ABSTRACT
SETTING: A non-governmental organisation (NGO) supported tuberculosis control programme in Bangladesh with good smear microscopy. OBJECTIVE: To verify whether bleach sedimentation method increases the sensitivity of sputum smear microscopy for acid-fast bacilli (AFB), and if so, how. DESIGN: Duplicate smears from successive routine specimens, peripheral centres examining direct smears, and blind examination of bleach sediment smears at central laboratories. RESULTS: When all 3,287 sputum samples were examined in duplicate and the International Union Against Tuberculosis and Lung Disease cut-off for positivity was applied, more positives were not found by bleach sedimentation. Using the much lower American Thoracic Society (ATS) threshold, the percentage positives rose slightly from 15.5% for direct smear to 16.6% after bleach. The gain was more evident when suspect examinations only were taken into consideration, as bleach missed many positives identified by direct follow-up smear. When patients rather than individual smears were counted, more suspects were detected by bleach (10% gain on average), but with considerable variation between the centres (range 6-16%). To arrive at this gain, the ATS cut-off was used, with corrections for false results. Under routine conditions, however, this threshold is too low in view of possible transfer of AFB. CONCLUSIONS: Bleach sedimentation can increase the diagnostic yield, but only to a minor extent if all other factors have been optimised already; it is not a panacea. Precautions against false negatives as well as false positives should be taken, and the additional workload is not negligible.
Subject(s)
Bacteriological Techniques , Mycobacterium tuberculosis , Sodium Hypochlorite , Specimen Handling/methods , Sputum/microbiology , Tuberculosis, Pulmonary/diagnosis , Tuberculosis, Pulmonary/microbiology , Bangladesh , Bias , Colony Count, Microbial , False Negative Reactions , False Positive Reactions , Humans , Microscopy , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
A 14 year old boy is presented who was admitted to the psychiatric ward because of delirium. He also had gynaecomastia, facial oedema, striae, and hypertension. He was finally proved to have a mixed oestrogen and cortisol producing adrenal tumour which was removed surgically with complete improvement and no relapse.
