Prevalence of primary multidrug resistance to anti-tuberculosis drugs in Pakistan

SETTING: Pakistan ranks sixth in the world in terms of tuberculosis (TB) burden, with a World Health Organization estimated incidence of 181 per 100 000, or 286 000 new cases annually. Hospital-based data indicate a significant problem of multidrug-resistant TB (MDR-TB) in the country and highlight the need to assess its extent at community level. In this cross-sectional study, sputum samples from 742 untreated newly diagnosed pulmonary TB patients from all over the country were used. OBJECTIVE: To assess the prevalence of primary drug resistance in Pakistan. RESULTS: Of 672 culture-positive patients, 76 (11.3%) showed resistance to one or more drugs. Resistance to streptomycin (10 μg/ml) was found in 36 (5.4%) patients, isoniazid (INH) (1 μg/ml) in 51 (7.6%), rifampicin (RMP) (5 μg/ml) in 15 (2.2%), ethambutol (10 μg/ml) in 12 (1.8%) and pyrazinamide in 22 (3.3%) samples. Forty-six (6.8%) of the isolates tested were resistant to a single drug, 10 (1.5%) to two drugs, 12 (1.8%) to three drugs, and 6 (0.9%) to four drugs, while 2 (0.3%) isolates were resistant to all five first-line agents. Primary MDR-TB was 1.8% (n = 12) (INH 1 μg/ml, RMP 5 μg/ml). CONCLUSION: The results of this study show a prevalence of primary MDR-TB in Pakistan of <2%, which needs to be addressed through an effective DOTS strategy.