Bleach sedimentation: an opportunity to optimize smear microscopy for tuberculosis diagnosis in settings of high prevalence of HIV
dc.contributor.author | Bonnet, M | |
dc.contributor.author | Ramsay, A | |
dc.contributor.author | Githui, W | |
dc.contributor.author | Gagnidze, L | |
dc.contributor.author | Varaine, F | |
dc.contributor.author | Guerin, P J | |
dc.date.accessioned | 2008-07-14T15:45:25Z | |
dc.date.available | 2008-07-14T15:45:25Z | |
dc.date.issued | 2008-06-01 | |
dc.date.submitted | 2008-06-14 | |
dc.identifier.citation | Clin Infect Dis 2008;46(11):1710-6 | en |
dc.identifier.issn | 1537-6591 | |
dc.identifier.pmid | 18444789 | |
dc.identifier.doi | 10.1086/587891 | |
dc.identifier.uri | http://hdl.handle.net/10144/31935 | |
dc.description.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. | |
dc.language.iso | en | en |
dc.publisher | Infectious Diseases Society of America | en |
dc.relation.url | http://www.journals.uchicago.edu/CID/ | en |
dc.rights | Archived on this site with permission and copyright 2008 by the Infectious Diseases Society of America | en |
dc.subject.mesh | Bacteriological Techniques | en |
dc.subject.mesh | Diagnosis | en |
dc.subject.mesh | Diagnostic Techniques, Respiratory System | en |
dc.subject.mesh | HIV | en |
dc.subject.mesh | Kenya | en |
dc.subject.mesh | Mycobacterium tuberculosis | en |
dc.subject.mesh | Specimen Handling | en |
dc.subject.mesh | Sputum | en |
dc.subject.mesh | Tuberculosis | en |
dc.subject.mesh | Tuberculosis, Pulmonary | en |
dc.subject.mesh | Urban Population | en |
dc.subject.mesh | Workload | en |
dc.title | Bleach sedimentation: an opportunity to optimize smear microscopy for tuberculosis diagnosis in settings of high prevalence of HIV | en |
dc.type | Article | en |
dc.contributor.department | 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 | en |
dc.identifier.journal | Clinical Infectious Diseases | en |
refterms.dateFOA | 2019-03-04T11:14:36Z | |
html.description.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. |