[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"$fxLN3MUwXCdr5RPjwZYIDpOj8CHyjOmngWTgoKXPtZbg":3,"$fRRd8P4H3EMAUO8UpdlJJgsY8TSanEd66-xkg20ciHM0":32,"$f3Ft0rKFJHppdzE-vuveecxx1BUcg9iOlMLtyzf_MJDg":219},[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":61,"related":63},"trans-isolate-t-medium-introduction-uses","Trans-Isolate (T-I) Medium: Inoculation, Transport, and the Rules","Why three of the most feared meningitis pathogens die within hours outside the CSF, and the one venting decision that's easy to reverse by mistake when a sample has to travel.",null,"Acharya Tankeshwar","2013-11-08","2026-07-05",false,"culture-media","**The sample that has to outlast the trip**\n\nA rural hospital performs a lumbar puncture on a child with suspected bacterial meningitis. The nearest laboratory equipped to culture and test susceptibility on the sample is hours away. *Neisseria meningitidis*, *Streptococcus pneumoniae*, and *Haemophilus influenzae*, the three organisms responsible for the overwhelming majority of bacterial meningitis cases, are all notoriously fragile once outside the protected environment of CSF. A delay of even a few hours in a dry, unsupported specimen can mean the difference between confirming the exact pathogen and its susceptibility pattern, information that matters for both individual treatment and outbreak surveillance, and a falsely negative culture that leaves the diagnosis unconfirmed.\n\n**Trans-Isolate (T-I) medium exists specifically to close that gap.** Its biphasic design, a solid charcoal-and-starch slant paired with a buffered liquid broth, keeps all three of these fastidious organisms alive for as long as a week if needed, buying exactly the time a specimen needs to reach wherever it's going. This is why the World Health Organization distributes T-I media directly to national reference laboratories for meningitis surveillance in settings where immediate processing isn't realistic, this medium's entire reason for existing is bridging that specific, high-stakes gap.\n\n## Tran-isolate (T-I) Medium Overview\n\nTran-isolate (T-I) is a biphasic medium used to inoculate and transport CSF samples of patients suspected of having bacterial meningitis. If the CSF cannot be transported to a microbiology laboratory immediately (within 1 hour from the time of collection) for culture, a T-I medium is used.\n\n![Fig. Trans Isolate (T-I) Medium - Fig. Trans Isolate (T-I) Medium](https:\u002F\u002Fassets.microbeonline.com\u002Fblogs\u002FTrans-Isolate-Medium-300x224.jpg)Figure: Fig. Trans Isolate (T-I) Medium\n\nT-I medium consists of a **solid phase** (a slant containing activated charcoal, soluble starch, and agar) and a **liquid phase** (soybean-casein digest-gelatin broth buffered at pH 7.2 with MOPS buffer). It supports the growth and survival of *N. meningitidis*, *S. pneumoniae*, and *H. influenzae*, and in stock culture form supports growth for at least three months. National Reference Laboratories can procure T-I media directly from the WHO.\n\n## Quality Control\n\nUpon receipt, visually inspect all media for signs of contamination and physical defects. Examination of contamination includes turbid liquid, color change, or growth of bacteria or mold on the slant. Material defects include cracked glass, broken seal, leaking, reduced volume, or absent liquid phase. If you see any of the above signs, discard the T-I bottle.\n\nAfter visual inspection, store all eligible T-I media at 4°C.\n\n### Sterility Testing\n\n- Incubate one T-I bottle vented and one non-vented for 48 hours at 37°C.\n- Using a sterile syringe, withdraw 50 μL of the liquid phase of T-I and plate it onto a chocolate agar plate.\n- Incubate the plate at 37°C with 5% CO2 for 48 hours. Any growth on the media is indicative of contamination.\n\n### Growth Promotion\n\n1. Using sterile technique, inoculate one T-I bottle with 100 μL of an inoculum containing 103 CFU\u002Fml for each of the following pathogens: *N. meningitidis, H. influenzae,* and *S. pneumoniae.*\n2. Incubate the plate at 37°C with 5% CO2 for 48 hours.\n3. Observe for growth of bacterial colonies.\n\n## T-I Inoculation\n\nRemove T-I bottles from the refrigerator at least 30 minutes before inoculating them with the CSF sample and allow them to warm at room temperature.\n\n![Disinfecting the rubber stopper of the T-I bottle - Disinfecting the rubber stopper of the T-I bottle(Source: US Centers for Disease Control and Prevention)](https:\u002F\u002Fassets.microbeonline.com\u002Fblogs\u002FDisinfecting-the-rubber-stopper-of-the-T-I-bottle.png)Figure: Disinfecting the rubber stopper of the T-I bottle(Source: US Centers for Disease Control and Prevention)\n\n1. **Lift the small metal cap** on top of the T-I bottle using sterile forceps. *(Do not completely remove the aluminum cover).*\n2. Wipe the rubber stopper with a 70% alcohol swab (do not use povidone-iodine as it may be carried into the medium by the passing needle, thus inhibiting the growth of bacteria.)\n3. Aseptically inoculate 0.5-1.0 ml of the CSF into the T-I medium using a 21G (0.88 mm) sterile syringe through the rubber stopper of the lid.\n4. Invert the T-I bottle several times and incubate the inoculated T-I medium at 35-37°C with \\~5% CO2 (or in a candle jar) overnight or until transport is possible.\n5. Label the T-I bottle clearly with the patient’s date and name. Include identification number and other necessary information.\n\n## Transport of T-I media\n\n![Ventilating T-I media with cotton plugged needle - Ventilating T-I media with cotton plugged needle(Source: US Centers for Disease Control and Prevention)](https:\u002F\u002Fassets.microbeonline.com\u002Fblogs\u002FVentilating-T-I-Media.png)Figure: Ventilating T-I media with cotton plugged needle(Source: US Centers for Disease Control and Prevention)\n\n1. If T-I media cannot be shipped within 24 hours, ventilate with cotton plugged needle inserted through the rubber stopper without touching the media and incubate at 37°C. Before transporting the T-I media, remove the venting needle and disinfect the rubber stopper. Then **transport in triple packaging following guidance for transport of infectious biological material.** Transport T-I media at ambient temperature. **If the T-I medium can be transported to a microbiology laboratory on the same day of inoculation, do not vent the T-I bottle until it arrives in the receiving laboratory.**\n2. While shipping the sample to a national or reference laboratory, include a case report along with T-I media.\n3. Upon arrival, wipe the rubber stopper with 70% alcohol, insert a venting needle into the T-I bottle, incubate at 35-37°C with \\~5% CO2 (or in a candle-jar), and observe daily for turbidity in the liquid phase for up to 7 days.\n4. Before subculture, remove the venting needle and wipe the rubber stopper with 70% alcohol.\n5. Use a sterile needle and syringe to transfer 50-100 µl of the liquid portion of the T-I medium onto both a [blood agar plate (BAP)](\u002Fblood-agar-composition-preparation-uses-and-types-of-hemolysis\u002F) and [chocolate agar (CAP)](\u002Fchocolate-agar-composition-uses-colony-characteristics\u002F) for primary culture.\n6. Approximately 50-100 µl is used to streak each plate. To streak two plates, draw approximately 100-200 µl with the syringe at one time to minimize the possibility of contaminating the T-I medium.\n7. Streak the BAP and CAP for isolation, incubate the plates at 35-37°C with \\~5% CO2 (or in a candle jar), and examine the plates daily for up to 72 hours.\n8. If no growth is observed, subculture the T-I medium again on day 4 and day 7.\n9. Dispose of all inoculated T-I media in the same manner as infectious bacterial cultures.\n\nIsolates should always be inspected for purity of growth by looking at colony morphology before any testing is performed. Cultures should be re-streaked if contamination is seen to ensure purity before testing.\n\n## Venting or Not?\n\nThe decision to vent or not vent depends entirely on **how long the sample will take to reach the lab**:\n\n- **Same-day transport:** Do **not** vent the bottle. Leave it sealed until it arrives at the receiving laboratory.\n- **Transport delayed beyond 24 hours:** **Do** vent, using a cotton-plugged needle inserted through the rubber stopper without touching the medium, and incubate at 37°C until shipping.\n\nGetting this backwards, venting a bottle that was going to arrive the same day, or failing to vent one that's going to sit for days, isn't a cosmetic error. It's exactly the kind of small procedural reversal that can compromise a sample that otherwise had every chance of surviving the trip intact.\n\n***Anchor for the venting rule: \"vent for the long haul, seal for the sprint.\"*** *A same-day trip stays sealed until it arrives. A multi-day trip gets vented so trapped gas doesn't become a problem long before the sample ever reaches the lab.*\n\n**A second easy-to-miss detail:** disinfect the rubber stopper with a 70% alcohol swab only, never povidone-iodine. A needle passing through iodine-treated rubber can carry trace amounts into the medium, quietly inhibiting the growth of the very organisms the medium exists to preserve. Alcohol, reached for by default in most other clinical contexts as \"the milder option,\" is specifically the correct and required choice here, not an alternative.\n\n## Key exam facts in one table\n\n| Fact | Detail |\n| --- | --- |\n| Purpose | Inoculation and transport of CSF when immediate (within 1 hour) processing isn't possible |\n| Design | Biphasic: solid slant (charcoal, starch, agar) + liquid broth (soybean-casein digest-gelatin, MOPS buffer, pH 7.2) |\n| Organisms supported | *Neisseria meningitidis*, *Streptococcus pneumoniae*, *Haemophilus influenzae* |\n| Stock culture shelf life | At least 3 months |\n| Source for national reference labs | WHO |\n| Same-day transport | Do not vent until arrival |\n| Transport delayed >24 hours | Vent with a cotton-plugged needle |\n| Stopper disinfection | 70% alcohol only; never povidone-iodine (risk of carrying inhibitory iodine into the medium) |\n| Subculture schedule after arrival | Blood agar + chocolate agar, examine daily up to 72 hours; if no growth, re-subculture on day 4 and day 7 |\n\n## Where Students Get Confused\n\n- **Applying the venting rule backwards.** Same-day transport means sealed; a delay beyond 24 hours means vented. Reversing this can genuinely compromise the sample.\n- **Assuming any antiseptic works for stopper disinfection.** Povidone-iodine specifically risks inhibiting the target organisms if carried into the medium by the needle; only alcohol is correct here.\n- **Assuming a single failed subculture attempt means the sample is negative.** The protocol specifically calls for re-subculturing on day 4 and day 7 before ruling out growth.\n- **Not appreciating why this specific trio of organisms drives the whole design.** *N. meningitidis*, *S. pneumoniae*, and *H. influenzae* aren't an arbitrary panel, they're the three organisms responsible for the overwhelming majority of bacterial meningitis, and all three are notoriously fragile outside CSF, which is exactly the problem this medium is built to solve.\n\n**References**\n\n1. Ajello, G. W., Feeley, J. C., Hayes, P. S., Reingold, A. L., Bolan, G., Broome, C. V., & Phillips, C. J. (1984). Trans-isolate medium: a new medium for primary culturing and transport of Neisseria meningitidis, Streptococcus pneumoniae, and Haemophilus influenzae. *Journal of clinical microbiology*, *20*(1), 55–58. \u003Chttps:\u002F\u002Fdoi.org\u002F10.1128\u002Fjcm.20.1.55-58.1984>\n2. Wasas, A. D., Huebner, R. E., & Klugman, K. P. (1999). Use of Dorset egg medium for maintenance and transport of Neisseria meningitidis and Haemophilus influenzae type b. *Journal of clinical microbiology*, *37*(6), 2045–2046. \u003Chttps:\u002F\u002Fdoi.org\u002F10.1128\u002FJCM.37.6.2045-2046.1999>",[46,49,52,55,58],{"question":47,"answer":48},"What is Trans-Isolate (T-I) medium used for?","Inoculating and transporting CSF samples from patients with suspected bacterial meningitis when the specimen can't reach a laboratory within an hour of collection.",{"question":50,"answer":51},"What organisms does T-I medium support?","Neisseria meningitidis, Streptococcus pneumoniae, and Haemophilus influenzae, the three most common causes of bacterial meningitis.",{"question":53,"answer":54},"When should a T-I bottle be vented versus left sealed?","If transport will happen the same day, leave it sealed until arrival. If transport will be delayed beyond 24 hours, vent it with a cotton-plugged needle.",{"question":56,"answer":57},"Why should povidone-iodine never be used to disinfect the T-I bottle's stopper?","A needle passing through iodine-treated rubber can carry trace iodine into the medium, inhibiting growth of the organisms the medium is meant to preserve. Only 70% alcohol should be used.",{"question":59,"answer":60},"What happens if no growth is seen after the first subculture?","The T-I medium should be re-subcultured on day 4 and again on day 7 before growth is ruled out.",[62],"specimen-collection-transport",[64,72,104,140,147,154,189,212],{"slug":65,"title":66,"description":66,"seoTitle":38,"seoDescription":38,"author":39,"createdDate":67,"lastUpdatedDate":68,"draft":42,"category":69,"image":38,"faq":70,"tags":71},"blood-collection-tubes","Blood Collection Tubes: Significance of Color Coding","2023-01-26","2026-07-19","lab-equipment",[],[62],{"slug":73,"title":74,"description":75,"seoTitle":38,"seoDescription":38,"author":39,"createdDate":76,"lastUpdatedDate":77,"draft":42,"category":69,"image":38,"faq":78,"tags":103},"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",[79,82,85,88,91,94,97,100],{"question":80,"answer":81},"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":83,"answer":84},"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":86,"answer":87},"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":89,"answer":90},"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":92,"answer":93},"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":95,"answer":96},"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":98,"answer":99},"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":101,"answer":102},"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.",[62],{"slug":105,"title":106,"description":107,"seoTitle":108,"seoDescription":38,"author":109,"createdDate":110,"lastUpdatedDate":77,"draft":42,"category":69,"image":38,"faq":111,"tags":139},"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",[112,115,118,121,124,127,130,133,136],{"question":113,"answer":114},"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":116,"answer":117},"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":119,"answer":120},"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":122,"answer":123},"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":125,"answer":126},"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":128,"answer":129},"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":131,"answer":132},"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":134,"answer":135},"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":137,"answer":138},"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.",[62],{"slug":141,"title":142,"description":142,"seoTitle":38,"seoDescription":38,"author":39,"createdDate":143,"lastUpdatedDate":41,"draft":42,"category":144,"image":38,"faq":145,"tags":146},"rejection-criteria-for-microbiological-specimens","Microbiology Sample Collection Guidelines and Rejection Criteria","2021-05-04","bacteriology",[],[62],{"slug":148,"title":149,"description":149,"seoTitle":38,"seoDescription":38,"author":39,"createdDate":150,"lastUpdatedDate":41,"draft":42,"category":151,"image":38,"faq":152,"tags":153},"sample-collections-for-laboratory-diagnosis-of-fungal-infections","Sample Collections for Lab Diagnosis of Fungal Infections","2021-04-03","mycology",[],[62],{"slug":155,"title":156,"description":157,"seoTitle":158,"seoDescription":38,"author":39,"createdDate":159,"lastUpdatedDate":77,"draft":42,"category":43,"image":38,"faq":160,"tags":188},"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",[161,164,167,170,173,176,179,182,185],{"question":162,"answer":163},"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":165,"answer":166},"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":168,"answer":169},"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":171,"answer":172},"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":174,"answer":175},"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":177,"answer":178},"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":180,"answer":181},"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":183,"answer":184},"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":186,"answer":187},"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.",[62],{"slug":190,"title":191,"description":192,"seoTitle":38,"seoDescription":38,"author":193,"createdDate":194,"lastUpdatedDate":41,"draft":42,"category":43,"image":38,"faq":195,"tags":211},"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",[196,199,202,205,208],{"question":197,"answer":198},"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":200,"answer":201},"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":203,"answer":204},"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":206,"answer":207},"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":209,"answer":210},"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.",[62],{"slug":213,"title":214,"description":214,"seoTitle":38,"seoDescription":38,"author":39,"createdDate":215,"lastUpdatedDate":216,"draft":42,"category":144,"image":38,"faq":217,"tags":218},"pus-sample-collection-staining-culture","Pus Sample: Collection, Processing, Staining and Culture","2019-02-07","2026-07-08",[],[62],[220,226,233,237,241,245,250,255,259,263],{"slug":221,"name":39,"description":222,"image":223,"body":224,"postCount":225},"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":227,"name":228,"description":229,"image":230,"body":231,"postCount":232},"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":234,"name":109,"description":235,"image":38,"body":38,"postCount":236},"sushmita-baniya","Author \u002F Contributor",32,{"slug":238,"name":239,"description":235,"image":38,"body":38,"postCount":240},"samikshya-acharya","Samikshya Acharya",20,{"slug":242,"name":243,"description":235,"image":38,"body":38,"postCount":244},"alisha-tripathi","Alisha Tripathi",6,{"slug":246,"name":247,"description":248,"image":38,"body":38,"postCount":249},"aastha-shrestha","Aastha Shrestha"," Author \u002F Contributor",10,{"slug":251,"name":252,"description":253,"image":38,"body":38,"postCount":254},"guest-author","Guest Author","Guest Author \u002F Contributor",2,{"slug":256,"name":257,"description":235,"image":38,"body":38,"postCount":258},"srijana-khanal","Srijana Khanal",18,{"slug":260,"name":261,"description":253,"image":38,"body":38,"postCount":262},"dr-poonam-acharya","Dr. Poonam Acharya",1,{"slug":264,"name":193,"description":235,"image":38,"body":265,"postCount":266},"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]