[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"$fxLN3MUwXCdr5RPjwZYIDpOj8CHyjOmngWTgoKXPtZbg":3,"$fMyKEy6iU2x2FccNFSWaaKPwZSgx7Zvf6bK3GDJRiWB4":36,"$f3Ft0rKFJHppdzE-vuveecxx1BUcg9iOlMLtyzf_MJDg":256,"$fucxFBm2ZjZfGSdmdRaSNGBI_F0jJme4f0GTvzUhQfL8":320},[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},"Abbreviations","abbreviations","\u002Fabbreviations\u002F",{"title":25,"slug":26,"path":27},"Microbes","microbes","\u002Fmicrobes\u002F",{"title":29,"slug":30,"path":31},"Books","recommended-books","\u002Frecommended-books\u002F",{"title":33,"slug":34,"path":35},"Utilization Tests for Bacterial Identification","utilization-tests","\u002Futilization-tests\u002F",{"type":37,"data":38},"blog",{"slug":39,"title":40,"description":41,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":44,"lastUpdatedDate":44,"draft":45,"category":46,"image":42,"body":47,"faq":48,"commentsClosed":45,"tags":70,"related":72,"comments":252},"laboratory-workup-positive-blood-culture","Laboratory Workup of a Positive Blood Culture","\u003Cp>What the laboratory does the moment a blood culture flags positive: the immediate Gram stain, subculture, identification by MALDI-TOF or molecular panels, susceptibility testing, and how to tell a true pathogen from a skin contaminant.\u003C\u002Fp>",null,"Acharya Tankeshwar","2026-08-20",false,"bacteriology","A blood culture bottle flags positive at 2 in the morning. The patient is on empiric antibiotics that may or may not be right. What the laboratory does in the next few minutes, and the next few hours, can change the treatment before the ward round. The flag itself says almost nothing: the instrument detected carbon dioxide, not an identified organism. This article is about that workup, the sequence from a positive bottle to a named, susceptibility-tested organism, and the judgment that runs through it.\n\nFor how the bottle is flagged positive in the first place, see the [BACTEC automated blood culture system](https:\u002F\u002Fmicrobeonline.com\u002Fbactec-automated-blood-culture-system\u002F). For how the blood should have been collected, see [Blood Culture: Indications, Timing, and Volume](https:\u002F\u002Fmicrobeonline.com\u002Fblood-culture-indications-timing-and-volume\u002F). This article picks up the moment the bottle turns positive.\n\n\u003Cfigure>\n\u003Cimg src=\"https:\u002F\u002Fassets.microbeonline.com\u002Fblogs\u002Fpositive-blood-culture-workup-timeline.png\" alt=\"The positive bottle becomes an identified, susceptibility-tested organism two ways. The Gram stain is the shared pivot; from there the rapid track reaches an answer in hours while the conventional track takes days.\" width=\"2816\" height=\"2240\" draggable=\"false\" contenteditable=\"false\">\u003Cfigcaption>Figure: The positive bottle becomes an identified, susceptibility-tested organism two ways. The Gram stain is the shared pivot; from there the rapid track reaches an answer in hours while the conventional track takes days.\u003C\u002Ffigcaption>\n\u003C\u002Ffigure>\n\n### Step 1: the immediate Gram stain, the highest-value few minutes in the lab\n\nThe instant a bottle flags positive, a drop of the broth is Gram stained and read. This single step does more, sooner, than anything else in the workup:\n\n- It confirms organisms are actually present (the flag can occasionally be false).\n- It tells you the broad category, gram-positive cocci in clusters, gram-positive cocci in chains, gram-negative rods, yeast, which immediately narrows the likely pathogen and the likely right antibiotic.\n- It is reported to the clinician at once as a [preliminary (critical) result](https:\u002F\u002Fmicrobeonline.com\u002Fcritical-panic-values-microbiology\u002F), often hours to a day before identification. A \"gram-negative rods in blood\" call can prompt a change in empiric therapy the same hour.\n- It guides the rest of the workup: which media to subculture onto, and which rapid test to run.\n\nThe Gram stain is also the gatekeeper for the rapid molecular panels below, which are approved for use on a positive bottle only after organisms are seen on the Gram film.\n\n**The judgment point:** read the morphology carefully, because it drives the first treatment decision. Gram-positive cocci in clusters suggest staphylococci (is it [*Staphylococcus aureus*](https:\u002F\u002Fmicrobeonline.com\u002Fstaphylococcus-aureusdisease-properties-pathogenesis-and-laboratory-diagnosis\u002F), which is always significant, or a coagulase-negative staphylococcus, often a contaminant?). Gram-negative rods suggest [Enterobacterales](https:\u002F\u002Fmicrobeonline.com\u002Fenterobacteriaceae\u002F) or [*Pseudomonas*](https:\u002F\u002Fmicrobeonline.com\u002Fpseudomonas-aeruginosa-infection-mortality-pathogenesis-and-diagnosis\u002F). Yeast changes the whole approach toward [antifungal therapy](https:\u002F\u002Fmicrobeonline.com\u002Fmechanism-of-action-of-antifungal-drugs\u002F).\n\n### Step 2: subculture onto solid media\n\nA portion of the positive broth is subcultured onto solid media so that isolated colonies grow for identification and susceptibility testing. The media are chosen to match the Gram result:\n\n- [Blood agar](https:\u002F\u002Fmicrobeonline.com\u002Fblood-agar-composition-preparation-uses-and-types-of-hemolysis\u002F) and [chocolate agar](https:\u002F\u002Fmicrobeonline.com\u002Fchocolate-agar-composition-uses-colony-characteristics\u002F) for most organisms, including fastidious ones.\n- [MacConkey agar](https:\u002F\u002Fmicrobeonline.com\u002Fmacconkey-agar-mac-composition-preparation-uses-and-colony-characteristics\u002F) when gram-negative rods are seen, to separate lactose fermenters.\n- [Anaerobic media](https:\u002F\u002Fmicrobeonline.com\u002Fcommonly-used-anaerobic-media-for-anaerobic-bacteriology) if the anaerobic bottle is positive or anaerobes are suspected.\n- Sabouraud or fungal media if yeast is seen.\n\nSubculture is still the backbone of the workup because it provides pure colonies for confirmatory identification and, in many laboratories, for susceptibility testing. Its drawback is time: colonies usually need overnight incubation, which is the main delay the rapid methods below are designed to remove.\n\n### Step 3: identification\n\nOnce organisms are available, the isolate is identified. There are now three tiers, from slowest and cheapest to fastest.\n\n**MALDI-TOF mass spectrometry from a subcultured colony.** The routine modern method. A colony from the overnight subculture is identified to species in minutes by its protein fingerprint. This is fast and cheap once a colony exists, and it is the standard identification step in most laboratories. For how MALDI-TOF works, see the [MALDI-TOF MS article](https:\u002F\u002Fmicrobeonline.com\u002Fmaldi-tof-ms-principle-applications-microbiology).\n\n**MALDI-TOF directly from the positive bottle.** To skip the overnight wait, the organisms can be concentrated straight from the positive broth (by centrifugation and washing, or with a commercial preparation cartridge) and identified by MALDI-TOF the same shift. It identifies most monomicrobial samples to species directly from the bottle, though a minority are missed or need the subculture after all. This shortens time to identification from a day to a few hours.\n\n**Rapid molecular panels from the positive bottle.** [Multiplex PCR panels](https:\u002F\u002Fmicrobeonline.com\u002Fmultiplex-pcr-principle-applications-and-limitations\u002F) (for example the BioFire Blood Culture Identification panel or the Verigene system) run directly on a drop of positive broth and return, in about an hour, both the organism identity and key resistance genes. A panel can report, for instance, *Staphylococcus aureus* with the *mecA* gene (marking it as MRSA), or an Enterobacterales with a carbapenemase gene, long before phenotypic susceptibility is available. These panels are the fastest route from positive bottle to actionable identification, and they detect resistance markers, but they only detect the organisms and genes on the panel, and they do not replace full susceptibility testing.\n\n### Step 4: antimicrobial susceptibility testing\n\nIdentification tells you what the organism is; susceptibility testing tells you what will treat it. As with identification, there is a conventional route and a rapid one.\n\n- **Conventional AST** is performed from the pure subculture, by disc diffusion (modified Kirby-Bauer) or an automated broth microdilution system, and read after overnight incubation. For the method, see the [modified Kirby-Bauer article](https:\u002F\u002Fmicrobeonline.com\u002Fantimicrobial-susceptibility-testing-procedure-modified-kirby-bauer-method).\n- **Rapid AST** shortens this. Susceptibility can be run directly from the positive bottle or from a short-incubation growth using automated systems, giving phenotypic results in hours rather than the next day. Molecular panels add resistance-gene information even faster, though a detected gene predicts resistance and does not fully replace a phenotypic result.\n\nThe distinction worth keeping clear: a resistance gene from a molecular panel is a fast prediction (mecA means methicillin resistance), while phenotypic AST measures what actually happens when the organism meets the drug. The two are complementary, the gene is faster, the phenotype is definitive.\n\n### The judgment that runs through all of it: true pathogen or contaminant?\n\nNot every positive bottle means bloodstream infection. Skin flora introduced during collection can grow in the bottle and flag it positive. Distinguishing a true pathogen from a contaminant is one of the most important interpretive skills in the workup, because treating a contaminant wastes antibiotics and missing a true pathogen is dangerous.\n\nThe clues, taken together rather than singly:\n\n- **The organism.** Some organisms are almost always significant (*Staphylococcus aureus*, Enterobacterales, *Pseudomonas aeruginosa*, *Streptococcus pneumoniae*, *Candida*). Others are common skin contaminants (coagulase-negative staphylococci, *Cutibacterium*, diphtheroids), though these can be real pathogens in the right patient, for example with a prosthetic device.\n- **How many bottles or sets grew it.** The same organism in two separate sets points strongly to true infection; growth in only one set of several, especially a skin organism, suggests contamination. This is why two or more sets are collected from separate sites.\n- **Time to positivity.** [True bacteremia](https:\u002F\u002Fmicrobeonline.com\u002Fmost-common-cause-of-bacteremia-and-fungemia\u002F) tends to flag sooner (higher organism load); a skin contaminant introduced in small numbers often flags later.\n- **The clinical picture.** Fever, a plausible source, an indwelling line, and the patient's overall state all weigh in. The bottle is never read in isolation.\n\nThis is also where the paired-draw and differential-time-to-positivity logic for suspected line infection fits; see the[ blood culture collection article](https:\u002F\u002Fmicrobeonline.com\u002Fblood-culture-indications-timing-and-volume\u002F) for how paired peripheral and catheter cultures are interpreted.\n\n### The whole arc, and why speed matters\n\nConventionally, the path from a positive bottle to full identification and susceptibility took two to three days. The modern layered workup compresses it: the Gram stain in minutes, a molecular panel or direct MALDI in about an hour to a few hours, and rapid AST within the same day. Each step earlier that the right antibiotic is started improves the outcome in bloodstream infection, which is why these accelerations matter clinically and are not just laboratory convenience.\n\n### How to Remember\n\n**The flag is a doorbell, not a diagnosis.** The instrument only sensed CO₂. Everything you actually need comes from the workup: Gram stain, subculture, ID, AST. Start every positive bottle by remembering it has told you almost nothing yet.\n\n**Gram stain first, and it is the most valuable five minutes.** Before any machine, a drop of broth on a slide tells you the category and lets the clinician change therapy the same hour. It also decides your media and your rapid test.\n\n**Three speeds of ID: colony MALDI, direct MALDI, molecular panel.** Slowest to fastest. Colony MALDI needs the overnight subculture; direct MALDI skips it; the molecular panel runs off the bottle in an hour and adds resistance genes.\n\n**Gene is fast, phenotype is final.** A molecular panel predicts resistance from a gene (*mecA* means MRSA). Phenotypic AST measures what the drug actually does. Use the fast prediction to act early, the phenotype to confirm.\n\n**One bottle of skin bugs is a suspect; two sets of the same organism is a pathogen.** The contaminant question turns mostly on the organism, how many sets grew it, and the clinical picture. That is why sets are drawn from separate sites.\n\n### Key exam facts\n\n| Point | Fact |\n| --- | --- |\n| First step on a positive bottle | Immediate Gram stain from the broth |\n| Why the Gram stain matters most | Confirms growth, gives category, reported as a preliminary critical result |\n| Gram stain as gatekeeper | Molecular panels are approved only after organisms seen on the film |\n| Subculture media | Blood, chocolate, MacConkey (GNR), anaerobic or fungal as indicated |\n| Routine ID | MALDI-TOF from a subcultured colony |\n| Faster ID | MALDI-TOF directly from the positive bottle |\n| Fastest ID + resistance genes | Molecular panel (e.g. BioFire BCID, Verigene), about 1 hour |\n| Molecular panel limits | Only panel organisms and genes; does not replace full AST |\n| Conventional AST | Disc diffusion or automated, from pure subculture, overnight |\n| Rapid AST | Direct-from-bottle or short-incubation, phenotypic, hours |\n| Gene vs phenotype | Gene predicts resistance (*mecA* = MRSA); phenotype is definitive |\n| Always significant organisms | *S. aureus*, Enterobacterales, *P. aeruginosa*, *S. pneumoniae*, *Candida* |\n| Common contaminants | Coagulase-negative staphylococci, *Cutibacterium*, diphtheroids |\n| Best contaminant clue | Same organism in two separate sets = true infection |\n| Conventional total TAT | 2 to 3 days; modern workup compresses to hours |\n\n### Where Students Get Confused\n\n**\"The bottle flagged positive, so the organism is identified, right?\"** No. The instrument only detected carbon dioxide from growth. It has not identified anything. Identification comes later, from the Gram stain (category), then MALDI-TOF or a molecular panel (species). The flag is the start of the workup, not the end.\n\n**\"Why do the Gram stain when faster machines exist?\"** Because it is immediate, needs no instrument, and gives the clinician an actionable category (gram-negative rods, yeast) within minutes, often changing therapy the same hour. It also tells you which media to subculture and which rapid panel to run, and the panels are only approved for use once organisms are seen on the film.\n\n**\"If molecular panels give ID and resistance genes in an hour, why still subculture and do AST?\"** Because the panel only reports the organisms and genes it is designed for, and a resistance gene predicts resistance rather than measuring it. Full phenotypic susceptibility testing, from a pure subculture, remains the definitive answer and covers organisms and drugs the panel does not.\n\n**\"A gene said MRSA, so do we even need phenotypic testing?\"** The gene (*mecA*) is a fast, reliable prediction and is enough to act on early. Phenotypic AST still confirms it and provides susceptibility to the other drugs that will actually be used. Gene for speed, phenotype for the full picture.\n\n**\"Coagulase-negative staph grew, so treat it?\"** Usually not. Coagulase-negative staphylococci are among the commonest skin contaminants. Whether one matters depends on the organism, how many separate sets grew it, the time to positivity, and the clinical picture, especially whether the patient has a prosthetic device or line. A single bottle of coagulase-negative staph in an otherwise well patient is usually contamination.\n\n**\"Why does it matter how fast all this happens?\"** Because in bloodstream infection, every hour on the wrong or no antibiotic worsens the outcome. The layered workup exists to get the right drug started sooner: Gram stain in minutes, ID in an hour to a few hours, susceptibility within the day, instead of the two to three days conventional culture alone would take.\n\n### References\n\n1. CLSI. *Principles and Procedures for Blood Cultures.* 2nd ed. CLSI document M47. Wayne, PA: Clinical and Laboratory Standards Institute; 2022.\n2. Tille PM. *Bailey & Scott's Diagnostic Microbiology.* 15th ed. St. Louis: Elsevier; 2022.\n3. Leber AL, editor. *Clinical Microbiology Procedures Handbook.* 4th ed. Washington, DC: ASM Press; 2016. DOI: 10.1128\u002F9781683670438.CMPH",[49,52,55,58,61,64,67],{"question":50,"answer":51},"\u003Cp>What is the first thing done when a blood culture flags positive?\u003C\u002Fp>","\u003Cp>An immediate Gram stain from the positive broth. It confirms organisms are present, gives the broad category (such as gram-positive cocci in clusters or gram-negative rods), and is reported to the clinician at once as a preliminary result, often changing empiric therapy the same hour.\u003C\u002Fp>",{"question":53,"answer":54},"\u003Cp>Does a positive flag mean the organism has been identified?\u003C\u002Fp>","\u003Cp>No. The instrument detected carbon dioxide produced by growth, not the organism's identity. Identification follows from the Gram stain and then MALDI-TOF or a molecular panel.\u003C\u002Fp>",{"question":56,"answer":57},"\u003Cp>How is the organism identified from a positive blood culture?\u003C\u002Fp>","\u003Cp>Most often by MALDI-TOF mass spectrometry from a subcultured colony. To save time, MALDI-TOF can be run directly from the positive bottle, or a rapid molecular panel can identify the organism and key resistance genes in about an hour directly from the broth.\u003C\u002Fp>",{"question":59,"answer":60},"\u003Cp>What do rapid molecular panels add, and what are their limits?\u003C\u002Fp>","\u003Cp>Panels such as BioFire BCID or Verigene give organism identity plus resistance markers (for example \u003Cem>mecA\u003C\u002Fem> for MRSA) in about an hour from a positive bottle. They only detect the organisms and genes on the panel, and a resistance gene predicts resistance rather than measuring it, so they do not replace full susceptibility testing.\u003C\u002Fp>",{"question":62,"answer":63},"\u003Cp>How do you tell a true pathogen from a contaminant?\u003C\u002Fp>","\u003Cp>By combining several clues: the organism (some are almost always significant, others are common skin contaminants), how many separate sets grew it (the same organism in two sets points to true infection), the time to positivity, and the clinical picture. No single clue decides it alone.\u003C\u002Fp>",{"question":65,"answer":66},"\u003Cp>Why is the Gram stain still important when faster instruments exist?\u003C\u002Fp>","\u003Cp>It is immediate, requires no instrument, and gives an actionable category within minutes that can change treatment the same hour. It also determines which media to subculture and is required before a molecular panel can be run, since the panels are validated for bottles with organisms seen on the film.\u003C\u002Fp>",{"question":68,"answer":69},"\u003Cp>Why does the speed of the workup matter clinically?\u003C\u002Fp>","\u003Cp>In bloodstream infection, delay in starting the right antibiotic worsens outcomes. The layered workup compresses the path from a positive bottle to identification and susceptibility from two to three days down to hours, so effective therapy can start sooner.\u003C\u002Fp>",[71],"blood-culture",[73,81,113,120,144,170,206,217],{"slug":74,"title":75,"description":76,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":77,"lastUpdatedDate":78,"draft":45,"category":46,"image":42,"faq":79,"tags":80},"bactec-automated-blood-culture-system","BACTEC Automated Blood Culture System: Principle, Vials, and How It Detects Growth","\u003Cp>How the BD BACTEC system detects bloodstream infection: the CO₂ fluorescence principle, what the vials contain and why (SPS, resins), the vial types, how a positive is worked up, and how BACTEC compares with BacT\u002FALERT and VersaTREK.\u003C\u002Fp>","2019-11-15","2026-08-19",[],[71],{"slug":82,"title":83,"description":84,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":85,"lastUpdatedDate":78,"draft":45,"category":46,"image":42,"faq":86,"tags":111},"blood-culture-indications-timing-and-volume","Blood Culture: Indications, Timing, and Volume","\u003Cp>When to draw blood cultures and why, why volume matters more than timing, how many sets to collect, how to draw from a peripheral vein versus a central line, and how paired cultures diagnose a line infection.\u003C\u002Fp>","2018-09-25",[87,90,93,96,99,102,105,108],{"question":88,"answer":89},"\u003Cp>Why does blood volume matter more than the timing of collection?\u003C\u002Fp>","\u003Cp>Most adult bacteremias carry very few organisms per millilitre of blood, so the more blood cultured, the higher the chance of catching one. Studies show total volume drives yield far more than the exact minute of collection.\u003C\u002Fp>",{"question":91,"answer":92},"\u003Cp>How many blood culture sets should be collected, and why not just one?\u003C\u002Fp>","\u003Cp>At least two, preferably three, each from a separate venipuncture. A single set gives too little volume and cannot distinguish a skin contaminant from a true pathogen. A contaminant usually appears in only one set, while a real pathogen appears in several.\u003C\u002Fp>",{"question":94,"answer":95},"\u003Cp>How much blood goes into each bottle for an adult?\u003C\u002Fp>","\u003Cp>About 10 mL per bottle, with two bottles (aerobic and anaerobic) per set, so roughly 20 mL per set. Under-filling is a common reason a true infection is missed.\u003C\u002Fp>",{"question":97,"answer":98},"\u003Cp>Should blood cultures be drawn from a peripheral vein or an existing line?\u003C\u002Fp>","\u003Cp>A fresh peripheral venipuncture is preferred, because drawing through a catheter picks up hub organisms and raises the false-positive rate. Draw from a line only when peripheral access fails, or deliberately as a paired sample when the line itself is the suspected source of infection.\u003C\u002Fp>",{"question":100,"answer":101},"\u003Cp>What is differential time to positivity?\u003C\u002Fp>","\u003Cp>When a catheter set and a peripheral set are drawn at the same time, the catheter bottle turns positive earlier if the line is colonized, because it carries a heavier bacterial load. A catheter set flagging positive 2 hours or more before the peripheral set supports a catheter-related bloodstream infection.\u003C\u002Fp>",{"question":103,"answer":104},"\u003Cp>Which skin antiseptic should be used before drawing blood cultures?\u003C\u002Fp>","\u003Cp>Chlorhexidine-alcohol is preferred because it gives lower contamination rates and does not need to be wiped off. Tincture of iodine is an acceptable alternative. Povidone-iodine works but must be left to dry in contact for at least 2 minutes.\u003C\u002Fp>",{"question":106,"answer":107},"\u003Cp>Can blood culture bottles be refrigerated if there is a delay?\u003C\u002Fp>","\u003Cp>No. Keep them at room temperature and get them to the incubator, for a maximum of about 4 hours. Refrigeration harms the organisms you are trying to grow.\u003C\u002Fp>",{"question":109,"answer":110},"\u003Cp>How much blood is safe to take from an infant?\u003C\u002Fp>","\u003Cp>The volume is based on the child's weight, and no more than about 4 to 4.5% of total blood volume should be taken. Pediatric bottles are designed to keep the correct blood-to-broth ratio at these smaller volumes.\u003C\u002Fp>",[112,71],"specimen-collection-transport",{"slug":114,"title":115,"description":115,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":116,"lastUpdatedDate":117,"draft":45,"category":46,"image":42,"faq":118,"tags":119},"critical-panic-values-microbiology","Critical (Panic) Values in Microbiology","2021-05-05","2025-12-29",[],[],{"slug":121,"title":122,"description":123,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":124,"lastUpdatedDate":125,"draft":45,"category":46,"image":42,"faq":126,"tags":142},"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",[127,130,133,136,139],{"question":128,"answer":129},"\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":131,"answer":132},"\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":134,"answer":135},"\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":137,"answer":138},"\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":140,"answer":141},"\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>",[143],"gram-positive-cocci",{"slug":145,"title":146,"description":147,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":148,"lastUpdatedDate":149,"draft":45,"category":46,"image":42,"faq":150,"tags":169},"enterobacteriaceae","Enterobacteriaceae: How to Identify and Tell Them Apart","A working guide to the Enterobacteriaceae: which genera matter, how lactose fermentation and biochemical tests separate them, and how to reason from a MacConkey plate to a genus.","2013-10-01","2026-08-18",[151,154,157,160,163,166],{"question":152,"answer":153},"\u003Cp>What is the single fastest test to know a Gram-negative rod belongs to the Enterobacteriaceae?\u003C\u002Fp>","\u003Cp>The oxidase test. Members of this family are oxidase-negative. If a Gram-negative rod is oxidase-positive, it is not in this family, and you should think of organisms such as \u003Cem>Pseudomonas\u003C\u002Fem> or \u003Cem>Vibrio\u003C\u002Fem> instead.\u003C\u002Fp>",{"question":155,"answer":156},"\u003Cp>Why are Salmonella and Shigella pale on MacConkey agar?\u003C\u002Fp>","\u003Cp>Because they do not ferment lactose. MacConkey agar turns pink only when an organism ferments lactose and lowers the pH. \u003Cem>Salmonella\u003C\u002Fem> and \u003Cem>Shigella\u003C\u002Fem> are non-lactose fermenters, so their colonies stay colorless. This is why a pale colony in a diarrheal stool is the one worth investigating.\u003C\u002Fp>",{"question":158,"answer":159},"\u003Cp>Is Enterobacteriaceae the same as Enterobacterales?\u003C\u002Fp>","\u003Cp>Not exactly. In 2016 the old family was reorganized into a larger order called Enterobacterales, and some genera were moved into separate families. In everyday clinical and exam use, the term Enterobacteriaceae is still used broadly for this whole group of enteric Gram-negative rods.\u003C\u002Fp>",{"question":161,"answer":162},"\u003Cp>What does IMViC stand for and why is it useful?\u003C\u002Fp>","\u003Cp>IMViC stands for Indole, Methyl red, Voges-Proskauer, and Citrate. These four tests together separate the common genera. The classic contrast is \u003Cem>E. coli\u003C\u002Fem> (+ + − −) versus \u003Cem>Klebsiella\u003C\u002Fem> and \u003Cem>Enterobacter\u003C\u002Fem> (− − + +).\u003C\u002Fp>",{"question":164,"answer":165},"\u003Cp>Which Enterobacteriaceae are the main antibiotic-resistance concerns?\u003C\u002Fp>","\u003Cp>Three groups: organisms with inducible AmpC beta-lactamase (such as \u003Cem>Enterobacter\u003C\u002Fem>, \u003Cem>Serratia\u003C\u002Fem>, \u003Cem>Citrobacter freundii\u003C\u002Fem>, \u003Cem>Klebsiella aerogenes\u003C\u002Fem>), ESBL-producers (common in \u003Cem>E. coli\u003C\u002Fem> and \u003Cem>Klebsiella\u003C\u002Fem>), and carbapenem-resistant Enterobacteriaceae (CRE), where treatment options become very limited.\u003C\u002Fp>",{"question":167,"answer":168},"\u003Cp>What is the Vi antigen?\u003C\u002Fp>","\u003Cp>It is a special capsular antigen of \u003Cem>Salmonella\u003C\u002Fem> Typhi. \"Vi\" stands for virulence. It can cover the O antigen on fresh isolates, which is why an O-antigen agglutination test may read negative until the culture is heated.\u003C\u002Fp>",[145],{"slug":171,"title":172,"description":173,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":174,"lastUpdatedDate":175,"draft":45,"category":46,"image":42,"faq":176,"tags":204},"pseudomonas-aeruginosa-infection-mortality-pathogenesis-and-diagnosis"," Pseudomonas aeruginosa: Properties, Virulence Factors, Lab Diagnosis, and Antibiotic Resistance","\u003Cp>\u003Cem>Pseudomonas aeruginosa\u003C\u002Fem> is a WHO High priority pathogen causing HAP, VAP, burn wound infections, and cystic fibrosis lung disease. Learn its virulence factors (exotoxin A, T3SS, alginate), grape-like odor, pyocyanin, cetrimide agar selection, biochemical ID, and intrinsic antibiotic resistance mechanisms.\u003C\u002Fp>","2012-12-06","2026-08-16",[177,180,183,186,189,192,195,198,201],{"question":178,"answer":179},"Is P. aeruginosa still a WHO Priority 1 (Critical) pathogen?","\u003Cp>Not as of the 2024 update. In the 2017 list, carbapenem-resistant \u003Cem>P. aeruginosa\u003C\u002Fem> was in the Critical (Priority 1) tier. In the 2024 WHO Bacterial Priority Pathogens List it was moved to the High-priority tier. The downgrade reflects newer anti-pseudomonal drugs reaching the clinic since 2017, not any reduction in the organism's difficulty to treat. It remains one of the highest-burden hospital pathogens worldwide.\u003C\u002Fp>",{"question":181,"answer":182},"Can you catch Pseudomonas from water or the environment?","\u003Cp>\u003Cem>P. aeruginosa \u003C\u002Fem>is widespread in moist environments, including soil, water, sink drains, and hospital equipment, and hospital water sources are a well-recognized reservoir for infections. Healthy people with intact defenses are generally not at risk of serious infection. The concern is for hospitalized, immunocompromised, or barrier-breached patients, which is why infection prevention focuses on water sources, equipment, and hand hygiene in high-risk units.\u003C\u002Fp>",{"question":184,"answer":185},"\u003Cp>What does \u003Cem>Pseudomonas aeruginosa\u003C\u002Fem> smell like?\u003C\u002Fp>","\u003Cp>It has a distinctive sweet, grape-like (sometimes described as tortilla-like or corn-taco-like) odor, caused by a compound called 2-aminoacetophenone. Experienced lab staff often suspect \u003Cem>P. aeruginosa\u003C\u002Fem> from the smell of a plate alone, though smell is only a presumptive clue and is always confirmed with oxidase testing, pigment, and growth at 42°C.\u003C\u002Fp>",{"question":187,"answer":188},"\u003Cp>Why is \u003Cem>Pseudomonas aeruginosa\u003C\u002Fem> resistant to so many antibiotics?\u003C\u002Fp>","Resistance comes in three layers. First, intrinsic resistance is present in every strain: a low-permeability outer membrane that keeps drugs out, a chromosomal AmpC β-lactamase that destroys many β-lactams, and the MexAB-OprM efflux pump that actively pumps drugs back out. On top of that, strains can acquire further resistance during treatment (losing the OprD porin to block carbapenems, overexpressing efflux pumps, or picking up metallo-β-lactamases). Finally, in biofilms the organism becomes physically shielded and needs far higher drug concentrations. The combination is why it remains a WHO high-priority pathogen.",{"question":190,"answer":191},"\u003Cp>Why does \u003Cem>P. aeruginosa\u003C\u002Fem> turn wound dressings and pus blue-green?\u003C\u002Fp>","\u003Cp>The blue-green color comes mainly from pyocyanin, a phenazine pigment the organism secretes, often together with the yellow-green fluorescent pigment pyoverdine. Blue-green pus or discoloration of a burn dressing is a classic bedside clue to \u003Cem>P. aeruginosa \u003C\u002Fem>infection. Pyocyanin is not just a color: it is an active virulence factor that generates tissue-damaging reactive oxygen species and impairs the clearance mechanisms of the airway.\u003C\u002Fp>",{"question":193,"answer":194},"\u003Cp>Why can \u003Cem>P. aeruginosa \u003C\u002Fem>grow at 42°C when many other \u003Cem>Pseudomonas\u003C\u002Fem> species cannot?\u003C\u002Fp>","\u003Cp>Growth at 42°C is a species-level trait that helps separate \u003Cem>P. aeruginosa\u003C\u002Fem> from close relatives such as \u003Cem>P. fluorescens\u003C\u002Fem> and \u003Cem>P. putida\u003C\u002Fem>, which do not grow at that temperature. In the lab, the combination of pyocyanin production plus growth at 42°C is generally enough to distinguish \u003Cem>P. aeruginosa\u003C\u002Fem> from other pseudomonads.\u003C\u002Fp>",{"question":196,"answer":197},"\u003Cp>How is \u003Cem>P. aeruginosa\u003C\u002Fem> identified in the laboratory?\u003C\u002Fp>","It grows on routine media (blood agar, chocolate agar, MacConkey agar) as a non-lactose-fermenting, often β-hemolytic colony, and can be selected on cetrimide agar. Key identifying features are a rapid positive oxidase test (within 10 seconds), the grape-like odor, blue-green pyocyanin pigment, growth at 42°C, and a K\u002FK (alkaline\u002Falkaline) reaction on TSI indicating a non-fermenter. Definitive identification uses biochemical panels or automated systems.",{"question":199,"answer":200},"\u003Cp>Why is \u003Cem>P. aeruginosa\u003C\u002Fem> so dangerous for burn patients, cystic fibrosis patients, and neutropenic patients?\u003C\u002Fp>","It is an opportunist: it rarely causes disease in a healthy person but exploits any breach in host defense. Burns destroy the skin barrier, cystic fibrosis provides a thick mucus environment for chronic biofilm infection, and neutropenia removes the neutrophils that normally contain it. In each case a specific defense is missing, and the organism's broad virulence arsenal lets it invade almost any tissue.",{"question":202,"answer":203},"\u003Cp>Is \u003Cem>Stenotrophomonas maltophilia\u003C\u002Fem> the same as Pseudomonas?\u003C\u002Fp>","\u003Cp>No. \u003Cem>Stenotrophomonas maltophilia\u003C\u002Fem> was once called \u003Cem>Pseudomonas maltophilia,\u003C\u002Fem> but it has been reclassified into its own genus. It is a separate Gram-negative non-fermenter that is grouped alongside \u003Cem>Pseudomonas\u003C\u002Fem> in teaching because of its similar hospital setting and multidrug-resistant profile. Several other former pseudomonads were also reclassified, including Burkholderia cepacia, \u003Cem>Burkholderia pseudomallei \u003C\u002Fem>(melioidosis)\u003Cem>,\u003C\u002Fem> and \u003Cem>Burkholderia mallei\u003C\u002Fem> (glanders).\u003C\u002Fp>",[205],"gram-negative-rods",{"slug":207,"title":208,"description":209,"seoTitle":42,"seoDescription":42,"author":210,"createdDate":211,"lastUpdatedDate":212,"draft":45,"category":213,"image":42,"faq":214,"tags":215},"mechanism-of-action-of-antifungal-drugs","Mechanism of Action of Antifungal Drugs","Antifungal drug mechanisms — polyenes, azoles, echinocandins, allylamines, and antimetabolites explained with clinical drug-to-organism mapping, spectrum comparison table, and connection to azole resistance and treatment selection errors.","Srijana Khanal","2022-07-20","2026-07-05","mycology",[],[216],"antimicrobials-moa-amr",{"slug":218,"title":219,"description":220,"seoTitle":221,"seoDescription":222,"author":43,"createdDate":223,"lastUpdatedDate":125,"draft":45,"category":224,"image":42,"faq":225,"tags":250},"blood-agar-composition-preparation-uses-and-types-of-hemolysis","Blood Agar: Composition, Preparation, and How to Read Hemolysis","Blood agar composition and preparation, how to tell alpha, beta, gamma, and alpha-prime hemolysis apart, and the double-zone target pattern, with a colony-appearance table for 20+ organisms and common modifications (chocolate, CNA, CVBA).","Blood Agar: Preparation, Hemolysis Patterns, and Identification Clues","Learn blood agar composition and preparation, distinguish alpha, beta, and gamma hemolysis, and use colony patterns to support bacterial identification.","2013-08-22","culture-media",[226,229,232,235,238,241,244,247],{"question":227,"answer":228},"What is the difference between alpha and beta hemolysis?","\u003Cp>Alpha is partial lysis, green\u002Fbrown discoloration: \u003Cem>S. pneumoniae,\u003C\u002Fem> viridans streptococci. Beta is complete clear lysis: \u003Cem>S. pyogenes, S. agalactiae, S. aureus\u003C\u002Fem>. Gamma is no hemolysis: \u003Cem>Enterococcus, Klebsiella.\u003C\u002Fem>\u003C\u002Fp>",{"question":230,"answer":231},"Why is sheep blood used instead of human blood?","Consistent availability, no biohazard risk, reliable hemolysis patterns. Human blood may contain antibiotics or inhibitors and introduces infection risk.",{"question":233,"answer":234},"\u003Cp>Why does \u003Cem>S. pneumoniae\u003C\u002Fem> produce alpha not beta hemolysis?\u003C\u002Fp>","\u003Cp>The H₂O₂ produced by \u003Cem>S. pneumoniae\u003C\u002Fem> oxidizes hemoglobin to green products (verdohemoglobin), a partial degradation rather than true lysis. \u003Cem>S. pneumoniae\u003C\u002Fem> lacks the streptolysins O and S that produce the complete, clear lysis of beta hemolysis.\u003C\u002Fp>",{"question":236,"answer":237},"What does the size of the beta-hemolytic zone tell you?","\u003Cp>GAS (\u003Cem>S. pyogenes\u003C\u002Fem>): large zone 2-4× colony diameter. GBS (\u003Cem>S. agalactiae\u003C\u002Fem>): narrow zone barely beyond colony edge. Helps preliminary differentiation at 24 hours with CAMP test and bacitracin.\u003C\u002Fp>",{"question":239,"answer":240},"\u003Cp>What is the umbilicated colony appearance of \u003Cem>S. pneumoniae\u003C\u002Fem>?\u003C\u002Fp>","\u003Cp>Autolysin LytA causes central autolysis at 48-72 hours, raised ring with sunken center. Umbilicated appearance + alpha hemolysis = strong presumptive \u003Cem>S. pneumoniae.\u003C\u002Fem>\u003C\u002Fp>",{"question":242,"answer":243},"How does incubation atmosphere affect blood agar hemolysis?","\u003Cp>Streptolysin O is oxygen-labile, best seen in stab areas or anaerobically. Streptolysin S is oxygen-stable, visible aerobically on surface. Always stab blood agar.\u003C\u002Fp>",{"question":245,"answer":246},"\u003Cp>Why does \u003Cem>C. perfringens\u003C\u002Fem> produce double-zone hemolysis?\u003C\u002Fp>","\u003Cp>Theta-toxin: outer partial (alpha) zone. Alpha-toxin\u002Flecithinase: inner complete (beta) zone. Double-zone target pattern on anaerobic blood agar = strong presumptive \u003Cem>C. perfringens.\u003C\u002Fem>\u003C\u002Fp>",{"question":248,"answer":249},"Can blood agar be used for susceptibility testing?","\u003Cp>Yes. MH-F (Mueller-Hinton + 5% sheep blood) is CLSI-recommended for fastidious organisms: \u003Cem>S. pneumoniae, S. pyogenes, H. influenzae, N. gonorrhoeae.\u003C\u002Fem>\u003C\u002Fp>",[251],"bacterial-culture-media",{"enabled":253,"threads":254,"total":255},true,[],0,[257,263,270,277,283,288,294,299,304,307,314],{"slug":258,"name":43,"description":259,"image":260,"body":261,"postCount":262},"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.*",474,{"slug":264,"name":265,"description":266,"image":267,"body":268,"postCount":269},"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.",78,{"slug":271,"name":272,"description":273,"image":274,"body":275,"postCount":276},"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":278,"name":279,"description":273,"image":280,"body":281,"postCount":282},"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":284,"name":285,"description":273,"image":42,"body":286,"postCount":287},"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":289,"name":290,"description":291,"image":42,"body":292,"postCount":293},"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":295,"name":296,"description":297,"image":42,"body":42,"postCount":298},"guest-author","Guest Author","Guest Author \u002F Contributor",1,{"slug":300,"name":210,"description":273,"image":301,"body":302,"postCount":303},"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.",16,{"slug":305,"name":306,"description":297,"image":42,"body":42,"postCount":298},"dr-poonam-acharya","Dr. Poonam Acharya",{"slug":308,"name":309,"description":310,"image":311,"body":312,"postCount":313},"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.*",54,{"slug":315,"name":316,"description":317,"image":318,"body":319,"postCount":298},"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.",[321,328,334,338,342,347,351,355,358,363,368,373,376,381,385,389,393,397,402,407,411,415,419,424,428,432,436,440,445,450,454,458,462,465,469,473,477,481,485,489,493,497,501,505,509,513,517,521,526,530,534,538,542,546,550,554,558,562,566,570,574,578,582,586,590,594,598,602,605,609,612,615,617],{"slug":322,"name":323,"description":324,"image":325,"body":326,"postCount":327},"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":329,"name":330,"description":331,"image":42,"body":332,"postCount":333},"microscopy","Microscopy","Microscope types, components, and microscopy techniques","These are list of blog posts related to microscopy. ",12,{"slug":143,"name":335,"description":336,"image":42,"body":42,"postCount":337},"Gram-Positive Cocci","Staphylococcus, Streptococcus, Enterococcus, Micrococcus — organisms, diseases, and identification tests",11,{"slug":205,"name":339,"description":340,"image":42,"body":42,"postCount":341},"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":343,"name":344,"description":345,"image":42,"body":42,"postCount":346},"gram-positive-rods","Gram-Positive Rods","Bacillus, Clostridium, Listeria, Corynebacterium, Actinomyces and related organisms",8,{"slug":348,"name":349,"description":350,"image":42,"body":42,"postCount":337},"mycobacteria","Mycobacteria","Mycobacterium tuberculosis, leprosy, atypical mycobacteria, and acid-fast organism diagnosis",{"slug":352,"name":353,"description":354,"image":42,"body":42,"postCount":337},"anaerobic-bacteriology","Anaerobic Bacteriology","Anaerobic organisms, anaerobic culture methods, and anaerobic infection diagnosis",{"slug":145,"name":356,"description":357,"image":42,"body":42,"postCount":333},"Enterobacteriaceae","Identification, differentiation, and clinical significance of Enterobacteriaceae family members",{"slug":359,"name":360,"description":361,"image":42,"body":42,"postCount":362},"spirochetes","Spirochetes","Treponema, Leptospira, Borrelia and spirochetal infections",7,{"slug":364,"name":365,"description":366,"image":42,"body":42,"postCount":367},"food-microbiology","Food Microbiology","Food-borne pathogens, food safety, spoilage, and preservation",15,{"slug":369,"name":370,"description":371,"image":42,"body":42,"postCount":372},"antimicrobial-susceptibility-testing","Antimicrobial Susceptibility Testing","Methods for testing antibiotic susceptibility in clinical microbiology",21,{"slug":216,"name":374,"description":375,"image":42,"body":42,"postCount":346},"Antimicrobials (MOA & AMR)","Mechanisms, detection, and clinical significance of antimicrobial resistance",{"slug":377,"name":378,"description":379,"image":42,"body":42,"postCount":380},"sterilization-disinfection","Sterilization and Disinfection","Methods of sterilization and disinfection in healthcare and laboratory settings",10,{"slug":112,"name":382,"description":383,"image":42,"body":42,"postCount":384},"Specimen Collection and Transport","Collection, handling, and transport of clinical specimens for microbiological testing",27,{"slug":386,"name":387,"description":388,"image":42,"body":42,"postCount":372},"bacterial-structure-physiology","Bacterial Structure and Physiology","Bacterial cell structure, growth, physiology, and environmental factors affecting growth",{"slug":390,"name":391,"description":42,"image":42,"body":392,"postCount":287},"horizontal-gene-transfer","Horizontal Gene Transfer","Articles related to **Horizontal Gene Transfer**",{"slug":394,"name":395,"description":42,"image":42,"body":396,"postCount":380},"chromatography","Chromatography","Information about chromatographic techniques.",{"slug":398,"name":399,"description":400,"image":42,"body":401,"postCount":362},"electrophoresis","Electrophoresis","Information about Electrophoresis Techniques ","Detailed information  about Electrophoresis Techniques ",{"slug":403,"name":404,"description":405,"image":42,"body":406,"postCount":287},"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":408,"name":409,"description":410,"image":42,"body":42,"postCount":287},"bacteriophage","Bacteriophage","Description about Bacteriophage.",{"slug":412,"name":413,"description":414,"image":42,"body":42,"postCount":287},"malaria","Malaria","It is the collections of articles regarding malarial disease. ",{"slug":416,"name":417,"description":418,"image":42,"body":42,"postCount":287},"anaerobic-culture-techniques","Anaerobic Culture Techniques","Posts related with Anaerobic Culture Techniques.",{"slug":420,"name":421,"description":422,"image":42,"body":42,"postCount":423},"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":425,"name":426,"description":427,"image":42,"body":42,"postCount":362},"biosafety-levels","Biosafety levels ","Articles related to Biosafety Levels",{"slug":429,"name":430,"description":431,"image":42,"body":42,"postCount":341},"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":433,"name":434,"description":435,"image":42,"body":42,"postCount":287},"pipette","Pipette","Posts related with Pipette. ",{"slug":437,"name":438,"description":439,"image":42,"body":42,"postCount":346},"bacteriology-mcqs","Bacteriology MCQs","This sections lists MCQs in Bacteriology.",{"slug":441,"name":442,"description":443,"image":42,"body":42,"postCount":444},"parasitology-mcqs","Parasitology MCQs","This section lists MCQs in Parasitology.",2,{"slug":446,"name":447,"description":448,"image":42,"body":42,"postCount":449},"virology-mcqs","Virology MCQs","This is the collections of Multiple Choice Questions in Virology.",4,{"slug":451,"name":452,"description":453,"image":42,"body":42,"postCount":341},"mcqs-in-microbiology","MCQs in Microbiology","This section lists the collections of Multiple Choice Questions in General Microbiology Topics. ",{"slug":455,"name":456,"description":457,"image":42,"body":42,"postCount":346},"immunology-mcqs","Immunology MCQs","In this section; we are posting collections of Multiple Choice Questions about Immunology. ",{"slug":459,"name":460,"description":461,"image":42,"body":42,"postCount":293},"microbial-curiosities","Microbial Curiosities","In this clusters, we are posting interesting and unique information about Microorganisms. ",{"slug":251,"name":463,"description":464,"image":42,"body":42,"postCount":372},"Bacterial Culture Media","Posts related to Bacterial Culture Media. ",{"slug":466,"name":467,"description":468,"image":42,"body":42,"postCount":287},"fungal-culture-media","Fungal Culture Media","Posts related to Fungal Culture Media.",{"slug":470,"name":471,"description":472,"image":42,"body":42,"postCount":341},"motility-test","Motility Test","This lists the procedure regarding various tests methods for bacterial motility.",{"slug":474,"name":475,"description":476,"image":42,"body":42,"postCount":380},"bacterial-enumeration","Bacterial enumeration","These posts are related to isolation and enumeration of bacteria. ",{"slug":478,"name":479,"description":480,"image":42,"body":42,"postCount":444},"gram-positive-coccobacillus","Gram-positive coccobacillus","List of Gram Positive Coccobacilli",{"slug":482,"name":483,"description":484,"image":42,"body":42,"postCount":449},"dimorphic-fungi","Dimorphic Fungi","This is about various dimorphic fungi. ",{"slug":486,"name":487,"description":488,"image":42,"body":42,"postCount":362},"bacterial-classification","Bacterial Classification","These posts are related with various approaches used for the classification of Bacteria. ",{"slug":490,"name":491,"description":492,"image":42,"body":42,"postCount":341},"immunofluorescence","Immunofluorescence ","Various Tests related to Immunofluorescence ",{"slug":494,"name":495,"description":496,"image":42,"body":42,"postCount":293},"antibody-mediated-immunity","Antibody-mediated Immunity","This clusters links the articles that are sharing insights about Antibody-mediated immunity. ",{"slug":498,"name":499,"description":500,"image":42,"body":42,"postCount":362},"hypersensitivity","Hypersensitivity","Articles related to Hypersensitivity.",{"slug":502,"name":503,"description":42,"image":42,"body":42,"postCount":504},"haemophilus","Haemophilus",3,{"slug":506,"name":507,"description":508,"image":42,"body":42,"postCount":449},"sexually-transmitted-infections-stis","Sexually transmitted infections (STIs)","This is the clusters of infections that are transmitted sexually. ",{"slug":510,"name":511,"description":512,"image":42,"body":42,"postCount":333},"adaptive-immunity","Adaptive Immunity","Blog posts related to B Cell Immunity and T Cell Immunity.",{"slug":514,"name":515,"description":516,"image":42,"body":42,"postCount":327},"fungal-diagnostics","Fungal Diagnostics","Various methods used for the Diagnosis of Fungal Infections. ",{"slug":518,"name":519,"description":520,"image":42,"body":42,"postCount":341},"laboratory-storage-and-preservation","Laboratory Storage and Preservation","Articles about Laboratory Storage of Antimicrobial Disk, Test organisms and Equipment used for this process. ",{"slug":522,"name":523,"description":524,"image":42,"body":525,"postCount":287},"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":527,"name":528,"description":529,"image":42,"body":42,"postCount":346},"laboratory-glassware","Laboratory Glassware","Posts about Laboratory Glassware. ",{"slug":531,"name":532,"description":533,"image":42,"body":42,"postCount":287},"helminths","Helminths","In this section, we are covering properties, life cycle, pathogenesis and laboratory diagnosis of Helminths\u002FHelminthic infestations. ",{"slug":535,"name":536,"description":537,"image":42,"body":42,"postCount":287},"protozoan-parasite","Protozoan Parasite","In this cluster, we are covering protozoan parasites. ",{"slug":539,"name":540,"description":541,"image":42,"body":42,"postCount":298},"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":543,"name":544,"description":545,"image":42,"body":42,"postCount":380},"bacterial-staining-technique","Bacterial Staining Technique","Lists of various staining techniques that are used to stain bacteria. ",{"slug":547,"name":548,"description":549,"image":42,"body":42,"postCount":282},"enzyme-tests","Enzyme Tests","\u003Cp>Various Biochemical Test that are based on enzymatic activity of the microorganisms. \u003C\u002Fp>",{"slug":551,"name":552,"description":553,"image":42,"body":42,"postCount":337},"carbohydrate-utilization","Carbohydrate Utilization","\u003Cp>Various biochemical tests which are related to Carbohydrate fermentation or Utilization\u003C\u002Fp>",{"slug":555,"name":556,"description":557,"image":42,"body":42,"postCount":341},"susceptibility-based-id","Susceptibility-based ID","\u003Cp>These are susceptibility based identification test such as optochin sensitivity, bacitracin sensitivity etc. \u003C\u002Fp>",{"slug":559,"name":560,"description":561,"image":42,"body":42,"postCount":449},"microbial-metabolism","Microbial Metabolism","\u003Cp>Tests about Microbial Metabolism. \u003C\u002Fp>",{"slug":563,"name":564,"description":565,"image":42,"body":42,"postCount":346},"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":567,"name":568,"description":569,"image":42,"body":42,"postCount":504},"atypical-pneumonia","Atypical Pneumonia","\u003Cp>Organisms responsible for Atypical Pneumonia. \u003C\u002Fp>",{"slug":571,"name":572,"description":573,"image":42,"body":42,"postCount":341},"antigen","Antigen","\u003Cp>Various articles related to Antigens.\u003C\u002Fp>",{"slug":575,"name":576,"description":577,"image":42,"body":42,"postCount":362},"innate-immunity","Innate Immunity","\u003Cp>Articles related to Innate Immunity. \u003C\u002Fp>",{"slug":579,"name":580,"description":581,"image":42,"body":42,"postCount":449},"respiratory-tract-infection","Respiratory Tract Infection","\u003Cp>In this cluster, you can see various etiological agents that causes respiratory tract infection. \u003C\u002Fp>",{"slug":583,"name":584,"description":585,"image":42,"body":42,"postCount":341},"torch-infection","TORCH Infection","\u003Cp>In this section; you can find articles related with TOCH infection. \u003C\u002Fp>",{"slug":587,"name":588,"description":589,"image":42,"body":42,"postCount":362},"microbiology-for-beginners","Microbiology for Beginners","\u003Cp>These articles are very basic articles, which will share general concepts in Microbiology. \u003C\u002Fp>",{"slug":591,"name":592,"description":593,"image":42,"body":42,"postCount":287},"dna-replication","DNA Replication","\u003Cp>Articles related to DNA and Replication of DNA. \u003C\u002Fp>",{"slug":595,"name":596,"description":597,"image":42,"body":42,"postCount":362},"genetic-code","Genetic Code","\u003Cp>Articles related to Genetic Code.\u003C\u002Fp>",{"slug":599,"name":600,"description":601,"image":42,"body":42,"postCount":341},"molecular-technique","Molecular Technique","\u003Cp>Posts related to Molecular Techniques. \u003C\u002Fp>",{"slug":603,"name":604,"description":42,"image":42,"body":42,"postCount":298},"colorimetric-assay","Colorimetric Assay ",{"slug":606,"name":607,"description":608,"image":42,"body":42,"postCount":341},"pharmaceutical-microbiology","Pharmaceutical Microbiology","\u003Cp>Various articles related to Pharmaceutical Microbiology\u003C\u002Fp>",{"slug":610,"name":611,"description":42,"image":42,"body":42,"postCount":504},"blood-and-immune-cells","Blood and Immune Cells",{"slug":613,"name":614,"description":42,"image":42,"body":42,"postCount":341},"host-pathogen-interaction","Host Pathogen Interaction",{"slug":71,"name":616,"description":42,"image":42,"body":42,"postCount":449},"Blood Culture",{"slug":618,"name":619,"description":42,"image":42,"body":42,"postCount":449},"environmental-microbiology","Environmental microbiology "]