Laboratory Diagnosis of Pulmonary Tuberculosis: A Comparison of Different Methods.

Abstract

A laboratory study designed to compare the sensitivity of microscopy (direct and concentrated smears): Direct and Concentrated sputum culture as well as comparing Ziehl-Neelsen and Auramine-Phenol staining methods in the diagnosis or pulmonary tuberculosis was carried out. The survey involved one hundred and Eighty Six (180) new patients seen at the chest and General Out-patient clinics of the Jos Universitv Teaching Hospital (JUTH) and the out-patient Department of the Evangel Hospital Jos. with symptoms of broncho-pulmonary disorders and who were sent to the Microbiology Laboratory for Acid fast bacilli (AFB) Microscopy between February, 1996 and November. I<)1)7. Also included were one hundred and thirty (130) sputum smears made from different samples sent to the laboratory Within the same period. A total of 55 (29.57%) patients were positive for acid fast bacilli by both microscopy and culture methods. Thirty-eight, 38 (69.1 %) of the 55 positive cases were detected by direct smear. 43 (78.2%) by concentrated smear, 16 (29.1 %) by direct sputum culture and 33 (60.0%) by concentrated sputum culture. The difference between a single concentrated smear, 78.2% and 3 consecutive direct smears (69.1 %) for identifying tubercle bacilli was not statistically significant (P>0.05) but was significantly different from 60.0% for concentrated culture and 28.57% direct culture (P<0.05). Concentrated sputum smear examination for routine diagnosis of pulmonary tuberculosis is indicated