Patterns of Initial Drug Resistance of Mycobacterium tuberculosis Isolates from Kashmir Valley, India

Aims: We carried out this study to determine the patterns of initial drug resistance in Mycobacterium tuberculosis isolates and prevalence of MDR-TB among category-I pulmonary TB patients in Kashmir Valley. MDR-TB was defined as tuberculosis caused by bacilli showing resistance to at least isoniazid and rifampicin.

Study Design: Prospective study.

Place and Duration of Study: Department of Microbiology, Sher-i-Kashmir Institute of Medical Sciences, Srinagar, Kashmir, J&K, India between May 2007 and April 2010.

Methodology: This study involved 300 category-I pulmonary TB patients attending DOTS clinics in different districts of Kashmir Valley. AFB positive sputum samples were randomly collected in 1% cetylpyridinium chloride from such patients and were subjected to repeat AFB staining and mycobacterial culture in Department of Microbiology, SKIMS. Drug susceptibility testing (DST) to the first line drugs; isoniazid, rifampicin, ethambutol and streptomycin was performed on cultures identified as Mycobacterium tuberculosis using the indirect proportion method on LJ medium.

Results: Out of 300 samples, culture results were available only for 207 samples. Out of 207 samples, 134 (64.73%) were culture positive, 52 sterile (25.12%) and 21(10.14%) showed contamination. Out of the 134 isolates, 123 were identified as MTB and 11 as mycobacteria other than tuberculosis (MOTT). Of the 101 DST results available, 74.25% were sensitive to all four first line drugs, 17.82% showed monoresistance, 7.92% showed polyresistance and 3.96% were MDR.

Conclusion: Resistance to any one drug was 39.60% with a high streptomycin resistance of 20.79%. Since most of these patients harboured organisms susceptible to isoniazid and rifampicin, standard short-course chemotherapy is likely to remain highly effective among the great majority of new TB patients in Kashmir Valley. Prevalence of MDR was relatively low but with a high rifampicin resistance of 6.93% there is a need for restricting use of rifampicin (supervised therapy only for TB and leprosy). It is important to strengthen the capacity of laboratories in Kashmir Valley for TB culture and DST for correct management of TB patients and to prevent emergence of drug resistance. Also, continuous monitoring of resistance in both new and previously treated TB cases needs to be done to know the changing trend of drug resistance in future.