Susceptibility pattern of Mycobacterium tuberculosis over a period of five years at Indus Hospital and Health Network, Karachi, Pakistan

Objective: To determine the susceptibility pattern and frequency of isolation of multidrug, pre-extensively drug and extensively drug resistant TB in a tertiary care hospital in Karachi, Pakistan.

Method: A cross-sectional study was designed. Samples received in the lab were processed for growth and sensitivity testing of Mycobacterium tuberculosis. Isolation of MTB was done on Mycobacteria growth indicator tube (MGIT) followed by identification using MPT64. Samples were than evaluated for drug sensitivity against first and second-line antimycobacterial drugs. Statistical analysis was performed using SPSS version 24.0.

Results: Of the 20014 samples received, 23.1% were identified as Mycobacterium tuberculosis. Drug sensitivity testing was performed on 95.9% isolates. Fifty-two percent samples were from males and 48% female patients. The study found statistically non-significant relationship between gender and likelihood of disease with drug-resistant (DR)-MTB organisms. The rate of isolation of MDR-TB was highest (43%) among ages 25-55 years and previously treated patients compared to newly diagnosed patients (62% vs 36%). Among MTB positive samples, 91.5% were pulmonary while 8.5% were extrapulmonary samples. Extrapulmonary samples were more likely to be sensitive to antimycobacterial drugs. The highest resistance was observed against Isoniazid (pulmonary=58%; extrapulmonary=12.7%), Rifampicin (pulmonary=58.7%; extrapulmonary=8.2%), and Levofloxacin (pulmonary=29.2%; extrapulmonary=20%).

Conclusion: A considerable number of drug resistant tuberculosis cases were identified in the present study. It is essential to develop further strategies to reduce the spread of this disease.