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Bonnet, M., Ramsay, Andrew, Githui, W., Gagnidze, L., Varaine, F. and Guerin, P. J. (2008) 'Bleach sedimentation: An opportunity to optimize smear microscopy for tuberculosis diagnosis in settings of high prevalence of HIV'. Clinical Infectious Diseases, Vol 46, Issue 11, pp. 1710-1716.
Full text not available from this repository.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: 110 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.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | pulmonary tuberculosis sputum sensitivity |
| Subjects: | WC Communicable Diseases > Virus Diseases > Acquired Immunodeficiency Syndrome. HIV Infections > WC 503 Acquired immunodeficiency syndrome. HIV infections WF Respiratory System > Tuberculosis > WF 220 Diagnosis. Prognosis |
| Digital Object Identifer (DOI): | https://doi.org/10.1086/587891 |
| Depositing User: | Users 43 not found. |
| Date Deposited: | 24 Aug 2010 11:14 |
| Last Modified: | 15 Jun 2018 14:41 |
| URI: | https://archive.lstmed.ac.uk/id/eprint/736 |
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