[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"$fxLN3MUwXCdr5RPjwZYIDpOj8CHyjOmngWTgoKXPtZbg":3,"$f8cjdhV7R49UsFsj-UTN9O9GhbO26o6MxYwSB3fdR5yc":36,"$f3Ft0rKFJHppdzE-vuveecxx1BUcg9iOlMLtyzf_MJDg":253,"$fucxFBm2ZjZfGSdmdRaSNGBI_F0jJme4f0GTvzUhQfL8":317},[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":43,"author":44,"createdDate":45,"lastUpdatedDate":46,"draft":47,"category":48,"image":49,"body":50,"faq":51,"commentsClosed":47,"tags":76,"related":78,"comments":249},"diagnostic-tests-biochemical-tests-coagulase-test","Coagulase Test: Principle, Procedure, Results","Learn the coagulase test step by step: slide and tube methods, results interpretation, MRSA limitations, and reporting guide for clinical labs.","Coagulase Test: Slide vs Tube Methods, Results, and Pitfalls","Compare slide and tube coagulase methods, select controls, interpret clumping and clot formation, and avoid common errors in Staphylococcus identification.","Acharya Tankeshwar","2012-04-18","2026-08-05",false,"biochemical-tests",null,"**Two blood cultures, the same Gram stain, oppositive meaning**\n\nTwo patients, two positive blood cultures, and under the microscope the smears look identical: Gram-positive cocci in clusters. Both are catalase positive, so both are staphylococci.\n\nThe first patient has a central line and a low-grade fever. The second has a new heart murmur, a fever, and no obvious source.\n\nFor both, the next test is the same, and it costs almost nothing: coagulase.\n\nIf the organism is coagulase negative, the first result is probably a skin contaminant picked up when the line was drawn. One bottle, no fever spike, coagulase-negative staphylococci: the lab reports it, the clinician watches, and often nothing more is needed. But if that same patient had a prosthetic valve or an indwelling device, coagulase-negative *Staphylococcus epidermidis* becomes a real pathogen colonizing the hardware, and the test result reads the same.\n\nIf the organism is coagulase positive, it is [*Staphylococcus aureus*](https:\u002F\u002Fmicrobeonline.com\u002Fstaphylococcus-aureusdisease-properties-pathogenesis-and-laboratory-diagnosis\u002F) until proven otherwise, and the second patient's new murmur is now infective endocarditis until an echocardiogram says it is not. *S. aureus* in the blood is never dismissed. It seeds heart valves, bone, and joints, and it kills.\n\nCoagulase is the enzyme that separates these two paths. It is not a perfect test, and the ways it fails, a slide-negative *S. aureus*, a citrate false positive, a dog-associated species that mimics *aureus*, are the reason this article is longer than a three-second test seems to deserve.\n\n## Principle of the coagulase test\n\nCoagulase is an enzyme or more precisely, a protein with enzyme-like activity produced by *Staphylococcus aureus* that causes plasma to clot. Its detection is the cornerstone of *S. aureus* identification in clinical microbiology, because among clinically significant staphylococci, only *S. aureus* (and a few rarely encountered animal-associated species) produces coagulase in quantities sufficient to give a positive test.\n\n### Why does S. aureus produce coagulase?\n\nCoagulase functions as a **virulence factor of *S. aureus***. By converting soluble fibrinogen in plasma into insoluble fibrin, coagulase coats the bacterial cell surface with a layer of fibrin. This fibrin coat serves two protective purposes:\n\n1. It masks bacterial surface antigens from recognition by the host immune system\n2. It physically protects the organism from opsonization and subsequent phagocytosis by neutrophils and macrophages\n\nIn essence, *S. aureus* uses coagulase to hide inside a clot of the host's own plasma, evading the very immune mechanisms designed to destroy it.\n\n### Bound coagulase vs. free coagulase\n\n*S. aureus* produces two distinct forms of coagulase, and the coagulase test has a separate method for detecting each:\n\n| Feature | Bound coagulase (clumping factor) | Free coagulase (staphylocoagulase) |\n| --- | --- | --- |\n| Location | Cell wall surface receptor | Secreted into surrounding medium |\n| Mechanism | Binds fibrinogen directly on cell surface, causing immediate clumping | Reacts with coagulase-reacting factor (CRF) in plasma to form a thrombin-like complex that converts fibrinogen to fibrin |\n| Test used | Slide coagulase test | Tube coagulase test |\n| Speed | Result in 10 seconds | Result in 1–4 hours (up to overnight) |\n| Sensitivity | Lower. About 15% of *S. aureus* strains are negative | Higher: definitive test for *S. aureus* |\n| Clinical significance | Rapid screening | Confirmatory identification |\n\nBecause not all *S. aureus* strains express bound coagulase (particularly MRSA strains), a **negative slide test must always be confirmed by a tube coagulase test**. The tube test is the definitive, gold-standard method for *S. aureus* identification.\n\n## Slide Coagulase Test\n\nSlide coagulase test is done to detect “bound coagulase” or “clumping factor”. The clumping factor is a fibrinogen-binding cell surface receptor present in the cell walls of most, but not all, *S. aureus* strains. The clumping factor acts directly on the fibrinogen in the plasma, resulting in clumping. Slide coagulase test is rapid, but it requires several colonies and lacks sensitivity.\n\n\u003Cfigure>\n\u003Cimg src=\"https:\u002F\u002Fassets.microbeonline.com\u002Fblogs\u002Fslide-coagulase-test-1.jpg\" alt=\"Slide Coagulase Test\" width=\"320\" height=\"245\" draggable=\"false\" contenteditable=\"false\">\u003Cfigcaption>Slide Coagulase Test\u003C\u002Ffigcaption>\n\u003C\u002Ffigure>\n\nAs the clumping factors are not present in all *S. aureus*, some strains will give a negative slide coagulase test. In addition, clumping factors can be masked by cell surface capsular polysaccharides. So, the negative slide tests must be confirmed by tube coagulase test. Other species of Staphylococcus, namely, *S. lugdunensis* and *S. schleiferi* may give positive slide coagulase test results.\n\n> Note: Colonies from a mannitol salt agar (MSA) culture are not suitable for coagulase testing. The organism must first be cultured on nutrient agar or blood agar.\n\n### Slide Coagulase Test Procedure\n\n1. Emulsify a staphylococcal colony in a drop of water on a clean and grease-free glass slide with a minimum of spreading (If the isolate does not form a smooth, milky suspension, do not proceed with the test).\n2. Make similar suspensions of control positive and negative strains to confirm the proper reactivity of the plasma.\n3. Dip a flamed and cooled straight inoculating wire into the undiluted plasma at room temperature, withdraw, and stir the adhering traces of plasma (not a loopful) into the staphylococcal suspension on the slide. Flame the wire and repeat for the control suspensions.\n4. Read as positive a coarse clumping of cocci visible to the naked eye within 10 seconds. Read as negative the absence of clumping or any reaction taking more than 10 seconds to develop, but re-examine any slow reacting strains by the **tube coagulase test**.\n\n### Observation\n\n\u003Cfigure>\n\u003Cimg src=\"https:\u002F\u002Fassets.microbeonline.com\u002Fblogs\u002Fslide-coagulase-test-1.jpg\" alt=\"Slide Coagulase Test\" width=\"320\" height=\"245\" draggable=\"false\" contenteditable=\"false\">\u003Cfigcaption>Slide Coagulase Test\u003C\u002Ffigcaption>\n\u003C\u002Ffigure>\n\n1\\. **Coagulase positive**: Macroscopic clumping in 10 seconds or less in coagulated plasma drop and no clumping in saline or water drop.\n\n2\\. **Coagulase-negative**: No clumping in either drop\n\n### Interpretation\n\nSlide coagulase test is the main method used to identify *S. aureus* in clinical laboratories but it has some limitations.\n\n1. About 15% of ordinary strains of *S. aureus* and many more of [MRSA ](\u002Fmrsa-emergence-types-detection\u002F)give negative reactions.\n2. Few species of coagulase-negative staphylococci give positive reactions.\n\n**Note**: All coagulase-negative slides **must be confirmed using a tube coagulase test as the definitive test for *S. aureus.***\n\n## Tube Coagulase Test\n\nTube coagulase test detects free coagulase (staphylocoagulase) which reacts with **coagulase-reacting factor (CRF)**. CRF is a plasma protein, often described as a thrombin-like molecule, that serves as an activator. Staphylocoagulase forms a complex with CRF, and this complex then indirectly converts soluble fibrinogen in plasma to insoluble fibrin, resulting in a clot.\n\nWhen a suspension of the organism is incubated with plasma at 35°C, clot formation within 4 hours indicates a positive test.\n\nThe coagulase clot thus formed can be destroyed by *S. aureus* fibrinolysin or staphylokinase. Staphylokinase is more active at 35°C than at room temperature (around 25°C). Therefore, if a clot forms early and is then lysed by staphylokinase at incubation temperature, you might miss it. This is why tubes must be examined periodically, and **negative tubes are held overnight at room temperature, where staphylokinase activity is reduced, allowing any delayed or transient clot to persist and be observed.**\n\n### Tube Coagulase Test Procedure\n\n1. Prepare a 1-in-6 dilution of the plasma in saline (0.85% NaCl) and place 1 ml volumes of the diluted plasma in small tubes.\n2. Emulsify several isolated colonies of test organism in 1 ml of diluted rabbit plasma to give a milky suspension.\n3. Incubate the tube at 35°C in ambient air or in a water bath for 4 hours.\n4. Examine at 1, 2, and 4 hours for clot formation by tilting the tube through 90°.\n5. Leave negative tubes at room temperature overnight and re-examine. This step is essential for some strains of *S. aureus*, including many MRSA, which produce a delayed clot that is rapidly lysed at incubation temperature by the organism's staphylokinase.\n\n### Observation\n\nRead as positive any degree of clot formation. Often the plasma is converted into a stiff gel that remains in place when the tube is tilted or inverted, but sometimes clots are seen floating in the fluid.\n\n\u003Cfigure>\n\u003Cimg src=\"https:\u002F\u002Fassets.microbeonline.com\u002Fblogs\u002Ftue-coagulase-test.jpeg\" alt=\"Tube Coagulase Test\" width=\"235\" height=\"320\" draggable=\"false\" contenteditable=\"false\">\u003Cfigcaption>Tube Coagulase Test\u003C\u002Ffigcaption>\n\u003C\u002Ffigure>\n\n1. **Coagulase Positive**: Clot of any size eg. *Staphylococcus aureus*\n2. **Coagulase Negative**: No clot (plasma remains wholly liquid or shows only a flocculent or ropy precipitate). eg. *Staphylococcus epidermidis*\n\n**Note:** Rabbit plasma is preferable, as it gives better clotting, is free from inhibitors, and is safe. Human plasma contains sodium citrate as an anticoagulant, and some citrate utilizing bacteria such as [*Enterococcus faecalis*](https:\u002F\u002Fmicrobeonline.com\u002Fenterococcus-faecalis-pathogenesis-diagnosis\u002F) can destroy the anticoagulant and cause clotting. False-positive or false-negative results can occur if the plasma is not sterile.\n\n## Slide vs. tube coagulase test\n\n| Feature | Slide coagulase test | Tube coagulase test |\n| --- | --- | --- |\n| What it detects | Bound coagulase (clumping factor) | Free coagulase (staphylocoagulase) |\n| Plasma used | Undiluted rabbit plasma (trace amount) | 1-in-6 dilution of rabbit plasma (1 mL) |\n| Incubation | None: read within 10 seconds | 35°C for 4 hours; negative held overnight at room temperature |\n| Positive result | Coarse visible clumping within 10 seconds | Any degree of clot formation |\n| Negative result | No clumping or reaction after 10 seconds | Plasma remains liquid after overnight incubation |\n| Sensitivity for S. aureus | \\~85% (MRSA often negative) | \\~99% |\n| Specificity | Lower: *S. lugdunensis, S. schleiferi* can be positive | Higher, but not absolute. *S. intermedius, S. hyicus,* and *S. argenteus* are also tube-positive |\n| Role | Rapid screening | Confirmatory \u002F gold standard |\n| When to confirm | Always confirm negative slides with tube test | No further confirmation needed if positive |\n| Common false positives | *S. lugdunensis, S. schleiferi*, capsulated strains | Citrate-utilizing organisms (if human plasma used) |\n| Common false negatives | MRSA, capsule-forming S. aureus strains | Staphylokinase lysis of early clot (if not examined periodically) |\n\n## Reporting\n\n- Report as *Staphylococcus aureus* if the tube coagulase test is positive and the organism is [catalase-positive](https:\u002F\u002Fmicrobeonline.com\u002Fcatalase-test-principle-uses-procedure-results\u002F) and a Gram-positive coccus in clusters.\n- For a negative tube coagulase test from catalase-positive, Gram-positive cocci in clusters that have creamy white colonies, report as “coagulase-negative staphylococci.”\n- A positive slide coagulase test can be reported as *S. aureus*; however, the test should be confirmed with a tube test from nonhemolytic or only slightly hemolytic colonies from sterile sites, such as blood, to separate *S. aureus* from *S. lugdunensis* and *S. schleiferi*.\n- A negative slide coagulase test is not valid and should be followed with a tube test for confirmation.\n\n## Quality Control\n\n- Do not use plasma that has not been stored [refrigerated](https:\u002F\u002Fmicrobeonline.com\u002Flaboratory-refrigerator-temperature-and-storage\u002F) or frozen or that appears turbid.\n- Perform quality control of coagulase plasma on new lots prior to using them.\n- **Organisms**\n  - *S. aureus* ATCC 25923: coagulase positive\n  - *Staphylococcus epidermidis* ATCC 12228 or ATCC 14990: coagulase-negative\n\n## Where I can get the plasma?\n\nRabbit plasma may be obtained by centrifuging blood to which 0.1% EDTA has been added as anticoagulant. Alternatively, it may be obtained lyophilized from a commercial supplier and reconstituted by the addition of water.\n\nCitrated human plasma may be obtained from a blood bank, but the blood must have been screened and found free from viral (Hepatitis B, HIV) antigens and antibodies. It must be handled with the precautions appropriate for all human body fluids.\n\nStore the plasma in small portions at −20°C, and keep a stock of in-use plasma at 4°C, bringing it to room temperature before use.\n\n## Pitfalls and Limitations of the Coagulase Test\n\n1. Do not use citrated plasma, as false-positive results can occur. Sodium citrate anticoagulates by chelating calcium: it locks up the free calcium ions that the clotting cascade needs, keeping the plasma liquid. Some organisms, notably *Enterococcus faecalis*, can consume citrate as a carbon source. When they do, they remove the chelator. The calcium that was bound is now free again, the clotting cascade proceeds normally, and the plasma clots, producing a false-positive result that has nothing to do with staphylocoagulase. This is a property of the plasma being used, not of the test organism, which is why rabbit plasma (anticoagulated with EDTA rather than citrate) is preferred.\n2. **Do not perform coagulase testing from colonies grown on [mannitol salt agar](https:\u002F\u002Fmicrobeonline.com\u002Fmannitol-salt-agar-msa-composition-uses-and-colony-characteristics\u002F).** *High salt concentrations in MSA can interfere with the enzyme activity or cause autoagglutination of some Staphylococci, leading to false-positive or unclear results.*\n3. Methicillin-resistant *S. aureus* (MRSA) can be deficient in bound coagulase, which results in a negative slide test.\n4. *S. intermedius* and *S. hyicus* may be positive in the tube test; these species are usually associated with animals (dogs and pigs, respectively) and reach humans through animal contact. They can cause clinically significant, sometimes serious human infections and are easily mistaken for *S. aureus* on standard tests. Both form nonhemolytic colonies on fresh blood agar plates and are [Voges-Proskauer](\u002Fvoges-proskauer-test-principle-procedure-results\u002F) negative, which separates them from *S. aureus*. *S. intermedius* is also [pyrrolidonyl-β-naphthylamide (PYR)](\u002Fpyrrolidonyl-arylamidase-pyr-test-principle-procedure-results\u002F) positive\n5. *S. lugdunensis* and *S. schleiferi* give positive slide test but negative tube test. They can be separated from *S. aureus* by their strongly positive PYR reaction and from *S. intermedius* by a negative tube coagulase test.\n6. **Staphylococcus argenteus** is a recently described species that is tube coagulase-positive and, like *S. aureus*, PYR negative. Because it shares those results with *S. aureus*, biochemical tests cannot separate the two. One clue at the bench: *S. argenteus* lacks the golden carotenoid pigment of *S. aureus* and forms whiter or greyish colonies (hence *argenteus*, meaning silvery). Definitive identification is by molecular methods.\n\n## **How to Remember**\n\n- **Bound = Body of the cell = Brief.** Bound coagulase sits on the cell **b**ody and clumps in seconds on the slide. Free coagulase is **f**loating (secreted) and needs the **f**ull incubation in the tube. If you remember that \"bound is on the cell and fast,\" the whole slide-versus-tube split follows.\n- **Slide screens, tube confirms, and MRSA breaks the slide.** The one clinical rule that prevents the most errors: a negative slide is never final, because MRSA is the organism that most often reads slide-negative while tube-positive.\n\n## Where students get confused\n\n**\"A positive slide test is enough to call it *S. aureus*.\"** For most routine isolates it is, but the slide test detects bound coagulase (clumping factor), and *S. lugdunensis* and *S. schleiferi* also carry it. From a sterile site such as blood, a slide-positive result should be confirmed by the tube test before you commit to *S. aureus*, because those two species are tube-negative. The slide test screens; the tube test confirms.\n\n**Reading the two tests as detecting the same thing.** They do not. The slide test detects **bound** coagulase, a receptor fixed to the cell wall that grabs fibrinogen directly and clumps in seconds. The tube test detects **free** coagulase, secreted into the plasma, which works indirectly through coagulase-reacting factor to build a clot over hours. A negative slide with a positive tube is not a contradiction. It is one form of coagulase absent and the other present, which is exactly why a negative slide is never the final answer.\n\n**Forgetting which way MRSA fails.** Many MRSA strains lack bound coagulase, so they are the classic **slide-negative, tube-positive** organism. A student who stops at a negative slide will miscall an MRSA as coagulase-negative staphylococci, the opposite of the truth. If the slide is negative, go to the tube every time.\n\n**The citrate false positive.** This trips people because the clot has nothing to do with *Staphylococcus*. Human plasma is anticoagulated with citrate, which works by locking up calcium. Some organisms, notably *Enterococcus faecalis*, consume citrate, release the calcium, and let the plasma clot on its own. The result is a clot from an organism that makes no coagulase at all. The fix is the plasma, not the reading: use rabbit plasma anticoagulated with EDTA.\n\n**Testing straight from mannitol salt agar.** MSA is where you often first see a staphylococcus, so it is tempting to test from it directly. The high salt causes autoagglutination and interferes with the reaction, giving false or uninterpretable results. Subculture to blood agar or nutrient agar first, then test.\n\n**Assuming a tube-positive result is definitively *S. aureus*.** The tube test is the gold standard, but it is not perfectly specific. *S. intermedius* and *S. hyicus* (animal-associated) and the newer *S. argenteus* are all tube coagulase-positive. In routine human clinical work these are uncommon, but a tube-positive isolate that behaves oddly, nonhemolytic, from an animal-contact history, or PYR positive, deserves a second look before it is reported as *S. aureus*.\n\n**References and further readings**\n\n- Tille, P. M. (2022). *Bailey and Scott's Diagnostic Microbiology* (15th ed.). St. Louis: Elsevier.\n- Procop, G. W., Church, D. L., Hall, G. S., Janda, W. M., Koneman, E. W., Schreckenberger, P. C., & Woods, G. L. (2017). *Koneman's Color Atlas and Textbook of Diagnostic Microbiology* (7th ed.). Philadelphia: Wolters Kluwer.\n- Leber, A. L. (Ed.). (2016). *Clinical Microbiology Procedures Handbook* (4th ed.). Washington, DC: ASM Press. \u003Chttps:\u002F\u002Fdoi.org\u002F10.1128\u002F9781555818814>\n- Katz, D. S. (2010). *Coagulase test protocol.* American Society for Microbiology.\n- *Staphylococcus argenteus: another coagulase-positive Staphylococcus.* (2021). American Society for Microbiology, Editors in Conversation podcast.",[52,55,58,61,64,67,70,73],{"question":53,"answer":54},"What is the difference between bound coagulase and free coagulase?","Bound coagulase is a cell-wall surface receptor detected by the slide test. Free coagulase is secreted into the medium and detected by the tube test. Both are virulence factors of S. aureus but require different detection methods.",{"question":56,"answer":57},"Why must a negative slide coagulase test always be confirmed by a tube test?","\u003Cp>About 15% of \u003Cem>S. aureus\u003C\u002Fem> strains and many MRSA strains give false-negative slide tests due to absent or masked bound coagulase. The tube test is the definitive gold standard and must confirm all negative slide results.\u003C\u002Fp>",{"question":59,"answer":60},"Why are negative tube coagulase tests held overnight at room temperature?","\u003Cp>\u003Cem>S. aureus\u003C\u002Fem> produces staphylokinase which lyses clots at 37°C. Holding negative tubes overnight at room temperature reduces staphylokinase activity, allowing delayed clots from MRSA and other slow-clotting strains to persist and be detected.\u003C\u002Fp>",{"question":62,"answer":63},"Why is rabbit plasma preferred over human plasma for the coagulase test?","Rabbit plasma gives more reliable clotting and is free from inhibitors. Human plasma contains sodium citrate which some bacteria can break down, causing false-positive results. Human plasma also requires biohazard precautions.",{"question":65,"answer":66},"Can MRSA test negative for coagulase?","Yes. MRSA frequently gives a negative slide test as many strains lack bound coagulase. However, most MRSA strains remain positive in the tube test. A negative tube test in suspected MRSA should prompt additional confirmatory testing.",{"question":68,"answer":69},"Which coagulase-negative staphylococci can give a false-positive coagulase test?","\u003Cp>\u003Cem>S. lugdunensis\u003C\u002Fem> and \u003Cem>S. schleiferi\u003C\u002Fem> give false-positive slide tests but negative tube tests. S. intermedius and \u003Cem>S. hyicus\u003C\u002Fem> can give positive tube tests. \u003Cem>S. argenteus\u003C\u002Fem> is tube coagulase-positive and can only be distinguished from \u003Cem>S. aureus\u003C\u002Fem> by molecular methods.\u003C\u002Fp>",{"question":71,"answer":72},"Why can colonies from mannitol salt agar not be used for coagulase testing?","The high salt concentration in MSA interferes with coagulase enzyme activity and causes non-specific autoagglutination, producing false-positive or uninterpretable results. Always subculture to blood agar or nutrient agar first.",{"question":74,"answer":75},"\u003Cp>What is \u003Cem>Staphylococcus argenteus\u003C\u002Fem> and how does it affect coagulase test interpretation?\u003C\u002Fp>","\u003Cp>\u003Cem>S. argenteus\u003C\u002Fem> is a recently described species that is tube coagulase-positive and PYR-negative, identical to S. aureus by standard biochemical tests. It can only be definitively identified by whole-genome sequencing or advanced molecular methods.\u003C\u002Fp>",[77],"enzyme-tests",[79,104,111,129,163,188,198,218],{"slug":80,"title":81,"description":82,"seoTitle":49,"seoDescription":49,"author":44,"createdDate":83,"lastUpdatedDate":84,"draft":47,"category":85,"image":49,"faq":86,"tags":102},"staphylococcus-aureusdisease-properties-pathogenesis-and-laboratory-diagnosis","Staphylococcus aureus: Properties, Pathogenesis & Lab Diagnosis","\u003Cp>\u003Cem>Staphylococcus aureus\u003C\u002Fem> morphology, virulence factors and the diseases they cause, plus catalase, coagulase and other tests used for lab diagnosis.\u003C\u002Fp>","2013-04-27","2026-08-14","bacteriology",[87,90,93,96,99],{"question":88,"answer":89},"\u003Cp>What is the difference between \u003Cem>Staphylococcus aureus\u003C\u002Fem> and coagulase-negative staphylococci?\u003C\u002Fp>","\u003Cp>\u003Cem>S. aureus\u003C\u002Fem> produces coagulase, which clots plasma and walls the organism into a fibrin barricade, the basis of localized abscess formation. Coagulase-negative staphylococci (CoNS), such as \u003Cem>S. epidermidis\u003C\u002Fem> and \u003Cem>S. saprophyticus\u003C\u002Fem>, lack this enzyme and are differentiated from \u003Cem>S. aureus\u003C\u002Fem> by a negative coagulase test, then further identified among themselves using the novobiocin susceptibility test.\u003C\u002Fp>",{"question":91,"answer":92},"\u003Cp>Why is \u003Cem>Staphylococcus aureus\u003C\u002Fem> catalase-positive but \u003Cem>Streptococcus\u003C\u002Fem> is catalase-negative?\u003C\u002Fp>","\u003Cp>Catalase positivity is a genus-defining trait for \u003Cem>Staphylococcus\u003C\u002Fem>. The enzyme breaks down hydrogen peroxide, which also blunts the neutrophil oxidative burst as a virulence mechanism. \u003Cem>Streptococcus\u003C\u002Fem> lacks this enzyme entirely, which is why the catalase test is the fastest way to separate the two genera once Gram stain shows clusters versus chains.\u003C\u002Fp>",{"question":94,"answer":95},"\u003Cp>Can \u003Cem>Staphylococcus aureus\u003C\u002Fem> be part of normal flora?\u003C\u002Fp>","\u003Cp>Yes. Roughly a third of healthy people carry \u003Cem>S. aureus\u003C\u002Fem> asymptomatically in the nose at any given time. It only causes disease once it breaches skin or mucosal barriers, where its virulence factors take over.\u003C\u002Fp>",{"question":97,"answer":98},"\u003Cp>What is the difference between MRSA and regular \u003Cem>Staphylococcus aureus?\u003C\u002Fem>\u003C\u002Fp>","\u003Cp>MRSA (Methicillin-resistant S. aureus) carries the mecA gene, conferring resistance to methicillin and most beta-lactam antibiotics, detected using the cefoxitin disc screening test. Methicillin-susceptible \u003Cem>S. aureus\u003C\u002Fem> (MSSA) lacks this resistance and remains treatable with standard beta-lactams.\u003C\u002Fp>",{"question":100,"answer":101},"\u003Cp>Why does \u003Cem>Staphylococcus aureus\u003C\u002Fem> form abscesses while \u003Cem>Streptococcus pyogenes\u003C\u002Fem> spreads more diffusely?\u003C\u002Fp>","\u003Cp>\u003Cem>S. aureus\u003C\u002Fem> produces coagulase, which clots plasma into a fibrin wall around the infection site, localizing it into an abscess. \u003Cem>S. pyogenes\u003C\u002Fem> does the opposite: streptokinase dissolves fibrin clots and hyaluronidase breaks down connective tissue, both favoring diffuse spread rather than containment.\u003C\u002Fp>",[103],"gram-positive-cocci",{"slug":105,"title":106,"description":106,"seoTitle":49,"seoDescription":49,"author":44,"createdDate":107,"lastUpdatedDate":108,"draft":47,"category":85,"image":49,"faq":109,"tags":110},"mrsa-emergence-types-detection","MRSA: Emergence, Types, Detection Methods","2019-02-06","2026-08-01",[],[],{"slug":112,"title":113,"description":114,"seoTitle":49,"seoDescription":49,"author":115,"createdDate":116,"lastUpdatedDate":117,"draft":47,"category":85,"image":49,"faq":118,"tags":128},"enterococcus-faecalis-pathogenesis-diagnosis","Enterococcus faecalis: Properties, Pathogenesis, Lab Diagnosis","Enterococcus faecalis virulence factors, intrinsic antibiotic resistance, and the salt tolerance, bile esculin, and PYR tests used for lab diagnosis.","Nisha Rijal","2021-05-19","2026-08-02",[119,122,125],{"question":120,"answer":121},"\u003Cp>Why isn't a positive PYR test enough to identify \u003Cem>Enterococcus faecalis\u003C\u002Fem>?\u003C\u002Fp>","\u003Cp>PYR positivity is shared with \u003Cem>Streptococcus pyogenes\u003C\u002Fem>. A positive PYR result narrows the field but doesn't finish the identification, salt tolerance and bile esculin tests are needed to confirm Enterococcus, since GAS is PYR-positive too but salt-intolerant.\u003C\u002Fp>",{"question":123,"answer":124},"\u003Cp>Why are aminoglycosides ineffective against \u003Cem>Enterococcus\u003C\u002Fem> when used alone?\u003C\u002Fp>","Enterococci have a cell wall that aminoglycosides can't penetrate effectively on their own, making monotherapy ineffective. Combining an aminoglycoside with a cell-wall-active agent like penicillin or vancomycin weakens the wall enough for the aminoglycoside to get in, producing a synergistic bactericidal effect used to treat serious infections like endocarditis.",{"question":126,"answer":127},"Does vancomycin-resistant Enterococcus (VRE) mean the infection can't be treated?","\u003Cp>No. VRE, more commonly seen in \u003Cem>E. faecium\u003C\u002Fem> than\u003Cem> E. faecalis,\u003C\u002Fem> still responds to other agents such as linezolid. Resistance to vancomycin changes the treatment choice, it doesn't mean the infection is untreatable.\u003C\u002Fp>",[103],{"slug":130,"title":131,"description":132,"seoTitle":133,"seoDescription":134,"author":44,"createdDate":135,"lastUpdatedDate":136,"draft":47,"category":48,"image":49,"faq":137,"tags":162},"catalase-test-principle-uses-procedure-results","Catalase Test: The 3-Second Test That Separates Staph from Strep, and Five Ways It Lies","\u003Cp>Bubbles in 3 seconds means \u003Cem>Staphylococcus\u003C\u002Fem>. But red blood cells bubble, nichrome loops bubble, and enterococci grown on blood agar bubble weakly. Learn what the catalase test actually detects, why streptococci cannot make the enzyme, and how to tell a true positive from the four things that imitate one.\u003C\u002Fp>","Catalase Test: Procedure, Controls, False Results, and Interpretation","Run and interpret the catalase test with proper controls, distinguish staphylococci from streptococci, and avoid blood agar and loop-related false results.","2013-10-07","2026-08-16",[138,141,144,147,150,153,156,159],{"question":139,"answer":140},"What is the principle of the catalase test?","The catalase test detects the enzyme catalase, which breaks down hydrogen peroxide into water and oxygen. Visible bubbling indicates a positive result. Reaction: 2H₂O₂ → 2H₂O + O₂.",{"question":142,"answer":143},"Why is the catalase test important in clinical microbiology?","\u003Cp>It separates \u003Cem>Staphylococcus\u003C\u002Fem> (catalase-positive) from \u003Cem>Streptococcus\u003C\u002Fem> and \u003Cem>Enterococcus \u003C\u002Fem>(catalase-negative), guiding further identification. It also helps identify \u003Cem>Mycobacterium tuberculosis\u003C\u002Fem> and differentiate \u003Cem>Bacillus\u003C\u002Fem> from \u003Cem>Clostridium.\u003C\u002Fem>\u003C\u002Fp>",{"question":145,"answer":146},"What causes a false positive in the catalase test?","False positives are caused by using metal loops (which non-enzymatically decompose H₂O₂), carrying over red blood cells from blood agar, or testing on Mueller-Hinton agar.",{"question":148,"answer":149},"What causes a false negative in the catalase test?","The most common cause is using colonies older than 24 hours. Catalase production is highest during logarithmic growth; older cultures produce less enzyme, leading to insufficient bubbling.",{"question":151,"answer":152},"What is the difference between the slide and tube catalase test?","The slide test is quicker but risks RBC carryover from blood agar. The tube test is preferred for blood agar cultures as it reduces false positive risk.",{"question":154,"answer":155},"Why should you not use a metal loop in the catalase test?","Metal loops non-enzymatically decompose H₂O₂, producing bubbles that mimic a true positive result. Use a platinum loop, wooden stick, or plastic loop instead.",{"question":157,"answer":158},"\u003Cp>Are all \u003Cem>Staphylococcu\u003C\u002Fem>s species catalase positive?\u003C\u002Fp>","\u003Cp>Almost all \u003Cem>Staphylococcus\u003C\u002Fem> species are catalase positive, distinguishing them from \u003Cem>Streptococcus\u003C\u002Fem> and \u003Cem>Enterococcus.\u003C\u002Fem> Rare catalase-negative staphylococcal strains exist, so results should be interpreted with other tests.\u003C\u002Fp>",{"question":160,"answer":161},"What is pseudocatalase and which bacteria produce it?","\u003Cp>Pseudocatalase is a cytochrome-based mechanism in some \u003Cem>Enterococcus\u003C\u002Fem> and \u003Cem>Lactobacillus\u003C\u002Fem> strains that weakly decomposes H₂O₂, producing delayed weak bubbling after 20-30 seconds unlike the immediate vigorous bubbling of true catalase-positive organisms.\u003C\u002Fp>",[77],{"slug":164,"title":165,"description":166,"seoTitle":49,"seoDescription":49,"author":44,"createdDate":167,"lastUpdatedDate":168,"draft":47,"category":169,"image":49,"faq":170,"tags":186},"laboratory-refrigerator-temperature-and-storage","Laboratory Refrigerator: Temperature, What to Store at Each, and Storage Rules","Laboratory refrigerator temperatures explained, which reagents, sera, vaccines, and blood products belong at 2-8 degrees C, why freezing destroys some of them, and the storage rules that keep samples usable. A practical guide for lab science students.","2026-07-28","2026-08-12","lab-equipment",[171,174,177,180,183],{"question":172,"answer":173},"What temperature is a laboratory refrigerator set to?","A laboratory refrigerator is kept at 2–8°C, with about 4°C as the usual set point. This range slows chemical reactions, enzyme activity, and microbial growth while staying above freezing, which protects reagents, sera, vaccines, and blood products that ice crystals would damage.",{"question":175,"answer":176},"Why are some reagents and vaccines refrigerated instead of frozen?","Freezing forms ice crystals that denature proteins and rupture cells, which destroys many control sera, antibodies, and vaccines. For these items, 2–8°C preserves activity while freezing would ruin them, so colder is not automatically better.",{"question":178,"answer":179},"Why are platelets not stored in the refrigerator?","Platelets are stored at 20–24°C (room temperature) with continuous gentle agitation. Refrigeration damages platelet function and stillness causes them to clump, so unlike red cells and plasma, platelets are never refrigerated.",{"question":181,"answer":182},"Why should nothing sensitive be stored in the refrigerator door?","The door is the warmest and most temperature-variable part of the refrigerator, because it warms every time the fridge is opened. Sensitive items such as controls, sera, vaccines, and blood should be kept on the internal shelves where the temperature is stable.",{"question":184,"answer":185},"What is the difference between a laboratory refrigerator and a blood bank refrigerator?","A blood bank refrigerator is a specialized laboratory refrigerator held at 2–6°C with a tighter temperature tolerance, a continuous temperature log, and an audible alarm. The stricter monitoring exists because a temperature error can make blood unsafe to transfuse.",[187],"laboratory-storage-and-preservation",{"slug":189,"title":190,"description":191,"seoTitle":49,"seoDescription":49,"author":44,"createdDate":192,"lastUpdatedDate":193,"draft":47,"category":194,"image":49,"faq":195,"tags":196},"mannitol-salt-agar-msa-composition-uses-and-colony-characteristics","Mannitol Salt Agar (MSA): Principle, Composition, Uses, and Colony Characteristics","\u003Cp>Mannitol Salt Agar (MSA) is a selective and differential medium for isolating \u003Cem>Staphylococcus aureus.\u003C\u002Fem> Learn its principle, composition, colony colors of \u003Cem>S. aureus\u003C\u002Fem> vs CONS, and why \u003Cem>Enterococcus\u003C\u002Fem> and \u003Cem>Micrococcus\u003C\u002Fem> can give false-positive results.\u003C\u002Fp>","2013-08-13","2026-08-22","culture-media",[],[197],"bacterial-culture-media",{"slug":199,"title":200,"description":201,"seoTitle":49,"seoDescription":49,"author":44,"createdDate":202,"lastUpdatedDate":46,"draft":47,"category":48,"image":49,"faq":203,"tags":216},"voges-proskauer-test-principle-procedure-results","Voges-Proskauer (VP) Test: Principle, Procedure, Results & VP-Positive Organisms","VP test principle, the α-naphthol-then-KOH procedure, and how to tell a true positive from the copper-color false positive that trips up most students.","2015-03-17",[204,207,210,213],{"question":205,"answer":206},"I got a pale pink color — is that positive or negative?","A true VP positive is a clear, distinct pink-red color developing within 10–15 minutes. A faint or pale pink, especially outside that window, is unreliable — repeat the test rather than call it either way.",{"question":208,"answer":209},"Why does MR need 48 hours but VP only needs 24?","They're reading different chemistry on different timelines from the same broth. VP detects acetoin, which accumulates fast enough to screen at 24 hours (and can be re-tested at 48 hours if negative). MR detects stable acid accumulation, which genuinely needs the full 48 hours before the first reliable reading.",{"question":211,"answer":212},"Why does the order of reagents matter?","α-naphthol must go in before KOH. This was Barritt's 1936 modification to intensify and stabilize the reaction — reversing the order is one of the most common reasons for a weak-positive or false-negative VP result.",{"question":214,"answer":215},"Which organisms are VP-positive besides the Enterobacteriaceae?","VP is not limited to enteric bacteria. Among Gram-positive cocci, most viridans group streptococci are VP-positive, while the Streptococcus mitis group is VP-negative and S. vestibularis is variable, a distinction that helps narrow viridans strep in a blood culture. Bacillus species are characteristically VP-positive, which is one feature that separates them from Clostridium.",[217],"carbohydrate-utilization",{"slug":219,"title":220,"description":221,"seoTitle":49,"seoDescription":49,"author":44,"createdDate":222,"lastUpdatedDate":46,"draft":47,"category":48,"image":49,"faq":223,"tags":248},"pyrrolidonyl-arylamidase-pyr-test-principle-procedure-results","PYR Test: The 2-Minute Way to Call Group A Strep at the Bench","A cherry-red color within a minute means the organism makes pyrrolidonyl arylamidase, which among the streptococci points straight to Group A Strep, or to Enterococcus. It is faster and more specific than the old bacitracin disk. Here is the enzyme logic, the three separations PYR performs, and why you must confirm the organism is a catalase-negative Gram-positive coccus first.","2013-11-12",[224,227,230,233,236,239,242,245],{"question":225,"answer":226},"Why can't a PYR-positive result alone distinguish Streptococcus pyogenes from Enterococcus?","Both organisms are PYR-positive, along with Staphylococcus lugdunensis. The PYR test narrows the field rather than completing an identification, catalase testing and Gram stain morphology must be done first to determine which PYR-positive organism is actually present.",{"question":228,"answer":229},"Is a PYR-negative, indole-positive, lactose-positive Gram-negative rod always Escherichia coli?","Not always. Morganella, Providencia, and P. vulgaris can also be PYR-negative and indole-positive, mimicking E. coli. A quick urease test resolves the ambiguity, E. coli is urease-negative while those three organisms are urease-positive.",{"question":231,"answer":232},"What is the PYR test used for besides identifying Group A Streptococcus and Enterococcus?","PYR also helps differentiate Escherichia coli (PYR-negative) from other indole-positive, lactose-positive Gram-negative rods, and screens coagulase-negative staphylococci for Staphylococcus lugdunensis, which is PYR-positive unlike most other CoNS.",{"question":234,"answer":235},"What does a positive PYR test indicate?","A cherry-red color within a minute means the organism produces pyrrolidonyl arylamidase. In a catalase-negative Gram-positive coccus, that points to one of two things: among beta-hemolytic streptococci it is a presumptive identification of Group A Streptococcus (Streptococcus pyogenes), and among group D organisms it identifies Enterococcus. You must first confirm the organism is a catalase-negative Gram-positive coccus, because staphylococci, aerococci, and some other organisms are also PYR positive.",{"question":237,"answer":238},"Why must catalase be done before the PYR test?","Because PYR is only meaningful once the organism is known to be a catalase-negative Gram-positive coccus, which places it among the streptococci and enterococci. Several other organisms are also PYR positive, including some staphylococci, aerococci, Gemella, and Arcanobacterium haemolyticum. Running catalase and Gram stain first narrows the field so that a positive PYR actually points to Group A Strep or Enterococcus. PYR is a second-line test, always run after catalase.",{"question":240,"answer":241},"How does the PYR test separate Enterococcus from Streptococcus bovis?","Both are group D organisms, but Enterococcus species are PYR positive while Streptococcus bovis, now called S. gallolyticus, is PYR negative. This is a useful pairing with the starch hydrolysis test, where S. bovis is positive and enterococci are negative. Together the two tests cleanly separate the group D enterococci from the group D non-enterococcal streptococci.",{"question":243,"answer":244},"Why is PYR preferred over the bacitracin disk for Group A Strep?","PYR is both faster and more specific. The bacitracin (Taxo A) disk needs overnight incubation, while the PYR disk reads in about two minutes. And some Group C and G streptococci are bacitracin susceptible, which can give false-positive Group A calls, whereas those groups are PYR negative. For these reasons PYR has largely replaced bacitracin as the presumptive Group A Strep test, though bacitracin is still used where PYR is unavailable.",{"question":246,"answer":247},"What causes a false-negative PYR test?","The two most common causes are over-moistening the disk, which dilutes the substrate and developer, and inoculating from selective media or tubed biochemical agars, which can carry interfering substances. Moisten the disk without saturating it, and use growth from a non-selective medium such as blood agar. A pale pink color should also be read as negative, not upgraded to a weak positive.",[77],{"enabled":250,"threads":251,"total":252},true,[],0,[254,260,267,274,280,285,291,296,302,305,311],{"slug":255,"name":44,"description":256,"image":257,"body":258,"postCount":259},"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.*",481,{"slug":261,"name":262,"description":263,"image":264,"body":265,"postCount":266},"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.",79,{"slug":268,"name":269,"description":270,"image":271,"body":272,"postCount":273},"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":275,"name":276,"description":270,"image":277,"body":278,"postCount":279},"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":281,"name":282,"description":270,"image":49,"body":283,"postCount":284},"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":286,"name":287,"description":288,"image":49,"body":289,"postCount":290},"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":292,"name":293,"description":294,"image":49,"body":49,"postCount":295},"guest-author","Guest Author","Guest Author \u002F Contributor",1,{"slug":297,"name":298,"description":270,"image":299,"body":300,"postCount":301},"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":303,"name":304,"description":294,"image":49,"body":49,"postCount":295},"dr-poonam-acharya","Dr. Poonam Acharya",{"slug":306,"name":115,"description":307,"image":308,"body":309,"postCount":310},"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":312,"name":313,"description":314,"image":315,"body":316,"postCount":295},"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.",[318,325,331,335,340,345,349,353,357,362,366,371,376,381,386,390,394,398,403,408,412,416,420,425,429,433,437,441,446,451,455,459,463,467,471,475,479,483,487,491,495,499,503,507,511,515,519,522,527,531,535,539,543,547,550,553,557,561,565,569,573,577,581,585,589,593,597,601,604,608,611,614,617,620,623,626,629,632,635,638,641,644],{"slug":319,"name":320,"description":321,"image":322,"body":323,"postCount":324},"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":326,"name":327,"description":328,"image":49,"body":329,"postCount":330},"microscopy","Microscopy","Microscope types, components, and microscopy techniques","These are list of blog posts related to microscopy. ",12,{"slug":103,"name":332,"description":333,"image":49,"body":49,"postCount":334},"Gram-Positive Cocci","Staphylococcus, Streptococcus, Enterococcus, Micrococcus — organisms, diseases, and identification tests",11,{"slug":336,"name":337,"description":338,"image":49,"body":49,"postCount":339},"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":341,"name":342,"description":343,"image":49,"body":49,"postCount":344},"gram-positive-rods","Gram-Positive Rods","Bacillus, Clostridium, Listeria, Corynebacterium, Actinomyces and related organisms",8,{"slug":346,"name":347,"description":348,"image":49,"body":49,"postCount":334},"mycobacteria","Mycobacteria","Mycobacterium tuberculosis, leprosy, atypical mycobacteria, and acid-fast organism diagnosis",{"slug":350,"name":351,"description":352,"image":49,"body":49,"postCount":334},"anaerobic-bacteriology","Anaerobic Bacteriology","Anaerobic organisms, anaerobic culture methods, and anaerobic infection diagnosis",{"slug":354,"name":355,"description":356,"image":49,"body":49,"postCount":330},"enterobacteriaceae","Enterobacteriaceae","Identification, differentiation, and clinical significance of Enterobacteriaceae family members",{"slug":358,"name":359,"description":360,"image":49,"body":49,"postCount":361},"spirochetes","Spirochetes","Treponema, Leptospira, Borrelia and spirochetal infections",7,{"slug":363,"name":364,"description":365,"image":49,"body":49,"postCount":324},"food-microbiology","Food Microbiology","Food-borne pathogens, food safety, spoilage, and preservation",{"slug":367,"name":368,"description":369,"image":49,"body":49,"postCount":370},"antimicrobial-susceptibility-testing","Antimicrobial Susceptibility Testing","Methods for testing antibiotic susceptibility in clinical microbiology",21,{"slug":372,"name":373,"description":374,"image":49,"body":49,"postCount":375},"antimicrobials-moa-amr","Antimicrobials (MOA & AMR)","Mechanisms, detection, and clinical significance of antimicrobial resistance",13,{"slug":377,"name":378,"description":379,"image":49,"body":49,"postCount":380},"sterilization-disinfection","Sterilization and Disinfection","Methods of sterilization and disinfection in healthcare and laboratory settings",10,{"slug":382,"name":383,"description":384,"image":49,"body":49,"postCount":385},"specimen-collection-transport","Specimen Collection and Transport","Collection, handling, and transport of clinical specimens for microbiological testing",27,{"slug":387,"name":388,"description":389,"image":49,"body":49,"postCount":370},"bacterial-structure-physiology","Bacterial Structure and Physiology","Bacterial cell structure, growth, physiology, and environmental factors affecting growth",{"slug":391,"name":392,"description":49,"image":49,"body":393,"postCount":284},"horizontal-gene-transfer","Horizontal Gene Transfer","Articles related to **Horizontal Gene Transfer**",{"slug":395,"name":396,"description":49,"image":49,"body":397,"postCount":380},"chromatography","Chromatography","Information about chromatographic techniques.",{"slug":399,"name":400,"description":401,"image":49,"body":402,"postCount":361},"electrophoresis","Electrophoresis","Information about Electrophoresis Techniques ","Detailed information  about Electrophoresis Techniques ",{"slug":404,"name":405,"description":406,"image":49,"body":407,"postCount":284},"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":409,"name":410,"description":411,"image":49,"body":49,"postCount":284},"bacteriophage","Bacteriophage","Description about Bacteriophage.",{"slug":413,"name":414,"description":415,"image":49,"body":49,"postCount":284},"malaria","Malaria","It is the collections of articles regarding malarial disease. ",{"slug":417,"name":418,"description":419,"image":49,"body":49,"postCount":284},"anaerobic-culture-techniques","Anaerobic Culture Techniques","Posts related with Anaerobic Culture Techniques.",{"slug":421,"name":422,"description":423,"image":49,"body":49,"postCount":424},"immunoassays","Immunoassays","You will get information about all the diagnostic tests that rely on the specific binding between an antigen and an antibody to detect or quantify a substance.",19,{"slug":426,"name":427,"description":428,"image":49,"body":49,"postCount":361},"biosafety-levels","Biosafety levels ","Articles related to Biosafety Levels",{"slug":430,"name":431,"description":432,"image":49,"body":49,"postCount":339},"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":434,"name":435,"description":436,"image":49,"body":49,"postCount":284},"pipette","Pipette","Posts related with Pipette. ",{"slug":438,"name":439,"description":440,"image":49,"body":49,"postCount":344},"bacteriology-mcqs","Bacteriology MCQs","This sections lists MCQs in Bacteriology.",{"slug":442,"name":443,"description":444,"image":49,"body":49,"postCount":445},"parasitology-mcqs","Parasitology MCQs","This section lists MCQs in Parasitology.",2,{"slug":447,"name":448,"description":449,"image":49,"body":49,"postCount":450},"virology-mcqs","Virology MCQs","This is the collections of Multiple Choice Questions in Virology.",4,{"slug":452,"name":453,"description":454,"image":49,"body":49,"postCount":339},"mcqs-in-microbiology","MCQs in Microbiology","This section lists the collections of Multiple Choice Questions in General Microbiology Topics. ",{"slug":456,"name":457,"description":458,"image":49,"body":49,"postCount":344},"immunology-mcqs","Immunology MCQs","In this section; we are posting collections of Multiple Choice Questions about Immunology. ",{"slug":460,"name":461,"description":462,"image":49,"body":49,"postCount":290},"microbial-curiosities","Microbial Curiosities","In this clusters, we are posting interesting and unique information about Microorganisms. ",{"slug":197,"name":464,"description":465,"image":49,"body":49,"postCount":466},"Bacterial Culture Media","Posts related to Bacterial Culture Media. ",23,{"slug":468,"name":469,"description":470,"image":49,"body":49,"postCount":284},"fungal-culture-media","Fungal Culture Media","Posts related to Fungal Culture Media.",{"slug":472,"name":473,"description":474,"image":49,"body":49,"postCount":339},"motility-test","Motility Test","This lists the procedure regarding various tests methods for bacterial motility.",{"slug":476,"name":477,"description":478,"image":49,"body":49,"postCount":380},"bacterial-enumeration","Bacterial enumeration","These posts are related to isolation and enumeration of bacteria. ",{"slug":480,"name":481,"description":482,"image":49,"body":49,"postCount":445},"gram-positive-coccobacillus","Gram-positive coccobacillus","List of Gram Positive Coccobacilli",{"slug":484,"name":485,"description":486,"image":49,"body":49,"postCount":450},"dimorphic-fungi","Dimorphic Fungi","This is about various dimorphic fungi. ",{"slug":488,"name":489,"description":490,"image":49,"body":49,"postCount":361},"bacterial-classification","Bacterial Classification","These posts are related with various approaches used for the classification of Bacteria. ",{"slug":492,"name":493,"description":494,"image":49,"body":49,"postCount":339},"immunofluorescence","Immunofluorescence ","Various Tests related to Immunofluorescence ",{"slug":496,"name":497,"description":498,"image":49,"body":49,"postCount":290},"antibody-mediated-immunity","Antibody-mediated Immunity","This clusters links the articles that are sharing insights about Antibody-mediated immunity. ",{"slug":500,"name":501,"description":502,"image":49,"body":49,"postCount":361},"hypersensitivity","Hypersensitivity","Articles related to Hypersensitivity.",{"slug":504,"name":505,"description":49,"image":49,"body":49,"postCount":506},"haemophilus","Haemophilus",3,{"slug":508,"name":509,"description":510,"image":49,"body":49,"postCount":450},"sexually-transmitted-infections-stis","Sexually transmitted infections (STIs)","This is the clusters of infections that are transmitted sexually. ",{"slug":512,"name":513,"description":514,"image":49,"body":49,"postCount":330},"adaptive-immunity","Adaptive Immunity","Blog posts related to B Cell Immunity and T Cell Immunity.",{"slug":516,"name":517,"description":518,"image":49,"body":49,"postCount":324},"fungal-diagnostics","Fungal Diagnostics","Various methods used for the Diagnosis of Fungal Infections. ",{"slug":187,"name":520,"description":521,"image":49,"body":49,"postCount":339},"Laboratory Storage and Preservation","Articles about Laboratory Storage of Antimicrobial Disk, Test organisms and Equipment used for this process. ",{"slug":523,"name":524,"description":525,"image":49,"body":526,"postCount":284},"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":528,"name":529,"description":530,"image":49,"body":49,"postCount":290},"laboratory-glassware","Laboratory Glassware","Posts about Laboratory Glassware. ",{"slug":532,"name":533,"description":534,"image":49,"body":49,"postCount":284},"helminths","Helminths","In this section, we are covering properties, life cycle, pathogenesis and laboratory diagnosis of Helminths\u002FHelminthic infestations. ",{"slug":536,"name":537,"description":538,"image":49,"body":49,"postCount":361},"protozoan-parasite","Protozoan Parasite","In this cluster, we are covering protozoan parasites. ",{"slug":540,"name":541,"description":542,"image":49,"body":49,"postCount":295},"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":544,"name":545,"description":546,"image":49,"body":49,"postCount":380},"bacterial-staining-technique","Bacterial Staining Technique","Lists of various staining techniques that are used to stain bacteria. ",{"slug":77,"name":548,"description":549,"image":49,"body":49,"postCount":370},"Enzyme Tests","\u003Cp>Various Biochemical Test that are based on enzymatic activity of the microorganisms. \u003C\u002Fp>",{"slug":217,"name":551,"description":552,"image":49,"body":49,"postCount":334},"Carbohydrate Utilization","\u003Cp>Various biochemical tests which are related to Carbohydrate fermentation or Utilization\u003C\u002Fp>",{"slug":554,"name":555,"description":556,"image":49,"body":49,"postCount":339},"susceptibility-based-id","Susceptibility-based ID","\u003Cp>These are susceptibility based identification test such as optochin sensitivity, bacitracin sensitivity etc. \u003C\u002Fp>",{"slug":558,"name":559,"description":560,"image":49,"body":49,"postCount":450},"microbial-metabolism","Microbial Metabolism","\u003Cp>Tests about Microbial Metabolism. \u003C\u002Fp>",{"slug":562,"name":563,"description":564,"image":49,"body":49,"postCount":344},"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":566,"name":567,"description":568,"image":49,"body":49,"postCount":506},"atypical-pneumonia","Atypical Pneumonia","\u003Cp>Organisms responsible for Atypical Pneumonia. \u003C\u002Fp>",{"slug":570,"name":571,"description":572,"image":49,"body":49,"postCount":339},"antigen","Antigen","\u003Cp>Various articles related to Antigens.\u003C\u002Fp>",{"slug":574,"name":575,"description":576,"image":49,"body":49,"postCount":361},"innate-immunity","Innate Immunity","\u003Cp>Articles related to Innate Immunity. \u003C\u002Fp>",{"slug":578,"name":579,"description":580,"image":49,"body":49,"postCount":450},"respiratory-tract-infection","Respiratory Tract Infection","\u003Cp>In this cluster, you can see various etiological agents that causes respiratory tract infection. \u003C\u002Fp>",{"slug":582,"name":583,"description":584,"image":49,"body":49,"postCount":339},"torch-infection","TORCH Infection","\u003Cp>In this section; you can find articles related with TOCH infection. \u003C\u002Fp>",{"slug":586,"name":587,"description":588,"image":49,"body":49,"postCount":361},"microbiology-for-beginners","Microbiology for Beginners","\u003Cp>These articles are very basic articles, which will share general concepts in Microbiology. \u003C\u002Fp>",{"slug":590,"name":591,"description":592,"image":49,"body":49,"postCount":284},"dna-replication","DNA Replication","\u003Cp>Articles related to DNA and Replication of DNA. \u003C\u002Fp>",{"slug":594,"name":595,"description":596,"image":49,"body":49,"postCount":361},"genetic-code","Genetic Code","\u003Cp>Articles related to Genetic Code.\u003C\u002Fp>",{"slug":598,"name":599,"description":600,"image":49,"body":49,"postCount":361},"molecular-technique","Molecular Technique","\u003Cp>Posts related to Molecular Techniques. \u003C\u002Fp>",{"slug":602,"name":603,"description":49,"image":49,"body":49,"postCount":295},"colorimetric-assay","Colorimetric Assay ",{"slug":605,"name":606,"description":607,"image":49,"body":49,"postCount":339},"pharmaceutical-microbiology","Pharmaceutical Microbiology","\u003Cp>Various articles related to Pharmaceutical Microbiology\u003C\u002Fp>",{"slug":609,"name":610,"description":49,"image":49,"body":49,"postCount":506},"blood-and-immune-cells","Blood and Immune Cells",{"slug":612,"name":613,"description":49,"image":49,"body":49,"postCount":339},"host-pathogen-interaction","Host Pathogen Interaction",{"slug":615,"name":616,"description":49,"image":49,"body":49,"postCount":450},"blood-culture","Blood Culture",{"slug":618,"name":619,"description":49,"image":49,"body":49,"postCount":450},"environmental-microbiology","Environmental microbiology ",{"slug":621,"name":622,"description":49,"image":49,"body":49,"postCount":284},"copromicroscopic-technique","Copromicroscopic Technique",{"slug":624,"name":625,"description":49,"image":49,"body":49,"postCount":506},"quality-control","Quality Control",{"slug":627,"name":628,"description":49,"image":49,"body":49,"postCount":450},"dermatophytes","Dermatophytes",{"slug":630,"name":631,"description":49,"image":49,"body":49,"postCount":506},"viral-hemorrhagic-fevers","Viral Hemorrhagic Fevers",{"slug":633,"name":634,"description":49,"image":49,"body":49,"postCount":450},"h2s-production","H2S Production",{"slug":636,"name":637,"description":49,"image":49,"body":49,"postCount":445},"water-quality-testing","Water Quality Testing",{"slug":639,"name":640,"description":49,"image":49,"body":49,"postCount":339},"virology-basics","Virology basics",{"slug":642,"name":643,"description":49,"image":49,"body":49,"postCount":450},"typing-methods","Typing Methods",{"slug":645,"name":646,"description":49,"image":49,"body":49,"postCount":506},"blotting-technique","Blotting Technique"]