[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"$fxLN3MUwXCdr5RPjwZYIDpOj8CHyjOmngWTgoKXPtZbg":3,"$fGCcBC9o8myy60Tn5b6m3d7k8a34Tz6t9Fe1TQzmzM7Q":36,"$f3Ft0rKFJHppdzE-vuveecxx1BUcg9iOlMLtyzf_MJDg":281,"$fucxFBm2ZjZfGSdmdRaSNGBI_F0jJme4f0GTvzUhQfL8":345},[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":67,"comments":277},"furazolidone-disk-test","Furazolidone Susceptibility Test: The Nitrofuran Disk That Confirms Staphylococcus Over Micrococcus","Staphylococci are killed by furazolidone; micrococci grow right up to the disk. This nitrofuran, activated inside the bacterial cell to damage DNA, gives a clean genus-level separation: a zone over 15 mm means Staphylococcus, growth to the edge means Micrococcus. Here is the mechanism (not the monoamine-oxidase myth), the breakpoints, and how it pairs with bacitracin.",null,"Acharya Tankeshwar","2019-12-10","2026-08-05",false,"biochemical-tests","## Why It Matters\n\nA catalase-positive Gram-positive coccus needs to be placed in one of two genera: *Staphylococcus*, which contains major human pathogens, or *Micrococcus*, a largely harmless skin and environmental commensal. They look alike on routine media, and no single test settles it with certainty, so the laboratory uses a small battery of quick tests that each exploit a genuine biological difference.\n\nFurazolidone susceptibility is one of the most reliable of them. **Staphylococci are killed by furazolidone; micrococci are not.** Place a furazolidone disk on a lawn of the organism, and a staphylococcus produces a clear zone of inhibition around it, while a micrococcus grows right up to the disk edge, untroubled. In one published series, 99% of staphylococci were susceptible and all micrococci were resistant, which is why either furazolidone or the oxidase test is recommended as a primary separator.\n\nThe reason the two organisms respond so differently comes down to how furazolidone works, and here most descriptions (including the older version of this article) get it wrong. Furazolidone is a **nitrofuran**, and its antibacterial action has nothing to do with the monoamine-oxidase inhibition it causes in humans. This article covers the real mechanism, the reading breakpoints, and how furazolidone fits with the other Staphylococcus-versus-Micrococcus tests.\n\n![An area of growth inhibition of staphylococci around the furazolidone disk - An area of growth inhibition of staphylococci around the furazolidone disk](https:\u002F\u002Fassets.microbeonline.com\u002Fblogs\u002Ffurazolidone-Staphylococcus.png)Figure: An area of growth inhibition of staphylococci around the furazolidone disk\n\n## Principle\n\nFurazolidone (Furoxone) is a synthetic **nitrofuran** with antibacterial and antiprotozoal activity. Its antibacterial action works by reductive activation: inside the bacterial cell, **nitroreductase enzymes reduce the drug's nitro group** into highly reactive intermediates that damage bacterial DNA and other essential macromolecules, inhibiting and killing the organism.\n\n*(Furazolidone is also a monoamine oxidase inhibitor in humans, which is the basis of its dietary interactions when used as a drug, but that is a separate effect and is not how it kills bacteria.)*\n\nOccasionally, coagulase-negative staphylococci resistant to furazolidone are encountered, so the test is read alongside other differentiating tests.\n\nFurazolidone (furoxone) susceptibility test is performed as a disk susceptibility procedure using commercially available furazolidone disks. Staphylococci are inhibited by furazolidone, but micrococci and related species are resistant. Micrococci usually grow right up to the edge of the 6-mm furazolidone disk.\n\n**Reagents**\n\n1. Furazolidone disks, 100 μg\n2. Mueller-Hinton agar plate\n\n**Quality Control**\n\nKnown strains of *Staphylococcus* (either [S. aureus](\u002Fstaphylococcus-aureusdisease-properties-pathogenesis-and-laboratory-diagnosis\u002F) or a coagulase-negative strain) and *Micrococcus* species should be tested with each new lot of disks or weekly.\n\n### Procedure\n\n1. Prepare a suspension of the organism to be tested in sterile distilled water or broth. The suspension should be equivalent to a [0.5 McFarland turbidity standard](\u002Fpreparation-mcfarland-turbidity-standards\u002F).\n2. With a swab, spread the organism suspension onto one-half of a [Mueller-Hinton agar plate.](\u002Fmueller-hinton-agar\u002F)\n3. Aseptically place a furazolidone disk in the center of the inoculated area and gently tap the disk so that it adheres to the agar surface.\n4. Incubate the plate at 35°C in an ambient air incubator for 18–24 hours.\n\n![ - Furazolidone disk test](https:\u002F\u002Fassets.microbeonline.com\u002Fblogs\u002FFurazolidone-susceptibility-test.jpg)Figure: Furazolidone disk test\n\n### Results and Interpretations\n\n1. **Furazolidone resistant:** zone of inhibition ≤ 9 mm (growth up to or near the disk). Example: *Micrococcus luteus*\n2. **Furazolidone sensitive:** zone of inhibition > 15 mm. Example: *Staphylococcus aureus*, *Staphylococcus saprophyticus*\n3. **Intermediate (9-15 mm):** an indeterminate zone in this range should not be forced into a call; repeat the test or confirm with another Staph\u002FMicrococcus test (modified oxidase, bacitracin). Most true staphylococci give clearly larger zones and most micrococci clearly smaller, so an intermediate result warrants a second look.\n\n## Where the furazolidone test fits\n\nFurazolidone susceptibility is one of several tests that separate *Staphylococcus* from *Micrococcus*, and it is worth knowing how it lines up with the others, because two of them point in opposite directions:\n\n- **Furazolidone:** *Staphylococcus* susceptible (zone), *Micrococcus* resistant (no zone)\n- **Bacitracin (Taxo A):** *Staphylococcus* resistant (no zone), *Micrococcus* susceptible (zone), the exact reverse\n- **Modified oxidase (microdase):** *Micrococcus* positive (blue), *Staphylococcus* negative\n- **Lysostaphin:** *Staphylococcus* susceptible (lysed), *Micrococcus* resistant\n\nThe furazolidone and bacitracin results are mirror images, which is a useful check: a true *Staphylococcus* should be furazolidone-susceptible *and* bacitracin-resistant, while a *Micrococcus* is the opposite on both. For the full comparison and when to reach for each test, see the *Staphylococcus* vs *Micrococcus* article.\n\n## How to remember\n\n**Furazolidone favors finding Staph.** The alliteration helps: **F**urazolidone kills **F**staph (staphylococci are susceptible). Micrococci shrug it off and grow to the disk edge. Zone = Staph; no zone = Micrococcus.\n\n**Furazolidone and bacitracin are mirror images.** This is the cleanest way to remember both: *Staphylococcus* is **furazolidone-susceptible but bacitracin-resistant**; *Micrococcus* is the reverse (bacitracin-susceptible, furazolidone-resistant). If an organism is susceptible to one and resistant to the other, the pattern itself names the genus. If it is susceptible or resistant to both, something is off, recheck.\n\n**It's a nitrofuran, not an MAO story (for bacteria).** Furazolidone kills bacteria as a nitrofuran: bacterial enzymes reduce it into DNA-damaging intermediates. Its monoamine-oxidase-inhibiting effect is a human drug interaction, not the antibacterial mechanism. Do not confuse the two.\n\n**Read the zone, confirm the genus.** A clear zone (>15 mm) points to *Staphylococcus*, but because rare coagulase-negative staphylococci are resistant, pair furazolidone with modified oxidase or bacitracin before finalizing.\n\n## Key exam facts in one table\n\n| Question | Answer | The reason behind it |\n| --- | --- | --- |\n| What does the test differentiate? | *Staphylococcus* (susceptible) from *Micrococcus* (resistant) | Among catalase-positive Gram-positive cocci |\n| Drug class | Nitrofuran (furazolidone \u002F Furoxone) | Synthetic antimicrobial |\n| Antibacterial mechanism | Nitroreductase activation → DNA damage | Bacteria reduce the nitro group to reactive intermediates |\n| Not the mechanism | Monoamine oxidase inhibition | That is furazolidone's human drug effect, not antibacterial |\n| Disk | 100 µg furazolidone, on blood agar | Disk-diffusion procedure |\n| Staph result | Susceptible, zone > 15 mm | Killed by furazolidone |\n| Micrococcus result | Resistant, zone ≤ 9 mm | Grows to the disk edge |\n| Intermediate | 9-15 mm, indeterminate | Repeat or confirm with another test |\n| Reliability | \\~99% of staph susceptible; all micrococci resistant | (JCM 1984 series) |\n| Exception | Occasional furazolidone-resistant CoNS | Read with other tests |\n| Relationship to bacitracin | Mirror image (Staph: furazolidone-S, bacitracin-R) | Useful cross-check |\n| Positive QC (susceptible) | *Staphylococcus aureus* | Clear zone |\n| Negative QC (resistant) | *Micrococcus luteus* | Growth to disk edge |\n| Prerequisite | Gram-positive cocci, catalase-positive | Meaningless outside this group |\n| Sibling tests | Modified oxidase, bacitracin, lysostaphin | See Staph vs Micrococcus comparison |\n\n## Where students get confused\n\n**Thinking furazolidone kills bacteria by inhibiting monoamine oxidase.** It does not. That is furazolidone's effect in humans (the reason for its dietary tyramine interactions as a drug). Its antibacterial mechanism is as a nitrofuran: bacterial nitroreductases activate it into DNA-damaging intermediates. Two different mechanisms in two different contexts.\n\n**Reversing the result with bacitracin.** Furazolidone and bacitracin give opposite results, and it is easy to swap them. *Staphylococcus* is furazolidone-**susceptible** and bacitracin-**resistant**; *Micrococcus* is furazolidone-resistant and bacitracin-susceptible. Anchor on \"furazolidone kills Staph, bacitracin doesn't.\"\n\n**Forcing an intermediate zone into a call.** A zone between 9 and 15 mm is indeterminate. Do not round it to susceptible or resistant. Repeat or confirm with another test. Most true results fall clearly above 15 mm (Staph) or below 9 mm (Micrococcus).\n\n**Forgetting the resistant-staph exception.** A few coagulase-negative staphylococci are furazolidone-resistant, so a resistant result does not completely exclude *Staphylococcus*. This is why furazolidone is read alongside modified oxidase or bacitracin, not alone.\n\n**Running it outside the right group.** Furazolidone susceptibility differentiates Staph from Micrococcus among catalase-positive Gram-positive cocci. It is not a general susceptibility test to guide therapy here, and it is meaningless on catalase-negative cocci or Gram-negative organisms. Confirm Gram stain and catalase first.\n\n**Wrong disk potency.** The differentiation uses a 100 µg furazolidone disk. Using a different potency changes the zone sizes and invalidates the breakpoints.\n\n**References**\n\n1. von Rheinbaben KE, et al. Comparison of various methods for differentiation of staphylococci and micrococci. *J Clin Microbiol.* 1984;19(6):875-879. doi:10.1128\u002Fjcm.19.6.875-879.1984\n2. Baker JS. Comparison of various methods for differentiation of staphylococci and micrococci. *J Clin Microbiol.* 1984;19(6):875-879.\n3. Tille PM. *Bailey and Scott's Diagnostic Microbiology.* 15th ed. St. Louis: Elsevier; 2022.\n4. 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.",[50,53,56,59,62],{"question":51,"answer":52},"How does the furazolidone test differentiate Staphylococcus from Micrococcus?","Staphylococci are susceptible to furazolidone and micrococci are resistant. On a disk-diffusion test using a 100 microgram furazolidone disk on blood agar, a staphylococcus produces a zone of inhibition greater than 15 mm, while a micrococcus grows right up to the disk edge with a zone of 9 mm or less. In published series about 99% of staphylococci are susceptible and all micrococci are resistant, making it one of the more reliable tests for separating the two genera.",{"question":54,"answer":55},"How does furazolidone kill bacteria?","Furazolidone is a nitrofuran. Inside the bacterial cell, nitroreductase enzymes reduce its nitro group into highly reactive intermediates that damage bacterial DNA and other essential molecules, which inhibits and kills the organism. Importantly, this is different from furazolidone's effect in humans, where it acts as a monoamine oxidase inhibitor and causes dietary tyramine interactions. The monoamine oxidase inhibition is not the antibacterial mechanism.",{"question":57,"answer":58},"What is the relationship between the furazolidone and bacitracin tests?","They give opposite results, which makes them a useful cross-check. Staphylococcus is furazolidone-susceptible but bacitracin-resistant, while Micrococcus is the reverse, bacitracin-susceptible but furazolidone-resistant. So a true Staphylococcus should show a furazolidone zone and no bacitracin zone, and a Micrococcus the opposite. If an organism is susceptible or resistant to both, the result is inconsistent and should be rechecked.",{"question":60,"answer":61},"What does an intermediate furazolidone zone of 9 to 15 mm mean?","It is indeterminate and should not be forced into a susceptible or resistant call. Most true staphylococci give zones clearly larger than 15 mm and most micrococci clearly 9 mm or smaller, so a zone in the intermediate range warrants repeating the test or confirming the identification with another test such as modified oxidase or bacitracin susceptibility.",{"question":63,"answer":64},"Can a furazolidone-resistant organism still be a Staphylococcus?","Yes, occasionally. Although about 99% of staphylococci are furazolidone-susceptible, some coagulase-negative staphylococci are furazolidone-resistant. So a resistant result does not completely exclude Staphylococcus, which is why the furazolidone test is read alongside other differentiating tests such as the modified oxidase (microdase) test, bacitracin susceptibility, or lysostaphin susceptibility rather than being used alone.",[66],"susceptibility-based-id",[68,93,119,152,174,201,229,254],{"slug":69,"title":70,"description":71,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":72,"lastUpdatedDate":73,"draft":46,"category":74,"image":42,"faq":75,"tags":91},"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",[76,79,82,85,88],{"question":77,"answer":78},"\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":80,"answer":81},"\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":83,"answer":84},"\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":86,"answer":87},"\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":89,"answer":90},"\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>",[92],"gram-positive-cocci",{"slug":94,"title":95,"description":96,"seoTitle":97,"seoDescription":98,"author":43,"createdDate":99,"lastUpdatedDate":100,"draft":46,"category":74,"image":42,"faq":101,"tags":117},"preparation-mcfarland-turbidity-standards","McFarland Turbidity Standards: Preparation and Use in Susceptibility Testing","How McFarland turbidity standards are prepared, why the 0.5 standard (1.5 x 10^8 CFU\u002FmL) is the target for antimicrobial susceptibility testing, and how a wrong inoculum density gives false results.","McFarland Turbidity Standards: Preparation, Why 0.5 Matters for AST, and How to Match Inoculum","","2016-06-09","2026-08-24",[102,105,108,111,114],{"question":103,"answer":104},"\u003Cp>What is a McFarland turbidity standard?\u003C\u002Fp>","\u003Cp>It is a reference suspension of known turbidity used to estimate the density of a bacterial suspension without counting individual cells. It is made by mixing barium chloride and sulfuric acid to form a barium sulfate precipitate whose cloudiness corresponds to a known cell density.\u003C\u002Fp>",{"question":106,"answer":107},"\u003Cp>Why is the 0.5 McFarland standard used for susceptibility testing?\u003C\u002Fp>","\u003Cp>Disk diffusion susceptibility testing was standardized and validated using an inoculum equivalent to 0.5 McFarland, which is about 1.5 x 10^8 CFU\u002FmL. All the zone-diameter breakpoints assume this density, so using it is what makes the result valid and comparable between laboratories.\u003C\u002Fp>",{"question":109,"answer":110},"\u003Cp>What happens if the inoculum is too dense or too light?\u003C\u002Fp>","\u003Cp>If it is too dense, the zones of inhibition come out smaller than they should and a susceptible organism can be misread as resistant. If it is too light, the zones come out larger and a resistant organism can be misread as susceptible. Both errors can misdirect treatment.\u003C\u002Fp>",{"question":112,"answer":113},"\u003Cp>How is a bacterial suspension matched to the standard?\u003C\u002Fp>","\u003Cp>Hold the suspension and the 0.5 McFarland standard side by side against a white background with contrasting black lines in good light, and compare the turbidity. Dilute if too dense, add organisms if too light, then use the adjusted suspension within 15 minutes.\u003C\u002Fp>",{"question":115,"answer":116},"\u003Cp>What is the difference between a McFarland standard and a McFarland densitometer?\u003C\u002Fp>","\u003Cp>The standard is the reference suspension or target density. The densitometer is an instrument that measures a suspension's turbidity photometrically and reports it in McFarland units, removing the need to prepare and compare against chemical standards.\u003C\u002Fp>",[118],"antimicrobial-susceptibility-testing",{"slug":120,"title":121,"description":122,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":123,"lastUpdatedDate":124,"draft":46,"category":125,"image":42,"faq":126,"tags":151},"mueller-hinton-agar"," Mueller-Hinton Agar: Why It's the One Medium CLSI Won't Let You Substitute","Mueller-Hinton agar is the CLSI-standard medium for antimicrobial susceptibility testing. Learn why it's chosen over other media, the critical 4mm depth requirement, blood-supplemented MHA, and QC strains.","2013-07-20","2026-07-29","culture-media",[127,130,133,136,139,142,145,148],{"question":128,"answer":129},"Why is Mueller-Hinton agar specifically required for AST instead of any nutrient agar?","MHA shows good batch-to-batch reproducibility, supports satisfactory growth of most non-fastidious pathogens, and is low in sulfonamide, trimethoprim, and tetracycline inhibitors, so the medium itself does not interfere with antibiotic activity during testing.",{"question":131,"answer":132},"What happens if MHA plates are poured too thin or too thick?","Plates poured too thin often yield false-susceptible results, since the antibiotic diffuses further than it should. Plates poured too thick often yield false-resistant results, since diffusion is restricted.",{"question":134,"answer":135},"What is the correct final pH for prepared MHA, and why does it matter?","The target is pH 7.3 plus or minus 0.1 at 25 degrees C. If the pH is too low, aminoglycosides, quinolones, and macrolides can appear to lose potency while tetracycline can appear to have excessive activity. If the pH is too high, the opposite pattern occurs.",{"question":137,"answer":138},"Which organisms require a modified form of MHA instead of the standard formula?","Streptococcus pneumoniae and Neisseria meningitidis require MHA supplemented with 5% sheep blood. Haemophilus influenzae requires Haemophilus Test Medium, which is thymidine-free MHA supplemented with NAD, hemin, and yeast extract.",{"question":140,"answer":141},"What role does starch play in MHA?","Starch absorbs toxic metabolites produced during bacterial growth, preventing them from interfering with antibiotic activity, and its hydrolysis also yields dextrose as an energy source for the organism.",{"question":143,"answer":144},"What are the standard plate volumes for disk diffusion testing?","60 to 70 mL for a 150mm plate and 25 to 30 mL for a 100mm plate, poured to give a uniform standardized depth.",{"question":146,"answer":147},"Why is Mueller-Hinton agar the standard medium for antibiotic susceptibility testing?","Mueller-Hinton agar is chosen for AST because of specific properties: acceptable batch-to-batch reproducibility; support for satisfactory growth of most non-fastidious pathogens; low concentrations of sulphonamide, trimethoprim, and tetracycline inhibitors (particularly thymidine and thymine, which antagonise these antibiotic classes); and a large accumulated body of data validating zone size interpretive criteria against this specific medium. Using a different medium would invalidate the CLSI\u002FEUCAST interpretive breakpoints, which were derived from studies using Mueller-Hinton agar specifically.",{"question":149,"answer":150},"What are the consequences of incorrect agar depth in Mueller-Hinton plates?","Agar depth must be 4 mm ± 0.5 mm (20-25 mL per 90 mm plate). Agar that is too thick (greater than 4.5 mm) forces antibiotic to diffuse through more medium, reducing the zone size at any given concentration — producing falsely small zones and false resistance results. Agar that is too thin (less than 3.5 mm) allows antibiotic to diffuse further, producing falsely large zones and false susceptibility results. Both errors can directly change clinical treatment decisions — a patient may be denied effective antibiotics (false resistance) or given antibiotics that won't work (false susceptibility).",[118],{"slug":153,"title":154,"description":155,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":156,"lastUpdatedDate":45,"draft":46,"category":47,"image":42,"faq":157,"tags":173},"novobiocin-susceptibility-test-principle-procedure-and-interpretations","Novobiocin Susceptibility Test: How One Disk Tells S. saprophyticus From a Contaminant","A 5 µg novobiocin disk separates S. saprophyticus, a real cause of UTI in young women, from S. epidermidis, usually just skin contamination. Full procedure, the corrected 16mm breakpoint, and the species this test does and doesn't apply to.","2013-07-21",[158,161,164,167,170],{"question":159,"answer":160},"What does the novobiocin susceptibility test actually identify?","\u003Cp>It presumptively distinguishes \u003Cem>Staphylococcus saprophyticus\u003C\u002Fem>, which is novobiocin-resistant, from other coagulase-negative staphylococci like \u003Cem>S. epidermidis\u003C\u002Fem>, which are novobiocin-susceptible. It is most reliable when performed on urinary isolates from young, sexually active women.\u003C\u002Fp>",{"question":162,"answer":163},"What is the breakpoint for a susceptible result?","A zone diameter of 16 mm or greater is reported as susceptible. Anything below 16 mm is reported as resistant.",{"question":165,"answer":166},"Why is this test unreliable outside urinary specimens?","\u003Cp>Other novobiocin-resistant coagulase-negative staphylococci species, such as \u003Cem>S. cohnii, S. xylosus\u003C\u002Fem>, and \u003Cem>S. kloosii,\u003C\u002Fem> also exist. Outside urinary isolates from the typical patient population, a resistant result cannot be assumed to mean \u003Cem>S. saprophyticus.\u003C\u002Fem>\u003C\u002Fp>",{"question":168,"answer":169},"What does novobiocin actually inhibit in the bacterial cell?","Novobiocin is an aminocoumarin that binds the GyrB subunit of DNA gyrase and competitively inhibits its ATPase activity, blocking the ATP-driven supercoiling that DNA replication requires. This is a different target site from the fluoroquinolones, which act on the GyrA subunit. Susceptible organisms fail to grow within the diffusion zone around the disk.",{"question":171,"answer":172},"\u003Cp>Why does it matter clinically whether an isolate is\u003Cem> S. saprophyticus\u003C\u002Fem> or \u003Cem>S. epidermidis\u003C\u002Fem>?\u003C\u002Fp>","\u003Cp>\u003Cem>S. saprophyticus\u003C\u002Fem> is a genuine cause of urinary tract infection, particularly in young sexually active women, while \u003Cem>S. epidermidis\u003C\u002Fem> isolated from urine is usually a skin contaminant. Confusing the two can lead to either missing a real infection or unnecessarily treating a contaminated sample.\u003C\u002Fp>",[66],{"slug":175,"title":176,"description":177,"seoTitle":42,"seoDescription":42,"author":178,"createdDate":179,"lastUpdatedDate":180,"draft":46,"category":74,"image":42,"faq":181,"tags":200},"sxt-testing-principle-procedure-and-results","SXT Testing: Principle, Procedure, and Results","\u003Cp>SXT (trimethoprim-sulfamethoxazole) susceptibility helps presumptively group beta-hemolytic streptococci. Learn the principle, procedure, and how to read SXT with bacitracin to separate group A, group B, and other streptococci.\u003C\u002Fp>","Ashma Shrestha","2022-08-27","2026-08-16",[182,185,188,191,194,197],{"question":183,"answer":184},"\u003Cp>What does SXT stand for?\u003C\u002Fp>","\u003Cp>SXT is the disk containing trimethoprim and sulfamethoxazole, two antibiotics used together (co-trimoxazole). The disk holds 1.25 µg of trimethoprim and 23.75 µg of sulfamethoxazole.\u003C\u002Fp>",{"question":186,"answer":187},"\u003Cp>What does a clear zone around the SXT disk mean?\u003C\u002Fp>","\u003Cp>It means the organism is susceptible to SXT. Groups C, F, and G beta-hemolytic streptococci are susceptible and show a clear zone. Growth up to the edge of the disk means the organism is resistant, as seen with groups A and B.\u003C\u002Fp>",{"question":189,"answer":190},"\u003Cp>Why are both group A and group B resistant to SXT?\u003C\u002Fp>","\u003Cp>Both groups are naturally resistant, so SXT alone cannot tell them apart. SXT separates group A and group B together from the other beta-hemolytic groups, and bacitracin is then used to distinguish group A from group B.\u003C\u002Fp>",{"question":192,"answer":193},"\u003Cp>How do SXT and bacitracin work together?\u003C\u002Fp>","\u003Cp>Group A is bacitracin-susceptible and SXT-resistant. Group B is bacitracin-resistant and SXT-resistant. Groups C, F, and G are usually bacitracin-resistant and SXT-susceptible. Reading the two zones together gives a presumptive group.\u003C\u002Fp>",{"question":195,"answer":196},"\u003Cp>Is the SXT test enough to identify the organism?\u003C\u002Fp>","\u003Cp>No. It is presumptive. Group B is confirmed with the CAMP test and hippurate hydrolysis, and definitive identification uses Lancefield grouping or biochemical, molecular, or mass spectrometry methods.\u003C\u002Fp>",{"question":198,"answer":199},"\u003Cp>Why is SXT added to the blood agar in some methods?\u003C\u002Fp>","\u003Cp>Adding SXT to the agar suppresses the normal throat flora, which makes it easier to recover group A and group B streptococci from a throat swab.\u003C\u002Fp>",[66],{"slug":202,"title":203,"description":204,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":205,"lastUpdatedDate":45,"draft":46,"category":47,"image":42,"faq":206,"tags":228},"bacitracin-test-principle-procedure-expected-results-and-quality-control","Bacitracin Test: Principle, Procedure, Results","Bacitracin susceptibility test principle, procedure, and zone interpretation for presumptive identification of Streptococcus pyogenes (Group A Strep)","2013-05-17",[207,210,213,216,219,222,225],{"question":208,"answer":209},"Does the bacitracin test need a minimum zone size to count as sensitive?","No. Unlike the optochin test, which uses zone-size cutoffs, the bacitracin test is a binary call: any visible zone of inhibition around the disk counts as sensitive, and no zone at all is resistant.",{"question":211,"answer":212},"\u003Cp>Can organisms other than \u003Cem>Streptococcus pyogenes\u003C\u002Fem> be bacitracin sensitive?\u003C\u002Fp>","Yes. Group C and G streptococci occasionally show susceptibility to the 0.04 IU bacitracin disk as well. When the result is ambiguous, a PYR test resolves it, S. pyogenes is the only beta-hemolytic streptococcus that gives a positive PYR reaction.",{"question":214,"answer":215},"Why does it matter which agar the bacitracin disk is placed on in a throat culture?","When bacitracin and optochin are both used in a combined respiratory culture workup, bacitracin should be placed on chocolate agar (where it also suppresses normal flora and improves detection of Haemophilus influenzae), while optochin goes on blood agar. Using the wrong medium for either disk can affect the reading.",{"question":217,"answer":218},"How does the bacitracin test identify Group A streptococci?","\u003Cp>Group A beta-hemolytic streptococci (\u003Cem>Streptococcus pyogenes\u003C\u002Fem>) are inhibited by the small amount of bacitracin in a 0.04 unit Taxo A disk, while most other beta-hemolytic streptococci are not. So any zone of inhibition around the disk is a presumptive identification of Group A strep, and no zone is resistant. The test is a binary call: any visible zone counts as sensitive, with no minimum size cutoff, which is different from the optochin test where zone size matters.\u003C\u002Fp>",{"question":220,"answer":221},"Why is the PYR test used alongside bacitracin?","\u003Cp>Because bacitracin susceptibility is not fully specific to Group A strep: Lancefield groups C and G streptococci occasionally show susceptibility too, which can cause a false-positive Group A call. PYR resolves it, since \u003Cem>Streptococcus pyogenes\u003C\u002Fem> is the only beta-hemolytic streptococcus that is PYR positive. A bacitracin-sensitive, PYR-positive beta-hemolytic streptococcus is a confident presumptive Group A strep.\u003C\u002Fp>",{"question":223,"answer":224},"Why is there no zone-size cutoff in the bacitracin test?","Because the 0.04 unit differential disk gives a binary result: any visible zone of inhibition, however small, is read as sensitive, and no zone is resistant. This differs from the optochin test, which uses a measured cutoff (14 mm or greater around a 6 mm disk). Importing optochin's measurement logic into the bacitracin test is a common error; here the presence or absence of any zone is what matters.",{"question":226,"answer":227},"Why should bacitracin be read from a pure subculture rather than a primary plate?","Because reading straight off a primary culture plate is less reliable. Mixed flora and overcrowded colonies near the disk are the main causes of misreads. If a primary-plate result looks ambiguous, the correct next step is a purified subculture, not a second look at the same plate. A light inoculum can also produce a misleading zone, so confluent growth from a pure culture gives the most reliable reading.",[66],{"slug":230,"title":231,"description":232,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":205,"lastUpdatedDate":233,"draft":46,"category":47,"image":42,"faq":234,"tags":253},"optochin-test-principle-procedure-expected-results-and-quality-control","Optochin Sensitivity Test: Principle, Procedure, Results","Optochin test principle, procedure, and the 14mm zone cutoff used with bile solubility to confirm Streptococcus pneumoniae","2026-08-06",[235,238,241,244,247,250],{"question":236,"answer":237},"Why are some Streptococcus pneumoniae strains resistant to optochin?","Optochin's molecular target is the bacterial F0F1 ATP synthase. Point mutations in the genes coding for this enzyme, most often atpC and less commonly atpA, alter its structure enough that optochin no longer binds effectively, producing a resistant phenotype despite the isolate still being a true pneumococcus.",{"question":239,"answer":240},"Should an optochin-resistant alpha-hemolytic coccus from a CSF or blood culture be reported as viridans streptococci?","Not without confirmation. In invasive disease specimens, an optochin-resistant or equivocal result should be confirmed with bile solubility or molecular testing before being called viridans streptococci, since misidentifying a resistant pneumococcus carries real clinical consequences.",{"question":242,"answer":243},"What does it mean if colonies are growing inside an otherwise qualifying optochin zone of inhibition?","This can represent a heterogeneous population, a mix of optochin-susceptible and optochin-resistant cells from the same culture. A zone of 14mm or more with colonies visible inside it shouldn't automatically be dismissed as a measurement artifact; it can still indicate a resistant strain and warrants further confirmation.",{"question":245,"answer":246},"Why is Streptococcus pneumoniae sensitive to optochin when other alpha-hemolytic streptococci are not?","Because optochin targets the F0F1 ATP synthase, the enzyme that generates the cell's energy. The pneumococcal version of this enzyme is exquisitely sensitive to optochin at very low concentrations (5 micrograms per mL or less), while the enzyme in most other alpha-hemolytic (viridans) streptococci is not. Cells near the disk cannot sustain the energy metabolism needed to replicate, producing a zone of inhibition. This is why optochin sensitivity presumptively identifies S. pneumoniae.",{"question":248,"answer":249},"\u003Cp>Why must the optochin test be incubated in CO₂?\u003C\u002Fp>","\u003Cp>Because S. pneumoniae grows poorly in ambient air, producing smaller and less reliable zones of inhibition. Incubating in 5 to 10% CO₂ (or a candle jar) gives proper growth and a reliable zone. Skipping CO₂ enrichment can shrink the zone enough to manufacture a false equivocal or false resistant reading on a truly susceptible organism, so ambient air is a genuine source of error, not a shortcut.\u003C\u002Fp>",{"question":251,"answer":252},"What does a zone of inhibition less than 14 mm mean in the optochin test?","Any zone under 14 mm around a 6 mm, 5 microgram disk is equivocal and cannot presumptively identify pneumococcus on its own. Whether the zone is 10 mm or entirely absent, the next step is the same: perform the bile solubility test (or molecular testing). There is no special lower bound that makes a sub-14 mm result safe to call, so all such results are handled identically with a confirmatory test.",[66],{"slug":255,"title":256,"description":257,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":258,"lastUpdatedDate":45,"draft":46,"category":47,"image":42,"faq":259,"tags":275},"modified-oxidase-test-microdase-principle-procedure-uses","Modified Oxidase (Microdase) Test: The DMSO Trick That Separates Micrococcus From Staphylococcus","The standard oxidase reagent fails on Gram-positive cocci, so the microdase test dissolves it in DMSO to reach the cytochrome c inside. A blue disk means Micrococcus (which has cytochrome c); no color means Staphylococcus (which usually does not). Here is why DMSO matters, the mechanism, and the Staphylococcus sciuri exception that breaks the rule.","2015-10-30",[260,263,266,269,272],{"question":261,"answer":262},"What is the difference between the oxidase test and the modified oxidase (microdase) test?","They detect the same enzyme, cytochrome c oxidase, but are used on different organisms and with a different reagent solvent. The standard oxidase test uses a water-based reagent on Gram-negative rods, for example to separate Enterobacteriaceae from non-fermenters. The modified oxidase (microdase) test dissolves the reagent in DMSO so it can penetrate the thick cell walls of Gram-positive cocci, and it is used to separate Micrococcus (positive) from Staphylococcus (negative). Without the DMSO modification, the standard reagent gives unreliable results on Gram-positive cocci.",{"question":264,"answer":265},"Why is DMSO used in the microdase test?","Because the standard oxidase reagent cannot reliably reach the cytochrome c inside Gram-positive cocci; their cell walls block the water-based reagent, giving weak or false results. Dimethyl sulfoxide (DMSO) is a penetrating solvent that makes the cells permeable, carrying the reagent through the cell wall to the cytochrome, and it also stabilizes the reagent against auto-oxidation. Dissolving the reagent in DMSO instead of water is the single change that defines the modified oxidase test.",{"question":267,"answer":268},"What does a positive microdase test indicate?","A blue or purple-blue color on the disk within two minutes indicates the organism has cytochrome c oxidase, which among catalase-positive Gram-positive cocci points to Micrococcus. Staphylococcus usually lacks cytochrome c and gives no color change. The exceptions are Staphylococcus sciuri, S. lentus, and S. vitulinus, which carry c-type cytochromes and give a positive result despite being staphylococci.",{"question":270,"answer":271},"Which staphylococci give a positive microdase test?","Most staphylococci are microdase negative, but three species are exceptions: Staphylococcus sciuri, S. lentus, and S. vitulinus. These carry c-type cytochromes and produce a positive blue reaction, breaking the general rule that a positive microdase means Micrococcus. Because of these exceptions, a positive result should be interpreted alongside other tests such as bacitracin, furazolidone, or lysostaphin susceptibility.",{"question":273,"answer":274},"Why must the microdase test be read within 2 minutes?","Because the reagent, tetramethyl-p-phenylenediamine, spontaneously oxidizes in air and turns blue on its own over time. A color that develops after two minutes may be this auto-oxidation rather than true bacterial enzyme activity, giving a false positive. Reading and recording the result within two minutes ensures the blue color reflects the organism's cytochrome c oxidase, not the reagent aging.",[276],"enzyme-tests",{"enabled":278,"threads":279,"total":280},true,[],0,[282,288,294,301,307,312,318,323,329,332,339],{"slug":283,"name":43,"description":284,"image":285,"body":286,"postCount":287},"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.*",491,{"slug":289,"name":178,"description":290,"image":291,"body":292,"postCount":293},"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":295,"name":296,"description":297,"image":298,"body":299,"postCount":300},"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":302,"name":303,"description":297,"image":304,"body":305,"postCount":306},"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":308,"name":309,"description":297,"image":42,"body":310,"postCount":311},"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":313,"name":314,"description":315,"image":42,"body":316,"postCount":317},"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":319,"name":320,"description":321,"image":42,"body":42,"postCount":322},"guest-author","Guest Author","Guest Author \u002F Contributor",1,{"slug":324,"name":325,"description":297,"image":326,"body":327,"postCount":328},"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":330,"name":331,"description":321,"image":42,"body":42,"postCount":322},"dr-poonam-acharya","Dr. Poonam Acharya",{"slug":333,"name":334,"description":335,"image":336,"body":337,"postCount":338},"nisha-rijal","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.*",55,{"slug":340,"name":341,"description":342,"image":343,"body":344,"postCount":322},"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.",[346,353,359,363,368,373,377,381,385,390,394,398,402,407,412,417,421,425,430,435,439,443,447,451,455,459,463,467,472,477,481,485,489,494,498,502,506,510,514,518,522,526,530,534,538,542,546,550,555,559,563,567,571,575,578,582,585,589,593,597,601,605,609,613,617,621,625,629,632,636,639,642,645,648,651,654,657,660,663,666,669,672,675],{"slug":347,"name":348,"description":349,"image":350,"body":351,"postCount":352},"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":354,"name":355,"description":356,"image":42,"body":357,"postCount":358},"microscopy","Microscopy","Microscope types, components, and microscopy techniques","These are list of blog posts related to microscopy. ",12,{"slug":92,"name":360,"description":361,"image":42,"body":42,"postCount":362},"Gram-Positive Cocci","Staphylococcus, Streptococcus, Enterococcus, Micrococcus — organisms, diseases, and identification tests",11,{"slug":364,"name":365,"description":366,"image":42,"body":42,"postCount":367},"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":369,"name":370,"description":371,"image":42,"body":42,"postCount":372},"gram-positive-rods","Gram-Positive Rods","Bacillus, Clostridium, Listeria, Corynebacterium, Actinomyces and related organisms",8,{"slug":374,"name":375,"description":376,"image":42,"body":42,"postCount":358},"mycobacteria","Mycobacteria","Mycobacterium tuberculosis, leprosy, atypical mycobacteria, and acid-fast organism diagnosis",{"slug":378,"name":379,"description":380,"image":42,"body":42,"postCount":358},"anaerobic-bacteriology","Anaerobic Bacteriology","Anaerobic organisms, anaerobic culture methods, and anaerobic infection diagnosis",{"slug":382,"name":383,"description":384,"image":42,"body":42,"postCount":358},"enterobacteriaceae","Enterobacteriaceae","Identification, differentiation, and clinical significance of Enterobacteriaceae family members",{"slug":386,"name":387,"description":388,"image":42,"body":42,"postCount":389},"spirochetes","Spirochetes","Treponema, Leptospira, Borrelia and spirochetal infections",7,{"slug":391,"name":392,"description":393,"image":42,"body":42,"postCount":352},"food-microbiology","Food Microbiology","Food-borne pathogens, food safety, spoilage, and preservation",{"slug":118,"name":395,"description":396,"image":42,"body":42,"postCount":397},"Antimicrobial Susceptibility Testing","Methods for testing antibiotic susceptibility in clinical microbiology",22,{"slug":399,"name":400,"description":401,"image":42,"body":42,"postCount":352},"antimicrobials-moa-amr","Antimicrobials (MOA & AMR)","Mechanisms, detection, and clinical significance of antimicrobial resistance",{"slug":403,"name":404,"description":405,"image":42,"body":42,"postCount":406},"sterilization-disinfection","Sterilization and Disinfection","Methods of sterilization and disinfection in healthcare and laboratory settings",10,{"slug":408,"name":409,"description":410,"image":42,"body":42,"postCount":411},"specimen-collection-transport","Specimen Collection and Transport","Collection, handling, and transport of clinical specimens for microbiological testing",27,{"slug":413,"name":414,"description":415,"image":42,"body":42,"postCount":416},"bacterial-structure-physiology","Bacterial Structure and Physiology","Bacterial cell structure, growth, physiology, and environmental factors affecting growth",21,{"slug":418,"name":419,"description":42,"image":42,"body":420,"postCount":311},"horizontal-gene-transfer","Horizontal Gene Transfer","Articles related to **Horizontal Gene Transfer**",{"slug":422,"name":423,"description":42,"image":42,"body":424,"postCount":406},"chromatography","Chromatography","Information about chromatographic techniques.",{"slug":426,"name":427,"description":428,"image":42,"body":429,"postCount":389},"electrophoresis","Electrophoresis","Information about Electrophoresis Techniques ","Detailed information  about Electrophoresis Techniques ",{"slug":431,"name":432,"description":433,"image":42,"body":434,"postCount":311},"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":436,"name":437,"description":438,"image":42,"body":42,"postCount":311},"bacteriophage","Bacteriophage","Description about Bacteriophage.",{"slug":440,"name":441,"description":442,"image":42,"body":42,"postCount":311},"malaria","Malaria","It is the collections of articles regarding malarial disease. ",{"slug":444,"name":445,"description":446,"image":42,"body":42,"postCount":311},"anaerobic-culture-techniques","Anaerobic Culture Techniques","Posts related with Anaerobic Culture Techniques.",{"slug":448,"name":449,"description":450,"image":42,"body":42,"postCount":416},"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":452,"name":453,"description":454,"image":42,"body":42,"postCount":389},"biosafety-levels","Biosafety levels ","Articles related to Biosafety Levels",{"slug":456,"name":457,"description":458,"image":42,"body":42,"postCount":367},"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":460,"name":461,"description":462,"image":42,"body":42,"postCount":311},"pipette","Pipette","Posts related with Pipette. ",{"slug":464,"name":465,"description":466,"image":42,"body":42,"postCount":389},"bacteriology-mcqs","Bacteriology MCQs","This sections lists MCQs in Bacteriology.",{"slug":468,"name":469,"description":470,"image":42,"body":42,"postCount":471},"parasitology-mcqs","Parasitology MCQs","This section lists MCQs in Parasitology.",2,{"slug":473,"name":474,"description":475,"image":42,"body":42,"postCount":476},"virology-mcqs","Virology MCQs","This is the collections of Multiple Choice Questions in Virology.",4,{"slug":478,"name":479,"description":480,"image":42,"body":42,"postCount":367},"mcqs-in-microbiology","MCQs in Microbiology","This section lists the collections of Multiple Choice Questions in General Microbiology Topics. ",{"slug":482,"name":483,"description":484,"image":42,"body":42,"postCount":389},"immunology-mcqs","Immunology MCQs","In this section; we are posting collections of Multiple Choice Questions about Immunology. ",{"slug":486,"name":487,"description":488,"image":42,"body":42,"postCount":406},"microbial-curiosities","Microbial Curiosities","In this clusters, we are posting interesting and unique information about Microorganisms. ",{"slug":490,"name":491,"description":492,"image":42,"body":42,"postCount":493},"bacterial-culture-media","Bacterial Culture Media","Posts related to Bacterial Culture Media. ",23,{"slug":495,"name":496,"description":497,"image":42,"body":42,"postCount":311},"fungal-culture-media","Fungal Culture Media","Posts related to Fungal Culture Media.",{"slug":499,"name":500,"description":501,"image":42,"body":42,"postCount":367},"motility-test","Motility Test","This lists the procedure regarding various tests methods for bacterial motility.",{"slug":503,"name":504,"description":505,"image":42,"body":42,"postCount":406},"bacterial-enumeration","Bacterial enumeration","These posts are related to isolation and enumeration of bacteria. ",{"slug":507,"name":508,"description":509,"image":42,"body":42,"postCount":471},"gram-positive-coccobacillus","Gram-positive coccobacillus","List of Gram Positive Coccobacilli",{"slug":511,"name":512,"description":513,"image":42,"body":42,"postCount":476},"dimorphic-fungi","Dimorphic Fungi","This is about various dimorphic fungi. ",{"slug":515,"name":516,"description":517,"image":42,"body":42,"postCount":389},"bacterial-classification","Bacterial Classification","These posts are related with various approaches used for the classification of Bacteria. ",{"slug":519,"name":520,"description":521,"image":42,"body":42,"postCount":367},"immunofluorescence","Immunofluorescence ","Various Tests related to Immunofluorescence ",{"slug":523,"name":524,"description":525,"image":42,"body":42,"postCount":317},"antibody-mediated-immunity","Antibody-mediated Immunity","This clusters links the articles that are sharing insights about Antibody-mediated immunity. ",{"slug":527,"name":528,"description":529,"image":42,"body":42,"postCount":389},"hypersensitivity","Hypersensitivity","Articles related to Hypersensitivity.",{"slug":531,"name":532,"description":42,"image":42,"body":42,"postCount":533},"haemophilus","Haemophilus",3,{"slug":535,"name":536,"description":537,"image":42,"body":42,"postCount":476},"sexually-transmitted-infections-stis","Sexually transmitted infections (STIs)","This is the clusters of infections that are transmitted sexually. ",{"slug":539,"name":540,"description":541,"image":42,"body":42,"postCount":358},"adaptive-immunity","Adaptive Immunity","Blog posts related to B Cell Immunity and T Cell Immunity.",{"slug":543,"name":544,"description":545,"image":42,"body":42,"postCount":352},"fungal-diagnostics","Fungal Diagnostics","Various methods used for the Diagnosis of Fungal Infections. ",{"slug":547,"name":548,"description":549,"image":42,"body":42,"postCount":367},"laboratory-storage-and-preservation","Laboratory Storage and Preservation","Articles about Laboratory Storage of Antimicrobial Disk, Test organisms and Equipment used for this process. ",{"slug":551,"name":552,"description":553,"image":42,"body":554,"postCount":311},"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":556,"name":557,"description":558,"image":42,"body":42,"postCount":317},"laboratory-glassware","Laboratory Glassware","Posts about Laboratory Glassware. ",{"slug":560,"name":561,"description":562,"image":42,"body":42,"postCount":317},"helminths","Helminths","In this section, we are covering properties, life cycle, pathogenesis and laboratory diagnosis of Helminths\u002FHelminthic infestations. ",{"slug":564,"name":565,"description":566,"image":42,"body":42,"postCount":372},"protozoan-parasite","Protozoan Parasite","In this cluster, we are covering protozoan parasites. ",{"slug":568,"name":569,"description":570,"image":42,"body":42,"postCount":322},"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":572,"name":573,"description":574,"image":42,"body":42,"postCount":406},"bacterial-staining-technique","Bacterial Staining Technique","Lists of various staining techniques that are used to stain bacteria. ",{"slug":276,"name":576,"description":577,"image":42,"body":42,"postCount":416},"Enzyme Tests","\u003Cp>Various Biochemical Test that are based on enzymatic activity of the microorganisms. \u003C\u002Fp>",{"slug":579,"name":580,"description":581,"image":42,"body":42,"postCount":362},"carbohydrate-utilization","Carbohydrate Utilization","\u003Cp>Various biochemical tests which are related to Carbohydrate fermentation or Utilization\u003C\u002Fp>",{"slug":66,"name":583,"description":584,"image":42,"body":42,"postCount":367},"Susceptibility-based ID","\u003Cp>These are susceptibility based identification test such as optochin sensitivity, bacitracin sensitivity etc. \u003C\u002Fp>",{"slug":586,"name":587,"description":588,"image":42,"body":42,"postCount":476},"microbial-metabolism","Microbial Metabolism","\u003Cp>Tests about Microbial Metabolism. \u003C\u002Fp>",{"slug":590,"name":591,"description":592,"image":42,"body":42,"postCount":372},"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":594,"name":595,"description":596,"image":42,"body":42,"postCount":533},"atypical-pneumonia","Atypical Pneumonia","\u003Cp>Organisms responsible for Atypical Pneumonia. \u003C\u002Fp>",{"slug":598,"name":599,"description":600,"image":42,"body":42,"postCount":367},"antigen","Antigen","\u003Cp>Various articles related to Antigens.\u003C\u002Fp>",{"slug":602,"name":603,"description":604,"image":42,"body":42,"postCount":389},"innate-immunity","Innate Immunity","\u003Cp>Articles related to Innate Immunity. \u003C\u002Fp>",{"slug":606,"name":607,"description":608,"image":42,"body":42,"postCount":476},"respiratory-tract-infection","Respiratory Tract Infection","\u003Cp>In this cluster, you can see various etiological agents that causes respiratory tract infection. \u003C\u002Fp>",{"slug":610,"name":611,"description":612,"image":42,"body":42,"postCount":367},"torch-infection","TORCH Infection","\u003Cp>In this section; you can find articles related with TOCH infection. \u003C\u002Fp>",{"slug":614,"name":615,"description":616,"image":42,"body":42,"postCount":372},"microbiology-for-beginners","Microbiology for Beginners","\u003Cp>These articles are very basic articles, which will share general concepts in Microbiology. \u003C\u002Fp>",{"slug":618,"name":619,"description":620,"image":42,"body":42,"postCount":311},"dna-replication","DNA Replication","\u003Cp>Articles related to DNA and Replication of DNA. \u003C\u002Fp>",{"slug":622,"name":623,"description":624,"image":42,"body":42,"postCount":389},"genetic-code","Genetic Code","\u003Cp>Articles related to Genetic Code.\u003C\u002Fp>",{"slug":626,"name":627,"description":628,"image":42,"body":42,"postCount":389},"molecular-technique","Molecular Technique","\u003Cp>Posts related to Molecular Techniques. \u003C\u002Fp>",{"slug":630,"name":631,"description":42,"image":42,"body":42,"postCount":322},"colorimetric-assay","Colorimetric Assay ",{"slug":633,"name":634,"description":635,"image":42,"body":42,"postCount":367},"pharmaceutical-microbiology","Pharmaceutical Microbiology","\u003Cp>Various articles related to Pharmaceutical Microbiology\u003C\u002Fp>",{"slug":637,"name":638,"description":42,"image":42,"body":42,"postCount":533},"blood-and-immune-cells","Blood and Immune Cells",{"slug":640,"name":641,"description":42,"image":42,"body":42,"postCount":367},"host-pathogen-interaction","Host Pathogen Interaction",{"slug":643,"name":644,"description":42,"image":42,"body":42,"postCount":476},"blood-culture","Blood Culture",{"slug":646,"name":647,"description":42,"image":42,"body":42,"postCount":476},"environmental-microbiology","Environmental microbiology ",{"slug":649,"name":650,"description":42,"image":42,"body":42,"postCount":389},"copromicroscopic-technique","Copromicroscopic Technique",{"slug":652,"name":653,"description":42,"image":42,"body":42,"postCount":533},"quality-control","Quality Control",{"slug":655,"name":656,"description":42,"image":42,"body":42,"postCount":389},"dermatophytes","Dermatophytes",{"slug":658,"name":659,"description":42,"image":42,"body":42,"postCount":533},"viral-hemorrhagic-fevers","Viral Hemorrhagic Fevers",{"slug":661,"name":662,"description":42,"image":42,"body":42,"postCount":476},"h2s-production","H2S Production",{"slug":664,"name":665,"description":42,"image":42,"body":42,"postCount":471},"water-quality-testing","Water Quality Testing",{"slug":667,"name":668,"description":42,"image":42,"body":42,"postCount":367},"virology-basics","Virology basics",{"slug":670,"name":671,"description":42,"image":42,"body":42,"postCount":476},"typing-methods","Typing Methods",{"slug":673,"name":674,"description":42,"image":42,"body":42,"postCount":533},"blotting-technique","Blotting Technique",{"slug":676,"name":677,"description":42,"image":42,"body":42,"postCount":476},"history-microbiology","History of Microbiology"]