[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"$fxLN3MUwXCdr5RPjwZYIDpOj8CHyjOmngWTgoKXPtZbg":3,"$fUmGxV-y4HYBrTC-QTG2G5qBD9hOR10IS408zZlRGWW0":36,"$f3Ft0rKFJHppdzE-vuveecxx1BUcg9iOlMLtyzf_MJDg":151,"$fucxFBm2ZjZfGSdmdRaSNGBI_F0jJme4f0GTvzUhQfL8":216},[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":59,"related":60,"comments":147},"quellung-reaction-principle-procedure-results","Quellung Reaction: Principle, Procedure, Serotyping, and Clinical Applications","The Quellung reaction is the gold standard for pneumococcal capsule detection and serotyping. Learn the principle, step-by-step procedure, how to read results, and the pooled antiserum hierarchy used in reference laboratories.",null,"Acharya Tankeshwar","2015-12-29","2026-08-21",false,"bacteriology","A 68-year-old man is admitted with community-acquired pneumonia and bacteremia. Blood cultures grow gram-positive lancet-shaped diplococci, confirmed as *Streptococcus pneumoniae.* The reference laboratory wants to know the serotype: is this a vaccine-preventable serotype covered by PCV13? Was this a vaccine failure? Is there a community cluster of the same serotype?\n\nThe Quellung reaction answers all of these questions. By mixing the isolate with type-specific antisera and observing capsular swelling under the microscope, the exact serotype can be determined, **one of over 90 different capsular types**. The result determines whether the patient's infection should have been prevented by available vaccines and contributes to national surveillance data on pneumococcal serotype distribution.\n\nThe Quellung reaction, described by Friedrich Neufeld in 1902, remains the reference standard for pneumococcal serotyping more than a century after its discovery.\n\nThe Quellung (or Neufeld) reaction is the gold standard technique for serotyping [*Streptococcus pneumoniae* (pneumococcus)](\u002Fstreptococcus-pneumoniae-pneumococcus-disease-properties-pathogenesis-and-laboratory-diagnosis\u002F). This microscopic “precipitin test” can be used to identify pneumococci or to determine the capsular serotype of individual pneumococcal isolates.\n\nThere are over 90 different capsular serotypes of *S. pneumoniae*. This technique utilizes a high-quality microscope and specific pneumococcal antisera (commercially available as pooled, group, or serotype-specific) and is commonly used in reference and research laboratories worldwide.\n\n![Swollen-Pneumococci-Capsule](\u002Fblogs\u002FSwollen-Pneumococci-Capsule-300x118.jpg)Figure: Swollen pneumococci capsule\n\nThe Quellung reaction (swelling of the capsule) is reasonably simple to perform and can be applied wherever a suitable microscope and antisera are available.\n\nThis method involves testing a pneumococcal cell suspension with pooled and specific antisera directed against the **capsular polysaccharide**. The antigen-antibody reactions are observed microscopically.  A positive quellung reaction is the result of the binding of the capsular polysaccharide of pneumococci with type-specific antibodies contained in the typing antiserum.\n\nThe protocol has **three main steps:**\n\n1. preparation of a bacterial cell suspension,\n2. mixing of cells and antisera on a glass slide, and reading the Quellung reaction using a microscope.\n\n> It is recommended to initially test with pooled antisera in succession until a positive reaction is observed. Typing should then proceed by testing with the individual group and serotype-specific antisera included in the antisera pool that gave a positive reaction to determine the serogroup and serotype.\n\nSome strains of *H. influenzae* produce a polysaccharide capsule, which is demonstrable by capsule stains and a Quellung reaction with type-specific antisera.\n\n## Principle\n\nAnticapsular antibodies present in the serum react with the carbohydrate material of the pneumococcal capsule, causing a microprecipitin reaction on the surface of the *Streptococcus pneumoniae.* This antigen-antibody reaction causes a change in the refractive index of the capsule so that it appears “swollen” and more visible.\n\nAfter the addition of a counterstain (methylene blue), the pneumococcal cells stain dark blue and are surrounded by a sharply demarcated halo which represents the outer edge of the capsule. The light transmitted through the capsule appears brighter than either the pneumococcal cell or the background. Single cells, pairs, chains, and even clumps of cells may have positive quellung reactions.\n\n**Why the capsule appears to \"swell\"**: The dominant explanation is that the swelling is largely an optical effect, not true physical enlargement. When type-specific antibody binds to the capsular polysaccharide, it forms a microprecipitin layer on the capsule surface that changes the capsule's refractive index, thus making it refract light differently from the surrounding medium. The capsule becomes sharply demarcated and brightly visible as a halo around the dark blue cell body. The name *Quellung* (German: swelling) describes the visual appearance, not the underlying mechanism.\n\n## Procedure of the quellung reaction\n\n**A. Preparation of a bacterial cell suspension**\n\n1. Grow the isolate(s) to be tested for 18-24 hours on a [blood agar plate (BAP)](\u002Fblood-agar-composition-preparation-uses-and-types-of-hemolysis\u002F) at 35-37°C with \\~5% CO2 (or in a candle-jar).\n2. From overnight growth on the BAP, use a sterile loop to prepare a light to moderate cell suspension (approximately equal to a [**5.0 McFarland density standard**)](https:\u002F\u002Fmicrobeonline.com\u002Fpreparation-mcfarland-turbidity-standards\u002F) in 0.5 ml of 0.85% saline.\n\nOptimum quellung reactions can be observed when there are 25-50 cells visible in a microscopic field at 1000X magnification.\n\n**B. Mixing of cells and antisera on a glass slide**\n\n![Result of Quellung Reaction - Result of Quellung Reaction](\u002Fblogs\u002Fquellung-reaction-result-300x284.jpg)Figure: Result of Quellung Reaction\n\n1. Dispense equal amounts of antiserum (5 µl) and methylene blue (5 µl) onto a microscope slide.\n2. Add approximately 0.2-1.0 µl of the diluted cell suspension and mix all three with a pipette tip.\n3. Cover the suspension with a 22 mm square cover-slip and incubate at room temperature (25°C) for 10-15 minutes.\n4. Do not allow the fluid on the slide to dry.\n\n**C. Reading the Quellung reaction using a microscope**\n\n1. Examine the slide at 1000X using an oil immersion lens.\n2. Begin testing with pooled antisera. Once a positive reaction is obtained, proceed with individual group and serotype-specific antisera included in the pooled antisera that gave the positive reaction to determine the serogroup and serotype.\n\n## Results\n\n- A **positive** quellung reaction is observed when the **capsule appears as a sharply demarcated halo** around the dark blue stained cell\n- A **negative** quellung reaction is observed when there is **no appearance of a clear, enlarged halo** surrounding the stained cell.\n\n## The Pooled Antiserum Hierarchy: How Serotyping Works\n\n*S. pneumoniae* has over 90 capsular serotypes, which are organized into serogroups (based on structural similarity) and individual serotypes within each group. Reference laboratories use a hierarchical panel of antisera to determine the exact serotype efficiently rather than testing 90+ individual antisera on every isolate.\n\nThe standard approach uses antisera from Statens Serum Institut (SSI, Denmark), the global reference laboratory for pneumococcal typing:\n\n**Step 1. Omniserum (pool of all serotypes):** Test with omniserum first. This contains antibodies against all known pneumococcal capsular types. A positive reaction confirms the isolate is pneumococcal and is encapsulated. A negative omniserum reaction excludes pneumococcus (or indicates a very rare untypeable strain).\n\n**Step 2. Pool sera (A–O or similar groupings):** Several pool sera are available, each containing antibodies against a subset of serotypes. Test the isolate against each pool until a positive reaction is obtained. This narrows the serotype to one pool's subset.\n\n**Step 3. Group sera:** Within the positive pool, test with group-specific sera to identify the serogroup (e.g., group 19 contains serotypes 19A, 19B, 19C, 19F).\n\n**Step 4. Type-specific sera:** Finally, test with individual type-specific sera within the positive group to determine the exact serotype (e.g., 19F vs 19A, clinically important because 19A is a common multidrug-resistant serotype not covered by earlier PCV7 vaccines).\n\n**Practical note:** This hierarchical approach typically requires 10–15 individual antiserum tests per isolate rather than 90+, making routine typing feasible in a reference laboratory.\n\n## Clinical and Epidemiological Applications\n\n### Pneumococcal Serotyping for Vaccine Surveillance\n\nThe primary contemporary use of the Quellung reaction is determining whether pneumococcal disease strains are covered by available vaccines:\n\n- **PCV7** (7-valent, older): Serotypes 4, 6B, 9V, 14, 18C, 19F, 23F\n- **PCV13** (13-valent, widely used): PCV7 serotypes + 1, 3, 5, 6A, 7F, 19A\n- **PCV15\u002FPCV20** (newer): Extended coverage including additional serotypes\n\nWhen a vaccinated child develops invasive pneumococcal disease, Quellung serotyping determines whether this is:\n\n- A **vaccine failure** (infection with a covered serotype despite vaccination)\n- **Serotype replacement** (infection with a non-covered serotype, increasingly common post-vaccination)\n- **Vaccine escape** (rare: serotype switching)\n\nThis surveillance data drives national immunization policy decisions.\n\n### Outbreak Investigation\n\nWhen clusters of pneumococcal disease occur: in care homes, hospitals, schools, serotyping by Quellung confirms whether isolates from different patients are the same serotype, supporting or refuting a common source outbreak.\n\n### Direct CSF Testing (Bedside Application)\n\nThe Quellung reaction can be performed directly on CSF in suspected pneumococcal meningitis:\n\n- Mix a drop of CSF with pneumococcal omniserum and methylene blue\n- Examine under oil immersion\n- A positive reaction provides presumptive pneumococcal identification within minutes\n\n**Sensitivity limitation:** Direct CSF testing is less sensitive than culture-based Quellung because CSF may contain few organisms. A negative direct Quellung does not exclude pneumococcal meningitis.\n\n### *Haemophilus influenzae* Typing\n\nType b *H. influenzae* (Hib) is the cause of meningitis and epiglottitis in unvaccinated children. It also has a polysaccharide capsule demonstrable by Quellung with type-specific Hib antisera. Quellung remains a reference method for Hib confirmation, although agglutination tests have largely replaced it in routine use.\n\n## Limitations of the Quellung Reaction\n\n| Limitation | Detail |\n| --- | --- |\n| Requires specific antisera | Commercial antisera (SSI) are expensive and require careful storage and validation; availability is limited outside reference laboratories |\n| Requires expertise | Reading the reaction correctly requires experience: false positives (granular background) and false negatives (weak reactions) require an experienced microscopist |\n| Limited sensitivity on direct specimens | On CSF or other direct specimens, low organism numbers may give weak or negative reactions even with genuine pneumococcal infection |\n| Cannot detect all serotypes | Rare serotypes or novel variants may not react with available antisera; truly untypeable strains exist |\n| Time-consuming for large numbers | The hierarchical testing approach requires multiple antiserum tests per isolate; high-throughput laboratories prefer molecular methods |\n| Capsule loss during storage | Isolates should be tested fresh or stored carefully; repeated subculturing can lead to capsule loss and false-negative Quellung |\n\n## Modern Alternatives to the Quellung Reaction\n\nThe Quellung reaction remains the reference standard but is increasingly supplemented or replaced by molecular methods in high-throughput settings:\n\n| Method | Principle | Advantages | Limitations |\n| --- | --- | --- | --- |\n| **Quellung reaction** | Antigen-antibody capsular swelling | Gold standard; works on live culture; identifies serotype directly | Requires antisera, expertise, microscope; slow for large numbers |\n| **Latex agglutination** | Antibody-coated latex beads agglutinate with capsular antigen | Faster than Quellung; usable on CSF directly | Less discriminating for serotype (group level only for some) |\n| **Sequential multiplex PCR (seqPCR)** | PCR amplification of capsular biosynthesis genes | High throughput; no antisera required; works on culture and direct specimens | Cannot distinguish intact capsule expression from gene presence |\n| **Whole genome sequencing (WGS)** | In silico serotyping from genomic data | Simultaneous serotyping + resistance profiling + outbreak investigation | Expensive; requires bioinformatics; not yet routine outside reference labs |\n| **Microarray** | Hybridization to serotype-specific probes | High throughput | Research use only |\n\n**Current practice in most reference laboratories:** Quellung for confirmation and reference serotyping; seqPCR for high-throughput surveillance; WGS increasingly replacing both for comprehensive strain characterization.\n\n## How to Remember: Quellung Reaction\n\n**\"Quellung = Swelling, but it is not really swelling\":** The German word *Quellung* means swelling, and the capsule appears to swell visually. But the mechanism is a change in refractive index caused by antibody binding, not true enlargement. This distinction is frequently tested.\n\n**The three-component reaction:** Quellung = **Organism** + **Type-specific antiserum** + **Methylene blue** All three must be present. Without the specific antiserum, no reaction. Without methylene blue, the cell is invisible. Without the correct serotype antiserum, the capsule doesn't change appearance.\n\n**The hierarchy mnemonic: \"Omni → Pool → Group → Type\":** Start broad (omniserum confirms pneumococcus), narrow progressively (pool → group → type) until you reach the exact serotype. Like narrowing a diagnosis from \"infection\" to \"gram-positive bacteremia\" to \"pneumococcal bacteremia\" to \"pneumococcal serotype 19A.\"\n\n**Vaccine coverage hook:** 19A is the serotype you need to know which is not covered by PCV7, added in PCV13, a common cause of treatment failure in the era of penicillin-resistant pneumococcal disease.\n\n## Key Exam Facts\n\n| Feature | Detail |\n| --- | --- |\n| Full name | Quellung reaction (Neufeld reaction \u002F capsular swelling reaction) |\n| Named after | Friedrich Neufeld (1902) |\n| Principle | Type-specific anticapsular antibody + methylene blue → capsule changes refractive index → appears as bright refractile halo |\n| Positive result | Sharply demarcated bright halo around dark blue cell body |\n| Negative result | No halo, or identical to non-specific antiserum control |\n| Primary organism | *Streptococcus pneumoniae* (>90 serotypes) |\n| Other organisms | *Haemophilus influenzae* type b; other encapsulated bacteria |\n| Antiserum hierarchy | Omniserum → Pool sera → Group sera → Type-specific sera |\n| Clinical applications | Pneumococcal serotyping; vaccine surveillance; outbreak investigation; direct CSF testing |\n| McFarland density | \\~5 McFarland for optimal cell concentration (25-50 cells per field at 1000x) |\n| Reading magnification | 1000x oil immersion |\n| Gold standard status | Yes, reference method for pneumococcal serotyping |\n| Modern alternative | Sequential multiplex PCR (seqPCR); whole genome sequencing (WGS) |\n| Key limitation | Requires specific antisera; expertise; not applicable in most routine labs |\n\n**References**\n\n1. Henrichsen J. Six newly recognized types of Streptococcus pneumoniae. J Clin Microbiol. 1995;33(10):2759–2762.\n2. World Health Organization. Laboratory Methods for the Diagnosis of Meningitis caused by Neisseria meningitidis, Streptococcus pneumoniae, and Haemophilus influenzae. 2nd ed. Geneva: WHO; 2011.\n3. Statens Serum Institut. Pneumococcal Typing. \u003Chttps:\u002F\u002Fwww.ssi.dk\u002Fen\u002Fvaccines\u002Fpneumococcal-vaccine>\n4. Brueggemann AB, Peto TE, Crook DW, et al. Temporal and geographic stability of the serogroup-specific invasive disease potential of Streptococcus pneumoniae in children. J Infect Dis. 2004;190(7):1203–1211.\n5. Murray PR, Rosenthal KS, Pfaller MA. Medical Microbiology. 9th ed. Elsevier; 2020.",[50,53,56],{"question":51,"answer":52},"What is the Quellung reaction and what does it detect?","\u003Cp>The Quellung reaction (also called the Neufeld reaction or capsular swelling reaction) is performed by mixing a capsulated bacterium with its type-specific anti-capsular antiserum and methylene blue. When the antibody binds to the capsule, the capsule appears swollen and highly refractile under the microscope, though this is an optical effect from a change in refractive index rather than true physical swelling. It is the gold standard for serotyping Streptococcus pneumoniae (which has over 90 capsular serotypes) and is also used for \u003Cem>Haemophilus influenzae \u003C\u002Fem>type b confirmation.\u003C\u002Fp>",{"question":54,"answer":55},"How does the pooled antiserum hierarchy work in pneumococcal serotyping?","Pneumococcal serotyping by Quellung reaction uses a hierarchical approach with antisera from Statens Serum Institut. First, omniserum (containing antibodies against all known serotypes) confirms the organism is a capsulated pneumococcus. If positive, pool sera narrow the serotype to a subset. Group sera identify the serogroup (e.g., group 19). Finally, type-specific sera determine the exact serotype (e.g., 19A vs 19F). This hierarchical approach typically requires only 10-15 antiserum tests per isolate rather than testing all 90+ serotypes individually. Serotype 19A is clinically important as a common multidrug-resistant serotype not covered by the earlier PCV7 vaccine.",{"question":57,"answer":58},"What is the clinical use of the Quellung reaction in meningitis?","\u003Cp>The Quellung reaction can be performed directly on CSF in suspected pneumococcal meningitis by mixing a drop of CSF with pneumococcal omniserum and methylene blue. A positive reaction provides presumptive pneumococcal identification within minutes, before culture or PCR results are available, allowing antibiotic selection to be confirmed. Sensitivity on direct CSF is limited by organism density, so a negative direct Quellung reaction does not exclude pneumococcal meningitis. The reaction also has application in \u003Cem>Haemophilus influenzae\u003C\u002Fem> type b confirmation and outbreak investigation to identify whether cases share the same serotype.\u003C\u002Fp>",[],[61,85,121],{"slug":62,"title":63,"description":64,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":65,"lastUpdatedDate":66,"draft":46,"category":47,"image":42,"faq":67,"tags":83},"streptococcus-pneumoniae-pneumococcus-disease-properties-pathogenesis-and-laboratory-diagnosis","Streptococcus pneumoniae: Properties, Pathogenesis, and Diagnosis","\u003Cp>\u003Cem>Streptococcus pneumoniae\u003C\u002Fem> morphology, virulence factors like pneumolysin and capsule, and the optochin and bile solubility tests used for lab diagnosis.\u003C\u002Fp>","2013-05-13","2026-08-25",[68,71,74,77,80],{"question":69,"answer":70},"\u003Cp>Why is \u003Cem>Streptococcus pneumoniae\u003C\u002Fem> alpha-hemolytic like viridans streptococci, yet far more dangerous?\u003C\u002Fp>","\u003Cp>Hemolysis pattern alone doesn't reflect virulence. \u003Cem>S. pneumoniae\u003C\u002Fem>'s danger comes from its polysaccharide capsule (the major anti-phagocytic virulence factor) and pneumolysin, a pore-forming toxin that damages nearly any host cell containing cholesterol. Viridans streptococci lack a capsule and are far less invasive as a result.\u003C\u002Fp>",{"question":72,"answer":73},"What is the difference between bile solubility and bile esculin tests?","\u003Cp>Bile solubility uses bile salts to lyse \u003Cem>S. pneumoniae\u003C\u002Fem> colonies by triggering the organism's own autolysin, confirming pneumococcus. Bile esculin tests whether an organism can hydrolyze esculin in the presence of bile, used to identify \u003Cem>Enterococcus \u003C\u002Fem>and Group D streptococci. Same word \"bile,\" completely different organisms and mechanisms.\u003C\u002Fp>",{"question":75,"answer":76},"Why does the pneumococcal vaccine need to cover so many different serotypes?","\u003Cp>\u003Cem>S. pneumoniae \u003C\u002Fem>has more than 90 distinct capsular serotypes, and immunity to the capsule is type-specific. Antibodies raised against one serotype's capsule don't protect against a different serotype, so vaccines must include multiple capsular polysaccharides to provide broad coverage.\u003C\u002Fp>",{"question":78,"answer":79},"\u003Cp>Can\u003Cem> Streptococcus pneumoniae\u003C\u002Fem> be part of normal flora without causing disease?\u003C\u002Fp>","\u003Cp>Yes. \u003Cem>S. pneumoniae\u003C\u002Fem> commonly colonizes the upper respiratory tract harmlessly. Disease occurs when the organism spreads beyond its normal niche, such as into the lungs, bloodstream, or meninges.\u003C\u002Fp>",{"question":81,"answer":82},"Why does CSF show low glucose in pneumococcal meningitis?","Bacteria in the CSF consume glucose for their own metabolism, while the accompanying inflammatory response draws in white blood cells, producing the classic combination of high WBC and low glucose seen in bacterial meningitis.",[84],"gram-positive-cocci",{"slug":86,"title":87,"description":88,"seoTitle":89,"seoDescription":90,"author":43,"createdDate":91,"lastUpdatedDate":92,"draft":46,"category":93,"image":42,"faq":94,"tags":119},"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","2026-08-14","culture-media",[95,98,101,104,107,110,113,116],{"question":96,"answer":97},"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":99,"answer":100},"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":102,"answer":103},"\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":105,"answer":106},"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":108,"answer":109},"\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":111,"answer":112},"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":114,"answer":115},"\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":117,"answer":118},"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>",[120],"bacterial-culture-media",{"slug":122,"title":123,"description":124,"seoTitle":125,"seoDescription":126,"author":43,"createdDate":127,"lastUpdatedDate":128,"draft":46,"category":47,"image":42,"faq":129,"tags":145},"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",[130,133,136,139,142],{"question":131,"answer":132},"\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":134,"answer":135},"\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":137,"answer":138},"\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":140,"answer":141},"\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":143,"answer":144},"\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>",[146],"antimicrobial-susceptibility-testing",{"enabled":148,"threads":149,"total":150},true,[],0,[152,158,165,172,178,183,189,194,200,203,210],{"slug":153,"name":43,"description":154,"image":155,"body":156,"postCount":157},"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.*",487,{"slug":159,"name":160,"description":161,"image":162,"body":163,"postCount":164},"ashma-shrestha","Ashma Shrestha","SEO Copywriter and Science Communicator\nKathmandu, Nepal","https:\u002F\u002Fassets.microbeonline.com\u002Fauthors\u002Fashma-shrestha.png","Ashma Shrestha holds a Master of Science in Medical Microbiology from the Institute of Science and Technology (IOST), Tribhuvan University, Nepal, where she developed a strong foundation in virology, molecular biology, and diagnostic microbiology.\n\nShe now works as an SEO Copywriter at Resolution Digital, where she combines her scientific training with research-driven content strategy. She is certified in Google Analytics and Google Business Profile (GBP), and brings a data-informed approach to science communication writing content that is not only accurate but structured to reach and serve the students who need it most.\n\nAt microbeonline, Ashma contributes articles primarily in virology and molecular biology, areas she finds most compelling for their mechanistic depth and their growing clinical relevance. Her writing reflects the same standard the site is built on: factual rigor, clear explanation of the *why* behind microbiology concepts, and content that helps students move from memorization to genuine understanding.\n\nShe is passionate about making complex microbiological concepts accessible without sacrificing accuracy; a skill that sits at the intersection of her scientific training and her professional work in content and SEO.",79,{"slug":166,"name":167,"description":168,"image":169,"body":170,"postCount":171},"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":173,"name":174,"description":168,"image":175,"body":176,"postCount":177},"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":179,"name":180,"description":168,"image":42,"body":181,"postCount":182},"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":184,"name":185,"description":186,"image":42,"body":187,"postCount":188},"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":190,"name":191,"description":192,"image":42,"body":42,"postCount":193},"guest-author","Guest Author","Guest Author \u002F Contributor",1,{"slug":195,"name":196,"description":168,"image":197,"body":198,"postCount":199},"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":201,"name":202,"description":192,"image":42,"body":42,"postCount":193},"dr-poonam-acharya","Dr. Poonam Acharya",{"slug":204,"name":205,"description":206,"image":207,"body":208,"postCount":209},"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":211,"name":212,"description":213,"image":214,"body":215,"postCount":193},"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.",[217,224,230,234,239,244,248,252,256,261,265,269,273,278,283,287,291,295,300,305,309,313,317,322,326,330,334,338,343,348,352,356,360,364,368,372,376,380,384,388,392,396,400,404,408,412,416,420,425,429,433,437,441,445,449,453,457,461,465,469,473,477,481,485,489,493,497,501,504,508,511,514,517,520,523,526,529,532,535,538,541,544,547],{"slug":218,"name":219,"description":220,"image":221,"body":222,"postCount":223},"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":225,"name":226,"description":227,"image":42,"body":228,"postCount":229},"microscopy","Microscopy","Microscope types, components, and microscopy techniques","These are list of blog posts related to microscopy. ",12,{"slug":84,"name":231,"description":232,"image":42,"body":42,"postCount":233},"Gram-Positive Cocci","Staphylococcus, Streptococcus, Enterococcus, Micrococcus — organisms, diseases, and identification tests",11,{"slug":235,"name":236,"description":237,"image":42,"body":42,"postCount":238},"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":240,"name":241,"description":242,"image":42,"body":42,"postCount":243},"gram-positive-rods","Gram-Positive Rods","Bacillus, Clostridium, Listeria, Corynebacterium, Actinomyces and related organisms",8,{"slug":245,"name":246,"description":247,"image":42,"body":42,"postCount":233},"mycobacteria","Mycobacteria","Mycobacterium tuberculosis, leprosy, atypical mycobacteria, and acid-fast organism diagnosis",{"slug":249,"name":250,"description":251,"image":42,"body":42,"postCount":229},"anaerobic-bacteriology","Anaerobic Bacteriology","Anaerobic organisms, anaerobic culture methods, and anaerobic infection diagnosis",{"slug":253,"name":254,"description":255,"image":42,"body":42,"postCount":229},"enterobacteriaceae","Enterobacteriaceae","Identification, differentiation, and clinical significance of Enterobacteriaceae family members",{"slug":257,"name":258,"description":259,"image":42,"body":42,"postCount":260},"spirochetes","Spirochetes","Treponema, Leptospira, Borrelia and spirochetal infections",7,{"slug":262,"name":263,"description":264,"image":42,"body":42,"postCount":223},"food-microbiology","Food Microbiology","Food-borne pathogens, food safety, spoilage, and preservation",{"slug":146,"name":266,"description":267,"image":42,"body":42,"postCount":268},"Antimicrobial Susceptibility Testing","Methods for testing antibiotic susceptibility in clinical microbiology",21,{"slug":270,"name":271,"description":272,"image":42,"body":42,"postCount":223},"antimicrobials-moa-amr","Antimicrobials (MOA & AMR)","Mechanisms, detection, and clinical significance of antimicrobial resistance",{"slug":274,"name":275,"description":276,"image":42,"body":42,"postCount":277},"sterilization-disinfection","Sterilization and Disinfection","Methods of sterilization and disinfection in healthcare and laboratory settings",10,{"slug":279,"name":280,"description":281,"image":42,"body":42,"postCount":282},"specimen-collection-transport","Specimen Collection and Transport","Collection, handling, and transport of clinical specimens for microbiological testing",27,{"slug":284,"name":285,"description":286,"image":42,"body":42,"postCount":268},"bacterial-structure-physiology","Bacterial Structure and Physiology","Bacterial cell structure, growth, physiology, and environmental factors affecting growth",{"slug":288,"name":289,"description":42,"image":42,"body":290,"postCount":182},"horizontal-gene-transfer","Horizontal Gene Transfer","Articles related to **Horizontal Gene Transfer**",{"slug":292,"name":293,"description":42,"image":42,"body":294,"postCount":277},"chromatography","Chromatography","Information about chromatographic techniques.",{"slug":296,"name":297,"description":298,"image":42,"body":299,"postCount":260},"electrophoresis","Electrophoresis","Information about Electrophoresis Techniques ","Detailed information  about Electrophoresis Techniques ",{"slug":301,"name":302,"description":303,"image":42,"body":304,"postCount":182},"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":306,"name":307,"description":308,"image":42,"body":42,"postCount":182},"bacteriophage","Bacteriophage","Description about Bacteriophage.",{"slug":310,"name":311,"description":312,"image":42,"body":42,"postCount":182},"malaria","Malaria","It is the collections of articles regarding malarial disease. ",{"slug":314,"name":315,"description":316,"image":42,"body":42,"postCount":182},"anaerobic-culture-techniques","Anaerobic Culture Techniques","Posts related with Anaerobic Culture Techniques.",{"slug":318,"name":319,"description":320,"image":42,"body":42,"postCount":321},"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":323,"name":324,"description":325,"image":42,"body":42,"postCount":260},"biosafety-levels","Biosafety levels ","Articles related to Biosafety Levels",{"slug":327,"name":328,"description":329,"image":42,"body":42,"postCount":238},"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":331,"name":332,"description":333,"image":42,"body":42,"postCount":182},"pipette","Pipette","Posts related with Pipette. ",{"slug":335,"name":336,"description":337,"image":42,"body":42,"postCount":260},"bacteriology-mcqs","Bacteriology MCQs","This sections lists MCQs in Bacteriology.",{"slug":339,"name":340,"description":341,"image":42,"body":42,"postCount":342},"parasitology-mcqs","Parasitology MCQs","This section lists MCQs in Parasitology.",2,{"slug":344,"name":345,"description":346,"image":42,"body":42,"postCount":347},"virology-mcqs","Virology MCQs","This is the collections of Multiple Choice Questions in Virology.",4,{"slug":349,"name":350,"description":351,"image":42,"body":42,"postCount":238},"mcqs-in-microbiology","MCQs in Microbiology","This section lists the collections of Multiple Choice Questions in General Microbiology Topics. ",{"slug":353,"name":354,"description":355,"image":42,"body":42,"postCount":260},"immunology-mcqs","Immunology MCQs","In this section; we are posting collections of Multiple Choice Questions about Immunology. ",{"slug":357,"name":358,"description":359,"image":42,"body":42,"postCount":277},"microbial-curiosities","Microbial Curiosities","In this clusters, we are posting interesting and unique information about Microorganisms. ",{"slug":120,"name":361,"description":362,"image":42,"body":42,"postCount":363},"Bacterial Culture Media","Posts related to Bacterial Culture Media. ",23,{"slug":365,"name":366,"description":367,"image":42,"body":42,"postCount":182},"fungal-culture-media","Fungal Culture Media","Posts related to Fungal Culture Media.",{"slug":369,"name":370,"description":371,"image":42,"body":42,"postCount":238},"motility-test","Motility Test","This lists the procedure regarding various tests methods for bacterial motility.",{"slug":373,"name":374,"description":375,"image":42,"body":42,"postCount":277},"bacterial-enumeration","Bacterial enumeration","These posts are related to isolation and enumeration of bacteria. ",{"slug":377,"name":378,"description":379,"image":42,"body":42,"postCount":342},"gram-positive-coccobacillus","Gram-positive coccobacillus","List of Gram Positive Coccobacilli",{"slug":381,"name":382,"description":383,"image":42,"body":42,"postCount":347},"dimorphic-fungi","Dimorphic Fungi","This is about various dimorphic fungi. ",{"slug":385,"name":386,"description":387,"image":42,"body":42,"postCount":260},"bacterial-classification","Bacterial Classification","These posts are related with various approaches used for the classification of Bacteria. ",{"slug":389,"name":390,"description":391,"image":42,"body":42,"postCount":238},"immunofluorescence","Immunofluorescence ","Various Tests related to Immunofluorescence ",{"slug":393,"name":394,"description":395,"image":42,"body":42,"postCount":188},"antibody-mediated-immunity","Antibody-mediated Immunity","This clusters links the articles that are sharing insights about Antibody-mediated immunity. ",{"slug":397,"name":398,"description":399,"image":42,"body":42,"postCount":260},"hypersensitivity","Hypersensitivity","Articles related to Hypersensitivity.",{"slug":401,"name":402,"description":42,"image":42,"body":42,"postCount":403},"haemophilus","Haemophilus",3,{"slug":405,"name":406,"description":407,"image":42,"body":42,"postCount":347},"sexually-transmitted-infections-stis","Sexually transmitted infections (STIs)","This is the clusters of infections that are transmitted sexually. ",{"slug":409,"name":410,"description":411,"image":42,"body":42,"postCount":229},"adaptive-immunity","Adaptive Immunity","Blog posts related to B Cell Immunity and T Cell Immunity.",{"slug":413,"name":414,"description":415,"image":42,"body":42,"postCount":223},"fungal-diagnostics","Fungal Diagnostics","Various methods used for the Diagnosis of Fungal Infections. ",{"slug":417,"name":418,"description":419,"image":42,"body":42,"postCount":238},"laboratory-storage-and-preservation","Laboratory Storage and Preservation","Articles about Laboratory Storage of Antimicrobial Disk, Test organisms and Equipment used for this process. ",{"slug":421,"name":422,"description":423,"image":42,"body":424,"postCount":182},"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":426,"name":427,"description":428,"image":42,"body":42,"postCount":188},"laboratory-glassware","Laboratory Glassware","Posts about Laboratory Glassware. ",{"slug":430,"name":431,"description":432,"image":42,"body":42,"postCount":182},"helminths","Helminths","In this section, we are covering properties, life cycle, pathogenesis and laboratory diagnosis of Helminths\u002FHelminthic infestations. ",{"slug":434,"name":435,"description":436,"image":42,"body":42,"postCount":243},"protozoan-parasite","Protozoan Parasite","In this cluster, we are covering protozoan parasites. ",{"slug":438,"name":439,"description":440,"image":42,"body":42,"postCount":193},"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":442,"name":443,"description":444,"image":42,"body":42,"postCount":277},"bacterial-staining-technique","Bacterial Staining Technique","Lists of various staining techniques that are used to stain bacteria. ",{"slug":446,"name":447,"description":448,"image":42,"body":42,"postCount":268},"enzyme-tests","Enzyme Tests","\u003Cp>Various Biochemical Test that are based on enzymatic activity of the microorganisms. \u003C\u002Fp>",{"slug":450,"name":451,"description":452,"image":42,"body":42,"postCount":233},"carbohydrate-utilization","Carbohydrate Utilization","\u003Cp>Various biochemical tests which are related to Carbohydrate fermentation or Utilization\u003C\u002Fp>",{"slug":454,"name":455,"description":456,"image":42,"body":42,"postCount":238},"susceptibility-based-id","Susceptibility-based ID","\u003Cp>These are susceptibility based identification test such as optochin sensitivity, bacitracin sensitivity etc. \u003C\u002Fp>",{"slug":458,"name":459,"description":460,"image":42,"body":42,"postCount":347},"microbial-metabolism","Microbial Metabolism","\u003Cp>Tests about Microbial Metabolism. \u003C\u002Fp>",{"slug":462,"name":463,"description":464,"image":42,"body":42,"postCount":243},"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":466,"name":467,"description":468,"image":42,"body":42,"postCount":403},"atypical-pneumonia","Atypical Pneumonia","\u003Cp>Organisms responsible for Atypical Pneumonia. \u003C\u002Fp>",{"slug":470,"name":471,"description":472,"image":42,"body":42,"postCount":238},"antigen","Antigen","\u003Cp>Various articles related to Antigens.\u003C\u002Fp>",{"slug":474,"name":475,"description":476,"image":42,"body":42,"postCount":260},"innate-immunity","Innate Immunity","\u003Cp>Articles related to Innate Immunity. \u003C\u002Fp>",{"slug":478,"name":479,"description":480,"image":42,"body":42,"postCount":347},"respiratory-tract-infection","Respiratory Tract Infection","\u003Cp>In this cluster, you can see various etiological agents that causes respiratory tract infection. \u003C\u002Fp>",{"slug":482,"name":483,"description":484,"image":42,"body":42,"postCount":238},"torch-infection","TORCH Infection","\u003Cp>In this section; you can find articles related with TOCH infection. \u003C\u002Fp>",{"slug":486,"name":487,"description":488,"image":42,"body":42,"postCount":243},"microbiology-for-beginners","Microbiology for Beginners","\u003Cp>These articles are very basic articles, which will share general concepts in Microbiology. \u003C\u002Fp>",{"slug":490,"name":491,"description":492,"image":42,"body":42,"postCount":182},"dna-replication","DNA Replication","\u003Cp>Articles related to DNA and Replication of DNA. \u003C\u002Fp>",{"slug":494,"name":495,"description":496,"image":42,"body":42,"postCount":260},"genetic-code","Genetic Code","\u003Cp>Articles related to Genetic Code.\u003C\u002Fp>",{"slug":498,"name":499,"description":500,"image":42,"body":42,"postCount":260},"molecular-technique","Molecular Technique","\u003Cp>Posts related to Molecular Techniques. \u003C\u002Fp>",{"slug":502,"name":503,"description":42,"image":42,"body":42,"postCount":193},"colorimetric-assay","Colorimetric Assay ",{"slug":505,"name":506,"description":507,"image":42,"body":42,"postCount":238},"pharmaceutical-microbiology","Pharmaceutical Microbiology","\u003Cp>Various articles related to Pharmaceutical Microbiology\u003C\u002Fp>",{"slug":509,"name":510,"description":42,"image":42,"body":42,"postCount":403},"blood-and-immune-cells","Blood and Immune Cells",{"slug":512,"name":513,"description":42,"image":42,"body":42,"postCount":238},"host-pathogen-interaction","Host Pathogen Interaction",{"slug":515,"name":516,"description":42,"image":42,"body":42,"postCount":347},"blood-culture","Blood Culture",{"slug":518,"name":519,"description":42,"image":42,"body":42,"postCount":347},"environmental-microbiology","Environmental microbiology ",{"slug":521,"name":522,"description":42,"image":42,"body":42,"postCount":260},"copromicroscopic-technique","Copromicroscopic Technique",{"slug":524,"name":525,"description":42,"image":42,"body":42,"postCount":403},"quality-control","Quality Control",{"slug":527,"name":528,"description":42,"image":42,"body":42,"postCount":260},"dermatophytes","Dermatophytes",{"slug":530,"name":531,"description":42,"image":42,"body":42,"postCount":403},"viral-hemorrhagic-fevers","Viral Hemorrhagic Fevers",{"slug":533,"name":534,"description":42,"image":42,"body":42,"postCount":347},"h2s-production","H2S Production",{"slug":536,"name":537,"description":42,"image":42,"body":42,"postCount":342},"water-quality-testing","Water Quality Testing",{"slug":539,"name":540,"description":42,"image":42,"body":42,"postCount":238},"virology-basics","Virology basics",{"slug":542,"name":543,"description":42,"image":42,"body":42,"postCount":347},"typing-methods","Typing Methods",{"slug":545,"name":546,"description":42,"image":42,"body":42,"postCount":403},"blotting-technique","Blotting Technique",{"slug":548,"name":549,"description":42,"image":42,"body":42,"postCount":347},"history-microbiology","History of Microbiology"]