Bleach sedimentation: an opportunity to optimize smear microscopy for tuberculosis diagnosis in settings of high prevalence of HIV

Hdl Handle:
http://hdl.handle.net/10144/31935
Title:
Bleach sedimentation: an opportunity to optimize smear microscopy for tuberculosis diagnosis in settings of high prevalence of HIV
Authors:
Bonnet, M; Ramsay, A; Githui, W; Gagnidze, L; Varaine, F; Guerin, P J
Journal:
Clinical Infectious Diseases
Abstract:
BACKGROUND: The purpose of the study was to evaluate the performance and feasibility of tuberculosis diagnosis by sputum microscopy after bleach sedimentation, compared with by conventional direct smear microscopy, in a setting of high prevalence of HIV. METHODS: In a community-based study in Kenya (a population in which 50% of individuals with tuberculosis are infected with HIV), individuals with suspected pulmonary tuberculosis submitted 3 sputum specimens during 2 consecutive days, which were examined by blind evaluation. Ziehl-Neelsen-stained smears were made of fresh specimens and of specimens that were processed with 3.5% household bleach followed by overnight sedimentation. Two different cutoffs for acid-fast bacilli (AFB) per 100 high-power fields (HPF) were used to define a positive smear: >10 AFB/100 HPF and 1 AFB/100 HPF. Four smear-positive case definitions, based on 1 or 2 positive smears with the 1 AFB or 10 AFB cutoff, were used. RESULTS: Of 1879 specimens from 644 patients, 363 (19.3%) and 460 (24.5%) were positive by bleach sedimentation microscopy, compared with 301 (16.0%) and 374 (19.9%) by direct smear microscopy, with use of the 10 AFB/100 HPF (P < .001) and 1 AFB/100 HPF (P < .001) cutoffs, respectively. Regardless of the case definition used, bleach sedimentation microscopy detected significantly more positive cases than did direct smear microscopy: 26.7% (172 of 644) versus 21.7% (140 of 644), respectively, with the case definition of 1 positive smear and the 1 AFB/100 HPF cutoff (P < .001), and 21.4% (138 of 644) versus 18.6% (120 of 644), respectively, with the case definition of 1 positive smear and the 10 AFB/100 HPF cutoff (P < .001). Inter- and intrareader reproducibility were favorable, with kappa coefficients of 0.83 and 0.91, respectively. Bleach sedimentation was relatively inexpensive and was not time consuming. CONCLUSIONS: Bleach sedimentation microscopy is an effective, simple method to improve the yield of smear microscopy in a setting of high prevalence of HIV. Further evaluation of this method, under operational conditions, is urgently needed to determine its potential as a tool for tuberculosis control.
Affiliation:
Epicentre, Paris, France; Médecins Sans Frontières, Paris, France; Liverpool School of Tropical Medicine, Liverpool, United Kingdom; Centre for Respiratory Diseases Research, Kenya Medical Research Institute, Nairobi, Kenya
Publisher:
Infectious Diseases Society of America
Issue Date:
1-Jun-2008
URI:
http://hdl.handle.net/10144/31935
DOI:
10.1086/587891
PubMed ID:
18444789
Additional Links:
http://www.journals.uchicago.edu/CID/
Submitted date:
2008-06-14
Type:
Article
Language:
en
ISSN:
1537-6591
Appears in Collections:
TB

Full metadata record

DC FieldValue Language
dc.contributor.authorBonnet, M-
dc.contributor.authorRamsay, A-
dc.contributor.authorGithui, W-
dc.contributor.authorGagnidze, L-
dc.contributor.authorVaraine, F-
dc.contributor.authorGuerin, P J-
dc.date.accessioned2008-07-14T15:45:25Z-
dc.date.available2008-07-14T15:45:25Z-
dc.date.issued2008-06-01-
dc.date.submitted2008-06-14-
dc.identifier.citationClin Infect Dis 2008;46(11):1710-6en
dc.identifier.issn1537-6591-
dc.identifier.pmid18444789-
dc.identifier.doi10.1086/587891-
dc.identifier.urihttp://hdl.handle.net/10144/31935-
dc.description.abstractBACKGROUND: The purpose of the study was to evaluate the performance and feasibility of tuberculosis diagnosis by sputum microscopy after bleach sedimentation, compared with by conventional direct smear microscopy, in a setting of high prevalence of HIV. METHODS: In a community-based study in Kenya (a population in which 50% of individuals with tuberculosis are infected with HIV), individuals with suspected pulmonary tuberculosis submitted 3 sputum specimens during 2 consecutive days, which were examined by blind evaluation. Ziehl-Neelsen-stained smears were made of fresh specimens and of specimens that were processed with 3.5% household bleach followed by overnight sedimentation. Two different cutoffs for acid-fast bacilli (AFB) per 100 high-power fields (HPF) were used to define a positive smear: >10 AFB/100 HPF and 1 AFB/100 HPF. Four smear-positive case definitions, based on 1 or 2 positive smears with the 1 AFB or 10 AFB cutoff, were used. RESULTS: Of 1879 specimens from 644 patients, 363 (19.3%) and 460 (24.5%) were positive by bleach sedimentation microscopy, compared with 301 (16.0%) and 374 (19.9%) by direct smear microscopy, with use of the 10 AFB/100 HPF (P < .001) and 1 AFB/100 HPF (P < .001) cutoffs, respectively. Regardless of the case definition used, bleach sedimentation microscopy detected significantly more positive cases than did direct smear microscopy: 26.7% (172 of 644) versus 21.7% (140 of 644), respectively, with the case definition of 1 positive smear and the 1 AFB/100 HPF cutoff (P < .001), and 21.4% (138 of 644) versus 18.6% (120 of 644), respectively, with the case definition of 1 positive smear and the 10 AFB/100 HPF cutoff (P < .001). Inter- and intrareader reproducibility were favorable, with kappa coefficients of 0.83 and 0.91, respectively. Bleach sedimentation was relatively inexpensive and was not time consuming. CONCLUSIONS: Bleach sedimentation microscopy is an effective, simple method to improve the yield of smear microscopy in a setting of high prevalence of HIV. Further evaluation of this method, under operational conditions, is urgently needed to determine its potential as a tool for tuberculosis control.en
dc.language.isoenen
dc.publisherInfectious Diseases Society of Americaen
dc.relation.urlhttp://www.journals.uchicago.edu/CID/en
dc.rightsArchived on this site with permission and copyright 2008 by the Infectious Diseases Society of Americaen
dc.subject.meshBacteriological Techniquesen
dc.subject.meshDiagnosisen
dc.subject.meshDiagnostic Techniques, Respiratory Systemen
dc.subject.meshHIVen
dc.subject.meshKenyaen
dc.subject.meshMycobacterium tuberculosisen
dc.subject.meshSpecimen Handlingen
dc.subject.meshSputumen
dc.subject.meshTuberculosisen
dc.subject.meshTuberculosis, Pulmonaryen
dc.subject.meshUrban Populationen
dc.subject.meshWorkloaden
dc.titleBleach sedimentation: an opportunity to optimize smear microscopy for tuberculosis diagnosis in settings of high prevalence of HIVen
dc.typeArticleen
dc.contributor.departmentEpicentre, Paris, France; Médecins Sans Frontières, Paris, France; Liverpool School of Tropical Medicine, Liverpool, United Kingdom; Centre for Respiratory Diseases Research, Kenya Medical Research Institute, Nairobi, Kenyaen
dc.identifier.journalClinical Infectious Diseasesen

Related articles on PubMed

All Items in MSF are protected by copyright, with all rights reserved, unless otherwise indicated.