[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"$fxLN3MUwXCdr5RPjwZYIDpOj8CHyjOmngWTgoKXPtZbg":3,"$fu_ORq2o8jFkCw_7HZhoIdhnfn2RfL5RR3JQXAdMhmj8":36,"$f3Ft0rKFJHppdzE-vuveecxx1BUcg9iOlMLtyzf_MJDg":244,"$fucxFBm2ZjZfGSdmdRaSNGBI_F0jJme4f0GTvzUhQfL8":308},[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},"Abbreviations","abbreviations","\u002Fabbreviations\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},"Utilization Tests for Bacterial Identification","utilization-tests","\u002Futilization-tests\u002F",{"type":37,"data":38},"blog",{"slug":39,"title":40,"description":41,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":44,"lastUpdatedDate":45,"draft":46,"category":47,"image":42,"body":48,"faq":49,"commentsClosed":46,"tags":71,"related":73,"comments":240},"key-points-for-the-laboratory-diagnosis-of-central-nervous-system-infections","CSF Sample: Collection, Processing, Staining, and Culture","\u003Cp>How to collect CSF safely, which tube goes to which lab and why microbiology never gets the first tube, why CSF must never be refrigerated, when to use Trans-Isolate medium, and how the CSF picture separates bacterial from viral and TB meningitis.\u003C\u002Fp>",null,"Acharya Tankeshwar","2013-08-08","2026-08-12",false,"bacteriology","CSF from a suspected meningitis patient is a true emergency specimen. Two facts govern everything that follows. The organisms that cause acute bacterial meningitis (*Neisseria meningitidis*, *Haemophilus influenzae*, *Streptococcus pneumoniae*) are fastidious and fragile, so the sample must never be refrigerated and must be processed within about an hour. And because the first drops of CSF can carry skin and blood from the puncture, the order in which the tubes are filled decides which test can trust its result. Get these two right and the rest is routine.\n\nMeningitis is inflammation of the membranes covering the brain and spinal cord, the meninges. The most common causes of acute meningitis are enteroviruses (mainly echoviruses and coxsackieviruses) and bacteria (*Streptococcus pneumoniae*, *Neisseria meningitidis*, *Haemophilus influenzae*). Organisms that cause chronic meningitis (symptoms lasting 4 weeks or more) include *Mycobacterium tuberculosis*, fungi, and spirochetes.\n\nViral meningitis usually resolves without treatment, but bacterial meningitis is a medical emergency and a major cause of death and disability worldwide. The likely pathogen depends on the patient's age and on other factors such as immune status, recent neurosurgery, and trauma.\n\n## Common causes of meningitis by age\n\n| Age group | Common bacterial causes |\n| --- | --- |\n| Newborns | Group B *Streptococcus* (*Streptococcus agalactiae*), *Escherichia coli*, *Listeria monocytogenes* |\n| Infants and children | *Streptococcus pneumoniae*, *Neisseria meningitidis*, *Haemophilus influenzae* type b (Hib), Group B *Streptococcus* |\n| Adolescents and young adults | *Neisseria meningitidis*, *Streptococcus pneumoniae* |\n| Older adults | *Streptococcus pneumoniae*, *Neisseria meningitidis*, *Listeria monocytogenes*, Hib, Group B *Streptococcus* |\n\n## CSF Collection\n\nCSF is obtained aseptically by lumbar puncture, usually at the L3 to L4 or L4 to L5 interspace, from the subarachnoid space. Collect a minimum of 1 mL, ideally 3 to 4 mL, and up to 5 to 10 mL when multiple studies are requested (AFB and fungal cultures in particular need larger volumes). Collect before starting antimicrobial therapy whenever possible.\n\n![CSF Collection by Lumbar Puncture - Collection of cerebrospinal fluid (CSF) by lumbar puncture](\u002Fblogs\u002FCSF-Collection.gif)Figure: Collection of cerebrospinal fluid (CSF) by lumbar puncture\n\nCSF is collected into several sterile tubes, filled in order. The guiding principle is that the first tube may contain skin fragments and blood introduced by the needle, so the first tube is never the one sent for culture. A common allocation is:\n\n- **Tube 1: chemistry (total protein, glucose).** Any puncture blood here does not affect these results.\n- **Tube 2: microbiology (Gram stain and culture).** Send at least 0.5 to 1 mL. Because it is not the first tube, it is the least contaminated by the puncture.\n- **Tube 3: hematology (cell count and differential).** Comparing the red cell count in the first and last tubes helps tell a traumatic tap from a true bleed.\n- **Tube 4 (if collected)**: additional microbiology or special studies (AFB culture, fungal culture, cryptococcal antigen, viral PCR, VDRL, cytology), depending on the clinical question.\n\nIf only one tube can be obtained, it goes to microbiology, because a culture cannot be repeated without another lumbar puncture, whereas chemistry and cell count can often be run on very small volumes.\n\n**A few more points at collection:**\n\n- If the volume is smaller than the requests need, tell the laboratory so testing can be prioritized. The default priority on a tiny sample is microbiology.\n- Collect two to four blood cultures as well if bacterial meningitis is suspected.\n- Warn the microbiology laboratory if unusual organisms are possible (such as *Nocardia*, fungi, or mycobacteria), so the special methods they need can be set up.\n- Do not refrigerate CSF.\n\n### Collection and transport at a glance\n\n| Question | Answer |\n| --- | --- |\n| How much? | Minimum 1 mL; ideally 3 to 4 mL; 5 to 10 mL if AFB, fungal, or multiple studies |\n| Which tube to microbiology? | Never the first tube; tube 2 (or a later tube) for culture |\n| If only one tube? | Send it to microbiology |\n| Container | Sterile, leak-proof, screw-cap; no anticoagulant, no preservative |\n| Transport time | Process within 1 hour |\n| If delay is unavoidable | Hold at 35°C (body temperature) or room temperature, or inoculate Trans-Isolate medium |\n| Refrigerate? | No. Never. Cold kills the fastidious meningitis pathogens |\n| Also collect | Two to four blood cultures if bacterial meningitis is suspected |\n| Warn the lab if | Unusual organisms possible (*Nocardia*, fungi, mycobacteria) |\n\nThe one rule that outranks the rest: do not refrigerate CSF. Every other specimen in this cluster has a \"refrigerate if delayed\" option. CSF is the exception, because [*Neisseria meningitidis*](https:\u002F\u002Fmicrobeonline.com\u002Fneisseria-meningitidis-properties-pathogenesis-and-laboratory-diagnosis\u002F), [*Haemophilus influenzae*](https:\u002F\u002Fmicrobeonline.com\u002Flaboratory-diagnosis-of-haemophilus-influenza\u002F), and [*Streptococcus pneumoniae*](https:\u002F\u002Fmicrobeonline.com\u002Fstreptococcus-pneumoniae-pneumococcus-disease-properties-pathogenesis-and-laboratory-diagnosis\u002F) die at low temperature. Keep it warm, and if it cannot be processed within an hour, use Trans-Isolate transport medium.\n\n> **When CSF is collected into five tubes (advanced variant):** Tube 1 to biochemistry (total protein, glucose, immunoglobulin index, oligoclonal banding); Tube 2 to microbiology (bacterial, viral, and fungal culture, cryptococcal antigen); Tube 3 to microbiology (AFB culture and special stain); Tube 4 to hematology (cell count, flow cytometry, cytology); Tube 5 for special pathogens (*Acanthamoeba*, West Nile virus, viral PCR, anaerobic culture, and the 14-3-3 protein for Creutzfeldt-Jakob disease). The principle is unchanged: the first tube, which may carry puncture blood, is not the one sent for culture.\n\n### CSF volume and production\n\n| Measure | Value |\n| --- | --- |\n| Total CSF, adult | 85 to 125 mL |\n| Total CSF, neonate | 10 to 60 mL |\n| Production rate, adult | About 20 mL per hour (roughly 500 mL per day) |\n\n## Processing of CSF Sample\n\nCSF must never be refrigerated before culture, because the fastidious organisms may not survive lowered temperatures. If culture cannot be set up at once, hold the CSF at 35°C to keep it near body temperature, or leave it at room temperature.\n\nCSF from a suspected meningitis patient is an emergency specimen that needs immediate processing. The common bacterial causes, *Neisseria meningitidis*, *Streptococcus pneumoniae*, and *Haemophilus influenzae*, are fastidious and fragile. To recover them, culture the CSF within one hour of collection, or inoculate it into Trans-Isolate (T-I) medium for transport if processing within an hour is not possible.\n\n**A delay in examining CSF:**\n\n- Reduces the chance of isolating the pathogen\n- Lowers the cell count as white cells lyse\n- Falsely lowers the glucose through ongoing glycolysis\n\n## Laboratory Tests\n\nBiochemical testing\n\n### CSF findings by type of meningitis\n\n| Finding | Normal | Viral | Acute bacterial | TB or fungal |\n| --- | --- | --- | --- | --- |\n| Leukocytes\u002Fmm³ | 0 to 5 | 2 to 2000 (mean \\~80) | 5 to 20,000 (mean \\~800) | 5 to 2000 (mean \\~100) |\n| Predominant cell | None | Mononuclear | Neutrophils (PMN) | Mononuclear |\n| Protein | 15 to 50 mg\u002FdL | Slightly raised (50 to 100) or normal | Raised (>100 mg\u002FdL) | Raised (>50 mg\u002FdL) |\n| Glucose | 45 to 100 mg\u002FdL | Normal | Low (<45 mg\u002FdL), may be normal early | Low (<45 mg\u002FdL) |\n\nThe key discriminator: bacterial meningitis gives many neutrophils, high protein, and low glucose; viral gives mononuclear cells with normal glucose; TB and fungal give mononuclear cells with low glucose. The CSF-to-serum glucose ratio (normally about 0.6) falls in bacterial, TB, and fungal meningitis, because the organisms and inflammatory cells consume glucose.\n\n### Microscopy and staining\n\nThe number of organisms in CSF can be as low as 10³ CFU\u002FmL, so CSF [Gram stains](https:\u002F\u002Fmicrobeonline.com\u002Fgram-staining-principle-procedure-results\u002F) should be prepared after cytocentrifugation, which concentrates cells and bacteria onto the slide. Report a positive Gram stain to the clinician immediately, usually within one hour of receipt.\n\n![Gram stain of N. meningitidis in CSF with associated PMNs - Gram stain of N. meningitidis in CSF with associated PMNs](\u002Fblogs\u002FGram-stain-of-N.-meningitidis-in-CSF-with-associated-PMNs.jpg)Figure: *Neisseria meningitidis* appearing as Gram negative diplococci in CSF Gram stain\n\n- ***Neisseria meningitidis*** appears as gram-negative, coffee-bean-shaped diplococci, inside or outside the PMN leukocytes.\n- ***Streptococcus pneumoniae*** appears as gram-positive, lanceolate diplococci, sometimes in short chains, inside or outside cells.\n- ***Haemophilus influenzae*** appears as small, pleomorphic gram-negative rods or coccobacilli with a random arrangement.\n\n![Streptococcus pneumoniae in Gram Stain - Streptococcus pnuemoniae: Gram positive diplococci](\u002Fblogs\u002FStreptococcus-pneumoniae.png)Figure: *Streptococcus pneumoniae* appearing as Gram positive diplococci in CSF Gram stain\n\nIf cryptococcal meningitis is suspected, the cryptococcal antigen test (lateral flow assay or latex agglutination) is the preferred and more sensitive method. [India ink preparation](\u002Fcapsule-stain-principle-procedure-results\u002F) can show the encapsulated yeast but misses many cases, so a negative India ink does not exclude cryptococcal meningitis.\n\n### Culture and sensitivity\n\nCSF is collected aseptically by lumbar puncture from a normally sterile site, so any organism recovered is a potential pathogen. Concentration before culture is unnecessary, because the plate inoculum is enough to detect the usually low numbers of organisms.\n\n| Chocolate agar | Blood agar | Gram stain | Presumptive ID |\n| --- | --- | --- | --- |\n| Growth | Growth | Gram-negative diplococci | *Neisseria meningitidis* |\n| Growth | Growth (alpha-hemolysis) | Gram-positive lanceolate diplococci | *Streptococcus pneumoniae* |\n| Growth | No growth (needs X and V factors) | Gram-negative pleomorphic coccobacilli | *Haemophilus influenzae* |\n\nBacterial meningitis is mostly caused by aerobes, though anaerobes may appear in CSF when there is a meningeal abscess or an adjacent focus. The media routinely used are:\n\n[**Chocolate agar**](https:\u002F\u002Fmicrobeonline.com\u002Fchocolate-agar-composition-uses-colony-characteristics\u002F)**:** *Haemophilus influenzae* forms large, colorless to grey, opaque colonies with no discoloration of the surrounding medium.\n\n[**Blood agar**](https:\u002F\u002Fmicrobeonline.com\u002Fblood-agar-composition-preparation-uses-and-types-of-hemolysis\u002F)**:** *Neisseria meningitidis* forms round, moist, glistening, convex colonies overnight. *Streptococcus pneumoniae* forms small greyish, mucoid colonies with a greenish zone of alpha-hemolysis.\n\n![Neisseria meningitidis in Blood Agar Plate - N. meningitidis on blood agar plate](\u002Fblogs\u002FN.-meningitidis-on-blood-agar-plate.gif)Figure: *N. meningitidis* on blood agar plate\n\n[**MacConkey agar**](https:\u002F\u002Fmicrobeonline.com\u002Fmacconkey-agar-mac-composition-preparation-uses-and-colony-characteristics\u002F)**:** Most meningitis pathogens do not grow on MacConkey. It is used to detect or identify gram-negative bacilli, which matter in neonatal and post-neurosurgical meningitis (for example *Escherichia coli* or *Klebsiella*).\n\n**Antigen and antibody tests**\n\n**Antigen testing:** The cryptococcal antigen test (latex agglutination or lateral flow) is preferred when cryptococcal meningitis is suspected. Bacterial antigen testing on CSF is not recommended, because it adds little to a good Gram stain and culture.\n\n**Serology:** Serologic diagnosis rests on a CSF-to-serum antibody index, a 4-fold rise in IgG between acute and convalescent samples, or a single positive IgM. Collect acute serum 3 to 10 days after onset and convalescent serum 2 to 3 weeks later.\n\n### Molecular diagnosis\n\nNucleic acid amplification tests (NAAT) are available for most pathogens in well-resourced settings but may not be available in resource-poor ones. Molecular testing has replaced viral culture for diagnosing enteroviral meningitis.\n\n## How to Remember\n\n**CSF breaks the cluster's refrigeration rule.** Every other specimen says \"refrigerate if delayed.\" CSF says never. The meningitis trio (*Neisseria meningitidis*, *Streptococcus pneumoniae*, *Haemophilus influenzae*) is fragile and dies cold. Keep CSF warm, and use Trans-Isolate if it must travel.\n\n**Microbiology never gets the first tube.** The first drops carry skin and puncture blood. Chemistry can tolerate that, culture cannot. First tube to chemistry, second to microbiology. If you get only one tube, culture wins, because you cannot repeat a lumbar puncture on demand.\n\n**Bacterial meningitis: high cells, high protein, low sugar.** Neutrophils flood in (high cells), the inflamed barrier leaks protein through (high protein), and bacteria plus cells eat the glucose (low sugar). Viral keeps the sugar normal. TB and fungal look like viral on cells but drop the sugar like bacterial.\n\n**Low glucose means something is eating it.** Bacteria, TB, and fungi consume glucose; viruses mostly do not. A low CSF sugar points away from a simple viral cause.\n\n**The three morphologies:** *Neisseria meningitidis* is a gram-negative coffee-bean diplococcus, *Streptococcus pneumoniae* a gram-positive lance-shaped diplococcus, *Haemophilus influenzae* a tiny gram-negative coccobacillus. Shape plus Gram color names the organism on the smear.\n\n## Key exam facts in one table\n\n| Point | Fact |\n| --- | --- |\n| Collection method | Lumbar puncture, L3 to L4 or L4 to L5, aseptic |\n| Volume | Min 1 mL; ideally 3 to 4 mL; 5 to 10 mL for AFB, fungal, multiple studies |\n| First tube | Never to microbiology (puncture blood or skin) |\n| Micro tube | Tube 2 (or later); at least 0.5 to 1 mL |\n| One tube only | Send to microbiology |\n| Transport time | Within 1 hour |\n| Storage | 35°C or room temperature; NEVER refrigerate |\n| If delayed | Trans-Isolate transport medium |\n| Also collect | 2 to 4 blood cultures if bacterial meningitis suspected |\n| Smear prep | Cytocentrifuge (organisms may be as few as 10³ CFU\u002FmL) |\n| Report Gram stain | Immediately, within about 1 hour |\n| Bacterial CSF | Neutrophils high, protein high, glucose low |\n| Viral CSF | Mononuclear, glucose normal |\n| TB\u002Ffungal CSF | Mononuclear, glucose low |\n| CSF:serum glucose | Normal \\~0.6; falls in bacterial, TB, fungal |\n| Cryptococcus | Cryptococcal antigen preferred over India ink |\n| Bacterial antigen testing | Not recommended on CSF |\n| Newborn causes | Group B *Streptococcus*, *Escherichia coli*, *Listeria monocytogenes* |\n\n## Where Students Get Confused\n\n**\"Why can't CSF be refrigerated when almost everything else can?\"** The common bacterial causes of meningitis are fastidious and cold-sensitive. Refrigeration kills *Neisseria meningitidis*, *Streptococcus pneumoniae*, and *Haemophilus influenzae*, lowering the chance of growing them. Hold CSF at body or room temperature and process it fast.\n\n**\"Which tube should go to the microbiology lab?\"** Not the first one. The first drops can carry skin and blood from the needle, which contaminates a culture. Send the second tube to microbiology. Only when a single tube is available does the first tube go to micro, and then culture is the priority.\n\n**\"If only a tiny volume is obtained, which test comes first?\"** Microbiology. A culture cannot be repeated without another lumbar puncture, and it identifies the organism and guides treatment. Cell count and chemistry can often run on very small volumes.\n\n**\"Bacterial and TB meningitis both have low glucose, so how do I tell them apart?\"** By the cells. Bacterial meningitis is dominated by neutrophils; TB and fungal meningitis are mononuclear. Both drop the glucose, but the cell type separates them.\n\n**\"Is India ink enough to rule out cryptococcal meningitis?\"** 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 exclude the diagnosis.\n\n**\"Why prepare the Gram stain by cytocentrifugation?\"** Because CSF can contain very few organisms (as low as 10³ CFU\u002FmL). Cytocentrifugation concentrates the cells and bacteria onto the slide, which greatly raises the chance of seeing them.\n\n### Reference and further reading\n\n1. World Health Organization. *Laboratory Methods for the Diagnosis of Meningitis.* 2nd ed. Geneva: WHO.\n2. Tille PM. *Bailey & Scott's Diagnostic Microbiology.* 15th ed. St. Louis: Elsevier; 2022.\n3. Leber AL, editor. *Clinical Microbiology Procedures Handbook.* 4th ed. Washington, DC: ASM Press; 2016. DOI: 10.1128\u002F9781683670438.CMPH\n4. Centers for Disease Control and Prevention. Meningitis. \u003Chttps:\u002F\u002Fwww.cdc.gov\u002Fmeningitis\u002F>",[50,53,56,59,62,65,68],{"question":51,"answer":52},"\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. Hold CSF at 35°C or room temperature, and use Trans-Isolate medium if processing will be delayed beyond an hour.\u003C\u002Fp>",{"question":54,"answer":55},"\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":57,"answer":58},"\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":60,"answer":61},"\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":63,"answer":64},"\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":66,"answer":67},"\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":69,"answer":70},"\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>",[72],"specimen-collection-transport",[74,84,108,131,151,164,174,207],{"slug":75,"title":76,"description":77,"seoTitle":42,"seoDescription":42,"author":78,"createdDate":79,"lastUpdatedDate":80,"draft":46,"category":47,"image":42,"faq":81,"tags":82},"neisseria-meningitidis-properties-pathogenesis-and-laboratory-diagnosis"," Neisseria meningitidis: Properties, Pathogenesis, Virulence Factors, and Lab Diagnosis","Neisseria meningitidis causes life-threatening bacterial meningitis and meningococcaemia. Learn its serogroups (A, B, C, W, X, Y), virulence factors (capsule, LOS, fimbriae, IgA protease), clinical features including petechial rash, lab diagnosis (CSF Gram stain, culture, PCR), and vaccines.","Nisha Rijal","2020-07-12","2026-08-02",[],[83],"gram-negative-cocci",{"slug":85,"title":86,"description":87,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":88,"lastUpdatedDate":89,"draft":46,"category":47,"image":42,"faq":90,"tags":106},"laboratory-diagnosis-of-haemophilus-influenza","Haemophilus influenzae: Properties, Virulence Factors, Diseases, and Lab Diagnosis","Haemophilus influenzae lab diagnosis: Hib vs NTHi, virulence factors, chocolate agar culture, X and V factor identification, serotyping, treatment, and beta-lactamase\u002FBLNAR resistance","2013-07-30","2026-08-03",[91,94,97,100,103],{"question":92,"answer":93},"Why is chocolate agar used instead of blood agar for Haemophilus influenzae?","H. influenzae needs both hemin (X) and NAD (V). On plain blood agar, hemin stays locked in intact red cells and NAD is degraded by red-cell enzymes. Gentle heating to make chocolate agar lyses the cells (freeing hemin) and inactivates those enzymes (sparing NAD), so both factors become available.",{"question":95,"answer":96},"What is the difference between Hib and nontypeable H. influenzae?","Hib is encapsulated (type b PRP capsule), causes invasive disease such as meningitis and epiglottitis, and is prevented by the Hib conjugate vaccine. Nontypeable strains have no capsule, cause mostly mucosal infections (otitis media, sinusitis, COPD exacerbations), and are not covered by the vaccine.",{"question":98,"answer":99},"Why must specimens for H. influenzae never be refrigerated?","The organism is extremely cold-sensitive and dies at refrigeration temperatures before it can be cultured. CSF and blood cultures must be transported and processed at room temperature or 37°C.",{"question":101,"answer":102},"What is a BLNAR strain and why does it matter?","BLNAR stands for beta-lactamase-negative, ampicillin-resistant. These strains resist ampicillin through altered penicillin-binding proteins rather than beta-lactamase, so the nitrocefin test is negative but ampicillin still fails. They require alternative therapy and are an emerging concern in parts of Asia.",{"question":104,"answer":105},"Does the Hib vaccine protect against all Haemophilus influenzae infections?","No. It protects only against type b. Nontypeable strains and non-b serotypes are not covered, which is why H. influenzae mucosal infections still occur in vaccinated people.",[107],"haemophilus",{"slug":109,"title":110,"description":111,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":112,"lastUpdatedDate":80,"draft":46,"category":47,"image":42,"faq":113,"tags":129},"streptococcus-pneumoniae-pneumococcus-disease-properties-pathogenesis-and-laboratory-diagnosis","Streptococcus pneumoniae: Properties, Pathogenesis, and Diagnosis","Streptococcus pneumoniae morphology, virulence factors like pneumolysin and capsule, and the optochin and bile solubility tests used for lab diagnosis.","2013-05-13",[114,117,120,123,126],{"question":115,"answer":116},"\u003Cp>Why is \u003Cem>Streptococcus pneumoniae\u003C\u002Fem> alpha-hemolytic like viridans streptococci, yet far more dangerous?\u003C\u002Fp>","\u003Cp>Hemolysis pattern alone doesn't reflect virulence. \u003Cem>S. pneumoniae\u003C\u002Fem>'s danger comes from its polysaccharide capsule (the major anti-phagocytic virulence factor) and pneumolysin, a pore-forming toxin that damages nearly any host cell containing cholesterol. Viridans streptococci lack a capsule and are far less invasive as a result.\u003C\u002Fp>",{"question":118,"answer":119},"What is the difference between bile solubility and bile esculin tests?","\u003Cp>Bile solubility uses bile salts to lyse \u003Cem>S. pneumoniae\u003C\u002Fem> colonies by triggering the organism's own autolysin, confirming pneumococcus. Bile esculin tests whether an organism can hydrolyze esculin in the presence of bile, used to identify \u003Cem>Enterococcus \u003C\u002Fem>and Group D streptococci. Same word \"bile,\" completely different organisms and mechanisms.\u003C\u002Fp>",{"question":121,"answer":122},"Why does the pneumococcal vaccine need to cover so many different serotypes?","\u003Cp>\u003Cem>S. pneumoniae \u003C\u002Fem>has more than 90 distinct capsular serotypes, and immunity to the capsule is type-specific. Antibodies raised against one serotype's capsule don't protect against a different serotype, so vaccines must include multiple capsular polysaccharides to provide broad coverage.\u003C\u002Fp>",{"question":124,"answer":125},"\u003Cp>Can\u003Cem> Streptococcus pneumoniae\u003C\u002Fem> be part of normal flora without causing disease?\u003C\u002Fp>","\u003Cp>Yes. \u003Cem>S. pneumoniae\u003C\u002Fem> commonly colonizes the upper respiratory tract harmlessly. Disease occurs when the organism spreads beyond its normal niche, such as into the lungs, bloodstream, or meninges.\u003C\u002Fp>",{"question":127,"answer":128},"Why does CSF show low glucose in pneumococcal meningitis?","Bacteria in the CSF consume glucose for their own metabolism, while the accompanying inflammatory response draws in white blood cells, producing the classic combination of high WBC and low glucose seen in bacterial meningitis.",[130],"gram-positive-cocci",{"slug":132,"title":133,"description":134,"seoTitle":135,"seoDescription":136,"author":43,"createdDate":137,"lastUpdatedDate":80,"draft":46,"category":138,"image":42,"faq":139,"tags":149},"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","staining-techniques",[140,143,146],{"question":141,"answer":142},"What does it mean if neutrophil nuclei appear blue instead of red on a Gram stain?","Neutrophil nuclei staining blue\u002Fpurple instead of red\u002Fpink indicates under-decolourisation — the decolorising agent (alcohol or acetone-alcohol) was not applied for long enough, or was too dilute. 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 decolourisation technique: drop-by-drop application until the effluent runs clear, approximately 10-15 seconds.",{"question":144,"answer":145},"What is the clinical significance of gram-negative intracellular diplococci in a urethral smear?","Gram-negative intracellular diplococci (GNID) in a urethral or cervical smear is presumptive evidence of Neisseria gonorrhoeae infection and is sufficient justification to start treatment immediately, before culture confirmation. 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 Neisseria meningitidis meningitis, a medical emergency requiring immediate ceftriaxone.",{"question":147,"answer":148},"Why do gram-positive bacteria sometimes stain gram-negative?","Gram-positive bacteria can appear gram-negative due to: over-decolourisation (most common — decoloriser 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.",[150],"bacterial-staining-technique",{"slug":152,"title":153,"description":154,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":155,"lastUpdatedDate":80,"draft":46,"category":138,"image":42,"faq":156,"tags":163},"capsule-stain-principle-procedure-results","Capsule Stain: Principle, Procedure, and Results","Capsule staining detects bacterial capsules — a key virulence factor. Learn the India ink and Anthony's methods, clinically important capsulated organisms, and the Quellung reaction for pneumococcal identification.","2016-10-15",[157,160],{"question":158,"answer":159},"Why can bacterial capsules not be stained directly?","Bacterial capsules are composed primarily of polysaccharides (occasionally polypeptides), which are non-ionic — they carry no net electrical charge. Since conventional dyes are either cationic (basic dyes) or anionic (acidic dyes), they have no charged surface to bind to on the capsule. 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.",{"question":161,"answer":162},"\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. India ink is a rapid, inexpensive bedside diagnostic test with approximately 50-80% sensitivity in cryptococcal meningitis — higher in HIV-positive patients who tend to have higher organism burdens. 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>",[150],{"slug":165,"title":166,"description":167,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":168,"lastUpdatedDate":169,"draft":46,"category":170,"image":42,"faq":171,"tags":172},"chocolate-agar-composition-uses-colony-characteristics","Chocolate Agar (CAP): Composition, Preparation, Uses, and Colony Morphology","\u003Cp>Chocolate agar is an enriched medium for isolating fastidious pathogens like \u003Cem>Haemophilus\u003C\u002Fem> and \u003Cem>Neisseria.\u003C\u002Fem> Learn its composition, preparation, CO₂ requirement, colony morphology, and key modifications like Thayer-Martin.\u003C\u002Fp>","2013-09-08","2026-08-14","culture-media",[],[173],"bacterial-culture-media",{"slug":175,"title":176,"description":177,"seoTitle":178,"seoDescription":179,"author":43,"createdDate":180,"lastUpdatedDate":169,"draft":46,"category":170,"image":42,"faq":181,"tags":206},"blood-agar-composition-preparation-uses-and-types-of-hemolysis","Blood Agar: Composition, Preparation, and How to Read Hemolysis","Blood agar composition and preparation, how to tell alpha, beta, gamma, and alpha-prime hemolysis apart, and the double-zone target pattern, with a colony-appearance table for 20+ organisms and common modifications (chocolate, CNA, CVBA).","Blood Agar: Preparation, Hemolysis Patterns, and Identification Clues","Learn blood agar composition and preparation, distinguish alpha, beta, and gamma hemolysis, and use colony patterns to support bacterial identification.","2013-08-22",[182,185,188,191,194,197,200,203],{"question":183,"answer":184},"What is the difference between alpha and beta hemolysis?","\u003Cp>Alpha is partial lysis, green\u002Fbrown discoloration: \u003Cem>S. pneumoniae,\u003C\u002Fem> viridans streptococci. Beta is complete clear lysis: \u003Cem>S. pyogenes, S. agalactiae, S. aureus\u003C\u002Fem>. Gamma is no hemolysis: \u003Cem>Enterococcus, Klebsiella.\u003C\u002Fem>\u003C\u002Fp>",{"question":186,"answer":187},"Why is sheep blood used instead of human blood?","Consistent availability, no biohazard risk, reliable hemolysis patterns. Human blood may contain antibiotics or inhibitors and introduces infection risk.",{"question":189,"answer":190},"\u003Cp>Why does \u003Cem>S. pneumoniae\u003C\u002Fem> produce alpha not beta hemolysis?\u003C\u002Fp>","\u003Cp>The H₂O₂ produced by \u003Cem>S. pneumoniae\u003C\u002Fem> oxidizes hemoglobin to green products (verdohemoglobin), a partial degradation rather than true lysis. \u003Cem>S. pneumoniae\u003C\u002Fem> lacks the streptolysins O and S that produce the complete, clear lysis of beta hemolysis.\u003C\u002Fp>",{"question":192,"answer":193},"What does the size of the beta-hemolytic zone tell you?","\u003Cp>GAS (\u003Cem>S. pyogenes\u003C\u002Fem>): large zone 2-4× colony diameter. GBS (\u003Cem>S. agalactiae\u003C\u002Fem>): narrow zone barely beyond colony edge. Helps preliminary differentiation at 24 hours with CAMP test and bacitracin.\u003C\u002Fp>",{"question":195,"answer":196},"\u003Cp>What is the umbilicated colony appearance of \u003Cem>S. pneumoniae\u003C\u002Fem>?\u003C\u002Fp>","\u003Cp>Autolysin LytA causes central autolysis at 48-72 hours, raised ring with sunken center. Umbilicated appearance + alpha hemolysis = strong presumptive \u003Cem>S. pneumoniae.\u003C\u002Fem>\u003C\u002Fp>",{"question":198,"answer":199},"How does incubation atmosphere affect blood agar hemolysis?","\u003Cp>Streptolysin O is oxygen-labile, best seen in stab areas or anaerobically. Streptolysin S is oxygen-stable, visible aerobically on surface. Always stab blood agar.\u003C\u002Fp>",{"question":201,"answer":202},"\u003Cp>Why does \u003Cem>C. perfringens\u003C\u002Fem> produce double-zone hemolysis?\u003C\u002Fp>","\u003Cp>Theta-toxin: outer partial (alpha) zone. Alpha-toxin\u002Flecithinase: inner complete (beta) zone. Double-zone target pattern on anaerobic blood agar = strong presumptive \u003Cem>C. perfringens.\u003C\u002Fem>\u003C\u002Fp>",{"question":204,"answer":205},"Can blood agar be used for susceptibility testing?","\u003Cp>Yes. MH-F (Mueller-Hinton + 5% sheep blood) is CLSI-recommended for fastidious organisms: \u003Cem>S. pneumoniae, S. pyogenes, H. influenzae, N. gonorrhoeae.\u003C\u002Fem>\u003C\u002Fp>",[173],{"slug":208,"title":209,"description":210,"seoTitle":211,"seoDescription":212,"author":43,"createdDate":213,"lastUpdatedDate":169,"draft":46,"category":170,"image":42,"faq":214,"tags":239},"macconkey-agar-mac-composition-preparation-uses-and-colony-characteristics","MacConkey Agar: Composition, Principle, Preparation, Uses, and Colony Characteristics","\u003Cp>MacConkey agar: composition, principle, uses, and detailed colony morphology of 20+ organisms including \u003Cem>E. coli, Klebsiella, Salmonella, Pseudomonas, Acinetobacter\u003C\u002Fem>, and more. Updated for clinical lab use.\u003C\u002Fp>","MacConkey Agar: Preparation, Colony Results, and Interpretation","Understand how MacConkey agar selects Gram-negative bacteria, differentiates lactose fermentation, and supports interpretation of common colony appearances.","2013-08-14",[215,218,221,224,227,230,233,236],{"question":216,"answer":217},"What is the difference between lactose fermenters and non-lactose fermenters on MacConkey agar?","\u003Cp>Lactose fermenters produce acid which lowers the pH, turning the neutral red indicator pink\u002Fred. Strong fermenters like \u003Cem>E. coli \u003C\u002Fem>additionally precipitate bile salts, producing a darker pink halo. Non-lactose fermenters cannot metabolize lactose, so no acid is produced and colonies appear colorless.\u003C\u002Fp>",{"question":219,"answer":220},"\u003Cp>Why do \u003Cem>Klebsiella\u003C\u002Fem> colonies appear mucoid on MacConkey agar?\u003C\u002Fp>","\u003Cp>\u003Cem>Klebsiella\u003C\u002Fem> produces a thick polysaccharide capsule. During lactose fermentation, some lactose is used to synthesize additional capsular polysaccharide, resulting in large, wet-appearing, mucoid colonies that may string when touched with an inoculation loop.\u003C\u002Fp>",{"question":222,"answer":223},"\u003Cp>How do you differentiate \u003Cem>Salmonella\u003C\u002Fem> from \u003Cem>Shigella\u003C\u002Fem> on MacConkey agar?\u003C\u002Fp>","\u003Cp>Both appear as colorless non-lactose fermenting colonies and cannot be reliably differentiated by MacConkey alone. \u003Cem>Salmonella\u003C\u002Fem> colonies are typically convex, 2-3mm with smooth margins; Shigella are flatter, 1-2mm with irregular edges. Definitive differentiation requires biochemical testing or agglutination with specific antisera.\u003C\u002Fp>",{"question":225,"answer":226},"\u003Cp>Why does \u003Cem>Proteus\u003C\u002Fem> swarm on some media but not on MacConkey agar?\u003C\u002Fp>","MacConkey agar's bile salt content partially inhibits swarming by acting on the bacterial surface and reducing motility. The higher agar concentration also physically restricts movement. However, swarming is not completely eliminated and may still occur toward the plate periphery.",{"question":228,"answer":229},"Can fungi or yeast grow on MacConkey agar?","\u003Cp>Standard MacConkey agar does not support most fungi and yeasts. \u003Cem>Cryptococcus neoformans\u003C\u002Fem> has been reported to grow under certain conditions. For fungal isolation, Sabouraud dextrose agar (SDA) is the appropriate medium.\u003C\u002Fp>",{"question":231,"answer":232},"Why is MacConkey agar incubated at 35-37°C and not at room temperature?","35-37°C approximates human body temperature and is optimal for clinically important gram-negative pathogens, producing reliable colony morphology within 18-24 hours. Exception: Yersinia enterocolitica grows better at 25-28°C and should be incubated at room temperature for 48-72 hours.",{"question":234,"answer":235},"\u003Cp>What does a pink halo around \u003Cem>E. coli\u003C\u002Fem> colonies on MacConkey agar indicate?\u003C\u002Fp>","\u003Cp>The pink halo indicates strong acid production from vigorous lactose fermentation. The large amount of acid drops the local pH so significantly that bile salts precipitate out of solution, forming a visible turbid pink zone. This is specific to strong lactose fermenters and is a useful rapid indicator of \u003Cem>E. coli\u003C\u002Fem> in mixed cultures.\u003C\u002Fp>",{"question":237,"answer":238},"\u003Cp>Why is \u003Cem>Pseudomonas aeruginosa\u003C\u002Fem> described as a non-lactose fermenter on MacConkey agar?\u003C\u002Fp>","\u003Cp>\u003Cem>Pseudomonas aeruginosa\u003C\u002Fem> is an obligate aerobe that uses oxygen as its primary electron acceptor and does not ferment lactose. Its oxidative metabolism does not produce enough acid to change the neutral red indicator, so colonies remain colorless. Its blue-green pyocyanin pigment and sweet grape-like odor are more useful identifying features.\u003C\u002Fp>",[173],{"enabled":241,"threads":242,"total":243},true,[],0,[245,251,258,265,271,276,282,287,293,296,302],{"slug":246,"name":43,"description":247,"image":248,"body":249,"postCount":250},"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.*",468,{"slug":252,"name":253,"description":254,"image":255,"body":256,"postCount":257},"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.",78,{"slug":259,"name":260,"description":261,"image":262,"body":263,"postCount":264},"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":266,"name":267,"description":261,"image":268,"body":269,"postCount":270},"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":272,"name":273,"description":261,"image":42,"body":274,"postCount":275},"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":277,"name":278,"description":279,"image":42,"body":280,"postCount":281},"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":283,"name":284,"description":285,"image":42,"body":42,"postCount":286},"guest-author","Guest Author","Guest Author \u002F Contributor",1,{"slug":288,"name":289,"description":261,"image":290,"body":291,"postCount":292},"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.",17,{"slug":294,"name":295,"description":285,"image":42,"body":42,"postCount":286},"dr-poonam-acharya","Dr. Poonam Acharya",{"slug":297,"name":78,"description":298,"image":299,"body":300,"postCount":301},"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.*",54,{"slug":303,"name":304,"description":305,"image":306,"body":307,"postCount":286},"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.",[309,315,321,325,330,335,339,343,347,352,356,361,365,370,374,378,382,386,391,396,400,404,408,413,417,421,425,429,434,439,443,447,451,454,458,462,466,470,474,478,482,486,490,493,497,501,505,509,514,518,522,526,530,533,537,541,545,549,553,557,561,565,569,573,577,581,585,589,592,596],{"slug":83,"name":310,"description":311,"image":312,"body":313,"postCount":314},"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":316,"name":317,"description":318,"image":42,"body":319,"postCount":320},"microscopy","Microscopy","Microscope types, components, and microscopy techniques","These are list of blog posts related to microscopy. ",12,{"slug":130,"name":322,"description":323,"image":42,"body":42,"postCount":324},"Gram-Positive Cocci","Staphylococcus, Streptococcus, Enterococcus, Micrococcus — organisms, diseases, and identification tests",11,{"slug":326,"name":327,"description":328,"image":42,"body":42,"postCount":329},"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":331,"name":332,"description":333,"image":42,"body":42,"postCount":334},"gram-positive-rods","Gram-Positive Rods","Bacillus, Clostridium, Listeria, Corynebacterium, Actinomyces and related organisms",8,{"slug":336,"name":337,"description":338,"image":42,"body":42,"postCount":324},"mycobacteria","Mycobacteria","Mycobacterium tuberculosis, leprosy, atypical mycobacteria, and acid-fast organism diagnosis",{"slug":340,"name":341,"description":342,"image":42,"body":42,"postCount":324},"anaerobic-bacteriology","Anaerobic Bacteriology","Anaerobic organisms, anaerobic culture methods, and anaerobic infection diagnosis",{"slug":344,"name":345,"description":346,"image":42,"body":42,"postCount":320},"enterobacteriaceae","Enterobacteriaceae","Identification, differentiation, and clinical significance of Enterobacteriaceae family members",{"slug":348,"name":349,"description":350,"image":42,"body":42,"postCount":351},"spirochetes","Spirochetes","Treponema, Leptospira, Borrelia and spirochetal infections",7,{"slug":353,"name":354,"description":355,"image":42,"body":42,"postCount":314},"food-microbiology","Food Microbiology","Food-borne pathogens, food safety, spoilage, and preservation",{"slug":357,"name":358,"description":359,"image":42,"body":42,"postCount":360},"antimicrobial-susceptibility-testing","Antimicrobial Susceptibility Testing","Methods for testing antibiotic susceptibility in clinical microbiology",21,{"slug":362,"name":363,"description":364,"image":42,"body":42,"postCount":334},"antimicrobials-moa-amr","Antimicrobials (MOA & AMR)","Mechanisms, detection, and clinical significance of antimicrobial resistance",{"slug":366,"name":367,"description":368,"image":42,"body":42,"postCount":369},"sterilization-disinfection","Sterilization and Disinfection","Methods of sterilization and disinfection in healthcare and laboratory settings",10,{"slug":72,"name":371,"description":372,"image":42,"body":42,"postCount":373},"Specimen Collection and Transport","Collection, handling, and transport of clinical specimens for microbiological testing",27,{"slug":375,"name":376,"description":377,"image":42,"body":42,"postCount":360},"bacterial-structure-physiology","Bacterial Structure and Physiology","Bacterial cell structure, growth, physiology, and environmental factors affecting growth",{"slug":379,"name":380,"description":42,"image":42,"body":381,"postCount":275},"horizontal-gene-transfer","Horizontal Gene Transfer","Articles related to **Horizontal Gene Transfer**",{"slug":383,"name":384,"description":42,"image":42,"body":385,"postCount":369},"chromatography","Chromatography","Information about chromatographic techniques.",{"slug":387,"name":388,"description":389,"image":42,"body":390,"postCount":351},"electrophoresis","Electrophoresis","Information about Electrophoresis Techniques ","Detailed information  about Electrophoresis Techniques ",{"slug":392,"name":393,"description":394,"image":42,"body":395,"postCount":275},"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":397,"name":398,"description":399,"image":42,"body":42,"postCount":275},"bacteriophage","Bacteriophage","Description about Bacteriophage.",{"slug":401,"name":402,"description":403,"image":42,"body":42,"postCount":275},"malaria","Malaria","It is the collections of articles regarding malarial disease. ",{"slug":405,"name":406,"description":407,"image":42,"body":42,"postCount":275},"anaerobic-culture-techniques","Anaerobic Culture Techniques","Posts related with Anaerobic Culture Techniques.",{"slug":409,"name":410,"description":411,"image":42,"body":42,"postCount":412},"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.",19,{"slug":414,"name":415,"description":416,"image":42,"body":42,"postCount":351},"biosafety-levels","Biosafety levels ","Articles related to Biosafety Levels",{"slug":418,"name":419,"description":420,"image":42,"body":42,"postCount":329},"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":422,"name":423,"description":424,"image":42,"body":42,"postCount":275},"pipette","Pipette","Posts related with Pipette. ",{"slug":426,"name":427,"description":428,"image":42,"body":42,"postCount":334},"bacteriology-mcqs","Bacteriology MCQs","This sections lists MCQs in Bacteriology.",{"slug":430,"name":431,"description":432,"image":42,"body":42,"postCount":433},"parasitology-mcqs","Parasitology MCQs","This section lists MCQs in Parasitology.",2,{"slug":435,"name":436,"description":437,"image":42,"body":42,"postCount":438},"virology-mcqs","Virology MCQs","This is the collections of Multiple Choice Questions in Virology.",4,{"slug":440,"name":441,"description":442,"image":42,"body":42,"postCount":329},"mcqs-in-microbiology","MCQs in Microbiology","This section lists the collections of Multiple Choice Questions in General Microbiology Topics. ",{"slug":444,"name":445,"description":446,"image":42,"body":42,"postCount":334},"immunology-mcqs","Immunology MCQs","In this section; we are posting collections of Multiple Choice Questions about Immunology. ",{"slug":448,"name":449,"description":450,"image":42,"body":42,"postCount":281},"microbial-curiosities","Microbial Curiosities","In this clusters, we are posting interesting and unique information about Microorganisms. ",{"slug":173,"name":452,"description":453,"image":42,"body":42,"postCount":360},"Bacterial Culture Media","Posts related to Bacterial Culture Media. ",{"slug":455,"name":456,"description":457,"image":42,"body":42,"postCount":275},"fungal-culture-media","Fungal Culture Media","Posts related to Fungal Culture Media.",{"slug":459,"name":460,"description":461,"image":42,"body":42,"postCount":329},"motility-test","Motility Test","This lists the procedure regarding various tests methods for bacterial motility.",{"slug":463,"name":464,"description":465,"image":42,"body":42,"postCount":369},"bacterial-enumeration","Bacterial enumeration","These posts are related to isolation and enumeration of bacteria. ",{"slug":467,"name":468,"description":469,"image":42,"body":42,"postCount":433},"gram-positive-coccobacillus","Gram-positive coccobacillus","List of Gram Positive Coccobacilli",{"slug":471,"name":472,"description":473,"image":42,"body":42,"postCount":438},"dimorphic-fungi","Dimorphic Fungi","This is about various dimorphic fungi. ",{"slug":475,"name":476,"description":477,"image":42,"body":42,"postCount":351},"bacterial-classification","Bacterial Classification","These posts are related with various approaches used for the classification of Bacteria. ",{"slug":479,"name":480,"description":481,"image":42,"body":42,"postCount":329},"immunofluorescence","Immunofluorescence ","Various Tests related to Immunofluorescence ",{"slug":483,"name":484,"description":485,"image":42,"body":42,"postCount":281},"antibody-mediated-immunity","Antibody-mediated Immunity","This clusters links the articles that are sharing insights about Antibody-mediated immunity. ",{"slug":487,"name":488,"description":489,"image":42,"body":42,"postCount":351},"hypersensitivity","Hypersensitivity","Articles related to Hypersensitivity.",{"slug":107,"name":491,"description":42,"image":42,"body":42,"postCount":492},"Haemophilus",3,{"slug":494,"name":495,"description":496,"image":42,"body":42,"postCount":438},"sexually-transmitted-infections-stis","Sexually transmitted infections (STIs)","This is the clusters of infections that are transmitted sexually. ",{"slug":498,"name":499,"description":500,"image":42,"body":42,"postCount":320},"adaptive-immunity","Adaptive Immunity","Blog posts related to B Cell Immunity and T Cell Immunity.",{"slug":502,"name":503,"description":504,"image":42,"body":42,"postCount":314},"fungal-diagnostics","Fungal Diagnostics","Various methods used for the Diagnosis of Fungal Infections. ",{"slug":506,"name":507,"description":508,"image":42,"body":42,"postCount":329},"laboratory-storage-and-preservation","Laboratory Storage and Preservation","Articles about Laboratory Storage of Antimicrobial Disk, Test organisms and Equipment used for this process. ",{"slug":510,"name":511,"description":512,"image":42,"body":513,"postCount":275},"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":515,"name":516,"description":517,"image":42,"body":42,"postCount":334},"laboratory-glassware","Laboratory Glassware","Posts about Laboratory Glassware. ",{"slug":519,"name":520,"description":521,"image":42,"body":42,"postCount":275},"helminths","Helminths","In this section, we are covering properties, life cycle, pathogenesis and laboratory diagnosis of Helminths\u002FHelminthic infestations. ",{"slug":523,"name":524,"description":525,"image":42,"body":42,"postCount":275},"protozoan-parasite","Protozoan Parasite","In this cluster, we are covering protozoan parasites. ",{"slug":527,"name":528,"description":529,"image":42,"body":42,"postCount":286},"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":150,"name":531,"description":532,"image":42,"body":42,"postCount":369},"Bacterial Staining Technique","Lists of various staining techniques that are used to stain bacteria. ",{"slug":534,"name":535,"description":536,"image":42,"body":42,"postCount":270},"enzyme-tests","Enzyme Tests","\u003Cp>Various Biochemical Test that are based on enzymatic activity of the microorganisms. \u003C\u002Fp>",{"slug":538,"name":539,"description":540,"image":42,"body":42,"postCount":324},"carbohydrate-utilization","Carbohydrate Utilization","\u003Cp>Various biochemical tests which are related to Carbohydrate fermentation or Utilization\u003C\u002Fp>",{"slug":542,"name":543,"description":544,"image":42,"body":42,"postCount":329},"susceptibility-based-id","Susceptibility-based ID","\u003Cp>These are susceptibility based identification test such as optochin sensitivity, bacitracin sensitivity etc. \u003C\u002Fp>",{"slug":546,"name":547,"description":548,"image":42,"body":42,"postCount":438},"microbial-metabolism","Microbial Metabolism","\u003Cp>Tests about Microbial Metabolism. \u003C\u002Fp>",{"slug":550,"name":551,"description":552,"image":42,"body":42,"postCount":334},"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":554,"name":555,"description":556,"image":42,"body":42,"postCount":492},"atypical-pneumonia","Atypical Pneumonia","\u003Cp>Organisms responsible for Atypical Pneumonia. \u003C\u002Fp>",{"slug":558,"name":559,"description":560,"image":42,"body":42,"postCount":329},"antigen","Antigen","\u003Cp>Various articles related to Antigens.\u003C\u002Fp>",{"slug":562,"name":563,"description":564,"image":42,"body":42,"postCount":351},"innate-immunity","Innate Immunity","\u003Cp>Articles related to Innate Immunity. \u003C\u002Fp>",{"slug":566,"name":567,"description":568,"image":42,"body":42,"postCount":438},"respiratory-tract-infection","Respiratory Tract Infection","\u003Cp>In this cluster, you can see various etiological agents that causes respiratory tract infection. \u003C\u002Fp>",{"slug":570,"name":571,"description":572,"image":42,"body":42,"postCount":329},"torch-infection","TORCH Infection","\u003Cp>In this section; you can find articles related with TOCH infection. \u003C\u002Fp>",{"slug":574,"name":575,"description":576,"image":42,"body":42,"postCount":351},"microbiology-for-beginners","Microbiology for Beginners","\u003Cp>These articles are very basic articles, which will share general concepts in Microbiology. \u003C\u002Fp>",{"slug":578,"name":579,"description":580,"image":42,"body":42,"postCount":275},"dna-replication","DNA Replication","\u003Cp>Articles related to DNA and Replication of DNA. \u003C\u002Fp>",{"slug":582,"name":583,"description":584,"image":42,"body":42,"postCount":351},"genetic-code","Genetic Code","\u003Cp>Articles related to Genetic Code.\u003C\u002Fp>",{"slug":586,"name":587,"description":588,"image":42,"body":42,"postCount":329},"molecular-technique","Molecular Technique","\u003Cp>Posts related to Molecular Techniques. \u003C\u002Fp>",{"slug":590,"name":591,"description":42,"image":42,"body":42,"postCount":286},"colorimetric-assay","Colorimetric Assay ",{"slug":593,"name":594,"description":595,"image":42,"body":42,"postCount":329},"pharmaceutical-microbiology","Pharmaceutical Microbiology","\u003Cp>Various articles related to Pharmaceutical Microbiology\u003C\u002Fp>",{"slug":597,"name":598,"description":42,"image":42,"body":42,"postCount":492},"blood-and-immune-cells","Blood and Immune Cells"]