[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"$fxLN3MUwXCdr5RPjwZYIDpOj8CHyjOmngWTgoKXPtZbg":3,"$fomRa8T9BHhZShyEQw7jTktZhArZL-5wMfFhTiY9B3HY":36,"$f3Ft0rKFJHppdzE-vuveecxx1BUcg9iOlMLtyzf_MJDg":131,"$fucxFBm2ZjZfGSdmdRaSNGBI_F0jJme4f0GTvzUhQfL8":195},[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":45,"draft":46,"category":47,"image":42,"body":48,"faq":49,"commentsClosed":46,"tags":59,"related":61,"comments":127},"albert-stain-principle-procedure-results-uses","Albert Stain: Principle, Composition, Procedure, and Results","Albert stain detects metachromatic (volutin) granules in Corynebacterium diphtheriae, a key presumptive identification test for diphtheria. Learn the two-reagent principle, step-by-step procedure, and how to interpret results.",null,"Nisha Rijal","2015-06-22","2026-08-02",false,"staining-techniques","A child presents with a grey pseudomembrane covering the tonsils and pharynx, a \"bull-neck\" appearance from cervical lymphadenopathy, and a hoarse voice. The clinician suspects diphtheria. A throat swab is taken and plated on Löffler's serum medium. After overnight incubation, small grey colonies are visible. A smear is prepared and stained with Albert stain.\n\nUnder oil immersion: blue-green bacilli arranged in V and L formations, i.e., Chinese letter patterns is seen. At the poles of the cells are dark bluish-black granules, sharply demarcated from the green cytoplasm. These are metachromatic (volutin) granules, the hallmark of *Corynebacterium diphtheriae* on Albert stain.\n\nAlbert stain is the standard presumptive identification test for *C. diphtheriae* in the clinical laboratory. A positive result is sufficient to start diphtheria antitoxin treatment immediately while awaiting confirmatory toxigenicity testing.\n\nAlbert stain is a type of differential stain used for staining high-molecular-weight polymers of polyphosphate known as **metachromatic granules or volutin granules** found in *Corynebacterium diphtheriae*. Metachromatic granules are also found in [*Yersinia pestis*](https:\u002F\u002Fmicrobeonline.com\u002Fcorynebacterium-diphtheriae-properties-pathogenesis-diagnosis\u002F), and *Mycobacterium* species.\n\nWhile metachromatic granules are also found in *Yersinia pestis* and some *Mycobacterium* species, Albert staining is almost exclusively used for *C. diphtheriae* in clinical practice. *Y. pestis* is identified by its characteristic bipolar (safety pin) staining on Wayson's stain rather than Albert stain, and *Mycobacterium* species are identified by [Ziehl-Neelsen acid-fast staining](https:\u002F\u002Fmicrobeonline.com\u002Fziehl-neelsen-technique-principle-procedure-reporting\u002F). Albert stain should be specifically requested when diphtheria is clinically suspected.\n\nIt is named metachromatic because of its property of changing color i.e when stained with blue stain they appear red in color. When grown in Loffler’s slopes, *C. diphtheriae* produces a large number of granules.\n\n![Fig: Albert Staining -Corynebacterium diphtheriae - Fig: Albert Staining –Corynebacterium diphtheriae](\u002Fblogs\u002FAlbert-stain.jpeg)Figure: Albert Staining of *Corynebacterium diphtheriae*\n\n## Principle of Albert Staining\n\nAlbert stain is basically made up of two stains that are **toluidine blue’ O’** and **malachite green** both of which are basic dyes with high affinity for **acidic** tissue components like cytoplasm. The pH of Albert stain is adjusted to 2.8 by using acetic acid which becomes basic for volutin granules as the pH of volutin granule is highly acidic.\n\nTherefore on applying Albert’s stain to the smear, toluidine blue’ O’ stains volutin granules i. e the most acidic part of cell and malachite green stains the cytoplasm blue-green. On adding Albert’s iodine due to effect of iodine, the metachromatic property is not observed and granules appear blue in color.\n\n## Composition of Albert Stain\n\nAlbert stain is composed of two reagents:\n\n**Albert’s A** solution consist of\n\n1. Toludine blue                      0.15 gm\n2. Malachite green                  0.20 gm\n3. Glacial acetic acid               1 ml\n4. Alcohol (95% ethanol)       2ml\n\n- Dissolve the dyes in alcohol and add to the distilled water and acetic acid.\n- Allow the stain to stand for one day and then filter.\n- Add Distilled water to make the final volume 100ml\n\n**Albert’s B** solution consist of\n\n1. Iodine                                    2gm\n2. Potassium iodide (KI)          3 gm\n\nDissolve KI in water and then add iodine. Dissolve iodine in potassium iodide solution\n\n**Requirements:** Smear on a glass slide, staining rack, Albert’s A solution, Albert’s B solution, blotting paper, immersion oil, microscope\n\n## Procedure of Albert Staining\n\n1. Prepare a smear on clean grease free slide.\n2. Air dry and heat fix the smear.\n3. Treat the smear with Albert’s stain and allow it to react for about 7 mins.\n4. Drain of the excess stain do not water wash the slide with water.\\\n   \\\n   **Why no water wash between Albert's A and Albert's B:** Water washing at this stage would remove the malachite green from the cytoplasm before Albert's iodine (Albert's B) has fixed it, resulting in pale or absent cytoplasmic staining. The iodine step must follow directly after draining the excess stain. Water washing is only performed after Albert's iodine has been applied and has acted for the full 2 minutes.\n5. Flood the smear with Albert’s iodine for 2 minutes.\n6. Wash the slide with water, air dry and observe under oil immersion lens.\n\n## Result\n\nIf *Corynebacterium diphtheriae* is present in the sample it appears green colored rod-shaped bacteria arranged at an angle to each other, resembling English letter ‘L’, ‘V’, or **Chinese letter pattern** along with bluish-black metachromatic granules at the poles.\n\n## Uses of Albert Stain\n\n**Presumptive identification of *Corynebacterium diphtheriae*:** Albert stain is the standard method for demonstrating metachromatic granules in throat swab cultures when diphtheria is clinically suspected. A positive result *(blue-green bacilli in Chinese letter arrangement with polar bluish-black granules)* provides strong presumptive evidence of *C. diphtheriae* and justifies immediate clinical action.\n\n**Important limitation:** Albert stain is a presumptive test only. Two further steps are required for definitive diagnosis:\n\n- **Species confirmation:** Biochemical tests distinguish *C. diphtheriae* from other *Corynebacterium* species and diphtheroids, which are normal commensal organisms that may produce similar morphology\n- **Toxigenicity testing:** Only toxin-producing strains cause diphtheria. The **Elek test** (immunodiffusion) or **PCR for the *tox* gene** confirms whether the isolate carries the diphtheria toxin gene, the essential virulence factor\n\n**Distinguishing pathogenic from non-pathogenic corynebacteria:** Non-pathogenic diphtheroids (e.g. *C. xerosis*, *C. pseudodiphtheriticum*) are normal throat commensals that may grow on Löffler's medium. They generally produce fewer or no metachromatic granules compared to *C. diphtheriae*, but this distinction is not absolute — toxigenicity testing is mandatory before a pathogenic diagnosis is made.\n\nFor the complete clinical picture of diphtheria: pathogenesis, clinical manifestations, toxin mechanism, and full laboratory diagnosis, check this article:  [*Corynebacterium diphtheriae*: Disease, Properties, and Laboratory Diagnosis](\u002Fcorynebacterium-diphtheriae\u002F)\n\n## How to Remember: Albert Stain\n\n**\"Albert's A stains the cell; Albert's B fixes the granules\":** Albert's A (toluidine blue O + malachite green) stains the cytoplasm blue-green and the granules dark. Albert's B (iodine solution) fixes and intensifies the granule colour to bluish-black while leaving the cytoplasm green. Two reagents, two jobs.\n\n**The color result  \"Green cells, Black granules\":**\n\n- Cytoplasm → **blue-green** (malachite green)\n- Metachromatic granules → **bluish-black** (toluidine blue + iodine intensification)\n- Arrangement → **Chinese letters** (V, L, Y shapes from snapping cell division)\n\n**Why the granules are dark and not blue:** Toluidine blue stains the highly acidic volutin granules metachromatically, changing from blue to dark bluish-black. The addition of iodine (Albert's B) intensifies this color change. This is the same metachromatic principle as toluidine blue alone, but with higher contrast.\n\n**The clinical sequence to remember:** Pseudomembrane + bull-neck → Throat swab → Löffler's medium → Albert stain (granules = presumptive) → Elek test (toxin = confirmatory)\n\n## Key Exam Facts in One Table\n\n| Feature | Detail |\n| --- | --- |\n| Primary organism | *Corynebacterium diphtheriae* |\n| Structure demonstrated | Metachromatic (volutin) granules, polymerized polyphosphate |\n| Albert's A components | Toluidine blue O + malachite green + glacial acetic acid + ethanol |\n| Albert's B components | Iodine + potassium iodide (Lugol's-type iodine) |\n| Cytoplasm color | Blue-green |\n| Metachromatic granule color | Bluish-black (dark) |\n| Cell arrangement | Chinese letter \u002F V \u002F L \u002F Y pattern (snapping division) |\n| Why no water wash between steps | Prevents removal of malachite green before iodine fixation |\n| Presumptive vs confirmatory | Presumptive only, Elek test or PCR for tox gene needed for toxin confirmation |\n| Other organisms with metachromatic granules | *Y. pestis* (identified by Wayson's stain), some *Mycobacterium* spp |\n| Culture medium for *C. diphtheriae* | Löffler's serum medium (stimulates granule production) |\n| Toluidine blue alone vs Albert stain | Both demonstrate granules; Albert stain has higher contrast and is standard |\n\n**References**\n\n1. Forbes BA, Sahm DF, Weissfeld AS. Bailey & Scott's Diagnostic Microbiology. 14th ed. Elsevier; 2023.\n2. Koneman EW, Allen SD, Janda WM, Schreckenberger PC, Winn WC. Koneman's Color Atlas and Textbook of Diagnostic Microbiology. 6th ed. Lippincott Williams & Wilkins; 2006.\n3. Murray PR, Rosenthal KS, Pfaller MA. Medical Microbiology. 9th ed. Elsevier; 2020.\n4. Levinson WE. Review of Medical Microbiology and Immunology. 17th ed. McGraw-Hill; 2022.",[50,53,56],{"question":51,"answer":52},"\u003Cp>What does Albert stain demonstrate and why is it used for \u003Cem>Corynebacterium diphtheriae\u003C\u002Fem>?\u003C\u002Fp>","\u003Cp>Albert stain demonstrates metachromatic (volutin) granules, stores of polymerized inorganic polyphosphate that accumulate in \u003Cem>Corynebacterium diphtheriae\u003C\u002Fem>. The granules stain dark bluish-black while the cell body stains blue-green, creating a distinctive appearance. This is used for presumptive identification of \u003Cem>C. diphtheriae\u003C\u002Fem> from cultures on Löffler's serum medium. However, Albert stain is presumptive only, toxigenicity must be confirmed by the Elek test or PCR for the tox gene, since non-toxigenic strains can produce similar morphology.\u003C\u002Fp>",{"question":54,"answer":55},"What are the two reagents in Albert stain and what does each do?","Albert's stain uses two reagents. Albert's A contains toluidine blue O and malachite green in glacial acetic acid and ethanol — the toluidine blue stains metachromatic granules dark (metachromatically) while malachite green stains the cell body blue-green. Albert's B is an iodine solution (iodine + potassium iodide) that acts as a mordant, intensifying and fixing the granule colour to bluish-black and increasing contrast. The critical procedural rule is never to water-wash between the two steps — this would remove the malachite green from the cytoplasm before Albert's B can fix it.",{"question":57,"answer":58},"\u003Cp>What is the arrangement of \u003Cem>Corynebacterium diphtheriae\u003C\u002Fem> on Albert stain?\u003C\u002Fp>","\u003Cp>\u003Cem>C. diphtheriae\u003C\u002Fem> appears as blue-green bacilli arranged in characteristic Chinese letter, cuneiform (V, L, Y) or picket fence patterns. This arrangement results from snapping cell division: daughter cells snap apart at angles rather than separating cleanly, leaving them attached in angular formations. The dark bluish-black metachromatic granules are typically located at the poles of the bacterial cells (polar granules), giving the classic barred or beaded appearance within the blue-green cell body.\u003C\u002Fp>",[60],"bacterial-staining-technique",[62,72,91,104],{"slug":63,"title":64,"description":64,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":65,"lastUpdatedDate":66,"draft":46,"category":67,"image":42,"faq":68,"tags":69},"corynebacterium-diphtheriae-properties-pathogenesis-diagnosis","Corynebacterium diphtheriae: Pathogenesis, Lab Diagnosis","2020-05-07","2026-08-16","bacteriology",[],[70,71],"gram-positive-coccobacillus","respiratory-tract-infection",{"slug":73,"title":74,"description":75,"seoTitle":42,"seoDescription":42,"author":76,"createdDate":77,"lastUpdatedDate":78,"draft":46,"category":47,"image":42,"faq":79,"tags":89},"ziehl-neelsen-technique-principle-procedure-reporting","Ziehl-Neelsen Staining: Principle, Procedure, Grading, and Interpretation","The hot ZN acid-fast staining method step by step, why mycolic acid holds carbol fuchsin against acid-alcohol, WHO smear grading from scanty to 3+, and what a negative smear does and does not rule out in TB.","Acharya Tankeshwar","2013-12-06","2026-08-12",[80,83,86],{"question":81,"answer":82},"Why does Ziehl-Neelsen staining require heat while other staining techniques do not?","\u003Cp>Mycobacteria have a cell wall rich in mycolic acids, long-chain fatty acids that make the wall waxy, hydrophobic, and impermeable to most dyes at room temperature. Heat acts as a mordant by disrupting this waxy barrier and allowing carbol fuchsin to penetrate the cell wall. Once inside, the stain is held so tightly by the mycolic acids that even acid-alcohol, one of the strongest decolorizers used in microbiology, cannot remove it. This is why the stain is called 'acid-fast',  the organisms hold fast to the dye even after acid treatment.\u003C\u002Fp>",{"question":84,"answer":85},"How is an AFB smear graded and what does the grade mean clinically?","\u003Cp>AFB smears are graded using the WHO\u002FIUATLD scale: No AFB seen (after examining 300 fields); Scanty: 1-9 AFB per 100 fields (report exact count and request repeat); 1+: 10-99 AFB per 100 fields; 2+: 1-10 AFB per field in at least 50 fields; 3+: more than 10 AFB per field in at least 20 fields. Higher grades indicate greater organism burden and greater infectiousness. Grade is recorded at treatment initiation and at months 2, 5, and 6 to monitor bacteriological response. Conversion from positive to negative smear during treatment indicates therapeutic response.\u003C\u002Fp>",{"question":87,"answer":88},"What is the difference between Ziehl-Neelsen and Kinyoun (cold) acid-fast staining?","\u003Cp>Both methods use carbolfuchsin as the primary stain and acid-alcohol for decolorization, but they differ in how the dye penetrates the mycobacterial cell wall. Ziehl-Neelsen uses heat (the hot technique), the slide is steamed to drive the dye through the waxy cell wall. Kinyoun's cold technique achieves penetration without heat by increasing the concentration of both carbolfuchsin and phenol and incorporating a wetting agent (Triton X-100 or similar). The results are equivalent. Kinyoun is preferred where open flames are unsafe or inconvenient, and for partial acid-fast organisms (Nocardia, Cryptosporidium) where lower decolorizer concentrations are needed.\u003C\u002Fp>",[60,90],"mycobacteria",{"slug":92,"title":93,"description":94,"seoTitle":42,"seoDescription":42,"author":76,"createdDate":95,"lastUpdatedDate":45,"draft":46,"category":47,"image":42,"faq":96,"tags":103},"capsule-stain-principle-procedure-results","Capsule Stain: Principle, Procedure, and Results","Capsule staining detects bacterial capsules — a key virulence factor. Learn the India ink and Anthony's methods, clinically important capsulated organisms, and the Quellung reaction for pneumococcal identification.","2016-10-15",[97,100],{"question":98,"answer":99},"Why can bacterial capsules not be stained directly?","Bacterial capsules are composed primarily of polysaccharides (occasionally polypeptides), which are non-ionic — they carry no net electrical charge. Since conventional dyes are either cationic (basic dyes) or anionic (acidic dyes), they have no charged surface to bind to on the capsule. Capsule staining is therefore always indirect: the bacterial cell is stained with a basic dye and the background is stained with an acidic dye, revealing the capsule as an unstained clear halo between them.",{"question":101,"answer":102},"\u003Cp>How is India ink used to diagnose Cryptococcal meningitis?\u003C\u002Fp>","\u003Cp>India ink (or nigrosin) is mixed with a drop of CSF on a microscope slide and examined under oil immersion. \u003Cem>Cryptococcus neoformans \u003C\u002Fem>appears as a yeast cell (round to oval, 4-20 μm) surrounded by a clear capsule halo against the dark ink background. The halo can be dramatically large relative to the cell body. India ink is a rapid, inexpensive bedside diagnostic test with approximately 50-80% sensitivity in cryptococcal meningitis — higher in HIV-positive patients who tend to have higher organism burdens. A negative India ink does not exclude cryptococcal meningitis; the cryptococcal antigen latex agglutination test is more sensitive and should be performed when clinical suspicion is high.\u003C\u002Fp>",[60],{"slug":105,"title":106,"description":107,"seoTitle":42,"seoDescription":42,"author":76,"createdDate":108,"lastUpdatedDate":109,"draft":46,"category":47,"image":42,"faq":110,"tags":126},"types-of-staining-techniques-used-in-microbiology-and-their-applications","Staining Techniques in Microbiology: Which Stain for Which Specimen","A specimen-to-stain decision guide for the microbiology bench: which stain to use for TB, fungi, capsules, blood parasites, and more, with the principle behind each and links to full procedures.","2013-08-10","2026-08-03",[111,114,117,120,123],{"question":112,"answer":113},"What is the difference between simple, differential, and special staining techniques?","\u003Cp>Simple staining uses a single dye that colors all bacteria the same color, revealing only morphology and arrangement. Differential staining uses two or more dyes to distinguish between different organisms or structures: Gram staining distinguishes gram-positive from gram-negative bacteria; Ziehl-Neelsen distinguishes acid-fast from non-acid-fast organisms. Special staining is designed to demonstrate a specific structure or organism: capsule stains, endospore stains, flagella stains, India ink for Cryptococcus, and LPCB for fungal identification are all special stains.\u003C\u002Fp>",{"question":115,"answer":116},"Which stain should I use for a sputum specimen from a suspected TB patient?","Ziehl-Neelsen (ZN) staining is the standard method for detecting acid-fast bacilli (AFB) in sputum. Where a fluorescence microscope is available, auramine-rhodamine fluorochrome staining is preferred by WHO as it is more sensitive and allows faster screening at lower magnification. A positive auramine-rhodamine result should be confirmed by ZN staining.",{"question":118,"answer":119},"\u003Cp>Which stain is used to identify \u003Cem>Cryptococcus neoformans \u003C\u002Fem>in CSF?\u003C\u002Fp>","\u003Cp>India ink (negative staining) is the classic method: \u003Cem>Cryptococcus neoformans\u003C\u002Fem> appears as a yeast cell surrounded by a clear capsule halo against a black background. Calcofluor white staining is an alternative that can also demonstrate the capsule. For antigen detection rather than direct visualization, the latex agglutination test for cryptococcal antigen in CSF is more sensitive than India ink.\u003C\u002Fp>",{"question":121,"answer":122},"What are fluorochrome staining techniques and when are they used?","Fluorochrome stains use dyes that fluoresce under ultraviolet light, producing bright signals against a dark background. The main fluorochrome stains in clinical microbiology are: auramine-rhodamine for mycobacteria (more sensitive than ZN, preferred by WHO where fluorescence microscopy is available); acridine orange for detecting bacteria in blood cultures when Gram stain is equivocal; and calcofluor white for fungal elements in clinical specimens. All fluorochrome methods require a fluorescence microscope with appropriate excitation filters.",{"question":124,"answer":125},"Why are capsule stains performed differently from other bacterial stains?","\u003Cp>Bacterial capsules are non-ionic polysaccharides that carry no electrical charge, so neither basic (cationic) nor acidic (anionic) dyes will bind directly to them. Capsule staining is always indirect: the background and the bacterial cell are stained, and the capsule is revealed as an unstained clear halo between them. For this reason, capsule staining must never use heat fixation (which melts the capsule) or water rinses (which dislodge it).\u003C\u002Fp>",[60],{"enabled":128,"threads":129,"total":130},true,[],0,[132,138,145,152,158,163,169,174,180,183,189],{"slug":133,"name":76,"description":134,"image":135,"body":136,"postCount":137},"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.*",468,{"slug":139,"name":140,"description":141,"image":142,"body":143,"postCount":144},"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":146,"name":147,"description":148,"image":149,"body":150,"postCount":151},"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":153,"name":154,"description":148,"image":155,"body":156,"postCount":157},"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":159,"name":160,"description":148,"image":42,"body":161,"postCount":162},"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":164,"name":165,"description":166,"image":42,"body":167,"postCount":168},"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":170,"name":171,"description":172,"image":42,"body":42,"postCount":173},"guest-author","Guest Author","Guest Author \u002F Contributor",1,{"slug":175,"name":176,"description":148,"image":177,"body":178,"postCount":179},"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.",17,{"slug":181,"name":182,"description":172,"image":42,"body":42,"postCount":173},"dr-poonam-acharya","Dr. Poonam Acharya",{"slug":184,"name":43,"description":185,"image":186,"body":187,"postCount":188},"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":190,"name":191,"description":192,"image":193,"body":194,"postCount":173},"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.",[196,203,209,214,219,224,227,231,235,240,244,249,253,258,263,267,271,275,280,285,289,293,297,302,306,310,314,318,323,328,332,336,340,344,348,352,356,359,363,367,371,375,379,383,387,391,395,399,404,408,412,416,420,423,427,431,435,439,443,447,451,455,458,462,466,470,474,478,481,485],{"slug":197,"name":198,"description":199,"image":200,"body":201,"postCount":202},"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":204,"name":205,"description":206,"image":42,"body":207,"postCount":208},"microscopy","Microscopy","Microscope types, components, and microscopy techniques","These are list of blog posts related to microscopy. ",12,{"slug":210,"name":211,"description":212,"image":42,"body":42,"postCount":213},"gram-positive-cocci","Gram-Positive Cocci","Staphylococcus, Streptococcus, Enterococcus, Micrococcus — organisms, diseases, and identification tests",11,{"slug":215,"name":216,"description":217,"image":42,"body":42,"postCount":218},"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":220,"name":221,"description":222,"image":42,"body":42,"postCount":223},"gram-positive-rods","Gram-Positive Rods","Bacillus, Clostridium, Listeria, Corynebacterium, Actinomyces and related organisms",8,{"slug":90,"name":225,"description":226,"image":42,"body":42,"postCount":213},"Mycobacteria","Mycobacterium tuberculosis, leprosy, atypical mycobacteria, and acid-fast organism diagnosis",{"slug":228,"name":229,"description":230,"image":42,"body":42,"postCount":213},"anaerobic-bacteriology","Anaerobic Bacteriology","Anaerobic organisms, anaerobic culture methods, and anaerobic infection diagnosis",{"slug":232,"name":233,"description":234,"image":42,"body":42,"postCount":208},"enterobacteriaceae","Enterobacteriaceae","Identification, differentiation, and clinical significance of Enterobacteriaceae family members",{"slug":236,"name":237,"description":238,"image":42,"body":42,"postCount":239},"spirochetes","Spirochetes","Treponema, Leptospira, Borrelia and spirochetal infections",7,{"slug":241,"name":242,"description":243,"image":42,"body":42,"postCount":202},"food-microbiology","Food Microbiology","Food-borne pathogens, food safety, spoilage, and preservation",{"slug":245,"name":246,"description":247,"image":42,"body":42,"postCount":248},"antimicrobial-susceptibility-testing","Antimicrobial Susceptibility Testing","Methods for testing antibiotic susceptibility in clinical microbiology",21,{"slug":250,"name":251,"description":252,"image":42,"body":42,"postCount":223},"antimicrobials-moa-amr","Antimicrobials (MOA & AMR)","Mechanisms, detection, and clinical significance of antimicrobial resistance",{"slug":254,"name":255,"description":256,"image":42,"body":42,"postCount":257},"sterilization-disinfection","Sterilization and Disinfection","Methods of sterilization and disinfection in healthcare and laboratory settings",10,{"slug":259,"name":260,"description":261,"image":42,"body":42,"postCount":262},"specimen-collection-transport","Specimen Collection and Transport","Collection, handling, and transport of clinical specimens for microbiological testing",27,{"slug":264,"name":265,"description":266,"image":42,"body":42,"postCount":248},"bacterial-structure-physiology","Bacterial Structure and Physiology","Bacterial cell structure, growth, physiology, and environmental factors affecting growth",{"slug":268,"name":269,"description":42,"image":42,"body":270,"postCount":162},"horizontal-gene-transfer","Horizontal Gene Transfer","Articles related to **Horizontal Gene Transfer**",{"slug":272,"name":273,"description":42,"image":42,"body":274,"postCount":257},"chromatography","Chromatography","Information about chromatographic techniques.",{"slug":276,"name":277,"description":278,"image":42,"body":279,"postCount":239},"electrophoresis","Electrophoresis","Information about Electrophoresis Techniques ","Detailed information  about Electrophoresis Techniques ",{"slug":281,"name":282,"description":283,"image":42,"body":284,"postCount":162},"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":286,"name":287,"description":288,"image":42,"body":42,"postCount":162},"bacteriophage","Bacteriophage","Description about Bacteriophage.",{"slug":290,"name":291,"description":292,"image":42,"body":42,"postCount":162},"malaria","Malaria","It is the collections of articles regarding malarial disease. ",{"slug":294,"name":295,"description":296,"image":42,"body":42,"postCount":162},"anaerobic-culture-techniques","Anaerobic Culture Techniques","Posts related with Anaerobic Culture Techniques.",{"slug":298,"name":299,"description":300,"image":42,"body":42,"postCount":301},"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":303,"name":304,"description":305,"image":42,"body":42,"postCount":239},"biosafety-levels","Biosafety levels ","Articles related to Biosafety Levels",{"slug":307,"name":308,"description":309,"image":42,"body":42,"postCount":218},"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":311,"name":312,"description":313,"image":42,"body":42,"postCount":162},"pipette","Pipette","Posts related with Pipette. ",{"slug":315,"name":316,"description":317,"image":42,"body":42,"postCount":223},"bacteriology-mcqs","Bacteriology MCQs","This sections lists MCQs in Bacteriology.",{"slug":319,"name":320,"description":321,"image":42,"body":42,"postCount":322},"parasitology-mcqs","Parasitology MCQs","This section lists MCQs in Parasitology.",2,{"slug":324,"name":325,"description":326,"image":42,"body":42,"postCount":327},"virology-mcqs","Virology MCQs","This is the collections of Multiple Choice Questions in Virology.",4,{"slug":329,"name":330,"description":331,"image":42,"body":42,"postCount":218},"mcqs-in-microbiology","MCQs in Microbiology","This section lists the collections of Multiple Choice Questions in General Microbiology Topics. ",{"slug":333,"name":334,"description":335,"image":42,"body":42,"postCount":223},"immunology-mcqs","Immunology MCQs","In this section; we are posting collections of Multiple Choice Questions about Immunology. ",{"slug":337,"name":338,"description":339,"image":42,"body":42,"postCount":168},"microbial-curiosities","Microbial Curiosities","In this clusters, we are posting interesting and unique information about Microorganisms. ",{"slug":341,"name":342,"description":343,"image":42,"body":42,"postCount":248},"bacterial-culture-media","Bacterial Culture Media","Posts related to Bacterial Culture Media. ",{"slug":345,"name":346,"description":347,"image":42,"body":42,"postCount":162},"fungal-culture-media","Fungal Culture Media","Posts related to Fungal Culture Media.",{"slug":349,"name":350,"description":351,"image":42,"body":42,"postCount":218},"motility-test","Motility Test","This lists the procedure regarding various tests methods for bacterial motility.",{"slug":353,"name":354,"description":355,"image":42,"body":42,"postCount":257},"bacterial-enumeration","Bacterial enumeration","These posts are related to isolation and enumeration of bacteria. ",{"slug":70,"name":357,"description":358,"image":42,"body":42,"postCount":322},"Gram-positive coccobacillus","List of Gram Positive Coccobacilli",{"slug":360,"name":361,"description":362,"image":42,"body":42,"postCount":327},"dimorphic-fungi","Dimorphic Fungi","This is about various dimorphic fungi. ",{"slug":364,"name":365,"description":366,"image":42,"body":42,"postCount":239},"bacterial-classification","Bacterial Classification","These posts are related with various approaches used for the classification of Bacteria. ",{"slug":368,"name":369,"description":370,"image":42,"body":42,"postCount":218},"immunofluorescence","Immunofluorescence ","Various Tests related to Immunofluorescence ",{"slug":372,"name":373,"description":374,"image":42,"body":42,"postCount":168},"antibody-mediated-immunity","Antibody-mediated Immunity","This clusters links the articles that are sharing insights about Antibody-mediated immunity. ",{"slug":376,"name":377,"description":378,"image":42,"body":42,"postCount":239},"hypersensitivity","Hypersensitivity","Articles related to Hypersensitivity.",{"slug":380,"name":381,"description":42,"image":42,"body":42,"postCount":382},"haemophilus","Haemophilus",3,{"slug":384,"name":385,"description":386,"image":42,"body":42,"postCount":327},"sexually-transmitted-infections-stis","Sexually transmitted infections (STIs)","This is the clusters of infections that are transmitted sexually. ",{"slug":388,"name":389,"description":390,"image":42,"body":42,"postCount":208},"adaptive-immunity","Adaptive Immunity","Blog posts related to B Cell Immunity and T Cell Immunity.",{"slug":392,"name":393,"description":394,"image":42,"body":42,"postCount":202},"fungal-diagnostics","Fungal Diagnostics","Various methods used for the Diagnosis of Fungal Infections. ",{"slug":396,"name":397,"description":398,"image":42,"body":42,"postCount":218},"laboratory-storage-and-preservation","Laboratory Storage and Preservation","Articles about Laboratory Storage of Antimicrobial Disk, Test organisms and Equipment used for this process. ",{"slug":400,"name":401,"description":402,"image":42,"body":403,"postCount":162},"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":405,"name":406,"description":407,"image":42,"body":42,"postCount":223},"laboratory-glassware","Laboratory Glassware","Posts about Laboratory Glassware. ",{"slug":409,"name":410,"description":411,"image":42,"body":42,"postCount":162},"helminths","Helminths","In this section, we are covering properties, life cycle, pathogenesis and laboratory diagnosis of Helminths\u002FHelminthic infestations. ",{"slug":413,"name":414,"description":415,"image":42,"body":42,"postCount":162},"protozoan-parasite","Protozoan Parasite","In this cluster, we are covering protozoan parasites. ",{"slug":417,"name":418,"description":419,"image":42,"body":42,"postCount":173},"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":60,"name":421,"description":422,"image":42,"body":42,"postCount":257},"Bacterial Staining Technique","Lists of various staining techniques that are used to stain bacteria. ",{"slug":424,"name":425,"description":426,"image":42,"body":42,"postCount":157},"enzyme-tests","Enzyme Tests","\u003Cp>Various Biochemical Test that are based on enzymatic activity of the microorganisms. \u003C\u002Fp>",{"slug":428,"name":429,"description":430,"image":42,"body":42,"postCount":213},"carbohydrate-utilization","Carbohydrate Utilization","\u003Cp>Various biochemical tests which are related to Carbohydrate fermentation or Utilization\u003C\u002Fp>",{"slug":432,"name":433,"description":434,"image":42,"body":42,"postCount":218},"susceptibility-based-id","Susceptibility-based ID","\u003Cp>These are susceptibility based identification test such as optochin sensitivity, bacitracin sensitivity etc. \u003C\u002Fp>",{"slug":436,"name":437,"description":438,"image":42,"body":42,"postCount":327},"microbial-metabolism","Microbial Metabolism","\u003Cp>Tests about Microbial Metabolism. \u003C\u002Fp>",{"slug":440,"name":441,"description":442,"image":42,"body":42,"postCount":223},"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":444,"name":445,"description":446,"image":42,"body":42,"postCount":382},"atypical-pneumonia","Atypical Pneumonia","\u003Cp>Organisms responsible for Atypical Pneumonia. \u003C\u002Fp>",{"slug":448,"name":449,"description":450,"image":42,"body":42,"postCount":218},"antigen","Antigen","\u003Cp>Various articles related to Antigens.\u003C\u002Fp>",{"slug":452,"name":453,"description":454,"image":42,"body":42,"postCount":239},"innate-immunity","Innate Immunity","\u003Cp>Articles related to Innate Immunity. \u003C\u002Fp>",{"slug":71,"name":456,"description":457,"image":42,"body":42,"postCount":327},"Respiratory Tract Infection","\u003Cp>In this cluster, you can see various etiological agents that causes respiratory tract infection. \u003C\u002Fp>",{"slug":459,"name":460,"description":461,"image":42,"body":42,"postCount":218},"torch-infection","TORCH Infection","\u003Cp>In this section; you can find articles related with TOCH infection. \u003C\u002Fp>",{"slug":463,"name":464,"description":465,"image":42,"body":42,"postCount":239},"microbiology-for-beginners","Microbiology for Beginners","\u003Cp>These articles are very basic articles, which will share general concepts in Microbiology. \u003C\u002Fp>",{"slug":467,"name":468,"description":469,"image":42,"body":42,"postCount":162},"dna-replication","DNA Replication","\u003Cp>Articles related to DNA and Replication of DNA. \u003C\u002Fp>",{"slug":471,"name":472,"description":473,"image":42,"body":42,"postCount":239},"genetic-code","Genetic Code","\u003Cp>Articles related to Genetic Code.\u003C\u002Fp>",{"slug":475,"name":476,"description":477,"image":42,"body":42,"postCount":218},"molecular-technique","Molecular Technique","\u003Cp>Posts related to Molecular Techniques. \u003C\u002Fp>",{"slug":479,"name":480,"description":42,"image":42,"body":42,"postCount":173},"colorimetric-assay","Colorimetric Assay ",{"slug":482,"name":483,"description":484,"image":42,"body":42,"postCount":218},"pharmaceutical-microbiology","Pharmaceutical Microbiology","\u003Cp>Various articles related to Pharmaceutical Microbiology\u003C\u002Fp>",{"slug":486,"name":487,"description":42,"image":42,"body":42,"postCount":382},"blood-and-immune-cells","Blood and Immune Cells"]