Drug-resistance profile of Mycobacterium tuberculosis to first-line anti-tuberculosis agents in new and previously treated pulmonary tuberculosis patients from Andhra Pradesh, India

Abstract Background: Multidrug-resistant tuberculosis (MDR-TB) is a global public health problem. Methods: We tested 104 strains each of Mycobacterium tuberculosis complex ( Mtb ) isolated from new cases and previously treated cases against four first line anti-tuberculosis agents by proportion method. Results: Of the total 208 cases, 37 (17.8%) had MDR-TB; mono-resistance (8.6%) and overall resistance (32.2%) were highest for isoniazid. In the new patients the overall resistance of the isolates was 50% and of them 13 (12.5%) were MDR-TB. In six cases, we found resistance to all the three common drugs- rifampicin, isoniazid, and ethambutol. Among the previously treated patients, the overall resistance was 57.7% and 24 of them (23.1%) were MDR-TB. The high prevalence of isoniazid resistance is of concern since it considered to be a fore-runner of MDR-TB. Rifampicin resistance without accompanying isoniazid resistance has been found to be very low. Conclusions: Strict adherence to the recent recommendations of National Tuberculosis Elimination Programme (NTEP) to test all rifampicin resistant isolates to other first line agents, and detection of isoniazid monoresistance where rifampicin resistance has not been detected will go a long way to prevent emergence of MDR-TB.