterilization-disinfection","Sterilization and Disinfection","Methods of sterilization and disinfection in healthcare and laboratory settings",10,{"slug":111,"name":487,"description":488,"image":42,"body":42,"postCount":378},"Specimen Collection and Transport","Collection, handling, and transport of clinical specimens for microbiological testing",{"slug":490,"name":491,"description":492,"image":42,"body":42,"postCount":493},"bacterial-structure-physiology","Bacterial Structure and Physiology","Bacterial cell structure, growth, physiology, and environmental factors affecting growth",21,{"slug":495,"name":496,"description":42,"image":42,"body":497,"postCount":389},"horizontal-gene-transfer","Horizontal Gene Transfer","Articles related to **Horizontal Gene Transfer**",{"slug":499,"name":500,"description":42,"image":42,"body":501,"postCount":485},"chromatography","Chromatography","Information about chromatographic techniques.",{"slug":503,"name":504,"description":505,"image":42,"body":506,"postCount":467},"electrophoresis","Electrophoresis","Information about Electrophoresis Techniques ","Detailed information  about Electrophoresis Techniques ",{"slug":508,"name":509,"description":510,"image":42,"body":511,"postCount":389},"pcr-techniques","PCR Techniques","Information about various types of Polymerase Chain Reaction Techniques ","More detailed information about various types of Polymerase Chain Reaction Techniques ",{"slug":513,"name":514,"description":515,"image":42,"body":42,"postCount":389},"bacteriophage","Bacteriophage","Description about Bacteriophage.",{"slug":517,"name":518,"description":519,"image":42,"body":42,"postCount":389},"malaria","Malaria","It is the collections of articles regarding malarial disease. ",{"slug":521,"name":522,"description":523,"image":42,"body":42,"postCount":389},"anaerobic-culture-techniques","Anaerobic Culture Techniques","Posts related with Anaerobic Culture Techniques.",{"slug":525,"name":526,"description":527,"image":42,"body":42,"postCount":493},"immunoassays","Immunoassays","You will get information about all the diagnostic tests that rely on the specific binding between an antigen and an antibody to detect or quantify a substance.",{"slug":529,"name":530,"description":531,"image":42,"body":42,"postCount":467},"biosafety-levels","Biosafety levels ","Articles related to Biosafety Levels",{"slug":533,"name":534,"description":535,"image":42,"body":42,"postCount":445},"environmental-factors","Environmental Factors ","In this case we are talking about growth requirements of microorganisms with deep dive in environmental factors that affect the growth. ",{"slug":537,"name":538,"description":539,"image":42,"body":42,"postCount":389},"pipette","Pipette","Posts related with Pipette. ",{"slug":541,"name":542,"description":543,"image":42,"body":42,"postCount":467},"bacteriology-mcqs","Bacteriology MCQs","This sections lists MCQs in Bacteriology.",{"slug":545,"name":546,"description":547,"image":42,"body":42,"postCount":548},"parasitology-mcqs","Parasitology MCQs","This section lists MCQs in Parasitology.",2,{"slug":550,"name":551,"description":552,"image":42,"body":42,"postCount":553},"virology-mcqs","Virology MCQs","This is the collections of Multiple Choice Questions in Virology.",4,{"slug":555,"name":556,"description":557,"image":42,"body":42,"postCount":558},"mcqs-in-microbiology","MCQs in Microbiology","This section lists the collections of Multiple Choice Questions in General Microbiology Topics. ",3,{"slug":560,"name":561,"description":562,"image":42,"body":42,"postCount":467},"immunology-mcqs","Immunology MCQs","In this section; we are posting collections of Multiple Choice Questions about Immunology. ",{"slug":564,"name":565,"description":566,"image":42,"body":42,"postCount":485},"microbial-curiosities","Microbial Curiosities","In this clusters, we are posting interesting and unique information about Microorganisms. ",{"slug":568,"name":569,"description":570,"image":42,"body":42,"postCount":571},"bacterial-culture-media","Bacterial Culture Media","Posts related to Bacterial Culture Media. ",23,{"slug":573,"name":574,"description":575,"image":42,"body":42,"postCount":389},"fungal-culture-media","Fungal Culture Media","Posts related to Fungal Culture Media.",{"slug":577,"name":578,"description":579,"image":42,"body":42,"postCount":445},"motility-test","Motility Test","This lists the procedure regarding various tests methods for bacterial motility.",{"slug":581,"name":582,"description":583,"image":42,"body":42,"postCount":485},"bacterial-enumeration","Bacterial enumeration","These posts are related to isolation and enumeration of bacteria. ",{"slug":585,"name":586,"description":587,"image":42,"body":42,"postCount":548},"gram-positive-coccobacillus","Gram-positive coccobacillus","List of Gram Positive Coccobacilli",{"slug":589,"name":590,"description":591,"image":42,"body":42,"postCount":389},"dimorphic-fungi","Dimorphic Fungi","This is about various dimorphic fungi. ",{"slug":593,"name":594,"description":595,"image":42,"body":42,"postCount":467},"bacterial-classification","Bacterial Classification","These posts are related with various approaches used for the classification of Bacteria. ",{"slug":597,"name":598,"description":599,"image":42,"body":42,"postCount":445},"immunofluorescence","Immunofluorescence ","Various Tests related to Immunofluorescence ",{"slug":601,"name":602,"description":603,"image":42,"body":42,"postCount":395},"antibody-mediated-immunity","Antibody-mediated Immunity","This clusters links the articles that are sharing insights about Antibody-mediated immunity. ",{"slug":605,"name":606,"description":607,"image":42,"body":42,"postCount":467},"hypersensitivity","Hypersensitivity","Articles related to Hypersensitivity.",{"slug":609,"name":610,"description":42,"image":42,"body":42,"postCount":558},"haemophilus","Haemophilus",{"slug":313,"name":612,"description":613,"image":42,"body":42,"postCount":467},"Sexually transmitted infections (STIs)","This is the clusters of infections that are transmitted sexually. ",{"slug":615,"name":616,"description":617,"image":42,"body":42,"postCount":618},"adaptive-immunity","Adaptive Immunity","Blog posts related to B Cell Immunity and T Cell Immunity.",13,{"slug":620,"name":621,"description":622,"image":42,"body":42,"postCount":430},"fungal-diagnostics","Fungal Diagnostics","Various methods used for the Diagnosis of Fungal Infections. ",{"slug":624,"name":625,"description":626,"image":42,"body":42,"postCount":445},"laboratory-storage-and-preservation","Laboratory Storage and Preservation","Articles about Laboratory Storage of Antimicrobial Disk, Test organisms and Equipment used for this process. ",{"slug":628,"name":629,"description":630,"image":42,"body":631,"postCount":389},"laboratory-heating-equipment","Laboratory Heating Equipment","A guide to laboratory heating equipment, including hot plates, water baths, Bunsen burners, incubators, and dry baths, and how to choose the right one for each task.","Laboratory heating equipment covers the instruments that warm, melt, incubate, or sterilize samples and media in a microbiology laboratory. Each one delivers heat differently. \n\nA hot plate gives high, direct, dry heat; a water bath gives gentle, even, wet heat up to about 100°C; a Bunsen burner gives an open flame for rapid, very high heat; an incubator holds cultures at a steady temperature over hours or days; and a dry bath heats small tubes without water. Choosing the right one depends on the temperature you need, how precise it must be, and whether the sample can tolerate direct or open-flame heat.\n\nThe articles below cover each piece of heating equipment in detail, including its parts, working principle, uses, and the mistakes that most often go wrong at the bench.",{"slug":633,"name":634,"description":635,"image":42,"body":42,"postCount":395},"laboratory-glassware","Laboratory Glassware","Posts about Laboratory Glassware. ",{"slug":637,"name":638,"description":639,"image":42,"body":42,"postCount":395},"helminths","Helminths","In this section, we are covering properties, life cycle, pathogenesis and laboratory diagnosis of Helminths\u002FHelminthic infestations. ",{"slug":641,"name":642,"description":643,"image":42,"body":42,"postCount":389},"protozoan-parasite","Protozoan Parasite","In this cluster, we are covering protozoan parasites. ",{"slug":645,"name":646,"description":647,"image":42,"body":42,"postCount":400},"tests-for-gram-positive-cocci","Biochemical Tests for Gram Positive Cocci","This is the lists of Biochemical Tests that are used for Gram Positive Cocci. ",{"slug":65,"name":649,"description":650,"image":42,"body":42,"postCount":651},"Bacterial Staining Technique","Lists of various staining techniques that are used to stain bacteria. ",11,{"slug":653,"name":654,"description":655,"image":42,"body":42,"postCount":493},"enzyme-tests","Enzyme Tests","\u003Cp>Various Biochemical Test that are based on enzymatic activity of the microorganisms. \u003C\u002Fp>",{"slug":657,"name":658,"description":659,"image":42,"body":42,"postCount":651},"carbohydrate-utilization","Carbohydrate Utilization","\u003Cp>Various biochemical tests which are related to Carbohydrate fermentation or Utilization\u003C\u002Fp>",{"slug":661,"name":662,"description":663,"image":42,"body":42,"postCount":445},"susceptibility-based-id","Susceptibility-based ID","\u003Cp>These are susceptibility based identification test such as optochin sensitivity, bacitracin sensitivity etc. \u003C\u002Fp>",{"slug":665,"name":666,"description":667,"image":42,"body":42,"postCount":553},"microbial-metabolism","Microbial Metabolism","\u003Cp>Tests about Microbial Metabolism. \u003C\u002Fp>",{"slug":669,"name":670,"description":671,"image":42,"body":42,"postCount":450},"substrate-utilization","Substrate Utilization","\u003Cp>The test in which a non-sugar carbon\u002Fnitrogen source is used or degraded (citrate, malonate, decarboxylases, indole, PAD).\u003C\u002Fp>",{"slug":673,"name":674,"description":675,"image":42,"body":42,"postCount":558},"atypical-pneumonia","Atypical Pneumonia","\u003Cp>Organisms responsible for Atypical Pneumonia. \u003C\u002Fp>",{"slug":677,"name":678,"description":679,"image":42,"body":42,"postCount":445},"antigen","Antigen","\u003Cp>Various articles related to Antigens.\u003C\u002Fp>",{"slug":681,"name":682,"description":683,"image":42,"body":42,"postCount":467},"innate-immunity","Innate Immunity","\u003Cp>Articles related to Innate Immunity. \u003C\u002Fp>",{"slug":685,"name":686,"description":687,"image":42,"body":42,"postCount":553},"respiratory-tract-infection","Respiratory Tract Infection","\u003Cp>In this cluster, you can see various etiological agents that causes respiratory tract infection. \u003C\u002Fp>",{"slug":689,"name":690,"description":691,"image":42,"body":42,"postCount":445},"torch-infection","TORCH Infection","\u003Cp>In this section; you can find articles related with TOCH infection. \u003C\u002Fp>",{"slug":693,"name":694,"description":695,"image":42,"body":42,"postCount":450},"microbiology-for-beginners","Microbiology for Beginners","\u003Cp>These articles are very basic articles, which will share general concepts in Microbiology. \u003C\u002Fp>",{"slug":697,"name":698,"description":699,"image":42,"body":42,"postCount":389},"dna-replication","DNA Replication","\u003Cp>Articles related to DNA and Replication of DNA. \u003C\u002Fp>",{"slug":701,"name":702,"description":703,"image":42,"body":42,"postCount":389},"genetic-code","Genetic Code","\u003Cp>Articles related to Genetic Code.\u003C\u002Fp>",{"slug":705,"name":706,"description":707,"image":42,"body":42,"postCount":450},"molecular-technique","Molecular Technique","\u003Cp>Posts related to Molecular Techniques. \u003C\u002Fp>",{"slug":709,"name":710,"description":42,"image":42,"body":42,"postCount":400},"colorimetric-assay","Colorimetric Assay ",{"slug":712,"name":713,"description":714,"image":42,"body":42,"postCount":445},"pharmaceutical-microbiology","Pharmaceutical Microbiology","\u003Cp>Various articles related to Pharmaceutical Microbiology\u003C\u002Fp>",{"slug":716,"name":717,"description":42,"image":42,"body":42,"postCount":558},"blood-and-immune-cells","Blood and Immune Cells",{"slug":719,"name":720,"description":42,"image":42,"body":42,"postCount":445},"host-pathogen-interaction","Host Pathogen Interaction",{"slug":722,"name":723,"description":42,"image":42,"body":42,"postCount":553},"blood-culture","Blood Culture",{"slug":725,"name":726,"description":42,"image":42,"body":42,"postCount":445},"environmental-microbiology","Environmental microbiology ",{"slug":728,"name":729,"description":42,"image":42,"body":42,"postCount":467},"copromicroscopic-technique","Copromicroscopic Technique",{"slug":731,"name":732,"description":42,"image":42,"body":42,"postCount":558},"quality-control","Quality Control",{"slug":734,"name":735,"description":42,"image":42,"body":42,"postCount":467},"dermatophytes","Dermatophytes",{"slug":737,"name":738,"description":42,"image":42,"body":42,"postCount":558},"viral-hemorrhagic-fevers","Viral Hemorrhagic Fevers",{"slug":740,"name":741,"description":42,"image":42,"body":42,"postCount":553},"h2s-production","H2S Production",{"slug":743,"name":744,"description":42,"image":42,"body":42,"postCount":548},"water-quality-testing","Water Quality Testing",{"slug":746,"name":747,"description":42,"image":42,"body":42,"postCount":445},"virology-basics","Virology basics",{"slug":749,"name":750,"description":42,"image":42,"body":42,"postCount":553},"typing-methods","Typing Methods",{"slug":752,"name":753,"description":42,"image":42,"body":42,"postCount":558},"blotting-technique","Blotting Technique",{"slug":755,"name":756,"description":42,"image":42,"body":42,"postCount":389},"history-microbiology","History of Microbiology",{"slug":758,"name":759,"description":42,"image":42,"body":42,"postCount":389},"trematodes","Trematodes",{"slug":761,"name":762,"description":42,"image":42,"body":42,"postCount":553},"coccidian-parasites","Coccidian Parasites",{"slug":764,"name":765,"description":766,"image":42,"body":42,"postCount":430},"cell-structure","Cell Structure","\u003Cp>Articles related to Cell Structure. \u003C\u002Fp>",{"slug":768,"name":769,"description":42,"image":42,"body":42,"postCount":548},"automation-in-microbiology","Automation in Microbiology",{"slug":771,"name":772,"description":42,"image":42,"body":42,"postCount":389},"laboratory-management","Laboratory Management",{"slug":774,"name":775,"description":42,"image":42,"body":42,"postCount":445},"viral-skin-infections","Viral Skin Infections",{"slug":777,"name":778,"description":42,"image":42,"body":42,"postCount":467},"syphilis-diagnosis","Syphilis Diagnosis"]