Tuberculosis Care , ISTC training Module

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Tuberculosis Care , ISTC training Module For every Medical Professional

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  • 1.MicrobiologicDiagnosis ofTuberculosis Coordinator - Dr.T.V.Rao MDInstitution/organization TravancoreMedical College, Kollam IndiaInternational Standards 2-6, 10, 11

2. I request all the Medical, Nursing and HealthCare workers go through this informativeprogramme on Tuberculosis created by International standards for Tuberculosis Please send to as many professionals asPossible to work with Tuberculosis on Scientificbasis Dr.T.V.Rao MD Travancore Medical College, Kollam India Copyright of ISTC TB trainingISTC TB Training Modules 2009 3. Microbiologic Diagnosis of TBObjectives: At the end of this presentation,participants will be able to: Understand the important role of sputumsmear microscopy in the diagnosis of TB Describe the various methods of sputumstaining and processing, and identifymethods that may enhance results Recognize the role of culture and drugsensitivity testing in the diagnosis andmanagement of TBISTC TB Training Modules 2009 4. Microbiologic Diagnosis of TBOverview: Significance of microbiologic testing in TB care Sputum staining and processing Direct smears, unconcentrated Fluorochrome staining and fluorescencemicroscopy Concentration and chemical processing Specimen collection and transport Culture and drug-susceptibility testing Rapid diagnostic testingInternational Standards 2, 3, 4, 5, 6, 10, and 11ISTC TB Training Modules 2009 5. Standards for DiagnosisISTC TB Training Modules 2009 6. Microbiologic Diagnosis of TBSignificance of microbiologic testing forpublic health goals and patient care: WHO global target of 70% case detection of newsmear-positive cases Rapid and accurate case detection coupled witheffective treatment is essential to reduce theincidence of TB Failure to perform a proper diagnostic evaluationbefore initiating treatment potentially: Exposes the patient to the risks of unnecessary orwrong treatment May delay accurate diagnosis and proper treatmentISTC TB Training Modules 2009 7. Sputum Smear Microscopy Sputum smear microscopy is the most important test for the diagnosis of pulmonary TB in many areas of the world Direct smears (unconcentrated specimen) are most common Fluorescence microscopy and chemical processing can increase sensitivity Assessment of laboratory quality is essentialISTC TB Training Modules 2009 8. Sputum Microscopy: Direct SmearsDirect smears ofunconcentrated sputum: Fast, simple, inexpensive, widely applicable Extremely specific for M. tuberculosis in high-incidence areas Ziehl-Neelsen staining (carbol fuchsin type) most commonISTC TB Training Modules 2009 9. Sputum Smear MicroscopyCarbolfuchsin-based stains Utilize a regular light microscope Must be read at a higher magnification Two types: Ziehl-Neelsen and Kinyoun. Bothuse carbolfuchsin/phenol as the primary dye Smear is then decolorized with acid (HCI)alcohol and counter-stained with methylene blueISTC TB Training Modules 2009 10. Ziehl-Neelsen (ZN) StainISTC TB Training Modules 2009 11. Auramine-rhodamine StainISTC TB Training Modules 2009 12. Fluorescence MicroscopyAdvantages: More accurate: 10% moresensitive than lightmicroscopy, with specificitycomparable to ZN staining Faster to examine = lesstechnician timeDisadvantages: Higher cost and technicalcomplexity, less feasible inmany areasSteingart KR, et al. Lancet Infect. Dis. 2006; 6 (9):570-81ISTC TB Training Modules 2009 13. Sputum ProcessingSputum processing for optimizing smearresults (vs. direct smear of unconcentratedsputum): Concentration by centrifugation and/orsedimentation Chemical pretreatment (e.g., bleach, NaOH,NaLC) for decontamination and digestion Usually both Higher sensitivity (15-20% increase) andhigher smear positive rateSteingart KR, et al. Lancet Infect. Dis. 2006; 6 (10):664-74ISTC TB Training Modules 2009 14. Specimen Collection and Transport Collect specimens in a laboratory-approved, leak-proof container Label all containers (name and datecollected) Collect specimens prior to initiation oftherapy Infection Control: Consider the safety ofother patients and healthcare workers Collect sputum in well-ventilated area, preferably outdoorsISTC TB Training Modules 2009 15. Specimen Collection and Transport Minimize contamination of specimens by: Instructing the patient to rinse mouthwith water before collection Transport the specimen to the lab assoon as feasible after collection Keep specimens refrigerated if possibleISTC TB Training Modules 2009 16. Performance of Sputum MicroscopyIncremental Yield of Incremental Sensitivity Specimensmear specimens of smear specimensNumber(of all smear-positive) (compared with culture)185.8% 53.8%211.9% 11.1%3 2.4%3.1%Total100%68.0%Average yield of single early morning specimen: 86.4%Average yield of single spot specimen: 73.9% Mase SR, Int J tuberc Lung Dis 2007;11(5): 485-95ISTC TB Training Modules 2009 17. Standard 2: Sputum MicroscopyStandard 2: All patients (adults,adolescents, and children who arecapable of producing sputum) suspectedof having pulmonary TB should have atleast two sputum specimens obtained formicroscopic examination in a quality-assured laboratory. When possible, atleast one early morning specimen shouldbe obtained.ISTC TB Training Modules 2009 18. Standards 3 & 4: Sputum MicroscopyStandard 3: For all patients (adults,adolescents, and children) suspected ofhaving extrapulmonary TB, appropriatespecimens from the suspected sites ofinvolvement should be obtained formicroscopy, culture, and histopathologicalexamination.Standard 4: All persons with chestradiographic findings suggestive oftuberculosis should have sputumspecimens submitted for microbiologicalexaminationISTC TB Training Modules 2009 19. Standard 10: Sputum MicroscopyStandard 10*: Response to therapy inpatients with pulmonary tuberculosisshould be monitored by follow-up sputumsmear microscopy (2 specimens) at thetime of completion of the initial phase oftreatment (2 months).If the sputum smear is positive atcompletion of the initial phase, sputumsmears should be examined again at 3months and, if possible, culture and drugsusceptibility testing should be performed.(* Partial Standard 10)ISTC TB Training Modules 2009 20. Culture and Drug Susceptibility TestingAlthough sputummicroscopy is the firstbacteriologic diagnostictest of choice, bothculture and drugsusceptibility testing(DST) can offersignificant advantagesin the diagnosis andmanagement of TB.ISTC TB Training Modules 2009 21. Culture: Advantages Higher sensitivity than smear microscopy(culture can make diagnosis despite fewerbacilli in specimen) If TB suspected and sputum smears arenegative, culture may provide diagnosis Allows for identification of mycobacterialspecies Allows for drug susceptibility testingISTC TB Training Modules 2009 22. Culture: Disadvantages Cost Technical complexity May take weeks to get results Requires ongoing quality assurance Therefore, more likely to be found inmajor referral centers. Avoid delayingappropriate TB treatment in suspiciouscases while awaiting results.ISTC TB Training Modules 2009 23. Culture: Solid Media Solid media have theadvantage that organisms(colonies) can be seen onthe surface of the medium Types most commonlyused are: Lowenstein-Jensen:egg-based Middlebrook 7H 10 or 7H11:agar-based OgawaISTC TB Training Modules 2009 24. Culture: Liquid Media More sophisticated equipment Faster detection of growth Higher sensitivity than solidmedia Can also be used for drug-susceptibility testing Two examples:BACTEC BACTEC MGIT Incubator MGITMGITISTC TB Training Modules 2009 25. Culture: Identification of MycobacteriaGrowth characteristics (preliminary ID) Preliminary indication of M.tb can be determinedfrom colony characteristics Rate of growth Colonial morphology PigmentationBiochemical tests There is a battery of 8 12 biochemical testsused to differentiate M.tb within the genus Nitrate reduction and niacin production aredefinitive for M.tbISTC TB Training Modules 2009 26. Culture: Identification of MycobacteriaVisual assessment of colony morphology:Smooth, buff-coloredcolonies suggestiveof Mycobacteriumavium complex Rough, buff-colored coloniessuggestive of MycobacteriumtuberculosisISTC TB Training Modules 2009 27. Culture: Cross-Contamination Be aware that faultytechnique can lead tolaboratory cross-contamination ofspecimens (difficult toverify without access tomore technical testing). Adequate qualitycontrol is an essentialcomponent of anymycobacteriologylaboratory.ISTC TB Training Modules 2009 28. Standard 5: Culture in Smear-Standard 5: The diagnosis of sputum smear- negative pulmonary TB should be based on the following criteria: At least two negative sputum smears (includingat least one early morning specimen) Chest radiography findings consistent with TB Lack of response to a trial of broad-spectrumantimicrobial agents (*avoid fluoroquinolones) For such patients, sputum cultures should be obtained. In persons are seriously ill or have known or suspected HIV infection, the diagnostic evaluation should be expedited and if clinical evidence strongly suggests TB, a course of antituberculosis treatment should be initiated.ISTC TB Training Modules 2009 29. Standard 6: Culture in Children (1 of 3)Standard 6: In all children suspected ofhaving intrathoracic (i.e., pulmonary,pleural, and mediastinal or hilar lymphnode) TB, bacteriological confirmationshould be sought through examination ofsputum (by expectoration, gastricwashings, or induced sputum) for smearmicroscopy and culture.ISTC TB Training Modules 2009 Training Modules 2008 30. Standard 6: Culture in children(2 of 3) In the event of negative bacteriologicalresults, a diagnosis of TB should bebased on: The presence of abnormalities consistent with TB on chest radiography A history of exposure to an infectious case, evidence of TB infection (positive tuberculin skin test or interferon gamma-release assay), and Clinical findings suggestive of TBISTC TB Training Modules 2009 Training Modules 2008 31. Standard 6: Culture in Child