Distribution and Antibiotic Susceptibility Testing of Mycobacterium Species Present in the Sputum of Suspected Pulmonary Tuberculosis Patients

Abstract

The study was carried out at National TB Centre, Thimi, Bhaktapur from September 2010 to August 2011 in collaboration with Central Department of Microbiology, Tribhuvan University with the objective to distribute the mycobacteria isolated from sputum of suspected PTB patients and to obtain their drug susceptibility pattern.

A total of 200 suspected new PTB patients were selected for cross-sectional study, on the basis of Bartlett's Pulmonary Specimen Culture Criteria, by observing sputum samples from 1500 patients. After their consent, Questionnaire was administered and sputum was subjected to ZN, Fluorescent microscopy and Culture; and biochemical and antibiotic susceptibility tests were performed on culture positive isolates. A total of 69% (n=138) sputum samples were positive for Mycobacterium either singly or multiply by ZN microscopy, fluorescent microscopy or culture; of which 90.58% (n=125) were positive by ZN microscopy, 92.75% (n=128) were positive by fluorescent microscopy and 93.48% (n=129) were positive by culture. Among culture positive 87.60% (n=113) strains belong to M. tuberculosis complex, all M. tuberculosis strains; and 12.40% (n=16) belong to NTM of which 81.25% (n=13) were Non-photochromogens, 12.50% (n=2) were Scoto-chromogens, and 11.11% (n=1) rapid grower identified as M. vaccae. Among M. tuberculosis complex only 7.96% (n=9) M. tuberculosis isolates were resistant to anti-tubercular drugs, all MDR, of which 11.11% (n=1) was resistant to INH and RMP only, 22.22% (n=2) were resistant to INH, RMP and STR, and remaining 66.67% (n=6) were resistant to all four anti-tubercular drugs INH, RMP, STR and EMB. Among 16 NTM isolates, 6.25% (n=1) isolate was resistant to INH and STR only, but all other 93.75% (n=15) isolates were resistant to all four anti- tubercular drugs, INH, RMP, STR and EMB. Hence, mycobacterial isolates obtained from suspected pulmonary TB patients, were distributed and drug susceptibility pattern determined.