[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"$fxLN3MUwXCdr5RPjwZYIDpOj8CHyjOmngWTgoKXPtZbg":3,"$flQGTa4mDqPr3_7KvcL40sfm4YfgBfXl2WXyP7cXVTbY":32,"$f3Ft0rKFJHppdzE-vuveecxx1BUcg9iOlMLtyzf_MJDg":165},[4,8,12,16,20,24,28],{"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",{"type":33,"data":34},"blog",{"slug":35,"title":36,"description":37,"seoTitle":38,"seoDescription":38,"author":39,"createdDate":40,"lastUpdatedDate":41,"draft":42,"category":43,"image":44,"body":45,"faq":46,"tags":47,"related":49},"tuberculin-skin-test-mantoux-test-principle-procedure-results","Tuberculin Skin Test (Mantoux test): Principle, Procedure, Results","Details about Tuberculin Skin Test.",null,"Nisha Rijal","2023-02-02","2026-07-19",false,"bacteriology","https:\u002F\u002Fassets.microbeonline.com\u002Fblogs\u002FMantoux_tuberculin_skin_test-1.jpg","The Mantoux tuberculin skin test is the standard method of determining whether a person is infected with *Mycobacterium tuberculosis* or has exposure to tubercle bacilli. Koch developed it in 1890, but the intradermal technique currently in use was described in 1912 by a French physician, Charles Mantoux, after whom the test is named.\n\n## Mantoux tuberculin skin test\n\n**Administration of the test**\n\nTuberculin skin test (TST) is an intradermal injection. It is performed by injecting 0.1 ml of tuberculin purified protein derivative (PPD) into the inner surface of the forearm. The injection should be made with a tuberculin syringe, with the needle bevel facing upward. When placed correctly, the injection should produce a pale elevation of the skin (a wheal) 6 to 10 mm in diameter.\n\n## Principle\n\nThe tuberculin skin test is the classic clinical demonstration of the function of the delayed-type hypersensitivity response. When purified protein derivative (PPD) of tubercle bacilli is injected intradermally into an individual. A person exposed to the bacteria is expected to mount an immune response within 48-72 hrs leading to the formation of induration (a raised bump in the area of injection) due to the influx and activation of macrophages.\n\n## Procedure\n\n1. Allow the patient to sit in a comfortable chair and place his hands on a table-turning the inner side of the forearm up.\n2. Clean the test area and allow it to air dry.\n3. Inject a standard dose of five tuberculin units (TU) (0.1ml) intradermally (into the skin) using 28 or 26-gauge needle or tuberculin syringe from which 0.1 ml can be delivered accurately. The fluid makes a little bump (wheal) under the skin. A circle may be drawn around the test area with a pen.\n4. Read the results within 48 to 72 hours.\n\n**Reading the results:**\n\nThe reading of the skin test reaction should be 48 to 72 hours after administration. The response should be measured in millimeters of the **induration** (palpable, raised, hardened area, or swelling). The reader *should not measure erythema (redness)*. **The diameter of the indurated area should be measured across the forearm (perpendicular to the long axis)**\n\n> *If a person does not return within 48-72 hours for a tuberculin skin test reading, a second test can be placed as soon as possible. There is no contraindication to repeating the TST, unless a previous TST was associated with a severe reaction.*\n\n## Interpretation\n\nInterpretation of tuberculin skin tests always remain difficult and controversial. Various factors like age, immunological status coexisting illness, etc. influence its outcome. Utmost care is required while interpreting the result and giving an opinion.\n\nAccording to the Center for Disease Control (CDC), skin test interpretation depends on two factors:\n\n- Measurement in millimeters of the induration\n- Person’s risk of being infected with TB and of progression to disease if infected\n\n**Positive Tuberculin Test**\n\n- An **induration of 5 or more millimeters** is considered positive in\n  1. HIV-infected persons\n  2. A recent contact with a person with TB disease\n  3. Persons with fibrotic changes on chest radiograph consistent with prior TB\n  4. Patients with organ transplants\n  5. Persons who are immunosuppressed for other reasons (e.g., taking the equivalent of >15 mg\u002Fday of prednisone for one month or longer, taking TNF-a antagonists)\n- An **induration of 10 or more millimeters** is considered positive in\n  1. Recent immigrants (< 5 years) from high-prevalence countries\n  2. Injection drug users\n  3. Residents and employees of high-risk congregate settings\n  4. Mycobacteriology laboratory personnel\n  5. Persons with clinical conditions that place them at high risk\n  6. Children < 4 years of age\n  7. Infants, children, and adolescents exposed to adults in high-risk categories\n- An **induration of 15 or more millimeters** is considered positive in\n  - any person, including persons with no known risk factors for TB. However, targeted skin testing programs should only be conducted among high-risk groups.\n\n## Limitation\n\nAlthough widely used, the test has several limitations\n\n1. A positive reaction may be observed in both latent and active TB infection. Therefore, it is unreliable in differentiating whether the person is currently having TB or had been infected in the past or at the carrier stage. Confirmatory tests such as chest X-ray, sputum culture, or both are usually done to rule out an active TB infection.\n\n2. **False-Positive Reactions**\\\n   Some persons may react to the tuberculin skin test even though they are not infected with *M. tuberculosis*. The causes of these false-positive reactions may include, but are not limited to, the following:\n\n   1. Infection with nontuberculosis mycobacteria\n   2. Previous BCG vaccination\n   3. Incorrect method of TST administration\n   4. Incorrect interpretation of reaction\n   5. Wrong bottle of antigen used\n\n3. **False-Negative Reactions**\n\n   A negative Mantoux test result usually signifies that the individual has never been exposed to M. tuberculosis. However, some factors may cause a false-negative result or diminished ability to respond to tuberculin even if the person is infected with *M. tuberculosis*. The reasons for these false-negative reactions may include, but are not limited to, the following:\n\n   - Cutaneous anergy *(anergy is the inability to react to skin tests because of a weakened immune system)*\n   - Recent TB infection (within 8-10 weeks of exposure)\n   - Very old TB infection (many years)\n   - Very young age (less than six months old)\n   - Recent live-virus vaccination (e.g., [\u003Cu>measles\u003C\u002Fu>](https:\u002F\u002Fweb.archive.org\u002Fweb\u002F20251214230528\u002Fhttps:\u002F\u002Fmicrobeonline.com\u002Fmeasles-virus-structure-pathogenesis-clinical-feature-complications-and-lab-diagnosis\u002F) and smallpox)\n   - Overwhelming TB disease\n   - Some viral illnesses (e.g., measles and chickenpox)\n   - Incorrect method of TST administration\n   - Incorrect interpretation of reaction\n\n**Who Can Receive a tuberculin skin test?**\n\nMost persons can receive a TST. TST is contraindicated only for persons with a severe reaction (e.g., necrosis, blistering, anaphylactic shock, or ulcerations) to a previous TST. It is not contraindicated for other persons, including infants, children, pregnant women, HIV-infected persons, or persons vaccinated with BCG.\n\n**Vaccination** with live viruses may interfere with TST reactions. For persons scheduled to receive a TST, testing should be done as follows:\n\n- Either on the same day as vaccination with a live-virus vaccine or 4-6 weeks after the administration of the live-virus vaccine\n- At least one month after the smallpox vaccination\n\n**Additional Information**\n\n- [\u003Cu>American Thoracic Society and CDC. Diagnostic standards and classification of tuberculosis in adults and children\u003C\u002Fu>](https:\u002F\u002Fweb.archive.org\u002Fweb\u002F20251214230528\u002Fhttp:\u002F\u002Fajrccm.atsjournals.org\u002Fcgi\u002Fcontent\u002Ffull\u002F161\u002F4\u002F1376). (PDF) *Am J Respir Crit Care Med 2000*; 161.\n- [\u003Cu>CDC. Guidelines for preventing the transmission of \u003C\u002Fu>*\u003Cu>Mycobacterium tuberculosis\u003C\u002Fu>*\u003Cu> in health-care settings, 2005\u003C\u002Fu>](https:\u002F\u002Fweb.archive.org\u002Fweb\u002F20251214230528\u002Fhttp:\u002F\u002Fwww.cdc.gov\u002Ftb\u002Fpublications\u002Fguidelines\u002Finfectioncontrol.htm). *MMWR* 2005; 54 (No. RR-17).\n- CDC. Mantoux Tuberculin Skin Test: Training Materials Kit (2003).\n- [\u003Cu>CDC. Targeted tuberculin testing and treatment of latent tuberculosis infection\u003C\u002Fu>](https:\u002F\u002Fweb.archive.org\u002Fweb\u002F20251214230528\u002Fhttp:\u002F\u002Fwww.cdc.gov\u002Fmmwr\u002FPDF\u002Frr\u002Frr4906.pdf) . *MMWR* 2000; 49 (No. RR-6).",[],[48],"mycobacteria",[50,56,66,111,128,135,152,159],{"slug":51,"title":52,"description":52,"seoTitle":38,"seoDescription":38,"author":39,"createdDate":53,"lastUpdatedDate":41,"draft":42,"category":43,"image":38,"faq":54,"tags":55},"mycobacterium-tuberculosis-lab-diagnosis","Laboratory Diagnosis of Mycobacterium tuberculosis Infection","2020-05-26",[],[48],{"slug":57,"title":58,"description":59,"seoTitle":38,"seoDescription":38,"author":60,"createdDate":61,"lastUpdatedDate":62,"draft":42,"category":63,"image":38,"faq":64,"tags":65},"preparation-uses-lowenstein-jensen-lj-medium","Löwenstein-Jensen (LJ) Medium: Principle, Preparation, Uses, and Colony Characteristics","Löwenstein-Jensen (LJ) medium is the standard solid culture medium for Mycobacterium tuberculosis. Learn its principle, preparation by inspissation, colony characteristics of M. tuberculosis and NTM, and how LJ compares to MGIT liquid culture.","Acharya Tankeshwar","2016-04-29","2026-07-05","culture-media",[],[48],{"slug":67,"title":68,"description":69,"seoTitle":70,"seoDescription":38,"author":60,"createdDate":71,"lastUpdatedDate":72,"draft":42,"category":43,"image":38,"faq":73,"tags":110},"genexpert-mtbrif-assay-principle-procedure-results-interpretations","GeneXpert MTB\u002FRIF: How to Read the Result and What to Do Next","Semi-quantitative grades, probe-level RIF calls, error codes, and the traps: why a \"RIF resistance detected\" result still needs confirmation and why \"not detected\" never rules out TB.","GeneXpert MTB\u002FRIF Assay: Principle, Procedure, Results, and Interpretation","2016-01-04","2026-07-25",[74,77,80,83,86,89,92,95,98,101,104,107],{"question":75,"answer":76},"Does GeneXpert detect isoniazid resistance?","No. The assay reads only the rpoB gene and reports rifampicin resistance. Isoniazid resistance requires a line probe assay, targeted sequencing, or phenotypic DST. Because rifampicin resistance usually co-exists with isoniazid resistance, a positive RIF result is used as a marker for probable MDR-TB, but it is an inference, not a measurement.",{"question":78,"answer":79},"Can GeneXpert replace sputum smear microscopy and culture?","It replaces smear microscopy as the initial diagnostic test under current WHO guidance. It does not replace culture. Culture is still needed for phenotypic drug susceptibility testing, genotyping, detection of non-tuberculous mycobacteria, and confirmation of cure.",{"question":81,"answer":82},"What does \"MTB detected, trace\" mean?","It means the multicopy IS6110 or IS1081 targets were detected but rpoB was essentially unread, so bacillary load is at the very bottom of the assay's range and rifampicin resistance cannot be reported. In children, people living with HIV, and extrapulmonary specimens, trace counts as bacteriological confirmation of TB. In previously treated adults it should be repeated on a fresh specimen, because it may represent residual DNA from cured disease.",{"question":84,"answer":85},"Why does the report say \"very low\" or \"high\"?","That is the semi-quantitative grade, derived from the cycle threshold of the first rpoB probe to bind. It estimates bacillary load, which relates to infectiousness, to how reliable the rifampicin call is, and to the likelihood that a weak positive represents old rather than active disease.",{"question":87,"answer":88},"What is the difference between Invalid and Error?","Invalid means the Sample Processing Control failed: something about the specimen, usually inhibitors or inadequate processing, prevented a trustworthy result. Repeat with a new specimen. Error means the run aborted on an instrument or cartridge fault, most often a failed probe check or a pressure problem. Repeat with a new cartridge.",{"question":90,"answer":91},"Can a GeneXpert result be falsely positive for rifampicin resistance?","Yes. The assay infers resistance from a probe failing to bind, not from reading the mutation, so silent mutations and non-resistance-conferring polymorphisms in the RRDR are reported as resistance. False positives are most common on paucibacillary specimens. This is why a positive result should be confirmed by a line probe assay, targeted sequencing, or phenotypic DST, while treatment is started in parallel.",{"question":93,"answer":94},"Can GeneXpert miss rifampicin resistance?","Yes. Approximately 5% of rifampicin-resistant strains carry mutations outside the 81-bp RRDR. These leave all probes binding normally and are reported as susceptible.",{"question":96,"answer":97},"How long does the GeneXpert MTB\u002FRIF test take?","Under two hours from loading. The standard Xpert MTB\u002FRIF run is about 112 minutes; Xpert Ultra is faster at roughly 65 to 87 minutes. Specimen preparation adds about 15 to 20 minutes before loading.",{"question":99,"answer":100},"Can GeneXpert be used on non-sputum specimens?","Yes. WHO endorses its use on CSF, lymph node aspirate and tissue, gastric aspirate, nasopharyngeal aspirate, and stool, with sensitivity varying by specimen type. It is strongly recommended as the initial test in suspected TB meningitis. Sensitivity is lowest in pleural fluid.",{"question":102,"answer":103},"Can GeneXpert be used to monitor response to treatment?","No. It detects DNA from both living and dead bacilli, so it can remain positive for months in patients who are responding well. Smear microscopy and culture are used for treatment monitoring.",{"question":105,"answer":106},"Does a positive GeneXpert distinguish M. tuberculosis from M. bovis?","No. It detects the M. tuberculosis complex as a group and cannot separate M. tuberculosis, M. bovis, M. africanum, or BCG. Species-level identification requires culture-based methods.",{"question":108,"answer":109},"Is a biological safety cabinet required to run GeneXpert?","Specimen manipulation before the 15-minute inactivation step should be done in a Class II BSC where available. After that step the cartridge is closed and the risk is minimal. WHO permits Xpert testing at the same biosafety level as direct sputum smear microscopy in settings without a BSC.",[48],{"slug":112,"title":113,"description":114,"seoTitle":38,"seoDescription":38,"author":60,"createdDate":115,"lastUpdatedDate":41,"draft":42,"category":116,"image":38,"faq":117,"tags":127},"auramine-rhodamine-fluorochrome-staining-principle-procedure-results-limitations","Auramine-Rhodamine Fluorochrome Staining: Principle, Procedure, and Results","Auramine-rhodamine is a WHO-recommended fluorochrome stain for detecting acid-fast bacilli — more sensitive than Ziehl-Neelsen and faster to screen. Learn the Truant method procedure, results grading, and when to confirm with ZN staining.","2015-04-03","staining-techniques",[118,121,124],{"question":119,"answer":120},"Why is auramine-rhodamine staining more sensitive than Ziehl-Neelsen for detecting acid-fast bacilli?","Auramine-rhodamine allows smear screening at 250x or 400x magnification — compared to 1,000x oil immersion required for ZN staining. At lower magnification, a much larger area of the slide can be examined per unit time (3-5 minutes vs 15-20 minutes per slide). This means more of the smear is examined, increasing the chance of detecting paucibacillary specimens. Studies consistently show auramine-rhodamine detects approximately 10% more positive cases than ZN in direct smear microscopy, which is why WHO recommends it as the preferred method where fluorescence microscopy is available.",{"question":122,"answer":123},"What is the two-step workflow for auramine-rhodamine results?","Positive auramine-rhodamine results should be confirmed by ZN staining of the same slide, as fluorescence artefacts (dust, fibres, non-AFB structures) can occasionally give false-positive fluorescence. Negative auramine-rhodamine results require examination of the minimum required number of fields before reporting — at 200-250x this is typically 30-100 fields. In high-suspicion patients, a negative fluorochrome result should prompt ZN confirmation and repeat specimen collection, as the minimum detection threshold for smear microscopy (approximately 5,000-10,000 AFB\u002FmL) means culture is more sensitive than any smear method.",{"question":125,"answer":126},"Can auramine-rhodamine staining detect organisms other than mycobacteria?","Yes. A modified fluorochrome method using a weaker decolouriser (0.5% sulphuric acid instead of 3% acid-alcohol) detects partially acid-fast organisms including Cryptosporidium parvum, Cyclospora cayetanensis, and Isospora belli oocysts in stool specimens, and Nocardia species in respiratory or wound specimens. These organisms share a partial acid-fast property with mycobacteria. The oocysts appear as bright yellow-orange fluorescent structures against a dark background. This application requires the modified decolouriser — the standard 3% acid-alcohol used for TB smears will over-decolourise these weakly acid-fast organisms.",[48],{"slug":129,"title":130,"description":130,"seoTitle":38,"seoDescription":38,"author":60,"createdDate":131,"lastUpdatedDate":132,"draft":42,"category":43,"image":38,"faq":133,"tags":134},"short-notes-atypical-mycobacterial-infections","Atypical Mycobacterial Infections","2014-11-07","2026-07-04",[],[48],{"slug":136,"title":137,"description":138,"seoTitle":38,"seoDescription":38,"author":60,"createdDate":139,"lastUpdatedDate":140,"draft":42,"category":116,"image":38,"faq":141,"tags":151},"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.","2013-12-06","2026-07-22",[142,145,148],{"question":143,"answer":144},"Why does Ziehl-Neelsen staining require heat while other staining techniques do not?","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 decolorisers 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.",{"question":146,"answer":147},"How is an AFB smear graded and what does the grade mean clinically?","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.",{"question":149,"answer":150},"What is the difference between Ziehl-Neelsen and Kinyoun (cold) acid-fast staining?","Both methods use carbolfuchsin as the primary stain and acid-alcohol for decolourisation, 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 decoloriser concentrations are needed.",[48],{"slug":153,"title":154,"description":154,"seoTitle":38,"seoDescription":38,"author":60,"createdDate":155,"lastUpdatedDate":132,"draft":42,"category":156,"image":38,"faq":157,"tags":158},"key-biochemical-methods-used-to-distinguish-mycobacterial-group","Biochemical Tests to identify Mycobacteria, NTM","2013-07-22","biochemical-tests",[],[48],{"slug":160,"title":161,"description":161,"seoTitle":38,"seoDescription":38,"author":60,"createdDate":162,"lastUpdatedDate":132,"draft":42,"category":43,"image":38,"faq":163,"tags":164},"introduction-transmission-pathogenesis-and-lab-diagnosis-of-leprosy-hansens-disease","Leprosy: Etiology, Pathogenesis, Lab Diagnosis","2012-05-15",[],[48],[166,172,179,184,188,192,197,202,206,210],{"slug":167,"name":60,"description":168,"image":169,"body":170,"postCount":171},"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.*",433,{"slug":173,"name":174,"description":175,"image":176,"body":177,"postCount":178},"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.",81,{"slug":180,"name":181,"description":182,"image":38,"body":38,"postCount":183},"sushmita-baniya","Sushmita Baniya","Author \u002F Contributor",32,{"slug":185,"name":186,"description":182,"image":38,"body":38,"postCount":187},"samikshya-acharya","Samikshya Acharya",20,{"slug":189,"name":190,"description":182,"image":38,"body":38,"postCount":191},"alisha-tripathi","Alisha Tripathi",6,{"slug":193,"name":194,"description":195,"image":38,"body":38,"postCount":196},"aastha-shrestha","Aastha Shrestha"," Author \u002F Contributor",9,{"slug":198,"name":199,"description":200,"image":38,"body":38,"postCount":201},"guest-author","Guest Author","Guest Author \u002F Contributor",2,{"slug":203,"name":204,"description":182,"image":38,"body":38,"postCount":205},"srijana-khanal","Srijana Khanal",18,{"slug":207,"name":208,"description":200,"image":38,"body":38,"postCount":209},"dr-poonam-acharya","Dr. Poonam Acharya",1,{"slug":211,"name":39,"description":182,"image":38,"body":212,"postCount":213},"nisha-rijal","**Nisha Rijal** is a microbiologist and quality assurance specialist. She served for nearly 12 years as a microbiologist at the National Public Health Laboratory (NPHL), Nepal's national reference laboratory, and continues to work as a consultant microbiologist in international public health organization. ",51]