[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"$fxLN3MUwXCdr5RPjwZYIDpOj8CHyjOmngWTgoKXPtZbg":3,"$fROViLPqyYZ4d6052ec59z7tn0TffqB8KSevsGyqkrMI":36,"$f3Ft0rKFJHppdzE-vuveecxx1BUcg9iOlMLtyzf_MJDg":308,"$fucxFBm2ZjZfGSdmdRaSNGBI_F0jJme4f0GTvzUhQfL8":371},[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":44,"draft":45,"category":46,"image":42,"body":47,"faq":48,"commentsClosed":45,"tags":70,"related":72,"comments":304},"wound-swab-collection-transport-lab-diagnosis","Wound Swab: Collection, the Levine Technique, and When Not to Swab","\u003Cp>Why an open-wound swab is only as good as the technique, how the Levine method samples deep fluid instead of surface flora, how to tell colonization from infection, and when tissue biopsy or aspirate is the right specimen instead.\u003C\u002Fp>",null,"Acharya Tankeshwar","2026-08-14",false,"bacteriology","An open wound is always covered in bacteria. That single fact makes the wound swab one of the most misread specimens in the lab, because a swab dragged across the surface of any chronic ulcer will grow something, and that something is **usually colonizing flora,** **not the cause of infection**. The value of a wound swab depends almost entirely on two decisions made before the swab is sent: is this wound actually infected, and was it sampled in a way that reaches the infecting organisms rather than the surface colonizers.\n\nThis article is about open wounds, ulcers, surgical sites, burns, and diabetic foot ulcers. For a closed abscess or a collection you can aspirate, the aspirate is the better specimen and the [pus sample article](https:\u002F\u002Fmicrobeonline.com\u002Fpus-sample-collection-staining-culture\u002F) covers that. **The rule is**: if you can aspirate pus or take tissue, do that. Swab only when you cannot.\n\n## First decision: is the wound infected, or just colonized?\n\n**Every open wound is colonized.** Colonization is bacteria living on the wound surface without causing harm. Infection is bacteria invading viable tissue and provoking a host response. A culture cannot tell you which one you are looking at; only the clinical picture can. **So the first question is not what to swab, but whether to swab at all.**\n\nSample a wound for culture only when it is clinically infected or is chronic and failing to heal. Signs that point to infection rather than colonization include increasing pain, spreading redness (erythema), warmth, swelling, purulent discharge, a foul smell, and a wound that is deteriorating or not healing as expected. Swabbing a clean, healing wound produces a list of colonizers that can trigger unnecessary antibiotics and drive resistance.\n\nThe core principle: **a wound swab answers \"which organisms are causing this infection,\" not \"is this wound infected.\" The clinician decides infection; the swab only names the organism.**\n\n## Second decision: sample the right way (the Levine technique)\n\nIf the wound is infected and no tissue or aspirate can be taken, the swab must be done well. The difference between a good and a useless wound swab is technique, and the evidence-based method is the Levine technique.\n\n**Before sampling:**\n\n- Debride the wound if appropriate, and clean the surface thoroughly with sterile saline (not an antiseptic, which would kill the organisms). Remove all superficial slough and exudate. This step separates surface colonizers from the infecting organisms underneath.\n\n\u003Cfigure>\n\u003Cimg src=\"https:\u002F\u002Fassets.microbeonline.com\u002Fblogs\u002Fwound-swab-surface-vs-levine.png\" alt=\"A surface swab samples the slough and colonizing flora on top of the wound, giving a misleading result. The Levine technique cleans the surface first, then presses and rotates the swab over 1 cm² of viable tissue to express fluid from the infected depth, recovering the true infecting organisms with quality close to a tissue biopsy.\" width=\"2720\" height=\"1840\" draggable=\"false\" contenteditable=\"false\">\u003Cfigcaption>A surface swab samples the slough and colonizing flora on top of the wound, giving a misleading result. The Levine technique cleans the surface first, then presses and rotates the swab over 1 cm² of viable tissue to express fluid from the infected depth, recovering the true infecting organisms with quality close to a tissue biopsy.\u003C\u002Ffigcaption>\n\u003C\u002Ffigure>\n\n### **The Levine technique:**\n\n- Rotate the swab over a 1 cm² area of clean, viable tissue near the center of the wound.\n- Press firmly enough to express fluid from the deep tissue, for about 5 seconds.\n- **The pressure is the point:** it draws up deep exudate, so the swab samples the tissue, not just the surface.\n\nDone this way, a Levine swab recovers organisms and colony counts close to what a [tissue biopsy](https:\u002F\u002Fmicrobeonline.com\u002Ftissue-biopsy-specimen-collection-transport\u002F) would show. Compare this with the older Z-technique (zig-zagging the swab across the whole wound surface), which samples more surface flora and performs worse.\n\n**What to avoid:**\n\n- Do not swab dry, necrotic tissue, slough, or pus crust. These carry colonizers, not the invading organisms.\n- Do not roll the swab across the wound surface without cleaning first. That is the classic error that grows contaminants.\n- Do not use an antiseptic to clean the wound just before swabbing; it suppresses the very organisms you want to grow. Use sterile saline.\n\n## When a swab is the wrong specimen: tissue biopsy and aspirate\n\n**The swab sits at the bottom of the specimen hierarchy for wounds.** Better specimens exist and should be used when the wound and the situation allow.\n\n| Rank | Specimen | When to use it | Why it is better or worse |\n| --- | --- | --- | --- |\n| 1 (best) | Tissue biopsy from the wound base or advancing margin | Deep, chronic, or serious infection (diabetic foot, osteomyelitis, non-healing ulcer) | Samples invading organisms in tissue; the reference standard |\n| 1 (equal) | Pus or fluid aspirate | Any closed collection or pocket of pus | Volume, protects anaerobes, avoids surface flora ([see the pus sample article](https:\u002F\u002Fmicrobeonline.com\u002Fpus-sample-collection-staining-culture\u002F)) |\n| 2 (acceptable) | Levine-technique swab | Infected wound where tissue or aspirate cannot be obtained | Near-biopsy quality if done correctly after cleaning |\n| 3 (poor) | Surface swab, no cleaning | Should be avoided | Grows colonizers, misleads treatment |\n\n**Diabetic foot ulcers and deep or non-healing wounds deserve tissue, not a surface swab.** A properly performed Levine swab is a reasonable alternative when biopsy is not possible, but a superficial swab of a diabetic foot ulcer is close to worthless and can send treatment in the wrong direction.\n\n**Sample the advancing margin or the base, not the middle of old slough.** Wherever you sample, target viable infected tissue at the edge or depth of the lesion. In a burn, organisms are unevenly distributed, so sample several areas.\n\n### Anaerobes and the swab problem\n\nMany wound infections, especially deep, chronic, foul-smelling, or bite wounds, involve anaerobes. Anaerobes survive poorly on a swab exposed to air. This is another reason tissue or aspirate beats a swab: a capped aspirate or a tissue sample in the right transport protects anaerobes far better. If anaerobes are suspected and only a swab is possible, use an anaerobic transport swab and get it to the lab fast.\n\n## Transport\n\n- Deliver the swab to the lab as soon as possible, ideally within 30 minutes, at room temperature.\n- If a delay is expected, place the swab in [Amies transport medium](https:\u002F\u002Fmicrobeonline.com\u002Famies-transport-medium\u002F) so it does not dry out; [a liquid-based swab (eSwab)](https:\u002F\u002Fmicrobeonline.com\u002Feswab-types-and-uses\u002F) is a good option because one collection can serve Gram stain and culture.\n- Tissue for culture goes in a sterile container with a little sterile saline to keep it moist. **Never put tissue for culture in formalin, which kills everything and makes culture impossible** (formalin is for histopathology, not microbiology).\n- [Refrigeration](https:\u002F\u002Fmicrobeonline.com\u002Flaboratory-refrigerator-temperature-and-storage\u002F) is acceptable for routine wound swabs if delayed, but not when anaerobes or fastidious organisms are suspected; keep those at room temperature and transport quickly.\n\n## Processing Wound Swab in Microbiology Lab\n\nEvery open wound is colonized, so the laboratory's task is to judge whether what grows represents infection or just normal flora. The Gram stain and the pattern of growth are the tools it uses to do that.\n\n**Direct examination.** The [Gram stain](https:\u002F\u002Fmicrobeonline.com\u002Fgram-staining-principle-procedure-results\u002F) is genuinely informative here and helps to differentiate colonization-verus-infection:\n\n- **The organisms present** (their Gram reaction and morphology), which gives an early clue to the likely pathogen.\n- The host response, meaning the **number of pus cells (neutrophils).** **Abundant pus cells with a single predominant organism point toward infection**, while scanty pus cells with many different organisms point toward colonization or contamination. The presence of squamous epithelial cells suggests surface or skin contamination rather than a deep sample.\n\n**Culture media.** The swab is inoculated onto media that cover the usual wound pathogens:\n\n- [Blood agar](https:\u002F\u002Fmicrobeonline.com\u002Fblood-agar-composition-preparation-uses-and-types-of-hemolysis\u002F) and [MacConkey agar](https:\u002F\u002Fmicrobeonline.com\u002Fmacconkey-agar-mac-composition-preparation-uses-and-colony-characteristics\u002F) for common aerobes and gram-negative bacilli.\n- An anaerobic medium and an enrichment broth (such as [thioglycollate](https:\u002F\u002Fmicrobeonline.com\u002Fthioglycollate-broth\u002F)) for deep, necrotic, chronic, or bite wounds, where anaerobes are common. As noted above, a swab recovers anaerobes poorly, so tissue or aspirate is preferred when anaerobes matter.\n- [Sabouraud agar](https:\u002F\u002Fmicrobeonline.com\u002Fsabouraud-dextrose-agar-sda-principle-composition-uses-colony-morphology\u002F) where a fungal wound infection is suspected.\n\n**Incubation.** Plates are incubated at 35 to 37 degrees C for 24 to 48 hours, with anaerobic cultures held longer.\n\n**Reading and interpretation.** This is where the swab's limitations show, and where the interpretation connects back to the collection decision:\n\n- Growth is assessed semiquantitatively (light, moderate, heavy) and against the Gram stain. A heavy, near-pure growth of a recognized pathogen with abundant pus cells supports infection.\n- A light, mixed growth of several organisms, especially skin and environmental flora, usually reflects colonization or contamination rather than infection.\n- Because a surface swab so often grows colonizers, the result is always read together with the clinical picture. A wound that is clinically infected but grows only mixed flora may have been sampled poorly (surface rather than depth).\n- The laboratory should report the likely pathogen and its significance rather than an undifferentiated list of every organism recovered, since reporting colonizers can drive unnecessary antibiotics.\n\n## **Identification and antimicrobial susceptibility testing**\n\nFollowing organisms are commonly isolated from wounds, and the first approach for their identification is:\n\n- ***Staphylococcus aureus***: gram-positive cocci in clusters, catalase and coagulase positive; the commonest wound pathogen, including methicillin-resistant strains. See the [*Staphylococcus aureus* article](https:\u002F\u002Fmicrobeonline.com\u002Fstaphylococcus-aureusdisease-properties-pathogenesis-and-laboratory-diagnosis\u002F).\n- ***Streptococcus pyogenes* (Group A) and other beta-hemolytic streptococci**: gram-positive cocci in chains, beta-hemolytic; important in spreading soft-tissue infection. See the [*Streptococcus pyogenes* article](https:\u002F\u002Fmicrobeonline.com\u002Fstreptococcus-pyogens-gas-common-characteristics-virulence-factors-diseases-key-tests\u002F).\n- ***Pseudomonas aeruginosa***: oxidase-positive, non-lactose-fermenting gram-negative rod with a green pigment and characteristic smell; common in burns and chronic wounds. See the [*Pseudomonas aeruginosa* article](https:\u002F\u002Fmicrobeonline.com\u002Fpseudomonas-aeruginosa-infection-mortality-pathogenesis-and-diagnosis\u002F).\n- **Enterobacterales (*Escherichia coli*, *Klebsiella*, *Proteus*)**: gram-negative bacilli separated on MacConkey by lactose fermentation; *Proteus* swarms on blood agar. Read about [*Enterobacteriaceae* in this article](https:\u002F\u002Fmicrobeonline.com\u002Fenterobacteriaceae\u002F).\n- **Anaerobes (*Bacteroides*, *Clostridium*, anaerobic cocci)**: common in deep, necrotic, and bite wounds; grown on anaerobic media. Read more about [anaerobic culture media in this article](https:\u002F\u002Fmicrobeonline.com\u002Fcommonly-used-anaerobic-media-for-anaerobic-bacteriology\u002F).\n\n## How to Remember\n\n**Every wound is colonized; the clinician decides infection.** A swab names the organism, it does not diagnose infection. Swab only wounds that are clinically infected or chronic and non-healing.\n\n**Clean first, then press: the Levine rule.** Debride and rinse with sterile saline, then rotate the swab over 1 cm² of viable tissue with firm pressure to express deep fluid. The pressure is what turns a surface smear into a real sample.\n\n**Tissue beats swab, aspirate beats swab.** If you can take tissue or aspirate pus, do it, especially in diabetic foot and deep or chronic wounds.\n\n**Sample the edge or the base, not the slough.** Viable infected tissue at the advancing margin holds the invading organisms. Dead slough and crust hold colonizers.\n\n**Saline to clean, never antiseptic.** Antiseptic before swabbing kills the organisms you are trying to grow. Clean with sterile saline only.\n\n**Formalin is for the pathologist, not the microbiologist.** Tissue for culture goes in saline. Formalin kills everything.\n\n## Key exam facts in one table\n\n| Point | Fact |\n| --- | --- |\n| When to swab | Only clinically infected or chronic non-healing wounds |\n| Colonization vs infection | Every open wound is colonized; clinician decides infection |\n| Best specimen | Tissue biopsy (base or advancing margin) |\n| Equal best | Pus or fluid aspirate (see pus sample page) |\n| Acceptable swab method | Levine technique |\n| Levine technique | Rotate over 1 cm² viable tissue, firm pressure, \\~5 s, expresses deep fluid |\n| Inferior swab method | Z-technique (surface zig-zag) |\n| Clean the wound with | Sterile saline (never antiseptic before swabbing) |\n| Where to sample | Advancing margin or base; several areas in burns |\n| Do not swab | Dry necrotic tissue, slough, crust |\n| Diabetic foot ulcer | Prefer tissue biopsy; superficial swab misleads |\n| Anaerobes | Poorly recovered on a swab; prefer tissue or aspirate |\n| Transport | Amies or liquid swab, room temperature, prompt (within 30 min) |\n| Tissue transport | Sterile saline; NEVER formalin |\n\n## Where Students Get Confused\n\n**\"The swab grew bacteria, so the wound is infected, right?\"** Not necessarily. Every open wound is colonized, so a swab almost always grows something. Whether that represents infection is a clinical judgment based on signs like spreading redness, pain, purulence, and failure to heal. The swab names the organism; it does not diagnose infection.\n\n**\"A swab is a swab, so why does the technique matter so much?\"** Because a swab rolled across an uncleaned surface samples colonizers, while a Levine swab, taken after cleaning and with firm pressure over 1 cm² of viable tissue, expresses deep fluid and recovers the actual infecting organisms.\n\n**\"Why clean with saline and not an antiseptic before swabbing?\"** Because antiseptic kills the organisms you are trying to identify. Cleaning removes surface colonizers so you can reach the infecting organisms underneath; sterile saline does this without suppressing the culture.\n\n**\"For a diabetic foot ulcer, is a surface swab good enough?\"** No. Diabetic foot and other deep or chronic wounds deserve a tissue biopsy, because the infecting organisms are in the tissue. A properly performed Levine swab is an acceptable alternative when biopsy is not possible.\n\n**\"The culture missed the anaerobes we expected, why?\"** Anaerobes survive poorly on a swab exposed to air. A tissue sample or a capped aspirate protects them far better. When anaerobes are likely (deep, chronic, foul-smelling, or bite wounds), avoid a plain swab if tissue or aspirate can be obtained.\n\n**\"Can I send the tissue in the same formalin pot as the histology sample?\"** No. Formalin kills all organisms and makes culture impossible. Tissue for culture goes in a sterile container with a little saline; formalin is only for histopathology.\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.",[49,52,55,58,61,64,67],{"question":50,"answer":51},"\u003Cp>When should a wound be swabbed for culture?\u003C\u002Fp>","\u003Cp>Only when it is clinically infected or chronic and failing to heal. Every open wound is colonized, so swabbing a clean, healing wound just grows colonizers and can lead to unnecessary antibiotics. Signs of infection, such as spreading redness, increasing pain, purulence, and non-healing, guide the decision.\u003C\u002Fp>",{"question":53,"answer":54},"\u003Cp>What is the Levine technique and why is it preferred?\u003C\u002Fp>","\u003Cp>The Levine technique involves rotating the swab over a 1 cm² area of clean, viable tissue with firm pressure for about 5 seconds, which expresses fluid from deep tissue. This samples the infecting organisms rather than surface flora and recovers results close to a tissue biopsy, outperforming the surface Z-technique.\u003C\u002Fp>",{"question":56,"answer":57},"\u003Cp>Why must the wound be cleaned with saline before swabbing?\u003C\u002Fp>","\u003Cp>Cleaning with sterile saline removes surface colonizers so the swab reaches the infecting organisms underneath. An antiseptic must not be used just before swabbing, because it suppresses the organisms you are trying to grow.\u003C\u002Fp>",{"question":59,"answer":60},"\u003Cp>When is a tissue biopsy or aspirate better than a swab?\u003C\u002Fp>","\u003Cp>For deep, chronic, or serious infections such as diabetic foot ulcers and osteomyelitis, and for any closed collection of pus. Tissue biopsy is the reference standard, and an aspirate protects anaerobes and avoids surface flora. A swab is the fallback when neither can be obtained.\u003C\u002Fp>",{"question":62,"answer":63},"\u003Cp>Why are anaerobes often missed on a wound swab?\u003C\u002Fp>","\u003Cp>Anaerobes survive poorly on a swab exposed to air. A tissue sample or a capped aspirate protects them much better. When anaerobes are suspected, avoid a plain swab if tissue or aspirate can be taken, or use an anaerobic transport swab.\u003C\u002Fp>",{"question":65,"answer":66},"\u003Cp>How should wound tissue for culture be transported?\u003C\u002Fp>","\u003Cp>In a sterile container with a little sterile saline to keep it moist. Never place tissue for culture in formalin, which kills all organisms; formalin is only for histopathology.\u003C\u002Fp>",{"question":68,"answer":69},"\u003Cp>Where in the wound should the sample be taken?\u003C\u002Fp>","\u003Cp>From viable infected tissue at the advancing margin or the base of the wound, not from dead slough or crust. In burns, sample several areas because organisms are unevenly distributed.\u003C\u002Fp>",[71],"specimen-collection-transport",[73,102,130,155,193,216,237,271],{"slug":74,"title":75,"description":76,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":77,"lastUpdatedDate":78,"draft":45,"category":46,"image":42,"faq":79,"tags":101},"pus-sample-collection-staining-culture","Pus Sample: Collection, Processing, Staining and Culture","\u003Cp>Why an abscess aspirate beats a swab, the correct fallback when you cannot aspirate, how much pus to collect, how to protect anaerobes in transport, and how the lab stains and cultures a pus sample.\u003C\u002Fp>","2019-02-07","2026-08-12",[80,83,86,89,92,95,98],{"question":81,"answer":82},"\u003Cp>Why is an aspirate preferred over a swab for pus?\u003C\u002Fp>","\u003Cp>An aspirate provides more sample, keeps air out so anaerobes survive, and avoids the skin surface where colonizing flora live. A swab loses on all three counts, which is why an aspirate from an undrained abscess is the ideal specimen.\u003C\u002Fp>",{"question":84,"answer":85},"\u003Cp>What do I do when I cannot get an aspirate?\u003C\u002Fp>","\u003Cp>Take two swabs from the depth of the wound after clearing superficial debris, one for culture and one for the Gram smear. If only one swab is available, inoculate the culture media first, then make the smear from the same swab.\u003C\u002Fp>",{"question":87,"answer":88},"\u003Cp>How much pus should be collected?\u003C\u002Fp>","\u003Cp>Aim for 1 to 5 mL. Larger volumes keep anaerobes viable longer and give the lab enough material for smear, culture, and any special testing.\u003C\u002Fp>",{"question":90,"answer":91},"\u003Cp>Is a swab in Amies medium enough when anaerobes are suspected?\u003C\u002Fp>","\u003Cp>No. Amies prevents the swab from drying but is not a true anaerobic transport method, so strict anaerobes still die. Use a capped syringe aspirate with the air expelled, or tissue in an anaerobic transport system.\u003C\u002Fp>",{"question":93,"answer":94},"\u003Cp>Should a pus sample be refrigerated if transport is delayed?\u003C\u002Fp>","\u003Cp>For routine aerobic culture, refrigeration is better than leaving the sample at room temperature. Do not refrigerate if anaerobes or fastidious organisms are suspected, because cold lowers their recovery. For those, transport quickly at room temperature, and remember that a capped aspirate protects anaerobes far better than any swab.\u003C\u002Fp>",{"question":96,"answer":97},"\u003Cp>How does the Gram stain distinguish colonization from infection?\u003C\u002Fp>","\u003Cp>By the number of pus cells. Few or no polymorphonuclear cells with abundant skin flora suggests colonization. Moderate to many pus cells suggests true infection.\u003C\u002Fp>",{"question":99,"answer":100},"\u003Cp>Is Cary-Blair medium used for pus samples?\u003C\u002Fp>","\u003Cp>No. Cary-Blair is for enteric (stool) specimens. If a pus swab must be held during a transport delay, Amies is the medium to use.\u003C\u002Fp>",[71],{"slug":103,"title":104,"description":105,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":106,"lastUpdatedDate":44,"draft":45,"category":46,"image":42,"faq":107,"tags":129},"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>","2026-08-15",[108,111,114,117,120,123,126],{"question":109,"answer":110},"\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":112,"answer":113},"\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":115,"answer":116},"\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":118,"answer":119},"\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":121,"answer":122},"\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":124,"answer":125},"\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":127,"answer":128},"\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>",[71],{"slug":131,"title":132,"description":133,"seoTitle":42,"seoDescription":42,"author":134,"createdDate":135,"lastUpdatedDate":136,"draft":45,"category":137,"image":42,"faq":138,"tags":154},"amies-transport-medium","Amies Transport Medium: Composition, Uses, and Why It Replaced Stuart's Medium","Why a fragile gonococcus swab can die before it ever reaches the lab, the design fix that made Amies better than Stuart's medium, and when to choose the charcoal-free version instead.","Nisha Rijal","2019-12-03","2026-07-05","culture-media",[139,142,145,148,151],{"question":140,"answer":141},"What is Amies transport medium used for?","Preserving swab specimens, such as throat, wound, vaginal, and genital swabs, in a stable, non-multiplying state during transport to the microbiology laboratory.",{"question":143,"answer":144},"Why did Amies medium replace Stuart's medium?","Stuart's medium used glycerophosphate as a buffer, but some organisms could use it as a carbon source and keep multiplying during transport. Amies replaced it with an inorganic phosphate buffer to remove that problem.",{"question":146,"answer":147},"When should Amies without charcoal be used instead of the charcoal version?","Specifically for Mycoplasma and Ureaplasma recovery, since charcoal, helpful for most other fastidious organisms, actually inhibits recovery of these two.",{"question":149,"answer":150},"Can Amies transport medium be frozen for longer storage?","No. Freezing causes ice crystals to rupture bacterial cells, killing the organism. Refrigeration, not freezing, is the correct way to slow deterioration during transport.",{"question":152,"answer":153},"How long can a specimen sit in Amies medium before processing?","Ideally within 6 hours, and no later than 24 hours, maintaining a cold chain throughout.",[71],{"slug":156,"title":157,"description":158,"seoTitle":159,"seoDescription":42,"author":160,"createdDate":161,"lastUpdatedDate":162,"draft":45,"category":163,"image":42,"faq":164,"tags":192},"eswab-types-and-uses","Liquid-Based Swab Transport Systems (eSwab): Types, Uses, and Limitations","How liquid Amies transport systems like eSwab let one collection serve culture, Gram stain, and PCR, which formats exist, and the specimens they are not suitable for.","Liquid-Based Swab Transport Systems: How eSwab Works and When to Use It","Sushmita Baniya","2022-11-03","2026-07-23","lab-equipment",[165,168,171,174,177,180,183,186,189],{"question":166,"answer":167},"What is eSwab and what does the E stand for?","eSwab is a liquid-based swab transport system consisting of a nylon flocked swab and 1 mL of liquid Amies medium in a sterile screw-cap tube. The E stands for elute, referring to the sample releasing off the swab into the liquid rather than remaining trapped in the fibers.",{"question":169,"answer":170},"Can I use eSwab for viral specimens such as influenza or SARS-CoV-2?","No. Liquid Amies is a bacterial maintenance medium and lacks the protein stabilizers and antimicrobials that viral transport medium provides. Viral specimens require viral transport medium or universal transport medium. The two systems look very similar, so check the medium stated on the label rather than relying on the appearance of the swab.",{"question":172,"answer":173},"How long do organisms survive in a liquid Amies system?","Up to 48 hours at either room temperature (20 to 25°C) or refrigerator temperature (4 to 8°C), validated against CLSI standard M40-A2. Neisseria gonorrhoeae is the exception and should be processed within 24 hours, since it is the most fragile of the commonly transported pathogens.",{"question":175,"answer":176},"How many tests can be run from one eSwab collection?","Because the specimen becomes a liquid suspension, it can be divided into aliquots, typically up to ten from the 1 mL supplied. One collection can therefore serve Gram stain, culture, rapid antigen testing, and molecular assays, whereas a dry swab is usually spent on the first test performed.",{"question":178,"answer":179},"Why is the device sterilized by gamma irradiation?","Sterilization during manufacture ensures the tube and swab arrive sterile and ready to use, and it destroys any residual nucleic acid in the device. That matters for molecular testing, because contaminating DNA in a collection device could produce a false positive. It happens before the swab ever meets a patient and has no effect on the specimen collected later.",{"question":181,"answer":182},"What is the difference between liquid Amies and gel Amies?","Gel Amies holds the specimen within the swab fibers, so it must be eluted at the bench and only part is recovered. Liquid Amies elutes the sample at the moment of collection, recovering far more of it and allowing multiple aliquots. Gel remains cheaper and adequate for a routine single-request bacterial swab; liquid earns its cost for multi-test requests, fastidious organisms, and molecular or automated workflows.",{"question":184,"answer":185},"Is a liquid-based swab as good as a tissue sample?","No. For anaerobic culture, deep wounds, and fungal infection, tissue or aspirated fluid remains the preferred specimen. Liquid-based systems substantially improve what a swab can deliver, but they do not make a swab equivalent to tissue.",{"question":187,"answer":188},"What is the breakpoint on the swab shaft?","A scored line that allows the shaft to be snapped cleanly once the swab is inside the tube, so the cap seals properly and the collector's fingers never enter the tube. Bend the shaft against the tube rim at the mark, holding the tube away from your face.",{"question":190,"answer":191},"Which eSwab format should I use for a pediatric or nasopharyngeal sample?","The single minitip format, which has a smaller flocked tip suited to narrow or small collection sites, pediatric patients, and urethral sampling. The single regular format suits routine adult collection from throat, wound, ear, eye, and genital sites.",[71],{"slug":194,"title":195,"description":196,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":197,"lastUpdatedDate":78,"draft":45,"category":163,"image":42,"faq":198,"tags":214},"laboratory-refrigerator-temperature-and-storage","Laboratory Refrigerator: Temperature, What to Store at Each, and Storage Rules","Laboratory refrigerator temperatures explained, which reagents, sera, vaccines, and blood products belong at 2-8 degrees C, why freezing destroys some of them, and the storage rules that keep samples usable. A practical guide for lab science students.","2026-07-28",[199,202,205,208,211],{"question":200,"answer":201},"What temperature is a laboratory refrigerator set to?","A laboratory refrigerator is kept at 2–8°C, with about 4°C as the usual set point. This range slows chemical reactions, enzyme activity, and microbial growth while staying above freezing, which protects reagents, sera, vaccines, and blood products that ice crystals would damage.",{"question":203,"answer":204},"Why are some reagents and vaccines refrigerated instead of frozen?","Freezing forms ice crystals that denature proteins and rupture cells, which destroys many control sera, antibodies, and vaccines. For these items, 2–8°C preserves activity while freezing would ruin them, so colder is not automatically better.",{"question":206,"answer":207},"Why are platelets not stored in the refrigerator?","Platelets are stored at 20–24°C (room temperature) with continuous gentle agitation. Refrigeration damages platelet function and stillness causes them to clump, so unlike red cells and plasma, platelets are never refrigerated.",{"question":209,"answer":210},"Why should nothing sensitive be stored in the refrigerator door?","The door is the warmest and most temperature-variable part of the refrigerator, because it warms every time the fridge is opened. Sensitive items such as controls, sera, vaccines, and blood should be kept on the internal shelves where the temperature is stable.",{"question":212,"answer":213},"What is the difference between a laboratory refrigerator and a blood bank refrigerator?","A blood bank refrigerator is a specialized laboratory refrigerator held at 2–6°C with a tighter temperature tolerance, a continuous temperature log, and an audible alarm. The stricter monitoring exists because a temperature error can make blood unsafe to transfuse.",[215],"laboratory-storage-and-preservation",{"slug":217,"title":218,"description":219,"seoTitle":220,"seoDescription":221,"author":43,"createdDate":222,"lastUpdatedDate":223,"draft":45,"category":224,"image":42,"faq":225,"tags":235},"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",[226,229,232],{"question":227,"answer":228},"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":230,"answer":231},"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":233,"answer":234},"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.",[236],"bacterial-staining-technique",{"slug":238,"title":239,"description":240,"seoTitle":241,"seoDescription":242,"author":43,"createdDate":243,"lastUpdatedDate":44,"draft":45,"category":137,"image":42,"faq":244,"tags":269},"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",[245,248,251,254,257,260,263,266],{"question":246,"answer":247},"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":249,"answer":250},"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":252,"answer":253},"\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":255,"answer":256},"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":258,"answer":259},"\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":261,"answer":262},"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":264,"answer":265},"\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":267,"answer":268},"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>",[270],"bacterial-culture-media",{"slug":272,"title":273,"description":274,"seoTitle":275,"seoDescription":276,"author":43,"createdDate":277,"lastUpdatedDate":44,"draft":45,"category":137,"image":42,"faq":278,"tags":303},"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",[279,282,285,288,291,294,297,300],{"question":280,"answer":281},"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":283,"answer":284},"\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":286,"answer":287},"\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":289,"answer":290},"\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":292,"answer":293},"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":295,"answer":296},"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":298,"answer":299},"\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":301,"answer":302},"\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>",[270],{"enabled":305,"threads":306,"total":307},true,[],0,[309,315,322,328,334,339,345,350,356,359,365],{"slug":310,"name":43,"description":311,"image":312,"body":313,"postCount":314},"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":316,"name":317,"description":318,"image":319,"body":320,"postCount":321},"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":323,"name":160,"description":324,"image":325,"body":326,"postCount":327},"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":329,"name":330,"description":324,"image":331,"body":332,"postCount":333},"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":335,"name":336,"description":324,"image":42,"body":337,"postCount":338},"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":340,"name":341,"description":342,"image":42,"body":343,"postCount":344},"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":346,"name":347,"description":348,"image":42,"body":42,"postCount":349},"guest-author","Guest Author","Guest Author \u002F Contributor",1,{"slug":351,"name":352,"description":324,"image":353,"body":354,"postCount":355},"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":357,"name":358,"description":348,"image":42,"body":42,"postCount":349},"dr-poonam-acharya","Dr. Poonam Acharya",{"slug":360,"name":134,"description":361,"image":362,"body":363,"postCount":364},"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":366,"name":367,"description":368,"image":369,"body":370,"postCount":349},"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.",[372,379,385,390,395,400,404,408,412,417,421,426,430,435,439,443,447,451,456,461,465,469,473,478,482,486,490,494,499,504,508,512,516,519,523,527,531,535,539,543,547,551,555,559,563,567,571,574,579,583,587,591,595,598,602,606,610,614,618,622,626,630,634,638,642,646,650,654,657,661],{"slug":373,"name":374,"description":375,"image":376,"body":377,"postCount":378},"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":380,"name":381,"description":382,"image":42,"body":383,"postCount":384},"microscopy","Microscopy","Microscope types, components, and microscopy techniques","These are list of blog posts related to microscopy. ",12,{"slug":386,"name":387,"description":388,"image":42,"body":42,"postCount":389},"gram-positive-cocci","Gram-Positive Cocci","Staphylococcus, Streptococcus, Enterococcus, Micrococcus — organisms, diseases, and identification tests",11,{"slug":391,"name":392,"description":393,"image":42,"body":42,"postCount":394},"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":396,"name":397,"description":398,"image":42,"body":42,"postCount":399},"gram-positive-rods","Gram-Positive Rods","Bacillus, Clostridium, Listeria, Corynebacterium, Actinomyces and related organisms",8,{"slug":401,"name":402,"description":403,"image":42,"body":42,"postCount":389},"mycobacteria","Mycobacteria","Mycobacterium tuberculosis, leprosy, atypical mycobacteria, and acid-fast organism diagnosis",{"slug":405,"name":406,"description":407,"image":42,"body":42,"postCount":389},"anaerobic-bacteriology","Anaerobic Bacteriology","Anaerobic organisms, anaerobic culture methods, and anaerobic infection diagnosis",{"slug":409,"name":410,"description":411,"image":42,"body":42,"postCount":384},"enterobacteriaceae","Enterobacteriaceae","Identification, differentiation, and clinical significance of Enterobacteriaceae family members",{"slug":413,"name":414,"description":415,"image":42,"body":42,"postCount":416},"spirochetes","Spirochetes","Treponema, Leptospira, Borrelia and spirochetal infections",7,{"slug":418,"name":419,"description":420,"image":42,"body":42,"postCount":378},"food-microbiology","Food Microbiology","Food-borne pathogens, food safety, spoilage, and preservation",{"slug":422,"name":423,"description":424,"image":42,"body":42,"postCount":425},"antimicrobial-susceptibility-testing","Antimicrobial Susceptibility Testing","Methods for testing antibiotic susceptibility in clinical microbiology",21,{"slug":427,"name":428,"description":429,"image":42,"body":42,"postCount":399},"antimicrobials-moa-amr","Antimicrobials (MOA & AMR)","Mechanisms, detection, and clinical significance of antimicrobial resistance",{"slug":431,"name":432,"description":433,"image":42,"body":42,"postCount":434},"sterilization-disinfection","Sterilization and Disinfection","Methods of sterilization and disinfection in healthcare and laboratory settings",10,{"slug":71,"name":436,"description":437,"image":42,"body":42,"postCount":438},"Specimen Collection and Transport","Collection, handling, and transport of clinical specimens for microbiological testing",27,{"slug":440,"name":441,"description":442,"image":42,"body":42,"postCount":425},"bacterial-structure-physiology","Bacterial Structure and Physiology","Bacterial cell structure, growth, physiology, and environmental factors affecting growth",{"slug":444,"name":445,"description":42,"image":42,"body":446,"postCount":338},"horizontal-gene-transfer","Horizontal Gene Transfer","Articles related to **Horizontal Gene Transfer**",{"slug":448,"name":449,"description":42,"image":42,"body":450,"postCount":434},"chromatography","Chromatography","Information about chromatographic techniques.",{"slug":452,"name":453,"description":454,"image":42,"body":455,"postCount":416},"electrophoresis","Electrophoresis","Information about Electrophoresis Techniques ","Detailed information  about Electrophoresis Techniques ",{"slug":457,"name":458,"description":459,"image":42,"body":460,"postCount":338},"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":462,"name":463,"description":464,"image":42,"body":42,"postCount":338},"bacteriophage","Bacteriophage","Description about Bacteriophage.",{"slug":466,"name":467,"description":468,"image":42,"body":42,"postCount":338},"malaria","Malaria","It is the collections of articles regarding malarial disease. ",{"slug":470,"name":471,"description":472,"image":42,"body":42,"postCount":338},"anaerobic-culture-techniques","Anaerobic Culture Techniques","Posts related with Anaerobic Culture Techniques.",{"slug":474,"name":475,"description":476,"image":42,"body":42,"postCount":477},"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":479,"name":480,"description":481,"image":42,"body":42,"postCount":416},"biosafety-levels","Biosafety levels ","Articles related to Biosafety Levels",{"slug":483,"name":484,"description":485,"image":42,"body":42,"postCount":394},"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":487,"name":488,"description":489,"image":42,"body":42,"postCount":338},"pipette","Pipette","Posts related with Pipette. ",{"slug":491,"name":492,"description":493,"image":42,"body":42,"postCount":399},"bacteriology-mcqs","Bacteriology MCQs","This sections lists MCQs in Bacteriology.",{"slug":495,"name":496,"description":497,"image":42,"body":42,"postCount":498},"parasitology-mcqs","Parasitology MCQs","This section lists MCQs in Parasitology.",2,{"slug":500,"name":501,"description":502,"image":42,"body":42,"postCount":503},"virology-mcqs","Virology MCQs","This is the collections of Multiple Choice Questions in Virology.",4,{"slug":505,"name":506,"description":507,"image":42,"body":42,"postCount":394},"mcqs-in-microbiology","MCQs in Microbiology","This section lists the collections of Multiple Choice Questions in General Microbiology Topics. ",{"slug":509,"name":510,"description":511,"image":42,"body":42,"postCount":399},"immunology-mcqs","Immunology MCQs","In this section; we are posting collections of Multiple Choice Questions about Immunology. ",{"slug":513,"name":514,"description":515,"image":42,"body":42,"postCount":344},"microbial-curiosities","Microbial Curiosities","In this clusters, we are posting interesting and unique information about Microorganisms. ",{"slug":270,"name":517,"description":518,"image":42,"body":42,"postCount":425},"Bacterial Culture Media","Posts related to Bacterial Culture Media. ",{"slug":520,"name":521,"description":522,"image":42,"body":42,"postCount":338},"fungal-culture-media","Fungal Culture Media","Posts related to Fungal Culture Media.",{"slug":524,"name":525,"description":526,"image":42,"body":42,"postCount":394},"motility-test","Motility Test","This lists the procedure regarding various tests methods for bacterial motility.",{"slug":528,"name":529,"description":530,"image":42,"body":42,"postCount":434},"bacterial-enumeration","Bacterial enumeration","These posts are related to isolation and enumeration of bacteria. ",{"slug":532,"name":533,"description":534,"image":42,"body":42,"postCount":498},"gram-positive-coccobacillus","Gram-positive coccobacillus","List of Gram Positive Coccobacilli",{"slug":536,"name":537,"description":538,"image":42,"body":42,"postCount":503},"dimorphic-fungi","Dimorphic Fungi","This is about various dimorphic fungi. ",{"slug":540,"name":541,"description":542,"image":42,"body":42,"postCount":416},"bacterial-classification","Bacterial Classification","These posts are related with various approaches used for the classification of Bacteria. ",{"slug":544,"name":545,"description":546,"image":42,"body":42,"postCount":394},"immunofluorescence","Immunofluorescence ","Various Tests related to Immunofluorescence ",{"slug":548,"name":549,"description":550,"image":42,"body":42,"postCount":344},"antibody-mediated-immunity","Antibody-mediated Immunity","This clusters links the articles that are sharing insights about Antibody-mediated immunity. ",{"slug":552,"name":553,"description":554,"image":42,"body":42,"postCount":416},"hypersensitivity","Hypersensitivity","Articles related to Hypersensitivity.",{"slug":556,"name":557,"description":42,"image":42,"body":42,"postCount":558},"haemophilus","Haemophilus",3,{"slug":560,"name":561,"description":562,"image":42,"body":42,"postCount":503},"sexually-transmitted-infections-stis","Sexually transmitted infections (STIs)","This is the clusters of infections that are transmitted sexually. ",{"slug":564,"name":565,"description":566,"image":42,"body":42,"postCount":384},"adaptive-immunity","Adaptive Immunity","Blog posts related to B Cell Immunity and T Cell Immunity.",{"slug":568,"name":569,"description":570,"image":42,"body":42,"postCount":378},"fungal-diagnostics","Fungal Diagnostics","Various methods used for the Diagnosis of Fungal Infections. ",{"slug":215,"name":572,"description":573,"image":42,"body":42,"postCount":394},"Laboratory Storage and Preservation","Articles about Laboratory Storage of Antimicrobial Disk, Test organisms and Equipment used for this process. ",{"slug":575,"name":576,"description":577,"image":42,"body":578,"postCount":338},"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":580,"name":581,"description":582,"image":42,"body":42,"postCount":399},"laboratory-glassware","Laboratory Glassware","Posts about Laboratory Glassware. ",{"slug":584,"name":585,"description":586,"image":42,"body":42,"postCount":338},"helminths","Helminths","In this section, we are covering properties, life cycle, pathogenesis and laboratory diagnosis of Helminths\u002FHelminthic infestations. ",{"slug":588,"name":589,"description":590,"image":42,"body":42,"postCount":338},"protozoan-parasite","Protozoan Parasite","In this cluster, we are covering protozoan parasites. ",{"slug":592,"name":593,"description":594,"image":42,"body":42,"postCount":349},"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":236,"name":596,"description":597,"image":42,"body":42,"postCount":434},"Bacterial Staining Technique","Lists of various staining techniques that are used to stain bacteria. ",{"slug":599,"name":600,"description":601,"image":42,"body":42,"postCount":333},"enzyme-tests","Enzyme Tests","\u003Cp>Various Biochemical Test that are based on enzymatic activity of the microorganisms. \u003C\u002Fp>",{"slug":603,"name":604,"description":605,"image":42,"body":42,"postCount":389},"carbohydrate-utilization","Carbohydrate Utilization","\u003Cp>Various biochemical tests which are related to Carbohydrate fermentation or Utilization\u003C\u002Fp>",{"slug":607,"name":608,"description":609,"image":42,"body":42,"postCount":394},"susceptibility-based-id","Susceptibility-based ID","\u003Cp>These are susceptibility based identification test such as optochin sensitivity, bacitracin sensitivity etc. \u003C\u002Fp>",{"slug":611,"name":612,"description":613,"image":42,"body":42,"postCount":503},"microbial-metabolism","Microbial Metabolism","\u003Cp>Tests about Microbial Metabolism. \u003C\u002Fp>",{"slug":615,"name":616,"description":617,"image":42,"body":42,"postCount":399},"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":619,"name":620,"description":621,"image":42,"body":42,"postCount":558},"atypical-pneumonia","Atypical Pneumonia","\u003Cp>Organisms responsible for Atypical Pneumonia. \u003C\u002Fp>",{"slug":623,"name":624,"description":625,"image":42,"body":42,"postCount":394},"antigen","Antigen","\u003Cp>Various articles related to Antigens.\u003C\u002Fp>",{"slug":627,"name":628,"description":629,"image":42,"body":42,"postCount":416},"innate-immunity","Innate Immunity","\u003Cp>Articles related to Innate Immunity. \u003C\u002Fp>",{"slug":631,"name":632,"description":633,"image":42,"body":42,"postCount":503},"respiratory-tract-infection","Respiratory Tract Infection","\u003Cp>In this cluster, you can see various etiological agents that causes respiratory tract infection. \u003C\u002Fp>",{"slug":635,"name":636,"description":637,"image":42,"body":42,"postCount":394},"torch-infection","TORCH Infection","\u003Cp>In this section; you can find articles related with TOCH infection. \u003C\u002Fp>",{"slug":639,"name":640,"description":641,"image":42,"body":42,"postCount":416},"microbiology-for-beginners","Microbiology for Beginners","\u003Cp>These articles are very basic articles, which will share general concepts in Microbiology. \u003C\u002Fp>",{"slug":643,"name":644,"description":645,"image":42,"body":42,"postCount":338},"dna-replication","DNA Replication","\u003Cp>Articles related to DNA and Replication of DNA. \u003C\u002Fp>",{"slug":647,"name":648,"description":649,"image":42,"body":42,"postCount":416},"genetic-code","Genetic Code","\u003Cp>Articles related to Genetic Code.\u003C\u002Fp>",{"slug":651,"name":652,"description":653,"image":42,"body":42,"postCount":394},"molecular-technique","Molecular Technique","\u003Cp>Posts related to Molecular Techniques. \u003C\u002Fp>",{"slug":655,"name":656,"description":42,"image":42,"body":42,"postCount":349},"colorimetric-assay","Colorimetric Assay ",{"slug":658,"name":659,"description":660,"image":42,"body":42,"postCount":394},"pharmaceutical-microbiology","Pharmaceutical Microbiology","\u003Cp>Various articles related to Pharmaceutical Microbiology\u003C\u002Fp>",{"slug":662,"name":663,"description":42,"image":42,"body":42,"postCount":558},"blood-and-immune-cells","Blood and Immune Cells"]