[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"$fxLN3MUwXCdr5RPjwZYIDpOj8CHyjOmngWTgoKXPtZbg":3,"$fvF79rkyPliGQJgZVXG_XZ2RZnkL4KGcM5Op0rDhtX-M":36,"$f3Ft0rKFJHppdzE-vuveecxx1BUcg9iOlMLtyzf_MJDg":157,"$fucxFBm2ZjZfGSdmdRaSNGBI_F0jJme4f0GTvzUhQfL8":220},[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},"Authors","authors","\u002Fauthors\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},"Tags","tags","\u002Ftags\u002F",{"type":37,"data":38},"blog",{"slug":39,"title":40,"description":41,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":44,"lastUpdatedDate":45,"draft":46,"category":47,"image":42,"body":48,"faq":49,"commentsClosed":46,"tags":65,"related":66,"comments":153},"tween-80-hydrolysis-test-principle-procedure-results","Tween 80 Hydrolysis Test: Amber to Pink, and Why It Separates the Mycobacteria","When a mycobacterial lipase splits Tween 80, the neutral red indicator can no longer bind it and turns from amber to pink-red. That color change separates pathogenic from saprophytic slow-growing mycobacteria, rapidly identifies M. kansasii, and tells M. gordonae from M. scrofulaceum. Here is the neutral-red mechanism (not the optical-rotation myth), the NTM differentiation logic, and how to read it.",null,"Acharya Tankeshwar","2015-02-17","2026-07-14",false,"biochemical-tests","## Why It Matters\n\nWhen a slow-growing *Mycobacterium* is isolated from a patient, the urgent question is whether it is a pathogen or a harmless environmental contaminant. Non-tuberculous mycobacteria (NTM) live in soil and water, and many are picked up as incidental colonizers, but some cause serious lung, lymph node, and disseminated disease, and they differ in which drugs they respond to. Telling them apart matters for treatment.\n\nOne of the simplest tools for that separation is the Tween 80 hydrolysis test, and it rests on a clinically useful pattern: among the slow-growing scotochromogens and non-chromogens, the **non-pathogenic** species tend to produce a lipase that hydrolyzes Tween 80, while the **pathogenic** ones often do not. So a positive Tween 80 result nudges the identification toward the more benign end of the spectrum, and a negative result raises concern.\n\nThe test does two specific, high-yield jobs. It rapidly flags ***Mycobacterium kansasii***, a genuine lung pathogen that hydrolyzes Tween 80 quickly. And it separates two scotochromogens that look identical as orange colonies on the slant: ***M. gordonae*** (positive, usually a harmless tap-water contaminant) from ***M. scrofulaceum*** (negative, a cause of cervical lymphadenitis in children). Same colony color, opposite Tween 80 result, different clinical meaning.\n\nThis article covers how the color change actually works, which is not what most sources claim, and how Tween 80 hydrolysis fits into the wider mycobacterial identification scheme.\n\nTween 80 is the trade name of the detergent polyethylene derivative of sorbitan mono-oleate. Some *Mycobacterium* species possess an enzyme-lipase, that splits the compound and releases oleic acid and polyoxyethylated sorbitol.\n\nPositive reactions occur in 1 to 4 days of incubation, and 10 days of incubation are required for confirmation of negative reactions.\n\nThe color change from amber (orange-yellow) to pink-red is the positive test, and the mechanism is worth getting right because most sources state it incorrectly. The substrate contains a **neutral red indicator**, and intact Tween 80 binds neutral red into an **amber complex**. When a lipase-positive organism hydrolyzes the Tween 80 into oleic acid and polyoxyethylated sorbitol, the detergent can no longer hold the neutral red, and the freed indicator reverts to its natural **pink-red** color at pH 7. So the color change is due to neutral red being released from its complex as the Tween 80 is destroyed. It is **not** a pH change, and it is **not** a change in optical rotation (a common but incorrect explanation).\n\n![Tween-80 hydrolysis test - Tween-80 hydrolysis test](https:\u002F\u002Fassets.microbeonline.com\u002Fblogs\u002FTween-80-hydrolysis-test.png)Figure: Tween-80 hydrolysis test\n\n## Uses\n\n1. This test is useful in identifying *Mycobacterium kansasii*, which hydrolyzes Tween 80 rapidly, often turning positive within hours to the first day rather than the several days most positive species require.\n2. To differentiate two scotochromogens with similar-appearing colonies, *M*. *gordonae* (positive) and *M. scrofulaceum* (negative). Read more about [Atypical Mycobacterial Infections](https:\u002F\u002Fmicrobeonline.com\u002Fshort-notes-atypical-mycobacterial-infections\u002F)\n\n## Specimen\n\nMature colony of the unknown *Mycobacterium* species recovered from clinical material, growth on a Lowenstein Jensen slant.\n\n## Materials\n\n1. **Supplies:** sterile applicator sticks; screw-capped tubes (12×100 mm) containing 2.0 mL deionized water per tube\n2. **Media:** [Lowenstein-Jensen slant](https:\u002F\u002Fmicrobeonline.com\u002Fpreparation-uses-lowenstein-jensen-lj-medium) (for the source culture)\n3. **Reagent:** Tween 80 hydrolysis reagent (Tween 80 in phosphate buffer with neutral red indicator)\n4. **Equipment:** biohazard hood\n\n## Procedure\n\n1. Add two drops of Tween reagent to 1 mL of sterile distilled water in screw-capped tubes\n2. Inoculate a loopful of organisms to be tested\n3. Incubate at **35°C in the dark** with caps tight\n4. Visually read tubes in 24 hours. If negative, read again at 5 and 10 days. Compare the color of the liquid with that in the control tubes.\n\n## Results\n\nA positive result is recorded when the liquid, turns from light orange to pink or red. *M. kansasii* usually turns positive rapidly, within the first 24 hours (some formulations show a reaction in as little as a few hours), unlike most positive species that require several days. Read again at 3, 5, and 10-12 days. Record results and discard positives. Discard all tubes at 12 days.\n\n## Quality Control\n\n1. Positive control: *M*. k*ansasii* (ATCC-12478) incubated for 12 days.\n2. Negative control: Stock culture of *M. intracellulare* (ATCC-13950)\n3. Negative reagent: Un-inoculated tube of a substrate incubated for 12 days.\n\n**Procedure Notes;**\n\nKeep Tween hydrolysis reagent in the dark. Do not store or incubate tubes in the light. The red color of a positive reaction is not due to a pH change. It occurs because neutral red, which was bound to intact Tween 80 in an amber complex, is released and reverts to its pink-red form once the Tween 80 is hydrolyzed.\n\n## Tween 80 hydrolysis among the lipid tests\n\nTween 80 hydrolysis is one of three related tests that detect the breakdown of lipids, and they are easy to confuse because all three involve a fat-splitting enzyme but read completely differently:\n\n| Test | Substrate | Enzyme | Positive result | Main use |\n| --- | --- | --- | --- | --- |\n| **Lipid hydrolysis (lipase)** | Tributyrin | Lipase | *Clear* zone in opaque agar | Lipolytic bacteria, *S. aureus* |\n| **Lecithinase (Nagler)** | Lecithin (egg yolk) | Lecithinase (phospholipase C) | *Opaque white* halo | *C. perfringens* (gas gangrene) |\n| **Tween 80 hydrolysis (this test)** | Tween 80 + neutral red | Mycobacterial lipase\u002Festerase | *Amber → pink-red* color change | Mycobacterial (NTM) identification |\n\nAll three detect a lipid-splitting enzyme, but the substrate, the indicator, and the visual result differ. Tween 80 hydrolysis is the mycobacterial member of the set. See the [lipid hydrolysis (lipase)](https:\u002F\u002Fmicrobeonline.com\u002Flipid-hydrolysis-test-principle-procedure-and-result\u002F) and [lecithinase (Nagler) ](https:\u002F\u002Fmicrobeonline.com\u002Fnagler-reaction-lecithinsae-test-principle-procedure-results-limitations\u002F)articles for the other two.\n\n## How to remember\n\n**Amber holds it, pink frees it.** Neutral red is bound to intact Tween 80 as an amber complex. When lipase chops up the Tween 80, the neutral red is set free and turns pink-red. Positive = pink. The color is about the *indicator being released*, not pH and not optical rotation (ignore that common myth).\n\n**Positive leans benign.** Among the slow growers, the harmless environmental species tend to hydrolyze Tween 80 (positive), while the pathogens often do not. So a pink tube nudges you toward a contaminant, a stubborn amber tube toward a pathogen. It is a lean, not a rule, always combined with other tests.\n\n**Two names to hold: kansasii fast, gordonae vs scrofulaceum.** *M. kansasii* goes positive fast (hours to a day). And for the two orange scotochromogens that look alike, *M. gordonae* (tap-water bug) is positive, *M. scrofulaceum* (child's neck node) is negative. Same color colony, opposite Tween result.\n\n**Tween is the mycobacterial lipid test.** Of the three lipid tests, tributyrin (clear zone) and egg yolk (opaque halo) are for ordinary bacteria; Tween 80 (amber to pink) is the one for mycobacteria.\n\n## Key exam facts in one table\n\n| Question | Answer | The reason behind it |\n| --- | --- | --- |\n| What does the test detect? | A mycobacterial lipase\u002Festerase | Hydrolyzes Tween 80 |\n| What is Tween 80? | Polysorbate 80, a detergent (sorbitan mono-oleate) | The substrate |\n| Products of hydrolysis | Oleic acid + polyoxyethylated sorbitol | The ester bond is split |\n| Indicator | Neutral red | Bound to intact Tween 80 as an amber complex |\n| Positive result | Amber (orange-yellow) → pink-red | Neutral red freed as Tween 80 is destroyed |\n| Negative result | Stays amber | Tween 80 intact, neutral red still bound |\n| Mechanism of color change | Neutral red released from Tween 80 complex | NOT pH change, NOT optical rotation (common myth) |\n| Timing | Positives 1-4 days; negatives confirmed at 10-12 days | Slow reaction; hold before calling negative |\n| Rapid positive | *M. kansasii* (hours to first day) | A genuine lung pathogen |\n| Scotochromogen split | *M. gordonae* (+) vs *M. scrofulaceum* (−) | Same orange colony, opposite result |\n| Clinical pattern | Non-pathogens tend positive; pathogens tend negative | Nudges pathogen-vs-contaminant call |\n| Positive QC | *M. kansasii* ATCC 12478 | Reliable positive |\n| Negative QC | *M. intracellulare* ATCC 13950 | Reliable negative |\n| Storage | Reagent in the dark, refrigerated, ≤2 weeks | Neutral red is light-sensitive |\n| Among the lipid tests | The mycobacterial one (vs tributyrin lipase, egg-yolk lecithinase) | Different substrate and readout |\n\n## Where students get confused\n\n**It is not a pH indicator reaction.** Neutral red is a pH indicator in other contexts, but here the color change is not driven by pH. The medium is buffered near pH 7 throughout. The change is about neutral red being bound (amber) versus free (pink-red), which depends on whether Tween 80 is intact.\n\n**Positive does not mean pathogen.** The clinical lean is the opposite: among the slow growers, non-pathogenic species tend to be Tween 80 positive, and pathogens tend to be negative. A positive result generally points toward a more benign identification. Never read positive as \"dangerous.\"\n\n**Reading negatives too early.** Positives can take up to 4 days, and a negative is only confirmed after 10-12 days of incubation. A tube read at 24 hours that is still amber is not yet negative, except for the rapid species like *M. kansasii*. Hold the full incubation before calling negative.\n\n**Keep it in the dark.** Neutral red is light-sensitive. Storing or incubating the tubes in light degrades the reagent and can cause false readings. Store refrigerated in the dark and incubate in the dark.\n\n**Don't confuse it with the other lipid tests.** Tween 80 hydrolysis (amber to pink, mycobacteria) is distinct from lipid hydrolysis on tributyrin (clear zone, ordinary bacteria) and lecithinase on egg yolk (opaque halo, *C. perfringens*). All three detect lipid-splitting enzymes but use different substrates and readouts.\n\n**References**\n\n1. Procop GW, Church DL, Hall GS, Janda WM, Koneman EW, Schreckenberger PC, Woods GL. *Koneman's Color Atlas and Textbook of Diagnostic Microbiology.* 7th ed. Philadelphia: Wolters Kluwer; 2017.\n2. Tille PM. *Bailey and Scott's Diagnostic Microbiology.* 15th ed. St. Louis: Elsevier; 2022.\n3. Leber AL, editor. *Clinical Microbiology Procedures Handbook.* 4th ed. Washington, DC: ASM Press; 2016. doi:10.1128\u002F9781683670438\n4. Kubica GP, et al. Rapid Tween 80 hydrolysis test for mycobacteria.",[50,53,56,59,62],{"question":51,"answer":52},"How does the color change work in the Tween 80 hydrolysis test?","The substrate contains a neutral red indicator, and intact Tween 80 binds neutral red into an amber-colored complex. When a lipase-positive mycobacterium hydrolyzes the Tween 80 into oleic acid and polyoxyethylated sorbitol, the detergent can no longer hold the neutral red. The freed indicator reverts to its natural pink-red color at pH 7. So the amber-to-pink change is caused by neutral red being released as the Tween 80 is destroyed. It is not due to a pH change, and it is not due to a change in optical rotation, which is a common but incorrect explanation.",{"question":54,"answer":55},"What is the Tween 80 hydrolysis test used for?","It is used to identify and differentiate mycobacteria, especially the slow-growing non-tuberculous mycobacteria (NTM). Among the slow growers, non-pathogenic species tend to hydrolyze Tween 80 while pathogens often do not, so the result helps sort pathogen from contaminant. Specifically, it rapidly identifies Mycobacterium kansasii, and it separates two scotochromogens with identical-looking orange colonies: M. gordonae (positive, usually a harmless tap-water organism) from M. scrofulaceum (negative, a cause of cervical lymphadenitis in children)",{"question":57,"answer":58},"Why does the Tween 80 test need to be kept in the dark?","Because the neutral red indicator in the substrate is light-sensitive. Exposure to light degrades the reagent, which can cause false or unreliable color readings. The reagent should be stored refrigerated in the dark for no more than about two weeks, and the inoculated tubes should be incubated in the dark as well.",{"question":60,"answer":61},"Does a positive Tween 80 hydrolysis test mean the mycobacterium is dangerous?","Generally the opposite. Among the slow-growing scotochromogens and non-chromogens, the non-pathogenic environmental species tend to be Tween 80 positive, while the pathogenic species tend to be negative. So a positive result usually nudges the identification toward a more benign organism, and a negative result raises concern. It is a lean rather than a rule, and it is always interpreted alongside other biochemical and growth characteristics.",{"question":63,"answer":64},"How long does the Tween 80 hydrolysis test take to read?","Positive reactions typically appear within 1 to 4 days, and a negative result is only confirmed after 10 to 12 days of incubation. Mycobacterium kansasii is an exception, hydrolyzing Tween 80 rapidly, often within the first 24 hours or even a few hours. Because most positives are slow, an amber tube at 24 hours is not yet negative and must be held for the full incubation period before being reported negative.",[],[67,98,107,130],{"slug":68,"title":69,"description":70,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":71,"lastUpdatedDate":72,"draft":46,"category":73,"image":42,"faq":74,"tags":96},"short-notes-atypical-mycobacterial-infections","Non-Tuberculous (Atypical) Mycobacteria: The Diseases, the Runyon Groups, and When to Suspect Them","\u003Cp>The non-tuberculous (atypical) mycobacteria: environmental organisms that cause lung disease, lymphadenitis, skin infections, and disseminated disease, how they differ from TB, and the Runyon classification.\u003C\u002Fp>","2014-11-07","2026-08-12","bacteriology",[75,78,81,84,87,90,93],{"question":76,"answer":77},"\u003Cp>What are non-tuberculous (atypical) mycobacteria?\u003C\u002Fp>","\u003Cp>All the mycobacteria except the \u003Cem>M. tuberculosis\u003C\u002Fem> complex and \u003Cem>M. leprae\u003C\u002Fem>. They are environmental organisms found in soil and water that usually cause disease only in people with damaged lungs, weakened immunity, or broken skin. They are also called atypical, environmental, or MOTT.\u003C\u002Fp>",{"question":79,"answer":80},"\u003Cp>How are NTM different from tuberculosis?\u003C\u002Fp>","\u003Cp>NTM come from the environment rather than from other people and do not spread person to person. They are often opportunistic, and a positive culture may reflect harmless colonization rather than disease, so it must be interpreted clinically. TB, by contrast, spreads between people and is almost always significant when isolated.\u003C\u002Fp>",{"question":82,"answer":83},"\u003Cp>What diseases do NTM cause?\u003C\u002Fp>","\u003Cp>Four main patterns: chronic lung disease (mainly MAC and \u003Cem>M. kansasii\u003C\u002Fem>), cervical lymphadenitis in children (\u003Cem>M. scrofulaceum\u003C\u002Fem>, MAC), skin and soft-tissue infection after water exposure or trauma (\u003Cem>M. marinum\u003C\u002Fem>, \u003Cem>M. ulcerans\u003C\u002Fem>, rapid growers), and disseminated disease in the severely immunocompromised (MAC in advanced AIDS).\u003C\u002Fp>",{"question":85,"answer":86},"\u003Cp>What is the Runyon classification?\u003C\u002Fp>","\u003Cp>A laboratory scheme that sorts NTM by growth rate and pigment: photochromogens (pigment in light), scotochromogens (pigment even in the dark), non-chromogens (no pigment), and rapid growers (colonies in under 7 days). It is being replaced by molecular identification but remains a common exam topic.\u003C\u002Fp>",{"question":88,"answer":89},"\u003Cp>What is fish-tank granuloma?\u003C\u002Fp>","\u003Cp>A skin infection caused by \u003Cem>Mycobacterium marinum\u003C\u002Fem>, acquired from contact with aquariums or swimming pools. It causes nodular skin lesions at the site of a minor injury, which can spread in a line up the arm along the lymphatics.\u003C\u002Fp>",{"question":91,"answer":92},"\u003Cp>What is Buruli ulcer?\u003C\u002Fp>","\u003Cp>A destructive skin and soft-tissue ulcer caused by \u003Cem>Mycobacterium ulcerans\u003C\u002Fem>. Its toxin, mycolactone, destroys tissue and numbs the area, so the ulcer is characteristically painless despite being large. It is the third most common mycobacterial disease worldwide after TB and leprosy.\u003C\u002Fp>",{"question":94,"answer":95},"\u003Cp>Why is a positive NTM culture sometimes ignored?\u003C\u002Fp>","\u003Cp>Because NTM are everywhere in the environment and can colonize the airways or contaminate a sample without causing disease. A single positive culture may not mean infection, so doctors look for repeated positive cultures plus compatible symptoms and imaging before treating.\u003C\u002Fp>",[97],"mycobacteria",{"slug":99,"title":100,"description":101,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":102,"lastUpdatedDate":103,"draft":46,"category":104,"image":42,"faq":105,"tags":106},"preparation-uses-lowenstein-jensen-lj-medium","Löwenstein-Jensen (LJ) Medium: Principle, Preparation, Uses, and Colony Characteristics","\u003Cp>Löwenstein-Jensen (LJ) medium is the standard solid culture medium for \u003Cem>Mycobacterium tuberculosis.\u003C\u002Fem> Learn its principle, preparation by inspissation, colony characteristics of\u003Cem> M. tuberculosis\u003C\u002Fem> and NTM, and how LJ compares to MGIT liquid culture.\u003C\u002Fp>","2016-04-29","2026-08-09","culture-media",[],[97],{"slug":108,"title":109,"description":110,"seoTitle":42,"seoDescription":42,"author":111,"createdDate":112,"lastUpdatedDate":45,"draft":46,"category":47,"image":42,"faq":113,"tags":129},"lipid-hydrolysis-test-principle-procedure-and-result","Lipase (Lipid Hydrolysis) Test: The Clear Zone That Reveals a Fat-Digesting Enzyme","Lipids are too large for a bacterium to import, so lipase-producing organisms digest them outside the cell, clearing the opaque tributyrin agar into a transparent halo. That clearing identifies lipase producers like Staphylococcus aureus and separates them from non-lipolytic bacteria. Here is the extracellular-enzyme mechanism, why lipase is a virulence factor, and how the test differs from the lecithinase (Nagler) test.","Ashma Shrestha","2023-04-26",[114,117,120,123,126],{"question":115,"answer":116},"What does a positive lipid hydrolysis (lipase) test look like?","A clear, transparent zone or halo around the bacterial growth on tributyrin agar. The agar is normally opaque because it is an emulsion of fat suspended in the medium. A lipase-positive organism secretes lipase that digests the surrounding fat, clearing the emulsion into a transparent window. So the positive result is the disappearance of cloudiness, not the appearance of a color or precipitate. If the medium stays cloudy right up to the colony, the organism is lipase-negative.",{"question":118,"answer":119},"Why is lipase considered a virulence factor?","Because some pathogens use lipase to break down the lipid-rich secretions of the body, especially skin sebum. Staphylococcus aureus and Cutibacterium acnes (formerly Propionibacterium acnes) both produce lipases that digest sebum, helping them colonize and persist on skin and contributing to the tissue damage of skin and wound infections. In C. acnes, the free fatty acids released drive the inflammation of acne. So the enzyme this test detects is the same one that helps these organisms live on and damage skin.",{"question":121,"answer":122},"What is the difference between the lipase test and the lecithinase (Nagler) test?","They detect different enzymes on different substrates and give opposite-looking results. The lipase test uses tributyrin agar and detects lipase acting on triglycerides; a positive is a clear zone. The lecithinase test uses egg yolk agar (the Nagler reaction) and detects lecithinase, a phospholipase C, acting on lecithin; a positive is a white, opaque precipitate zone. Clostridium perfringens is the classic contrast: lecithinase-positive but lipase-negative. So lipase clears the medium while lecithinase clouds it.",{"question":124,"answer":125},"Why does lipase have to act outside the bacterial cell?","Because lipids such as triglycerides are large, water-insoluble molecules that cannot cross the bacterial cell membrane intact. To use fat as a nutrient, the organism must first break it down outside the cell. Lipase is an extracellular enzyme secreted into the surroundings, where it cleaves the ester bonds of the triglyceride into glycerol and free fatty acids small enough to be absorbed and metabolized. This is why the clear zone forms in the agar around the colony rather than inside it.",{"question":127,"answer":128},"Why does the lipid hydrolysis test need long incubation?","Because lipase reactions are slow to produce a visible zone. Aerobic bacteria typically need 24 to 48 hours and anaerobes up to 72 hours or more, and some organisms take up to a week to generate a clear lipolytic zone. A plate read too early may look negative on a genuine but slow lipase producer, so the plate should be held for the full incubation period before being reported as negative.",[],{"slug":131,"title":132,"description":133,"seoTitle":42,"seoDescription":42,"author":134,"createdDate":135,"lastUpdatedDate":45,"draft":46,"category":47,"image":42,"faq":136,"tags":152},"nagler-reaction-lecithinsae-test-principle-procedure-results-limitations","Nagler's Reaction (Lecithinase Test): The Antitoxin Trick That Identifies Clostridium perfringens","Clostridium perfringens produces alpha-toxin, a lecithinase that clouds egg yolk agar with an opaque halo. The Nagler test proves it is the specific toxin by neutralizing it with antitoxin on half the plate. Here is the half-plate design, why the enzyme this test detects is the same one that destroys tissue in gas gangrene, and how lecithinase differs from lipase.","Nisha Rijal","2015-09-01",[137,140,143,146,149],{"question":138,"answer":139},"What is the Nagler reaction and what does it identify?","The Nagler reaction is a test that identifies Clostridium perfringens by detecting its alpha-toxin, a lecithinase (phospholipase C). On egg yolk agar, the lecithinase breaks down lecithin into an insoluble diglyceride that forms an opaque white halo around the growth. The test is made specific by applying C. perfringens type A antitoxin to half the plate: a true positive shows the opaque halo on the antitoxin-free half but not on the antitoxin half, because the antitoxin neutralizes the toxin. This proves the lecithinase is the neutralizable alpha-toxin, pointing to the C. perfringens group.",{"question":141,"answer":142},"How is the lecithinase (Nagler) test different from the lipase test?","They detect different enzymes and give opposite-looking results. Lecithinase acts on lecithin (a phospholipid) and produces an opaque white halo in egg yolk agar. Lipase acts on triglycerides and produces either an iridescent sheen on the colony surface (on egg yolk agar) or a clear zone (on tributyrin agar). C. perfringens is the clean contrast: lecithinase-positive but lipase-negative, while C. sporogenes is lipase-positive. So lecithinase clouds the medium and lipase clears it.",{"question":144,"answer":145},"Why is antitoxin used in the Nagler test?","To make the test specific for the C. perfringens alpha-toxin. Many organisms produce a lecithinase, so an opaque halo alone is not enough to identify C. perfringens. By applying C. perfringens type A antitoxin to half the plate, the test shows whether the lecithinase is the specific, neutralizable alpha-toxin: if the halo is inhibited on the antitoxin side but present on the antitoxin-free side, the reaction is a positive Nagler test. A halo on both sides means the lecithinase is not neutralizable alpha-toxin, so the test is negative.",{"question":147,"answer":148},"Is a positive Nagler reaction specific for Clostridium perfringens?","It is presumptive for the C. perfringens group rather than absolutely specific. The type A antitoxin can cross-neutralize the lecithinases of C. bifermentans, C. sordellii, and C. baratii, especially with a heavy inoculum, so these can also give a positive Nagler reaction. Definitive identification requires additional biochemical, immunological, or molecular testing. Clinically, though, a positive Nagler reaction on a suspicious wound isolate is a strong and rapid presumptive pointer to C. perfringens.",{"question":150,"answer":151},"Why does the Nagler test matter clinically?","Because the lecithinase it detects is the C. perfringens alpha-toxin, the enzyme responsible for the tissue destruction of gas gangrene (clostridial myonecrosis). The alpha-toxin is a phospholipase C that hydrolyzes membrane phospholipids, lysing red cells, platelets, and muscle cells and spreading through tissue. Gas gangrene is a surgical emergency, so a rapid presumptive identification of C. perfringens is clinically valuable, and the Nagler test provides one by detecting the toxin itself.",[],{"enabled":154,"threads":155,"total":156},true,[],0,[158,164,170,177,183,188,194,199,205,208,214],{"slug":159,"name":43,"description":160,"image":161,"body":162,"postCount":163},"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.*",489,{"slug":165,"name":111,"description":166,"image":167,"body":168,"postCount":169},"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.",79,{"slug":171,"name":172,"description":173,"image":174,"body":175,"postCount":176},"sushmita-baniya","Sushmita Baniya","Author \u002F Contributor","https:\u002F\u002Fassets.microbeonline.com\u002Fauthors\u002Fsushmita-baniya-1.png","Sushmita Baniya holds an M.Sc. in Medical Microbiology from Tribhuvan University (National College), with a research focus in Genetics and Molecular Biology. She is actively involved in teaching and research in the field of microbiology.",26,{"slug":178,"name":179,"description":173,"image":180,"body":181,"postCount":182},"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":184,"name":185,"description":173,"image":42,"body":186,"postCount":187},"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":189,"name":190,"description":191,"image":42,"body":192,"postCount":193},"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":195,"name":196,"description":197,"image":42,"body":42,"postCount":198},"guest-author","Guest Author","Guest Author \u002F Contributor",1,{"slug":200,"name":201,"description":173,"image":202,"body":203,"postCount":204},"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.",15,{"slug":206,"name":207,"description":197,"image":42,"body":42,"postCount":198},"dr-poonam-acharya","Dr. Poonam Acharya",{"slug":209,"name":134,"description":210,"image":211,"body":212,"postCount":213},"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":215,"name":216,"description":217,"image":218,"body":219,"postCount":198},"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.",[221,228,234,239,244,249,252,256,260,265,269,274,278,283,288,292,296,300,305,310,314,318,322,326,330,334,338,342,347,352,356,360,364,369,373,377,381,385,389,393,397,401,405,409,413,417,421,425,430,434,438,442,446,450,454,458,462,466,470,474,478,482,486,490,494,498,502,506,509,513,516,519,522,525,528,531,534,537,540,543,546,549,552],{"slug":222,"name":223,"description":224,"image":225,"body":226,"postCount":227},"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":229,"name":230,"description":231,"image":42,"body":232,"postCount":233},"microscopy","Microscopy","Microscope types, components, and microscopy techniques","These are list of blog posts related to microscopy. ",12,{"slug":235,"name":236,"description":237,"image":42,"body":42,"postCount":238},"gram-positive-cocci","Gram-Positive Cocci","Staphylococcus, Streptococcus, Enterococcus, Micrococcus — organisms, diseases, and identification tests",11,{"slug":240,"name":241,"description":242,"image":42,"body":42,"postCount":243},"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":245,"name":246,"description":247,"image":42,"body":42,"postCount":248},"gram-positive-rods","Gram-Positive Rods","Bacillus, Clostridium, Listeria, Corynebacterium, Actinomyces and related organisms",8,{"slug":97,"name":250,"description":251,"image":42,"body":42,"postCount":233},"Mycobacteria","Mycobacterium tuberculosis, leprosy, atypical mycobacteria, and acid-fast organism diagnosis",{"slug":253,"name":254,"description":255,"image":42,"body":42,"postCount":233},"anaerobic-bacteriology","Anaerobic Bacteriology","Anaerobic organisms, anaerobic culture methods, and anaerobic infection diagnosis",{"slug":257,"name":258,"description":259,"image":42,"body":42,"postCount":233},"enterobacteriaceae","Enterobacteriaceae","Identification, differentiation, and clinical significance of Enterobacteriaceae family members",{"slug":261,"name":262,"description":263,"image":42,"body":42,"postCount":264},"spirochetes","Spirochetes","Treponema, Leptospira, Borrelia and spirochetal infections",7,{"slug":266,"name":267,"description":268,"image":42,"body":42,"postCount":227},"food-microbiology","Food Microbiology","Food-borne pathogens, food safety, spoilage, and preservation",{"slug":270,"name":271,"description":272,"image":42,"body":42,"postCount":273},"antimicrobial-susceptibility-testing","Antimicrobial Susceptibility Testing","Methods for testing antibiotic susceptibility in clinical microbiology",21,{"slug":275,"name":276,"description":277,"image":42,"body":42,"postCount":227},"antimicrobials-moa-amr","Antimicrobials (MOA & AMR)","Mechanisms, detection, and clinical significance of antimicrobial resistance",{"slug":279,"name":280,"description":281,"image":42,"body":42,"postCount":282},"sterilization-disinfection","Sterilization and Disinfection","Methods of sterilization and disinfection in healthcare and laboratory settings",10,{"slug":284,"name":285,"description":286,"image":42,"body":42,"postCount":287},"specimen-collection-transport","Specimen Collection and Transport","Collection, handling, and transport of clinical specimens for microbiological testing",27,{"slug":289,"name":290,"description":291,"image":42,"body":42,"postCount":273},"bacterial-structure-physiology","Bacterial Structure and Physiology","Bacterial cell structure, growth, physiology, and environmental factors affecting growth",{"slug":293,"name":294,"description":42,"image":42,"body":295,"postCount":187},"horizontal-gene-transfer","Horizontal Gene Transfer","Articles related to **Horizontal Gene Transfer**",{"slug":297,"name":298,"description":42,"image":42,"body":299,"postCount":282},"chromatography","Chromatography","Information about chromatographic techniques.",{"slug":301,"name":302,"description":303,"image":42,"body":304,"postCount":264},"electrophoresis","Electrophoresis","Information about Electrophoresis Techniques ","Detailed information  about Electrophoresis Techniques ",{"slug":306,"name":307,"description":308,"image":42,"body":309,"postCount":187},"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":311,"name":312,"description":313,"image":42,"body":42,"postCount":187},"bacteriophage","Bacteriophage","Description about Bacteriophage.",{"slug":315,"name":316,"description":317,"image":42,"body":42,"postCount":187},"malaria","Malaria","It is the collections of articles regarding malarial disease. ",{"slug":319,"name":320,"description":321,"image":42,"body":42,"postCount":187},"anaerobic-culture-techniques","Anaerobic Culture Techniques","Posts related with Anaerobic Culture Techniques.",{"slug":323,"name":324,"description":325,"image":42,"body":42,"postCount":182},"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.",{"slug":327,"name":328,"description":329,"image":42,"body":42,"postCount":264},"biosafety-levels","Biosafety levels ","Articles related to Biosafety Levels",{"slug":331,"name":332,"description":333,"image":42,"body":42,"postCount":243},"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":335,"name":336,"description":337,"image":42,"body":42,"postCount":187},"pipette","Pipette","Posts related with Pipette. ",{"slug":339,"name":340,"description":341,"image":42,"body":42,"postCount":264},"bacteriology-mcqs","Bacteriology MCQs","This sections lists MCQs in Bacteriology.",{"slug":343,"name":344,"description":345,"image":42,"body":42,"postCount":346},"parasitology-mcqs","Parasitology MCQs","This section lists MCQs in Parasitology.",2,{"slug":348,"name":349,"description":350,"image":42,"body":42,"postCount":351},"virology-mcqs","Virology MCQs","This is the collections of Multiple Choice Questions in Virology.",4,{"slug":353,"name":354,"description":355,"image":42,"body":42,"postCount":243},"mcqs-in-microbiology","MCQs in Microbiology","This section lists the collections of Multiple Choice Questions in General Microbiology Topics. ",{"slug":357,"name":358,"description":359,"image":42,"body":42,"postCount":264},"immunology-mcqs","Immunology MCQs","In this section; we are posting collections of Multiple Choice Questions about Immunology. ",{"slug":361,"name":362,"description":363,"image":42,"body":42,"postCount":282},"microbial-curiosities","Microbial Curiosities","In this clusters, we are posting interesting and unique information about Microorganisms. ",{"slug":365,"name":366,"description":367,"image":42,"body":42,"postCount":368},"bacterial-culture-media","Bacterial Culture Media","Posts related to Bacterial Culture Media. ",23,{"slug":370,"name":371,"description":372,"image":42,"body":42,"postCount":187},"fungal-culture-media","Fungal Culture Media","Posts related to Fungal Culture Media.",{"slug":374,"name":375,"description":376,"image":42,"body":42,"postCount":243},"motility-test","Motility Test","This lists the procedure regarding various tests methods for bacterial motility.",{"slug":378,"name":379,"description":380,"image":42,"body":42,"postCount":282},"bacterial-enumeration","Bacterial enumeration","These posts are related to isolation and enumeration of bacteria. ",{"slug":382,"name":383,"description":384,"image":42,"body":42,"postCount":346},"gram-positive-coccobacillus","Gram-positive coccobacillus","List of Gram Positive Coccobacilli",{"slug":386,"name":387,"description":388,"image":42,"body":42,"postCount":351},"dimorphic-fungi","Dimorphic Fungi","This is about various dimorphic fungi. ",{"slug":390,"name":391,"description":392,"image":42,"body":42,"postCount":264},"bacterial-classification","Bacterial Classification","These posts are related with various approaches used for the classification of Bacteria. ",{"slug":394,"name":395,"description":396,"image":42,"body":42,"postCount":243},"immunofluorescence","Immunofluorescence ","Various Tests related to Immunofluorescence ",{"slug":398,"name":399,"description":400,"image":42,"body":42,"postCount":193},"antibody-mediated-immunity","Antibody-mediated Immunity","This clusters links the articles that are sharing insights about Antibody-mediated immunity. ",{"slug":402,"name":403,"description":404,"image":42,"body":42,"postCount":264},"hypersensitivity","Hypersensitivity","Articles related to Hypersensitivity.",{"slug":406,"name":407,"description":42,"image":42,"body":42,"postCount":408},"haemophilus","Haemophilus",3,{"slug":410,"name":411,"description":412,"image":42,"body":42,"postCount":351},"sexually-transmitted-infections-stis","Sexually transmitted infections (STIs)","This is the clusters of infections that are transmitted sexually. ",{"slug":414,"name":415,"description":416,"image":42,"body":42,"postCount":233},"adaptive-immunity","Adaptive Immunity","Blog posts related to B Cell Immunity and T Cell Immunity.",{"slug":418,"name":419,"description":420,"image":42,"body":42,"postCount":227},"fungal-diagnostics","Fungal Diagnostics","Various methods used for the Diagnosis of Fungal Infections. ",{"slug":422,"name":423,"description":424,"image":42,"body":42,"postCount":243},"laboratory-storage-and-preservation","Laboratory Storage and Preservation","Articles about Laboratory Storage of Antimicrobial Disk, Test organisms and Equipment used for this process. ",{"slug":426,"name":427,"description":428,"image":42,"body":429,"postCount":187},"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":431,"name":432,"description":433,"image":42,"body":42,"postCount":193},"laboratory-glassware","Laboratory Glassware","Posts about Laboratory Glassware. ",{"slug":435,"name":436,"description":437,"image":42,"body":42,"postCount":193},"helminths","Helminths","In this section, we are covering properties, life cycle, pathogenesis and laboratory diagnosis of Helminths\u002FHelminthic infestations. ",{"slug":439,"name":440,"description":441,"image":42,"body":42,"postCount":248},"protozoan-parasite","Protozoan Parasite","In this cluster, we are covering protozoan parasites. ",{"slug":443,"name":444,"description":445,"image":42,"body":42,"postCount":198},"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":447,"name":448,"description":449,"image":42,"body":42,"postCount":282},"bacterial-staining-technique","Bacterial Staining Technique","Lists of various staining techniques that are used to stain bacteria. ",{"slug":451,"name":452,"description":453,"image":42,"body":42,"postCount":273},"enzyme-tests","Enzyme Tests","\u003Cp>Various Biochemical Test that are based on enzymatic activity of the microorganisms. \u003C\u002Fp>",{"slug":455,"name":456,"description":457,"image":42,"body":42,"postCount":238},"carbohydrate-utilization","Carbohydrate Utilization","\u003Cp>Various biochemical tests which are related to Carbohydrate fermentation or Utilization\u003C\u002Fp>",{"slug":459,"name":460,"description":461,"image":42,"body":42,"postCount":243},"susceptibility-based-id","Susceptibility-based ID","\u003Cp>These are susceptibility based identification test such as optochin sensitivity, bacitracin sensitivity etc. \u003C\u002Fp>",{"slug":463,"name":464,"description":465,"image":42,"body":42,"postCount":351},"microbial-metabolism","Microbial Metabolism","\u003Cp>Tests about Microbial Metabolism. \u003C\u002Fp>",{"slug":467,"name":468,"description":469,"image":42,"body":42,"postCount":248},"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":471,"name":472,"description":473,"image":42,"body":42,"postCount":408},"atypical-pneumonia","Atypical Pneumonia","\u003Cp>Organisms responsible for Atypical Pneumonia. \u003C\u002Fp>",{"slug":475,"name":476,"description":477,"image":42,"body":42,"postCount":243},"antigen","Antigen","\u003Cp>Various articles related to Antigens.\u003C\u002Fp>",{"slug":479,"name":480,"description":481,"image":42,"body":42,"postCount":264},"innate-immunity","Innate Immunity","\u003Cp>Articles related to Innate Immunity. \u003C\u002Fp>",{"slug":483,"name":484,"description":485,"image":42,"body":42,"postCount":351},"respiratory-tract-infection","Respiratory Tract Infection","\u003Cp>In this cluster, you can see various etiological agents that causes respiratory tract infection. \u003C\u002Fp>",{"slug":487,"name":488,"description":489,"image":42,"body":42,"postCount":243},"torch-infection","TORCH Infection","\u003Cp>In this section; you can find articles related with TOCH infection. \u003C\u002Fp>",{"slug":491,"name":492,"description":493,"image":42,"body":42,"postCount":248},"microbiology-for-beginners","Microbiology for Beginners","\u003Cp>These articles are very basic articles, which will share general concepts in Microbiology. \u003C\u002Fp>",{"slug":495,"name":496,"description":497,"image":42,"body":42,"postCount":187},"dna-replication","DNA Replication","\u003Cp>Articles related to DNA and Replication of DNA. \u003C\u002Fp>",{"slug":499,"name":500,"description":501,"image":42,"body":42,"postCount":264},"genetic-code","Genetic Code","\u003Cp>Articles related to Genetic Code.\u003C\u002Fp>",{"slug":503,"name":504,"description":505,"image":42,"body":42,"postCount":264},"molecular-technique","Molecular Technique","\u003Cp>Posts related to Molecular Techniques. \u003C\u002Fp>",{"slug":507,"name":508,"description":42,"image":42,"body":42,"postCount":198},"colorimetric-assay","Colorimetric Assay ",{"slug":510,"name":511,"description":512,"image":42,"body":42,"postCount":243},"pharmaceutical-microbiology","Pharmaceutical Microbiology","\u003Cp>Various articles related to Pharmaceutical Microbiology\u003C\u002Fp>",{"slug":514,"name":515,"description":42,"image":42,"body":42,"postCount":408},"blood-and-immune-cells","Blood and Immune Cells",{"slug":517,"name":518,"description":42,"image":42,"body":42,"postCount":243},"host-pathogen-interaction","Host Pathogen Interaction",{"slug":520,"name":521,"description":42,"image":42,"body":42,"postCount":351},"blood-culture","Blood Culture",{"slug":523,"name":524,"description":42,"image":42,"body":42,"postCount":351},"environmental-microbiology","Environmental microbiology ",{"slug":526,"name":527,"description":42,"image":42,"body":42,"postCount":264},"copromicroscopic-technique","Copromicroscopic Technique",{"slug":529,"name":530,"description":42,"image":42,"body":42,"postCount":408},"quality-control","Quality Control",{"slug":532,"name":533,"description":42,"image":42,"body":42,"postCount":264},"dermatophytes","Dermatophytes",{"slug":535,"name":536,"description":42,"image":42,"body":42,"postCount":408},"viral-hemorrhagic-fevers","Viral Hemorrhagic Fevers",{"slug":538,"name":539,"description":42,"image":42,"body":42,"postCount":351},"h2s-production","H2S Production",{"slug":541,"name":542,"description":42,"image":42,"body":42,"postCount":346},"water-quality-testing","Water Quality Testing",{"slug":544,"name":545,"description":42,"image":42,"body":42,"postCount":243},"virology-basics","Virology basics",{"slug":547,"name":548,"description":42,"image":42,"body":42,"postCount":351},"typing-methods","Typing Methods",{"slug":550,"name":551,"description":42,"image":42,"body":42,"postCount":408},"blotting-technique","Blotting Technique",{"slug":553,"name":554,"description":42,"image":42,"body":42,"postCount":351},"history-microbiology","History of Microbiology"]