Resistance to Antituberculosis Drugs in Pulmonary Tuberculosis

Abstract

Background: Incidence of drug resistance and pattern of susceptibility to antitubercular drugs in pulmonary tuberculosis amongst soldiers and their families was studied for four years at a military hospital in northwest India.

Methods: Identification and susceptibility tests were carried out as per procedures laid out in laboratory manual of Tuberculosis Research Centre (TRC), Chennai.

Results: Of the 172 strains of Mycobacterium tuberculosis (MTB) isolated from sputum samples, 150 (87.21%) were sensitive and 22 (12.79%) showed resistance to one or more antitubercular drugs. Acquired drug resistance was observed in 7 (31.82%) and primary drug resistance in 15 (68.18%) cases. Among 22 drug resistant cases, who were on short course chemotherapy (SCC), resistance to single drug was observed in 12 (54.54%), two drugs in 7 (31.82%) and to three or more drugs in 3 (13.64%) isolates. Fourteen (18.14%) strains were resistant to Streptomycin, 8 (4.65%) to Rifampicin, 11 (6.40%) to Isoniazid, 1 (0.58%) to Pyrazinamide and 2 (1.16%) to Ethambutol. Multidrug resistance was observed in 5 (2.91%) cases, of which resistance to Isoniazid and Rifampicin was present in 2 (1.16%) and their combination with other drugs in other 3 (1.74%) isolates.

Conclusions: Drug susceptibility pattern to antitubercular drugs is discussed and compared with studies from other centres.

Keywords: Antitubercular drugs; Drug resistance; Mycobacterium tuberculosis.