[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"$fxLN3MUwXCdr5RPjwZYIDpOj8CHyjOmngWTgoKXPtZbg":3,"$fUH6GCXzq0ABvysQACthD_EMNfsUdWdnKBgKCYleMT_Y":32,"$f3Ft0rKFJHppdzE-vuveecxx1BUcg9iOlMLtyzf_MJDg":223},[4,8,12,16,20,24,28],{"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",{"type":33,"data":34},"blog",{"slug":35,"title":36,"description":37,"seoTitle":38,"seoDescription":38,"author":39,"createdDate":40,"lastUpdatedDate":41,"draft":42,"category":43,"image":38,"body":44,"faq":45,"tags":64,"related":66},"transport-medium-bacterial-viral-sample-transport-used-microbiology-laboratory","Transport Media Used in Microbiology Lab","Which transport medium to reach for depending on the suspected organism, why there's no single universal choice, and links to the full mechanism of each.",null,"Nisha Rijal","2015-02-05","2026-07-24",false,"culture-media","One morning, three specimens, three different tubes.\n\nA single morning's specimen log at a district hospital laboratory might include a stool sample from a suspected cholera case, a throat swab from a suspected diphtheria patient, and a genital swab for suspected gonorrhea, none of them processable on-site, all three headed to a central reference laboratory. Grabbing the wrong transport tube for any one of them doesn't just produce a slightly worse sample. It can mean the organism is dead on arrival, and a true infection comes back reported as a false negative.\n\nThere is no single, universal transport medium. The right choice depends entirely on which organism is actually suspected, and this article is a map of exactly which one to reach for, and why, with links to the full mechanism of each.\n\nTransport media are buffered solutions containing salts and, in some cases, carbohydrates or peptones, but deliberately excluding growth factors, designed to preserve the viability of an organism during transport without allowing it to multiply. The goal is to keep a specimen as close to its original state as possible between collection and processing.\n\n**This is the single most important conceptual distinction in this topic: a transport medium is not a growth medium.** Its entire design goal is to hold organisms in a stable, non-multiplying, non-dying state, the opposite job of a culture medium, which is built specifically to support active growth.\n\n### Which Transport Medium for Which Organism\n\nThe useful question is not \"which medium do I have?\" but \"what am I afraid might die in transit?\" The choice always starts with the suspected organism's fragility. A robust organism tolerates a wide range of conditions, while a fastidious one such as *Neisseria gonorrhoeae* or *Vibrio cholerae* demands exactly the right buffer, atmosphere, and timing. There is no generic swab medium that is correct for everything.\n\n| Suspected organism \u002F specimen | Recommended medium |\n| --- | --- |\n| Routine bacteriology (throat, wound, ear, eye) | Amies with or without charcoal, or a liquid-based system such as eSwab |\n| *Salmonella*, *Shigella*, *Campylobacter* (stool) | [Cary and Blair medium](https:\u002F\u002Fmicrobeonline.com\u002Fcary-blair-transport-medium-composition-preparation-uses\u002F) |\n| *Vibrio cholerae* (stool) | Cary and Blair medium (WHO-preferred); **alkaline peptone water** only as a backup if Cary-Blair is unavailable and subculture is possible within 6 hours |\n| *N. gonorrhoeae*, *H. influenzae*, *N. meningitidis*, *H. ducreyi* (swabs) | [Amies medium with charcoal](https:\u002F\u002Fmicrobeonline.com\u002Famies-transport-medium\u002F) |\n| *Mycoplasma*, *Ureaplasma* (swabs) | Amies medium without charcoal |\n| Bacillary dysentery, historical (stool) | Sach's buffered glycerol saline |\n| Anaerobic bacteria | Anaerobic transport medium (pre-reduced, with reducing agent and redox indicator) |\n| Viral pathogens (respiratory, ocular, tissue swabs) | Viral Transport Medium (VTM) |\n\n*Note: Full mechanism, composition, and handling rules for Cary-Blair and Amies are covered in their own dedicated articles, linked above; the sections below stay intentionally brief.*\n\n### Common Transport Media\n\n**Cary and Blair Medium.** A semi-solid, white-colored transport medium for feces that may contain *Salmonella*, *Shigella*, *Vibrio*, or *Campylobacter*.\n\n**Amies medium.** See the [full Amies Transport Medium article](https:\u002F\u002Fmicrobeonline.com\u002Famies-transport-medium\u002F) for the complete composition, the charcoal vs. charcoal-free distinction, and handling rules.\n\n**Stuart's medium.**  Still in use for throat, wound, and skin swabs, and historically the standard for gonococcal specimens. Amies medium was later developed specifically to improve on Stuart's design, removing a buffering component (glycerophosphate) that could accidentally serve as a carbon source for some organisms, letting them multiply during transport. See the Amies article linked above for the full explanation.\n\n**Venkatraman Ramakrishnan (VR) medium.** Historically used to transport feces from suspected cholera patients; no longer in use, replaced by Cary-Blair medium.\n\n**Alkaline Peptone Water (APW).** Primarily an enrichment medium rather than a pure transport medium. Its high pH (8.6) actively favors *Vibrio* while suppressing competing enteric flora, so the target organism increases during the holding period rather than merely surviving. This is why the window is short: beyond about 6 hours, competing organisms begin to adapt and the enrichment advantage is lost. Use [Alkaline Peptone Water (APW)](https:\u002F\u002Fmicrobeonline.com\u002Falkaline-peptone-water-apw-principle-preparation-uses\u002F) for suspected cholera only when Cary-Blair is unavailable and subculture can be performed within that window.\n\n**Sach's buffered glycerol saline.** Used to transport feces from patients suspected of bacillary dysentery,now largely superseded by Cary-Blair.\n\n**Viral Transport Medium (VTM)**\n\nRequires a Dacron or nylon flocked swab on a plastic shaft. Cotton, calcium alginate, and wooden-shafted swabs all compromise viral recovery or inhibit PCR, and wooden shafts risk splinter injury during nasopharyngeal collection. See the [full VTM article](https:\u002F\u002Fmicrobeonline.com\u002Fviral-transport-media-vtm\u002F) for sample types and handling, and Types of Swabs in Microbiology for swab material selection across all specimen types.\n\n![](\u002Fblogs\u002FBD-Viral-Tranport-Medium.jpg)**Anaerobic Transport Medium (ATM).** A mineral salt-base semi-solid medium with reducing agents (sodium thioglycollate, cysteine), designed to maintain anaerobic organism viability without significant multiplication. Resazurin may be added as a redox indicator, turning pink if the medium is exposed to oxygen.\n\nThioglycollate broth is often confused with anaerobic transport medium because both contain sodium thioglycollate as a reducing agent, but it is an enrichment and growth medium, designed to support multiplication rather than prevent it.\n\n## General Handling and Timing\n\n**Transport promptly.** The 24 and 48 hour figures quoted for various media are validated maxima under controlled conditions, not working targets. Recovery of fastidious organisms declines steadily with time in any medium.\n\n**Refrigerate, with two important exceptions.** Most bacterial specimens in transport medium hold better at 2 to 8°C. But specimens for *Neisseria gonorrhoeae* and *Neisseria meningitidis* are cold-sensitive and should be held at room temperature, and anaerobic specimens should not be refrigerated because oxygen dissolves more readily as temperature falls.\n\n**Never freeze bacterial specimens.** Freezing kills most vegetative bacteria. Freezing applies only to viral specimens held for longer periods, and then only at -70°C or below. For routine transport, viral specimens go at 2 to 8°C. A -20°C freezer damages viral specimens and should not be used.\n\n**Do not use expired or dried media.** Buffering capacity and reducing agents degrade over time. A semi-solid medium that has dried at the surface or changed color has lost the properties it was selected for.\n\n## Key exam facts in one table\n\n| Fact | Detail |\n| --- | --- |\n| Core principle | Preserves organism viability without allowing multiplication; not a growth medium |\n| Contains | Buffers and salts, sometimes small amounts of peptone or carbohydrate; no enrichment sufficient to support multiplication |\n| Classified by physical state | Semi-solid or liquid |\n| Classified by utility | Bacterial or viral transport media |\n| Cholera specimen, preferred | Cary-Blair medium (WHO-recommended) |\n| Cholera specimen, backup only | Alkaline peptone water (inferior to Cary-Blair; only if subculture within 6 hours) |\n| Fastidious swab pathogens | Amies with charcoal |\n| *Mycoplasma*\u002F*Ureaplasma* | Amies without charcoal |\n| Obsolete medium | VR medium (replaced by Cary-Blair) |\n\n## Where Students Get Confused\n\n- **Treating transport media as growth media.** The whole design goal is the opposite: hold the organism steady without letting it multiply, unlike a culture medium built to support active growth.\n- **Assuming alkaline peptone water is just as good as Cary-Blair for cholera.** It's a backup only, used specifically when Cary-Blair is unavailable and subculture can happen quickly.\n- **Assuming Amies and Stuart's medium are functionally identical.** Amies specifically fixed a design flaw in Stuart's medium (glycerophosphate acting as an unintended carbon source); they aren't interchangeable in principle, even though they serve similar specimen types.\n- **Citing VR medium as current practice.** It shows up in older references and textbooks but has been replaced by Cary-Blair medium.\n\n## How to Remember\n\n**Ask what might die in transit.** The organizing question for the whole topic. Medium selection follows from the suspected organism's fragility, not from what tube happens to be on the shelf.\n\n**A waiting room, not a dining hall.** A transport medium keeps organisms alive without feeding them. Anything that fed the pathogen would feed its faster-growing neighbors even better, and the specimen arriving would misrepresent the one collected. The poverty is deliberate.\n\n**Amies fixed Stuart's carbon leak.** Stuart's used glycerophosphate as buffer, which some organisms could metabolize. Amies swapped it for inorganic phosphate and added charcoal to adsorb toxic fatty acids. One change closed a loophole, the other added protection.\n\n**Charcoal is a sponge for poisons.** Wherever charcoal appears, its job is mopping up fatty acids and metabolic products that would otherwise kill delicate pathogens. That is why Amies with charcoal is the choice for Neisseria.\n\n**Cold for most, warm for Neisseria, never frozen for bacteria.** The three-part storage rule. Refrigerate bacterial specimens generally, keep gonococcal and meningococcal specimens at room temperature, and reserve freezing for viral specimens at -70°C only.\n\n## References\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.\n3. World Health Organization. Laboratory Methods for the Diagnosis of Epidemic Dysentery and Cholera. Geneva: WHO. \\[verify current edition\\]\n4. Johnson FB. Transport of viral specimens. Clin Microbiol Rev. 1990;3(2):120–131.\n5. McLeod SD, Kumar A, Cevallos V, Srinivasan M, Whitcher JP. Reliability of transport medium in the laboratory evaluation of corneal ulcers. Am J Ophthalmol. 2005;140(6):1027–1031.",[46,49,52,55,58,61],{"question":47,"answer":48},"Why do transport media contain no nutrients?","Transport media contain only buffers and salts — deliberately excluding carbon sources, nitrogen sources, and organic growth factors. The purpose is organism preservation, not growth. A medium that supports bacterial multiplication would change the relative proportions of organisms in a mixed specimen during transit — organisms that grow fastest would overgrow slower-growing pathogens, generating a misleading culture result. Transport media maintain viability of organisms without allowing proliferation, preserving the original specimen composition until laboratory processing.",{"question":50,"answer":51},"Can bacterial transport medium (Amies or Stuart's) be used for viral specimens?","No — bacterial and viral transport media are not interchangeable and must never be substituted for each other. Viral transport medium (VTM) contains antibiotics (gentamicin, amphotericin B) specifically to suppress bacterial and fungal contamination while maintaining viral viability. Bacterial transport media do not contain these antibiotics, so bacterial contamination rapidly overgrows viral material. Conversely, the antibiotics in VTM would inhibit bacterial cultures if used for bacterial specimens. Using the wrong transport medium for viral or chlamydial specimens results in specimen failure and missed diagnoses.",{"question":53,"answer":54},"Which transport medium should be used for a stool specimen when Vibrio cholerae is suspected?","Cary-Blair transport medium is the medium of choice for stool specimens when V. cholerae is suspected — its alkaline pH (8.4) maintains V. cholerae viability better than any other transport medium. Alkaline Peptone Water (APW, pH 8.6) can also be used but only if the subculture will occur within 6 hours of collection — after 6 hours, other enteric organisms overgrow V. cholerae in APW. Amies and Stuart's media are acceptable for Salmonella and Shigella transport but are inferior to Cary-Blair for V. cholerae. In a cholera outbreak setting, Cary-Blair should be the standard stool transport medium.",{"question":56,"answer":57},"How is a transport medium different from a culture medium?","Their design goals are opposite. A culture medium is built to support active growth. A transport medium is built to hold organisms in a stable, non-multiplying, non-dying state. This is why transport media deliberately lack enrichment such as blood, serum, and growth factors.",{"question":59,"answer":60},"Is thioglycollate broth a transport medium?","No. Thioglycollate broth is an enrichment and growth medium intended to support the multiplication of anaerobes and facultative organisms. It is often confused with anaerobic transport medium because both contain sodium thioglycollate as a reducing agent, but their purposes are opposite.",{"question":62,"answer":63},"How long can a specimen stay in transport medium?","The commonly quoted 24 to 48 hour figures are validated maxima under controlled conditions, not normal working windows. Recovery of fastidious organisms declines steadily with time, so transport promptly and treat the stated limit as the point beyond which results become unreliable.",[65],"specimen-collection-transport",[67,76,108,144,152,159,194,216],{"slug":68,"title":69,"description":69,"seoTitle":38,"seoDescription":38,"author":70,"createdDate":71,"lastUpdatedDate":72,"draft":42,"category":73,"image":38,"faq":74,"tags":75},"blood-collection-tubes","Blood Collection Tubes: Significance of Color Coding","Acharya Tankeshwar","2023-01-26","2026-07-19","lab-equipment",[],[65],{"slug":77,"title":78,"description":79,"seoTitle":38,"seoDescription":38,"author":70,"createdDate":80,"lastUpdatedDate":81,"draft":42,"category":73,"image":38,"faq":82,"tags":107},"types-of-swabs","Types of Swabs in Microbiology: Materials, Design, and Which Swab to Use","Compare cotton, calcium alginate, Dacron, rayon, and nylon flocked swabs, and see which swab and shaft to use for each specimen type, from throat and wound to pertussis and GC culture.","2022-11-08","2026-07-23",[83,86,89,92,95,98,101,104],{"question":84,"answer":85},"Which swab should I use for a nasopharyngeal specimen?","A nylon flocked or Dacron swab on a flexible plastic shaft, ideally a minitip for nasopharyngeal use. Cotton, calcium alginate, and wooden shafts should all be avoided, because they either inhibit PCR, inactivate viruses, or risk injury.",{"question":87,"answer":88},"Why can't I use cotton swabs for microbiology?","Cotton fails in two independent ways. Fatty acids in the fiber are directly toxic to fastidious organisms such as Bordetella pertussis and Neisseria gonorrhoeae, and residues from cotton inhibit PCR amplification. So a cotton swab can give a false negative either by killing the organism or by blocking its detection.",{"question":90,"answer":91},"Are calcium alginate swabs still used?","They are largely obsolete in diagnostic microbiology. Calcium alginate is toxic to tissue culture, inactivates certain viruses including herpes simplex virus, is toxic to gonococci and mycoplasmas, and interferes with PCR and fluorescent antibody tests. Older textbooks recommending it for nasopharyngeal collection are out of date.",{"question":93,"answer":94},"What is a flocked swab and why is it better?","A flocked swab has short nylon fibers standing perpendicular to the applicator with no internal core, rather than fiber wound around a core. Sample stays near the surface and elutes almost completely into liquid medium. Around 90 percent of the collected sample becomes available for testing, compared with roughly 10 percent from a traditional fiber swab, and one collection can supply several tests.",{"question":96,"answer":97},"Is a flocked swab always the best choice?","No. For nucleic acid testing, nylon flocked swabs give clearly better DNA yield, more than three and a half times that of rayon. But for antigen-based point-of-care tests, which depend on protein recovery, rayon and Dacron actually perform best and cost less. The best swab depends on the assay.",{"question":99,"answer":100},"Why are wooden shafts not recommended?","Wood is toxic to several organisms including Chlamydia trachomatis and various viruses, it releases substances that inhibit PCR, and it can splinter, which is a genuine injury risk in nasopharyngeal collection. Plastic shafts are recommended for all diagnostic collection.",{"question":102,"answer":103},"Which transport medium goes with which swab?","For general bacteriology use Amies medium, with charcoal for fastidious organisms. For enteric pathogens use Cary-Blair. For viral specimens use viral or universal transport medium, since bacterial transport media are unsuitable for viruses. Liquid-based systems such as eSwab combine a flocked swab with liquid Amies for multi-test workflows.",{"question":105,"answer":106},"Is a swab as good as a tissue sample or aspirate?","No. Where tissue, pus, or a needle aspirate can be obtained, it is almost always the better specimen, because it carries more organisms, provides enough material for multiple tests, and gives better anaerobe recovery. Swabs are appropriate where the site suits them, such as the throat or nasopharynx, or where nothing better can be obtained.",[65],{"slug":109,"title":110,"description":111,"seoTitle":112,"seoDescription":38,"author":113,"createdDate":114,"lastUpdatedDate":81,"draft":42,"category":73,"image":38,"faq":115,"tags":143},"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",[116,119,122,125,128,131,134,137,140],{"question":117,"answer":118},"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":120,"answer":121},"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":123,"answer":124},"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":126,"answer":127},"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":129,"answer":130},"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":132,"answer":133},"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":135,"answer":136},"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":138,"answer":139},"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":141,"answer":142},"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.",[65],{"slug":145,"title":146,"description":146,"seoTitle":38,"seoDescription":38,"author":70,"createdDate":147,"lastUpdatedDate":148,"draft":42,"category":149,"image":38,"faq":150,"tags":151},"rejection-criteria-for-microbiological-specimens","Microbiology Sample Collection Guidelines and Rejection Criteria","2021-05-04","2026-07-05","bacteriology",[],[65],{"slug":153,"title":154,"description":154,"seoTitle":38,"seoDescription":38,"author":70,"createdDate":155,"lastUpdatedDate":148,"draft":42,"category":156,"image":38,"faq":157,"tags":158},"sample-collections-for-laboratory-diagnosis-of-fungal-infections","Sample Collections for Lab Diagnosis of Fungal Infections","2021-04-03","mycology",[],[65],{"slug":160,"title":161,"description":162,"seoTitle":163,"seoDescription":38,"author":70,"createdDate":164,"lastUpdatedDate":81,"draft":42,"category":43,"image":38,"faq":165,"tags":193},"viral-transport-media-vtm","Viral Transport Media (VTM): Composition, Uses, Storage, and VTM vs UTM","What is in viral transport medium and why, how it differs from universal transport medium and bacterial media like Amies, correct storage temperatures, and the freezing mistake that destroys specimens.","Viral Transport Media (VTM): Composition, Uses, and Correct Storage","2020-03-23",[166,169,172,175,178,181,184,187,190],{"question":167,"answer":168},"What does viral transport medium contain?","A buffered balanced salt solution to hold pH and osmolality, a protein stabilizer such as serum, albumin, or gelatin to protect virions and stop them adsorbing to the tube wall, and antimicrobials (typically an antibiotic plus an antifungal) to suppress contaminating bacteria and fungi. Some formulations include phenol red as a pH indicator.",{"question":170,"answer":171},"Can I use one swab in VTM for both viral and bacterial testing?","No. VTM contains antibiotics and an antifungal specifically to prevent bacterial and fungal overgrowth, so bacteria in that specimen will be suppressed. If both viral and bacterial investigations are needed from the same site, collect two separate specimens.",{"question":173,"answer":174},"At what temperature should VTM specimens be stored?","Hold at 2 to 8°C and process within 48 to 72 hours. If processing will be delayed beyond that, freeze at -70°C or below and transport on dry ice. Room temperature is tolerated briefly during transit but is not equivalent to refrigeration.",{"question":176,"answer":177},"Why should viral specimens never be frozen at -20°C?","A -20°C freezer sits in the temperature range where ice crystals form and grow, and frost-free models repeatedly partially thaw and refreeze their contents. This shears viral envelopes and fragments nucleic acid. A specimen held at -20°C ends up in worse condition than one kept in the refrigerator. If -70°C is unavailable, refrigerate and expedite transport instead.",{"question":179,"answer":180},"What is the difference between VTM and UTM?","Universal transport medium is formulated to support viruses together with Chlamydia, Mycoplasma, and Ureaplasma, and to serve both culture and molecular testing. In practice the terms are used almost interchangeably and most commercial VTM sold today is a universal formulation. The distinction that matters at the bench is whether the medium is a viral one or a bacterial one.",{"question":182,"answer":183},"Can I use liquid Amies (eSwab) for a viral specimen?","No. Liquid Amies is a bacterial maintenance medium and lacks the protein stabilizer and antimicrobials a viral specimen requires. The two systems look nearly identical, both a flocked swab in liquid in a screw-cap tube, so check the medium named on the label rather than the appearance of the device.",{"question":185,"answer":186},"Why is VTM suitable for Chlamydia, Mycoplasma, and Ureaplasma if they are bacteria?","Because they are osmotically fragile in the same way viruses are. Chlamydia is an obligate intracellular organism, and Mycoplasma and Ureaplasma have no cell wall at all. All three die quickly in the salt-based media used for ordinary bacteria and need the protein stabilization and buffering that VTM provides.",{"question":188,"answer":189},"What is inactivating VTM and when should it be used?","Inactivating VTM contains a lysis agent that destroys the virus on contact while preserving its nucleic acid for PCR, which reduces the biohazard for anyone handling the specimen. The trade-off is absolute: culture, isolation, and any test requiring live virus become impossible. Use it when the request is molecular only, and use non-inactivating medium when culture may be needed.",{"question":191,"answer":192},"Should CSF or urine be placed in VTM?","No. Liquid specimens including cerebrospinal fluid, bronchoalveolar lavage fluid, urine, and ocular fluids are submitted neat in a sterile container. VTM exists to keep a swab from drying out and to stabilize what is on it. Adding it to a liquid specimen only dilutes the target, which costs sensitivity in specimens where viral load is often already low.",[65],{"slug":195,"title":196,"description":197,"seoTitle":38,"seoDescription":38,"author":39,"createdDate":198,"lastUpdatedDate":148,"draft":42,"category":43,"image":38,"faq":199,"tags":215},"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.","2019-12-03",[200,203,206,209,212],{"question":201,"answer":202},"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":204,"answer":205},"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":207,"answer":208},"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":210,"answer":211},"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":213,"answer":214},"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.",[65],{"slug":217,"title":218,"description":218,"seoTitle":38,"seoDescription":38,"author":70,"createdDate":219,"lastUpdatedDate":220,"draft":42,"category":149,"image":38,"faq":221,"tags":222},"pus-sample-collection-staining-culture","Pus Sample: Collection, Processing, Staining and Culture","2019-02-07","2026-07-08",[],[65],[224,230,237,241,245,249,254,259,263,267],{"slug":225,"name":70,"description":226,"image":227,"body":228,"postCount":229},"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.*",433,{"slug":231,"name":232,"description":233,"image":234,"body":235,"postCount":236},"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.",81,{"slug":238,"name":113,"description":239,"image":38,"body":38,"postCount":240},"sushmita-baniya","Author \u002F Contributor",32,{"slug":242,"name":243,"description":239,"image":38,"body":38,"postCount":244},"samikshya-acharya","Samikshya Acharya",20,{"slug":246,"name":247,"description":239,"image":38,"body":38,"postCount":248},"alisha-tripathi","Alisha Tripathi",6,{"slug":250,"name":251,"description":252,"image":38,"body":38,"postCount":253},"aastha-shrestha","Aastha Shrestha"," Author \u002F Contributor",10,{"slug":255,"name":256,"description":257,"image":38,"body":38,"postCount":258},"guest-author","Guest Author","Guest Author \u002F Contributor",2,{"slug":260,"name":261,"description":239,"image":38,"body":38,"postCount":262},"srijana-khanal","Srijana Khanal",18,{"slug":264,"name":265,"description":257,"image":38,"body":38,"postCount":266},"dr-poonam-acharya","Dr. Poonam Acharya",1,{"slug":268,"name":39,"description":239,"image":38,"body":269,"postCount":270},"nisha-rijal","**Nisha Rijal** is a microbiologist and quality assurance specialist. She served for nearly 12 years as a microbiologist at the National Public Health Laboratory (NPHL), Nepal's national reference laboratory, and continues to work as a consultant microbiologist in international public health organization. ",51]