[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"$fxLN3MUwXCdr5RPjwZYIDpOj8CHyjOmngWTgoKXPtZbg":3,"$fgd14QXc1cK73lvVRgprEREhV2lXTq27GRhDbOJmXFzY":36,"$f3Ft0rKFJHppdzE-vuveecxx1BUcg9iOlMLtyzf_MJDg":261,"$fucxFBm2ZjZfGSdmdRaSNGBI_F0jJme4f0GTvzUhQfL8":324},[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":257},"tissue-biopsy-specimen-collection-transport","Tissue and Biopsy Specimens: Collection, Transport, and Processing","\u003Cp>Why tissue is the reference-standard specimen for deep infection, why the microbiology portion must be split off before formalin or decalcification, when to mince instead of grind, and how one small biopsy is divided across bacterial, AFB, fungal, and histology testing.\u003C\u002Fp>",null,"Acharya Tankeshwar","2026-08-15","2026-08-14",false,"bacteriology","Tissue is the best specimen microbiology can receive for a deep or serious infection. A biopsy samples the organisms actually invading the tissue, not the flora on the surface, which is why it beats pus, wound, and sterile-fluid in terms of sensitivity. And yet tissue is one of the easiest specimens to waste, because the errors that destroy it happen in the first few minutes, at the bedside or on the cutting bench, before the sample ever reaches a culture plate. This article is about handling tissue so that its advantage is not thrown away.\n\nTissue is collected by a surgeon, an interventional radiologist, or a clinician performing a biopsy. Microbiology does not collect it, but what happens to the sample in the moments after it is collected decides whether the culture can work at all.\n\n## The one rule that outranks everything: split for microbiology first\n\nA biopsy is often small, and it is often wanted for more than one purpose. The instinct in operation theatre is to drop the whole piece into the formalin pot for the pathologist. If that happens, microbiology gets nothing usable, because formalin kills every organism and makes culture impossible.\n\n\u003Cfigure>\n\u003Cimg src=\"https:\u002F\u002Fassets.microbeonline.com\u002Fblogs\u002Ftissue-biopsy-split-first-vs-formalin.png\" alt=\"Tissue must be split before it is fixed. Take the microbiology portion off first into saline for culture, and only then send the remainder to formalin for histology. Once the whole specimen is in formalin, all organisms are dead and culture is impossible, so both questions can only be answered if the split comes first. Bone follows the same rule, split before acid decalcification, and suspected Mucorales tissue is minced rather than ground\" width=\"2720\" height=\"2240\" draggable=\"false\" contenteditable=\"false\">\u003Cfigcaption>Figure: Tissue must be split before it is fixed. Take the microbiology portion off first into saline for culture, and only then send the remainder to formalin for histology. Once the whole specimen is in formalin, all organisms are dead and culture is impossible.\u003C\u002Ffigcaption>\n\u003C\u002Ffigure>\n\nSo the governing rule is: **the portion for microbiology is separated first, into a sterile container, before any part of the specimen touches fixative.** Once tissue is in formalin, it is a histopathology specimen only. There is no way to recover it for culture. The same logic applies to bone and decalcification.\n\n## One tissue, many tests: how the sample is divided\n\nA single biopsy may need to answer several questions at once: routine bacteria, mycobacteria, fungi, and histopathology. Each has different handling, and some of the requirements conflict, so the division must be deliberate.\n\n| Test | Portion handling | Container | Key point |\n| --- | --- | --- | --- |\n| Bacterial culture (aerobic and anaerobic) | Fresh, kept moist | Sterile container with a few drops of sterile saline | Never formalin; anaerobic transport if anaerobes suspected |\n| Mycobacterial (AFB) culture | Fresh, kept moist | Sterile container, saline | Larger portion helps; TB is often paucibacillary |\n| Fungal culture | Fresh; minced, not ground, if a *Mucorales* mold is suspected | Sterile container, saline | Grinding destroys fragile mold hyphae (see below) |\n| Histopathology | Fixed | Formalin | Split off after the microbiology portions are taken, never before |\n\nThe workflow that protects every test: take the fresh microbiology portions first (dividing further for bacterial, AFB, and fungal as needed), keep them moist in a sterile container, and only then place the remaining piece in formalin for histology. When volume is very limited, the clinician and laboratory prioritize together based on the most likely diagnosis.\n\n### Grinding versus mincing: the mold exception\n\nTo release organisms trapped inside tissue, the laboratory normally [homogenizes (grinds)](https:\u002F\u002Fmicrobeonline.com\u002Fhomogenizer-parts-types-and-function\u002F) the specimen before culture. There is one important exception.\n\n**If a [mucormycosis (a *Mucorales* or zygomycete mold) infection](https:\u002F\u002Fmicrobeonline.com\u002Frhizopus-and-mucor-characteristics-and-diagnosis\u002F) is suspected, the tissue is minced or cut into small pieces, not ground.** The hyphae of these molds are broad, non-septate, and fragile, and grinding shatters them, so the culture turns falsely negative even when the fungus is clearly present on histology. Cutting the tissue into small fragments and pressing them onto the media preserves viable hyphae. This is why suspected mucormycosis must be mentioned on the request form.\n\n### Bone and osteomyelitis: the decalcification trap\n\nFor osteomyelitis, bone is the specimen, and the split-first rule becomes even more important because of an extra hazard.\n\nBone sent for histopathology is **decalcified**, usually in an acid solution, so that it can be sectioned and stained. That acid decalcification also kills any organisms present. So a piece of bone that goes straight to histology cannot then be cultured, for the same reason formalin-fixed tissue cannot: the processing has sterilized it.\n\nThe rule: **the microbiology portion of a bone specimen is split off before the bone is fixed or decalcified.** Send the culture portion fresh, in a sterile container, kept moist, and let histology decalcify only its own share. As with soft tissue, once bone has been through fixation or decalcification, it is a histopathology specimen only.\n\n### Keep it moist, but do not drown it\n\nSmall tissue pieces dry out quickly, and a desiccated specimen loses viable organisms. To prevent this, a few drops of sterile saline are added to keep the tissue moist during transport. Use enough saline to stop drying, not so much that it dilutes an already small specimen.\n\n## Transport\n\n- Deliver tissue to the laboratory as soon as possible.\n- Keep it in a sterile, leak-proof container with a few drops of sterile saline to prevent drying.\n- Never place tissue intended for culture in formalin. Formalin is for histopathology only.\n- If anaerobes are suspected (deep, necrotic, or abscess-associated tissue), use an anaerobic transport system.\n- Refrigeration is acceptable for a short delay for routine bacterial culture, but not when fastidious organisms are suspected; keep those at room temperature and transport quickly.\n- Flag suspected mycobacterial, fungal, or *Mucorales* infection on the request, because it changes how the lab processes the sample.\n\n## How Microbiology Lab Process Tissue and Biopsy Specimen\n\nOnce tissue reaches the bench, the microbiology portion is processed as follows.\n\n**Direct examination.** A portion is used for immediate microscopy, and this often gives the first clue before any culture grows:\n\n- [Gram stain](https:\u002F\u002Fmicrobeonline.com\u002Fgram-staining-principle-procedure-results\u002F) for bacteria and yeasts.\n- A [KOH](https:\u002F\u002Fmicrobeonline.com\u002Fkoh-preparation-test-principle-procedure-results-uses\u002F) or [calcofluor-white preparation](https:\u002F\u002Fmicrobeonline.com\u002Fcalcofluor-white-staining-principle-procedure-and-application\u002F) when a fungus is suspected, which shows hyphae or yeast forms. For a suspected *Mucorales* mold, the broad, non-septate (aseptate) hyphae branching at wide angles are the giveaway.\n- A [Ziehl-Neelsen](https:\u002F\u002Fmicrobeonline.com\u002Fziehl-neelsen-technique-principle-procedure-reporting\u002F) or [auramine-rhodamine stain](https:\u002F\u002Fmicrobeonline.com\u002Fauramine-rhodamine-fluorochrome-staining-principle-procedure-results-limitations\u002F) when mycobacteria are suspected.\n- A portion is sent in parallel for histopathology, which complements culture by showing the organism in the tissue and the host reaction around it.\n\n**Homogenization, with the mold exception.** For routine bacterial and fungal culture, the tissue is ground to release organisms trapped within it. As covered above, tissue from a suspected *Mucorales* infection is minced, not ground, to protect the fragile hyphae.\n\n**Culture media.** The prepared tissue is inoculated onto a range of media chosen to cover the likely pathogens, because tissue is often taken precisely when the cause is unknown:\n\n- [Blood agar](https:\u002F\u002Fmicrobeonline.com\u002Fblood-agar-composition-preparation-uses-and-types-of-hemolysis\u002F) and [chocolate agar](https:\u002F\u002Fmicrobeonline.com\u002Fchocolate-agar-composition-uses-colony-characteristics\u002F) for common aerobes and fastidious organisms.\n- [MacConkey agar](https:\u002F\u002Fmicrobeonline.com\u002Fmacconkey-agar-mac-composition-preparation-uses-and-colony-characteristics\u002F) for gram-negative bacilli.\n- An [anaerobic medium](https:\u002F\u002Fmicrobeonline.com\u002Fcommonly-used-anaerobic-media-for-anaerobic-bacteriology\u002F) (and an enrichment broth such as thioglycollate) for deep or necrotic tissue, where anaerobes are common.\n- [Sabouraud agar](https:\u002F\u002Fmicrobeonline.com\u002Fsabouraud-dextrose-agar-sda-principle-composition-uses-colony-morphology\u002F) when a fungus is suspected.\n- [Lowenstein-Jensen](https:\u002F\u002Fmicrobeonline.com\u002Fpreparation-uses-lowenstein-jensen-lj-medium\u002F) or a liquid mycobacterial medium when tuberculosis or another mycobacterial infection is suspected.\n\n**Incubation.** Bacterial plates are incubated at 35 to 37 degrees C, with chocolate agar and fastidious cultures in 5% CO2, and read over 24 to 48 hours and beyond. Fungal and mycobacterial cultures are held far longer, weeks, because these organisms grow slowly.\n\n**Reading and interpretation.** Tissue comes from a normally sterile site, so any organism recovered is potentially significant.\n\nGrowth is read against the direct smear and the histopathology: an organism seen on the Gram stain or in the tissue section and then grown in culture is far more convincing than a single colony with no supporting evidence, which may reflect contamination at collection.\n\n## Identification and antimicrobial susceptibility testing\n\nOnce an organism is isolated, it is identified and, where relevant, [tested for antimicrobial susceptibility](https:\u002F\u002Fmicrobeonline.com\u002Fantimicrobial-susceptibility-testing-procedure-modified-kirby-bauer-method\u002F). Tissue is taken when the cause is often unknown, so a wide range of organisms may grow. The most commonly isolated, and the first approach to each:\n\n- ***Staphylococcus aureus***: gram-positive cocci in clusters, catalase positive, coagulase positive. The commonest cause of bone, joint, and deep soft-tissue infection. See the [*Staphylococcus aureus* article](https:\u002F\u002Fmicrobeonline.com\u002Fstaphylococcus-aureusdisease-properties-pathogenesis-and-laboratory-diagnosis\u002F) for full identification and susceptibility, including methicillin resistance.\n- ***Streptococcus* and *Enterococcus* species**: gram-positive cocci in chains or pairs, catalase negative; distinguished by hemolysis and further reactions.\n- **Gram-negative bacilli (*Escherichia coli*, *Klebsiella*, *Pseudomonas aeruginosa*, *Proteus*)**: common in diabetic foot, chronic, and post-surgical tissue infections; separated on MacConkey by lactose fermentation, with *Pseudomonas* as a non-lactose fermenter with a characteristic look and smell.\n- **Anaerobes (*Bacteroides*, *Clostridium*, anaerobic cocci)**: common in deep, necrotic, and abscess-associated tissue; grow on anaerobic media and are identified from there.\n- **Mycobacteria (*Mycobacterium tuberculosis* and others)**: acid-fast on Ziehl-Neelsen; slow-growing on selective mycobacterial media. See the [tuberculosis diagnosis page](https:\u002F\u002Fmicrobeonline.com\u002Fmycobacterium-tuberculosis-lab-diagnosis\u002F).\n- **Fungi (*Aspergillus*, *Mucorales* molds, *Histoplasma*, *Candida*)**: shown on KOH or calcofluor-white and grown on Sabouraud agar; *Mucorales* handled by mincing, not grinding, as above.\n\n## How to Remember\n\n**Split for micro before anything is fixed.** Formalin and acid decalcification both kill organisms, so the culture portion comes off first, into saline, before histology gets its share.\n\n**Tissue beats swab because it holds the invaders.** A swab samples the surface; tissue samples the organisms inside. That is why for deep infection, tissue is the best specimen.\n\n**Grind routine tissue, mince a suspected mold.** Grinding releases organisms from ordinary tissue, but it shatters the fragile hyphae of *Mucorales* and gives a false-negative culture. Suspected mucormycosis is minced, not ground.\n\n**Bone adds the decalcification trap.** Bone for histology is dissolved in acid, which also kills organisms. So the culture portion of bone should be taken off before any fixing or decalcifying, exactly like the formalin rule for soft tissue.\n\n**Moist, not drowned.** A few drops of saline stop the tissue drying; a pool of saline dilutes a small sample. Aim for damp.\n\n## Key exam facts in one table\n\n| Point | Fact |\n| --- | --- |\n| Why tissue is preferred | Samples invading organisms, not surface flora; reference standard for deep infection |\n| Governing rule | Split the microbiology portion before any fixation |\n| Formalin | Kills all organisms; histopathology only, never for culture |\n| Bone for histology | Decalcified in acid, which also kills organisms |\n| Bone rule | Split culture portion before fixation or decalcification |\n| Container | Sterile, leak-proof, few drops of sterile saline |\n| Moisture | Damp, not submerged |\n| Routine processing | Ground (homogenized) to release organisms |\n| *Mucorales* exception | Minced, not ground (fragile non-septate hyphae) |\n| Flag on request | Suspected TB, fungal, or *Mucorales* infection |\n| Anaerobes | Anaerobic transport system for deep or necrotic tissue |\n| Multi-test priority | Micro portions first, then formalin for histology |\n| Refrigeration | Short delay OK for routine; not for fastidious organisms |\n\n## Where Students Get Confused\n\n**\"Why not just send the whole biopsy in formalin and let each lab take what it needs?\"** Because formalin kills every organism, so once tissue is fixed, culture is impossible. The microbiology portion must be separated into a sterile container before anything touches formalin. Fixed tissue is a histopathology specimen only.\n\n**\"Tissue is the best specimen, so how can it give a false-negative culture?\"** Most often through handling. Formalin fixation, acid decalcification of bone, and grinding a fragile mold all destroy the organisms before they can grow. The specimen was excellent; the processing wasted it.\n\n**\"Why mince rather than grind when mucormycosis is suspected?\"** The hyphae of *Mucorales* molds are broad, non-septate, and easily shattered. Grinding fragments them and the culture comes back negative even when histology clearly shows the fungus. Cutting the tissue into small pieces preserves viable hyphae, so suspected mucormycosis must be reported so the lab minces instead of grinds.\n\n**\"Bone went to histology and grew nothing on culture, why?\"** Bone for histology is decalcified in acid, which kills organisms just as formalin does. The culture portion of bone must be split off fresh before any fixation or decalcification, or there is nothing viable left to grow.\n\n**\"How much saline should go in with the tissue?\"** Just a few drops, enough to keep it moist. Too much saline dilutes an already small specimen. The goal is damp tissue, not tissue floating in fluid.\n\n### References and further reading\n\n1. Tille PM. *Bailey & Scott's Diagnostic Microbiology.* 15th ed. St. Louis: Elsevier; 2022.\n2. Leber AL, editor. *Clinical Microbiology Procedures Handbook.* 4th ed. Washington, DC: ASM Press; 2016. DOI: 10.1128\u002F9781683670438.CMPH\n3. Procop GW, Church DL, Hall GS, et al. *Koneman's Color Atlas and Textbook of Diagnostic Microbiology.* 7th ed. Philadelphia: Wolters Kluwer; 2017.",[50,53,56,59,62,65,68],{"question":51,"answer":52},"\u003Cp>Why is tissue considered the best specimen for deep infections?\u003C\u002Fp>","\u003Cp>A biopsy samples the organisms actually invading the tissue rather than the flora on the surface, so it is the reference-standard specimen for deep, chronic, and serious infections such as osteomyelitis and deep abscesses. This is why the pus, wound, and sterile-fluid pages point to tissue when it can be obtained.\u003C\u002Fp>",{"question":54,"answer":55},"\u003Cp>Why must tissue for culture never be placed in formalin?\u003C\u002Fp>","\u003Cp>Formalin kills all organisms, making culture impossible. The microbiology portion must be separated into a sterile container before any part of the specimen touches formalin. Once tissue is fixed, it can be used only for histopathology.\u003C\u002Fp>",{"question":57,"answer":58},"\u003Cp>How is a single small biopsy divided across several tests?\u003C\u002Fp>","\u003Cp>The fresh microbiology portions (bacterial, mycobacterial, and fungal) are taken first, kept moist in a sterile container, and only then is the remaining piece placed in formalin for histopathology. When volume is limited, the clinician and laboratory prioritize together based on the most likely diagnosis.\u003C\u002Fp>",{"question":60,"answer":61},"\u003Cp>Why is tissue minced instead of ground when mucormycosis is suspected?\u003C\u002Fp>","\u003Cp>The hyphae of \u003Cem>Mucorales\u003C\u002Fem> molds are broad, non-septate, and fragile. Grinding shatters them and produces a false-negative culture even when the fungus is visible on histology. Mincing the tissue preserves viable hyphae, so suspected mucormycosis must be flagged for the laboratory.\u003C\u002Fp>",{"question":63,"answer":64},"\u003Cp>Why can bone sent for histology not also be cultured?\u003C\u002Fp>","\u003Cp>Bone for histopathology is decalcified in acid, which kills organisms just as formalin does. The culture portion of a bone specimen must be split off fresh before any fixation or decalcification, or nothing viable remains to grow.\u003C\u002Fp>",{"question":66,"answer":67},"\u003Cp>How should tissue be kept during transport?\u003C\u002Fp>","\u003Cp>In a sterile, leak-proof container with only a few drops of sterile saline to keep it moist, not submerged. Deliver it promptly, use an anaerobic transport system if anaerobes are suspected, and flag any suspected TB, fungal, or \u003Cem>Mucorales\u003C\u002Fem> infection on the request.\u003C\u002Fp>",{"question":69,"answer":70},"\u003Cp>Should tissue specimens be refrigerated if delayed?\u003C\u002Fp>","\u003Cp>A short delay at refrigeration temperature is acceptable for routine bacterial culture, but not when fastidious organisms are suspected. Keep those at room temperature and transport quickly.\u003C\u002Fp>",[72],"specimen-collection-transport",[74,99,126,147,171,188,206,222],{"slug":75,"title":76,"description":77,"seoTitle":42,"seoDescription":42,"author":78,"createdDate":79,"lastUpdatedDate":80,"draft":46,"category":81,"image":42,"faq":82,"tags":98},"homogenizer-parts-types-and-function","Homogenizer: Types, How to Choose One, Parts, and Functions","The types of homogenizer (rotor-stator, pressure, bead-mill, ultrasonic), how each breaks a sample down, and which one to use for soft tissue, tough cells like fungi and spores, or emulsions.","Samikshya Acharya","2022-09-08","2026-07-30","lab-equipment",[83,86,89,92,95],{"question":84,"answer":85},"\u003Cp>What is a homogenizer used for?\u003C\u002Fp>","\u003Cp>A homogenizer breaks a sample into a uniform mixture, either by rupturing cells to release their contents (proteins, enzymes, nucleic acids) or by blending components into a stable emulsion. In the laboratory its main use is cell disruption before extraction and purification.\u003C\u002Fp>",{"question":87,"answer":88},"\u003Cp>What are the main types of homogenizer?\u003C\u002Fp>","\u003Cp>The four main types are rotor-stator (mechanical shearing), high-pressure (forcing the sample through a narrow valve), bead-mill or bead-beater (grinding cells with beads), and ultrasonic (cavitation from high-frequency sound). Each disrupts a sample by a different mechanism.\u003C\u002Fp>",{"question":90,"answer":91},"\u003Cp>Which homogenizer is best for tough cells like fungi or spores?\u003C\u002Fp>","\u003Cp>A bead-mill (bead-beater) is best for tough-walled cells such as fungi, yeast, bacterial spores, and mycobacteria. Their walls resist shearing, so they must be physically ground open by hard beads, which gentler methods like a rotor-stator cannot achieve.\u003C\u002Fp>",{"question":93,"answer":94},"\u003Cp>What is the difference between a homogenizer and a sonicator?\u003C\u002Fp>","\u003Cp>A sonicator is one type of homogenizer, the ultrasonic type, which uses cavitation to lyse cells and suits small volumes. Other homogenizers (rotor-stator, high-pressure, bead-mill) use mechanical shearing, pressure, or grinding and handle larger or tougher samples.\u003C\u002Fp>",{"question":96,"answer":97},"\u003Cp>Why does the sample get hot during homogenization?\u003C\u002Fp>","\u003Cp>Mechanical and ultrasonic homogenization put energy into the sample, which turns into heat. This heat can denature the proteins, enzymes, or nucleic acids being extracted, so heat-sensitive samples are kept cold, often on ice, during the process.\u003C\u002Fp>",[],{"slug":100,"title":101,"description":102,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":103,"lastUpdatedDate":104,"draft":46,"category":105,"image":42,"faq":106,"tags":125},"rhizopus-and-mucor-characteristics-and-diagnosis","Mucormycosis: Etiology, Pathogenesis, Clinical Features, Diagnosis and Treatment","Mucormycosis (black fungus): etiology, Rhizopus and Mucor characteristics, pathogenesis, clinical manifestations by organ system, laboratory diagnosis (KOH, histopathology, culture, PCR), and treatment.","2022-06-18","2026-07-27","mycology",[107,110,113,116,119,122],{"question":108,"answer":109},"Why is \"black fungus\" a misleading name for mucormycosis?","Mucorales are hyaline (colorless) fungi, not black. The name likely refers to black necrotic tissue in advanced rhinocerebral disease, not the fungus colour. True black-pigmented fungi (tinea nigra, chromoblastomycosis) are unrelated organisms.",{"question":111,"answer":112},"Why is diabetes mellitus the most important risk factor for mucormycosis?","DKA creates ideal growth conditions: acidic\u002Fhyperglycemic environment favors growth, ketones provide carbon source, impaired neutrophil function weakens first-line defence, and elevated free iron (released in acidic conditions) supports the fungus's high iron requirement.",{"question":114,"answer":115},"How do you distinguish mucormycosis from aspergillosis on microscopy?","Mucormycosis: broad, ribbon-like, non-septate hyphae, wide-angle (~90°) branching. Aspergillosis: narrower, uniform, septate hyphae, acute-angle (~45°) branching. Critical because voriconazole (first-line for aspergillosis) has no activity against mucormycosis.",{"question":117,"answer":118},"Why is surgical debridement essential, not optional, in mucormycosis treatment?","Angioinvasion causes thrombosis and tissue infarction. Necrotic tissue has no blood supply, so antifungals cannot reach the fungus within dead tissue regardless of dose. Debridement removes drug-inaccessible tissue and restores vascular access for remaining infected margins.",{"question":120,"answer":121},"Why does culture have low positivity despite organisms being visible on microscopy?","Non-septate hyphae are fragile and destroyed by tissue grinding during processing. Necrotic tissue contains few viable organisms. A negative culture does not rule out mucormycosis — diagnosis relies heavily on direct microscopy\u002Fhistopathology showing characteristic morphology and angioinvasion.",{"question":123,"answer":124},"Why don't fluconazole, voriconazole, and itraconazole work against mucormycosis?","Mucorales have structural differences in CYP51 (the triazole target enzyme) giving most triazoles reduced binding affinity — intrinsic resistance. Posaconazole and isavuconazole are exceptions. Amphotericin B (different mechanism) remains first-line treatment.",[],{"slug":127,"title":128,"description":129,"seoTitle":130,"seoDescription":131,"author":43,"createdDate":132,"lastUpdatedDate":133,"draft":46,"category":134,"image":42,"faq":135,"tags":145},"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","2026-08-02","staining-techniques",[136,139,142],{"question":137,"answer":138},"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":140,"answer":141},"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":143,"answer":144},"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.",[146],"bacterial-staining-technique",{"slug":148,"title":149,"description":150,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":151,"lastUpdatedDate":152,"draft":46,"category":105,"image":42,"faq":153,"tags":169},"koh-preparation-test-principle-procedure-results-uses","KOH Mount: Principle, Procedure, Results, Uses","KOH preparation: principle, procedure, 10% concentration rationale, organism-specific findings (dermatophytes, Candida, Mucorales, Coccidioides), troubleshooting artifacts vs true fungal elements, and comparison with calcofluor white.","2016-04-30","2026-07-28",[154,157,160,163,166],{"question":155,"answer":156},"Is KOH a stain?","No. KOH is a clearing agent, not a stain. It dissolves keratin and other tissue material so that the fungus, which resists the alkali, becomes visible against a cleared background. It does not color or bind the fungus the way true stains such as PAS, GMS, or calcofluor white do.",{"question":158,"answer":159},"Why is 10% KOH used for skin but 20% for nails?","The concentration has to be strong enough to dissolve keratin in a reasonable time without distorting the fungal elements. Skin scrapings clear quickly in 10% KOH. Nails are far more heavily keratinized, so they need 20% (sometimes with gentle warming) to clear in a practical timeframe.",{"question":161,"answer":162},"What is the most common false-positive in KOH microscopy?","The outlines of normal skin cell borders, sometimes called \"mosaic fungus.\" These can mimic pseudohyphae. The distinguishing feature is that true hyphae cross over cell borders, whereas the artifact follows the cell boundaries exactly and does not cross into neighboring cells.",{"question":164,"answer":165},"How can I tell true hyphae from a cotton fiber?","True hyphae have a consistent width, show true branching, and usually show septa (cross-walls). Cotton and textile fibers are typically wider, do not branch, have sharp broken ends, and often shine brightly (birefringent) under polarized light. When in doubt, add calcofluor white, fibers do not fluoresce the way chitin-containing fungi do.",{"question":167,"answer":168},"Does a positive KOH mount identify the fungal species?","No. KOH confirms that fungal elements are present and can suggest a broad category (for example, septate hyphae versus broad aseptate hyphae versus yeast with pseudohyphae), but it does not identify the species. Culture is needed for definitive identification.",[170],"fungal-diagnostics",{"slug":172,"title":173,"description":174,"seoTitle":42,"seoDescription":42,"author":175,"createdDate":176,"lastUpdatedDate":133,"draft":46,"category":134,"image":42,"faq":177,"tags":187},"calcofluor-white-staining-principle-procedure-and-application"," Calcofluor White Staining: Principle, Procedure, Results, and Clinical Applications","Calcofluor white binds chitin in fungal cell walls, producing bright fluorescence under UV light. Learn the principle, KOH-CFW combined method, specimen-specific applications, and how to interpret results for fungi, Pneumocystis, and Acanthamoeba.","Sushmita Baniya","2022-08-11",[178,181,184],{"question":179,"answer":180},"What does calcofluor white stain and why does it work on fungi?","\u003Cp>Calcofluor White is mainly used to rapidly detect fungi in clinical specimens such as skin scrapings, nail clippings, hair, corneal scrapings, sputum, bronchoalveolar lavage (BAL), tissue, and other body fluids. Because staining takes only a few minutes, it is often used as a quick screening test before culture results are available. The fluorescent stain makes even small numbers of fungal elements easier to see than routine light microscopy.\u003C\u002Fp>\u003Cp>\u003C\u002Fp>\u003Cp>One important limitation is that CFW is \u003Cstrong>not specific for fungi\u003C\u002Fstrong>. Any material containing chitin or cellulose, including cotton fibers, plant material, and some environmental debris, can also fluoresce. For this reason, a positive fluorescent structure should always be identified by its morphology, such as branching, septation, budding, or yeast shape, rather than by fluorescence alone.\u003C\u002Fp>",{"question":182,"answer":183},"What is the combined KOH-CFW method and when is it used?","The combined KOH-calcofluor white method mixes 10% potassium hydroxide with CFW stain for direct examination of skin scrapings, nail clippings, and hair. KOH dissolves keratin and host cell debris, clearing the specimen and making fungal elements more visible. CFW simultaneously stains any fungal elements bright fluorescent green under UV light. The combination is more sensitive than either method alone for detecting dermatophytes and yeasts in skin and nail specimens. A stronger KOH concentration (20%) is used for nail specimens due to the thicker keratin. The preparation requires a fluorescence microscope.",{"question":185,"answer":186},"","\u003Cp>Cotton fibres are the most common cause of false-positive results with calcofluor white (CFW) staining. They fluoresce very brightly under UV light, sometimes even more brightly than fungal hyphae, and can easily be mistaken for fungi.\u003C\u002Fp>\u003Cp>To avoid this error:\u003C\u002Fp>\u003Cp>Use \u003Cstrong>nylon or dacron swabs\u003C\u002Fstrong> instead of cotton-tipped swabs for specimen collection.\u003C\u002Fp>\u003Cp>Do not rely on fluorescence alone. Always examine the morphology of the fluorescent structure.\u003C\u002Fp>\u003Cp>True fungal hyphae have a \u003Cstrong>uniform width, branching, and septation\u003C\u002Fstrong>, whereas cotton fibres are \u003Cstrong>irregular, non-branching, and variable in width\u003C\u002Fstrong>. Careful examination under high power helps distinguish cotton fibres from fungal hyphae.\u003C\u002Fp>",[170],{"slug":189,"title":190,"description":191,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":192,"lastUpdatedDate":193,"draft":46,"category":134,"image":42,"faq":194,"tags":204},"ziehl-neelsen-technique-principle-procedure-reporting","Ziehl-Neelsen Staining: Principle, Procedure, Grading, and Interpretation","The hot ZN acid-fast staining method step by step, why mycolic acid holds carbol fuchsin against acid-alcohol, WHO smear grading from scanty to 3+, and what a negative smear does and does not rule out in TB.","2013-12-06","2026-08-12",[195,198,201],{"question":196,"answer":197},"Why does Ziehl-Neelsen staining require heat while other staining techniques do not?","\u003Cp>Mycobacteria have a cell wall rich in mycolic acids, long-chain fatty acids that make the wall waxy, hydrophobic, and impermeable to most dyes at room temperature. Heat acts as a mordant by disrupting this waxy barrier and allowing carbol fuchsin to penetrate the cell wall. Once inside, the stain is held so tightly by the mycolic acids that even acid-alcohol, one of the strongest decolorizers used in microbiology, cannot remove it. This is why the stain is called 'acid-fast',  the organisms hold fast to the dye even after acid treatment.\u003C\u002Fp>",{"question":199,"answer":200},"How is an AFB smear graded and what does the grade mean clinically?","\u003Cp>AFB smears are graded using the WHO\u002FIUATLD scale: No AFB seen (after examining 300 fields); Scanty: 1-9 AFB per 100 fields (report exact count and request repeat); 1+: 10-99 AFB per 100 fields; 2+: 1-10 AFB per field in at least 50 fields; 3+: more than 10 AFB per field in at least 20 fields. Higher grades indicate greater organism burden and greater infectiousness. Grade is recorded at treatment initiation and at months 2, 5, and 6 to monitor bacteriological response. Conversion from positive to negative smear during treatment indicates therapeutic response.\u003C\u002Fp>",{"question":202,"answer":203},"What is the difference between Ziehl-Neelsen and Kinyoun (cold) acid-fast staining?","\u003Cp>Both methods use carbolfuchsin as the primary stain and acid-alcohol for decolorization, but they differ in how the dye penetrates the mycobacterial cell wall. Ziehl-Neelsen uses heat (the hot technique), the slide is steamed to drive the dye through the waxy cell wall. Kinyoun's cold technique achieves penetration without heat by increasing the concentration of both carbolfuchsin and phenol and incorporating a wetting agent (Triton X-100 or similar). The results are equivalent. Kinyoun is preferred where open flames are unsafe or inconvenient, and for partial acid-fast organisms (Nocardia, Cryptosporidium) where lower decolorizer concentrations are needed.\u003C\u002Fp>",[146,205],"mycobacteria",{"slug":207,"title":208,"description":209,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":210,"lastUpdatedDate":133,"draft":46,"category":134,"image":42,"faq":211,"tags":221},"auramine-rhodamine-fluorochrome-staining-principle-procedure-results-limitations","Auramine-Rhodamine Fluorochrome Staining: Principle, Procedure, and Results","Auramine-rhodamine is a WHO-recommended fluorochrome stain for detecting acid-fast bacilli, which is more sensitive than Ziehl-Neelsen and faster to screen. Learn the Truant method procedure, results grading, and when to confirm with ZN staining.","2015-04-03",[212,215,218],{"question":213,"answer":214},"Why is auramine-rhodamine staining more sensitive than Ziehl-Neelsen for detecting acid-fast bacilli?","Auramine-rhodamine allows smear screening at 250x or 400x magnification — compared to 1,000x oil immersion required for ZN staining. At lower magnification, a much larger area of the slide can be examined per unit time (3-5 minutes vs 15-20 minutes per slide). This means more of the smear is examined, increasing the chance of detecting paucibacillary specimens. Studies consistently show auramine-rhodamine detects approximately 10% more positive cases than ZN in direct smear microscopy, which is why WHO recommends it as the preferred method where fluorescence microscopy is available.",{"question":216,"answer":217},"What is the two-step workflow for auramine-rhodamine results?","Positive auramine-rhodamine results should be confirmed by ZN staining of the same slide, as fluorescence artefacts (dust, fibres, non-AFB structures) can occasionally give false-positive fluorescence. Negative auramine-rhodamine results require examination of the minimum required number of fields before reporting — at 200-250x this is typically 30-100 fields. In high-suspicion patients, a negative fluorochrome result should prompt ZN confirmation and repeat specimen collection, as the minimum detection threshold for smear microscopy (approximately 5,000-10,000 AFB\u002FmL) means culture is more sensitive than any smear method.",{"question":219,"answer":220},"Can auramine-rhodamine staining detect organisms other than mycobacteria?","Yes. A modified fluorochrome method using a weaker decolouriser (0.5% sulphuric acid instead of 3% acid-alcohol) detects partially acid-fast organisms including Cryptosporidium parvum, Cyclospora cayetanensis, and Isospora belli oocysts in stool specimens, and Nocardia species in respiratory or wound specimens. These organisms share a partial acid-fast property with mycobacteria. The oocysts appear as bright yellow-orange fluorescent structures against a dark background. This application requires the modified decolouriser — the standard 3% acid-alcohol used for TB smears will over-decolourise these weakly acid-fast organisms.",[146,205],{"slug":223,"title":224,"description":225,"seoTitle":226,"seoDescription":227,"author":43,"createdDate":228,"lastUpdatedDate":45,"draft":46,"category":229,"image":42,"faq":230,"tags":255},"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","culture-media",[231,234,237,240,243,246,249,252],{"question":232,"answer":233},"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":235,"answer":236},"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":238,"answer":239},"\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":241,"answer":242},"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":244,"answer":245},"\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":247,"answer":248},"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":250,"answer":251},"\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":253,"answer":254},"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>",[256],"bacterial-culture-media",{"enabled":258,"threads":259,"total":260},true,[],0,[262,268,275,281,286,291,297,302,308,311,318],{"slug":263,"name":43,"description":264,"image":265,"body":266,"postCount":267},"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":269,"name":270,"description":271,"image":272,"body":273,"postCount":274},"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":276,"name":175,"description":277,"image":278,"body":279,"postCount":280},"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":282,"name":78,"description":277,"image":283,"body":284,"postCount":285},"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":287,"name":288,"description":277,"image":42,"body":289,"postCount":290},"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":292,"name":293,"description":294,"image":42,"body":295,"postCount":296},"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":298,"name":299,"description":300,"image":42,"body":42,"postCount":301},"guest-author","Guest Author","Guest Author \u002F Contributor",1,{"slug":303,"name":304,"description":277,"image":305,"body":306,"postCount":307},"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":309,"name":310,"description":300,"image":42,"body":42,"postCount":301},"dr-poonam-acharya","Dr. Poonam Acharya",{"slug":312,"name":313,"description":314,"image":315,"body":316,"postCount":317},"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.*",54,{"slug":319,"name":320,"description":321,"image":322,"body":323,"postCount":301},"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.",[325,332,338,343,348,353,356,360,364,369,373,378,382,387,391,395,399,403,408,413,417,421,425,430,434,438,442,446,451,456,460,464,468,471,475,479,483,487,491,495,499,503,507,511,515,519,522,526,531,535,539,543,547,550,554,558,562,566,570,574,578,582,586,590,594,598,602,606,609,613],{"slug":326,"name":327,"description":328,"image":329,"body":330,"postCount":331},"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":333,"name":334,"description":335,"image":42,"body":336,"postCount":337},"microscopy","Microscopy","Microscope types, components, and microscopy techniques","These are list of blog posts related to microscopy. ",12,{"slug":339,"name":340,"description":341,"image":42,"body":42,"postCount":342},"gram-positive-cocci","Gram-Positive Cocci","Staphylococcus, Streptococcus, Enterococcus, Micrococcus — organisms, diseases, and identification tests",11,{"slug":344,"name":345,"description":346,"image":42,"body":42,"postCount":347},"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":349,"name":350,"description":351,"image":42,"body":42,"postCount":352},"gram-positive-rods","Gram-Positive Rods","Bacillus, Clostridium, Listeria, Corynebacterium, Actinomyces and related organisms",8,{"slug":205,"name":354,"description":355,"image":42,"body":42,"postCount":342},"Mycobacteria","Mycobacterium tuberculosis, leprosy, atypical mycobacteria, and acid-fast organism diagnosis",{"slug":357,"name":358,"description":359,"image":42,"body":42,"postCount":342},"anaerobic-bacteriology","Anaerobic Bacteriology","Anaerobic organisms, anaerobic culture methods, and anaerobic infection diagnosis",{"slug":361,"name":362,"description":363,"image":42,"body":42,"postCount":337},"enterobacteriaceae","Enterobacteriaceae","Identification, differentiation, and clinical significance of Enterobacteriaceae family members",{"slug":365,"name":366,"description":367,"image":42,"body":42,"postCount":368},"spirochetes","Spirochetes","Treponema, Leptospira, Borrelia and spirochetal infections",7,{"slug":370,"name":371,"description":372,"image":42,"body":42,"postCount":331},"food-microbiology","Food Microbiology","Food-borne pathogens, food safety, spoilage, and preservation",{"slug":374,"name":375,"description":376,"image":42,"body":42,"postCount":377},"antimicrobial-susceptibility-testing","Antimicrobial Susceptibility Testing","Methods for testing antibiotic susceptibility in clinical microbiology",21,{"slug":379,"name":380,"description":381,"image":42,"body":42,"postCount":352},"antimicrobials-moa-amr","Antimicrobials (MOA & AMR)","Mechanisms, detection, and clinical significance of antimicrobial resistance",{"slug":383,"name":384,"description":385,"image":42,"body":42,"postCount":386},"sterilization-disinfection","Sterilization and Disinfection","Methods of sterilization and disinfection in healthcare and laboratory settings",10,{"slug":72,"name":388,"description":389,"image":42,"body":42,"postCount":390},"Specimen Collection and Transport","Collection, handling, and transport of clinical specimens for microbiological testing",27,{"slug":392,"name":393,"description":394,"image":42,"body":42,"postCount":377},"bacterial-structure-physiology","Bacterial Structure and Physiology","Bacterial cell structure, growth, physiology, and environmental factors affecting growth",{"slug":396,"name":397,"description":42,"image":42,"body":398,"postCount":290},"horizontal-gene-transfer","Horizontal Gene Transfer","Articles related to **Horizontal Gene Transfer**",{"slug":400,"name":401,"description":42,"image":42,"body":402,"postCount":386},"chromatography","Chromatography","Information about chromatographic techniques.",{"slug":404,"name":405,"description":406,"image":42,"body":407,"postCount":368},"electrophoresis","Electrophoresis","Information about Electrophoresis Techniques ","Detailed information  about Electrophoresis Techniques ",{"slug":409,"name":410,"description":411,"image":42,"body":412,"postCount":290},"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":414,"name":415,"description":416,"image":42,"body":42,"postCount":290},"bacteriophage","Bacteriophage","Description about Bacteriophage.",{"slug":418,"name":419,"description":420,"image":42,"body":42,"postCount":290},"malaria","Malaria","It is the collections of articles regarding malarial disease. ",{"slug":422,"name":423,"description":424,"image":42,"body":42,"postCount":290},"anaerobic-culture-techniques","Anaerobic Culture Techniques","Posts related with Anaerobic Culture Techniques.",{"slug":426,"name":427,"description":428,"image":42,"body":42,"postCount":429},"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":431,"name":432,"description":433,"image":42,"body":42,"postCount":368},"biosafety-levels","Biosafety levels ","Articles related to Biosafety Levels",{"slug":435,"name":436,"description":437,"image":42,"body":42,"postCount":347},"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":439,"name":440,"description":441,"image":42,"body":42,"postCount":290},"pipette","Pipette","Posts related with Pipette. ",{"slug":443,"name":444,"description":445,"image":42,"body":42,"postCount":352},"bacteriology-mcqs","Bacteriology MCQs","This sections lists MCQs in Bacteriology.",{"slug":447,"name":448,"description":449,"image":42,"body":42,"postCount":450},"parasitology-mcqs","Parasitology MCQs","This section lists MCQs in Parasitology.",2,{"slug":452,"name":453,"description":454,"image":42,"body":42,"postCount":455},"virology-mcqs","Virology MCQs","This is the collections of Multiple Choice Questions in Virology.",4,{"slug":457,"name":458,"description":459,"image":42,"body":42,"postCount":347},"mcqs-in-microbiology","MCQs in Microbiology","This section lists the collections of Multiple Choice Questions in General Microbiology Topics. ",{"slug":461,"name":462,"description":463,"image":42,"body":42,"postCount":352},"immunology-mcqs","Immunology MCQs","In this section; we are posting collections of Multiple Choice Questions about Immunology. ",{"slug":465,"name":466,"description":467,"image":42,"body":42,"postCount":296},"microbial-curiosities","Microbial Curiosities","In this clusters, we are posting interesting and unique information about Microorganisms. ",{"slug":256,"name":469,"description":470,"image":42,"body":42,"postCount":377},"Bacterial Culture Media","Posts related to Bacterial Culture Media. ",{"slug":472,"name":473,"description":474,"image":42,"body":42,"postCount":290},"fungal-culture-media","Fungal Culture Media","Posts related to Fungal Culture Media.",{"slug":476,"name":477,"description":478,"image":42,"body":42,"postCount":347},"motility-test","Motility Test","This lists the procedure regarding various tests methods for bacterial motility.",{"slug":480,"name":481,"description":482,"image":42,"body":42,"postCount":386},"bacterial-enumeration","Bacterial enumeration","These posts are related to isolation and enumeration of bacteria. ",{"slug":484,"name":485,"description":486,"image":42,"body":42,"postCount":450},"gram-positive-coccobacillus","Gram-positive coccobacillus","List of Gram Positive Coccobacilli",{"slug":488,"name":489,"description":490,"image":42,"body":42,"postCount":455},"dimorphic-fungi","Dimorphic Fungi","This is about various dimorphic fungi. ",{"slug":492,"name":493,"description":494,"image":42,"body":42,"postCount":368},"bacterial-classification","Bacterial Classification","These posts are related with various approaches used for the classification of Bacteria. ",{"slug":496,"name":497,"description":498,"image":42,"body":42,"postCount":347},"immunofluorescence","Immunofluorescence ","Various Tests related to Immunofluorescence ",{"slug":500,"name":501,"description":502,"image":42,"body":42,"postCount":296},"antibody-mediated-immunity","Antibody-mediated Immunity","This clusters links the articles that are sharing insights about Antibody-mediated immunity. ",{"slug":504,"name":505,"description":506,"image":42,"body":42,"postCount":368},"hypersensitivity","Hypersensitivity","Articles related to Hypersensitivity.",{"slug":508,"name":509,"description":42,"image":42,"body":42,"postCount":510},"haemophilus","Haemophilus",3,{"slug":512,"name":513,"description":514,"image":42,"body":42,"postCount":455},"sexually-transmitted-infections-stis","Sexually transmitted infections (STIs)","This is the clusters of infections that are transmitted sexually. ",{"slug":516,"name":517,"description":518,"image":42,"body":42,"postCount":337},"adaptive-immunity","Adaptive Immunity","Blog posts related to B Cell Immunity and T Cell Immunity.",{"slug":170,"name":520,"description":521,"image":42,"body":42,"postCount":331},"Fungal Diagnostics","Various methods used for the Diagnosis of Fungal Infections. ",{"slug":523,"name":524,"description":525,"image":42,"body":42,"postCount":347},"laboratory-storage-and-preservation","Laboratory Storage and Preservation","Articles about Laboratory Storage of Antimicrobial Disk, Test organisms and Equipment used for this process. ",{"slug":527,"name":528,"description":529,"image":42,"body":530,"postCount":290},"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":532,"name":533,"description":534,"image":42,"body":42,"postCount":352},"laboratory-glassware","Laboratory Glassware","Posts about Laboratory Glassware. ",{"slug":536,"name":537,"description":538,"image":42,"body":42,"postCount":290},"helminths","Helminths","In this section, we are covering properties, life cycle, pathogenesis and laboratory diagnosis of Helminths\u002FHelminthic infestations. ",{"slug":540,"name":541,"description":542,"image":42,"body":42,"postCount":290},"protozoan-parasite","Protozoan Parasite","In this cluster, we are covering protozoan parasites. ",{"slug":544,"name":545,"description":546,"image":42,"body":42,"postCount":301},"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":146,"name":548,"description":549,"image":42,"body":42,"postCount":386},"Bacterial Staining Technique","Lists of various staining techniques that are used to stain bacteria. ",{"slug":551,"name":552,"description":553,"image":42,"body":42,"postCount":285},"enzyme-tests","Enzyme Tests","\u003Cp>Various Biochemical Test that are based on enzymatic activity of the microorganisms. \u003C\u002Fp>",{"slug":555,"name":556,"description":557,"image":42,"body":42,"postCount":342},"carbohydrate-utilization","Carbohydrate Utilization","\u003Cp>Various biochemical tests which are related to Carbohydrate fermentation or Utilization\u003C\u002Fp>",{"slug":559,"name":560,"description":561,"image":42,"body":42,"postCount":347},"susceptibility-based-id","Susceptibility-based ID","\u003Cp>These are susceptibility based identification test such as optochin sensitivity, bacitracin sensitivity etc. \u003C\u002Fp>",{"slug":563,"name":564,"description":565,"image":42,"body":42,"postCount":455},"microbial-metabolism","Microbial Metabolism","\u003Cp>Tests about Microbial Metabolism. \u003C\u002Fp>",{"slug":567,"name":568,"description":569,"image":42,"body":42,"postCount":352},"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":571,"name":572,"description":573,"image":42,"body":42,"postCount":510},"atypical-pneumonia","Atypical Pneumonia","\u003Cp>Organisms responsible for Atypical Pneumonia. \u003C\u002Fp>",{"slug":575,"name":576,"description":577,"image":42,"body":42,"postCount":347},"antigen","Antigen","\u003Cp>Various articles related to Antigens.\u003C\u002Fp>",{"slug":579,"name":580,"description":581,"image":42,"body":42,"postCount":368},"innate-immunity","Innate Immunity","\u003Cp>Articles related to Innate Immunity. \u003C\u002Fp>",{"slug":583,"name":584,"description":585,"image":42,"body":42,"postCount":455},"respiratory-tract-infection","Respiratory Tract Infection","\u003Cp>In this cluster, you can see various etiological agents that causes respiratory tract infection. \u003C\u002Fp>",{"slug":587,"name":588,"description":589,"image":42,"body":42,"postCount":347},"torch-infection","TORCH Infection","\u003Cp>In this section; you can find articles related with TOCH infection. \u003C\u002Fp>",{"slug":591,"name":592,"description":593,"image":42,"body":42,"postCount":368},"microbiology-for-beginners","Microbiology for Beginners","\u003Cp>These articles are very basic articles, which will share general concepts in Microbiology. \u003C\u002Fp>",{"slug":595,"name":596,"description":597,"image":42,"body":42,"postCount":290},"dna-replication","DNA Replication","\u003Cp>Articles related to DNA and Replication of DNA. \u003C\u002Fp>",{"slug":599,"name":600,"description":601,"image":42,"body":42,"postCount":368},"genetic-code","Genetic Code","\u003Cp>Articles related to Genetic Code.\u003C\u002Fp>",{"slug":603,"name":604,"description":605,"image":42,"body":42,"postCount":347},"molecular-technique","Molecular Technique","\u003Cp>Posts related to Molecular Techniques. \u003C\u002Fp>",{"slug":607,"name":608,"description":42,"image":42,"body":42,"postCount":301},"colorimetric-assay","Colorimetric Assay ",{"slug":610,"name":611,"description":612,"image":42,"body":42,"postCount":347},"pharmaceutical-microbiology","Pharmaceutical Microbiology","\u003Cp>Various articles related to Pharmaceutical Microbiology\u003C\u002Fp>",{"slug":614,"name":615,"description":42,"image":42,"body":42,"postCount":510},"blood-and-immune-cells","Blood and Immune Cells"]