Primary drug resistance in pulmonary tuberculosis cases by standard proportion method and BACTEC radiometric method

OBJECTIVE: The objective was to study anti-tubercular drug susceptibility level among 'newly diagnosed' pulmonary tuberculosis (TB) cases by two methods of drug sensitivity testing i.e., standard proportion method (SPM) and BACTEC radiometric method. MATERIALS AND METHODS: Sputum samples from fifty new cases of pulmonary TB were cultured and subjected to antitubercular drug susceptibility testing by using conventional SPM and radiometric method (BACTEC 460 TB system) and compared. RESULTS: Monoresistance was found to be 2%, 8%, 0% and 2% for Streptomycin (S), Isoniazid (H), Rifampicin® and Ethambutol (E), respectively. Any resistance (with or without resistance to other drugs) was 4%, 28%, 10% and 16% for S, H, R and E, respectively. Primary multidrug resistance was 10% (5/50) namely H + R, 6% (3/50); H + R + E, 2% (1/50); H + R + S, 0% (0/50) and H + R + E + S, 2% (1/50). H + E resistance was found in 10% (5/50) of isolates. CONCLUSION: Comparing with other studies, the levels of H, R and multi drug resistance (MDR) were within the expected levels in our study. However, more number of similar studies on drug resistance need to be undertaken regularly to assess the changing trends.