Ethambutol resistance of indigenous Mycobacterium tuberculosis isolated from human patients

The present study was conducted to find out the ethambutol resistance pattern of indigenous isolates of Mycobacterium tuberculosis from Tuberculosis diagnosed human patients. A total of 172 specimens were collected from six different sources and comprised of 84.9% sputum, 10.5% pus and 4.7% bronchial washings. There were 70.9% males and 29.1% females with 84.30% pulmonary and 15.69% extra-pulmonary tuberculosis. The Mycobacterium tuberculosis isolates collected from primary culture were further studied to determine their pattern and level of resistance. The inoculums were prepared using 0.5 Mac Farland turbidity standards. Five different concentration of ethambutol were used in Lowenstein Jensen (LJ) medium i.e. 2µg/ml, 4µg/ml, 6µg/ml, 8µg/ml and 10µg/ml for sensitivity testing. Data showed 10 (5.8%) resistant and 162 (94.2%) sensitive Mycobacterium tuberculosis out of total 172 clinical isolates. The growth was not inhibited at 1(st) (2µg/ml) and 2(nd) (4µg/ml) drug levels, while growth of 50% isolates inhibited at 3(rd) level (6µg/ml), 30% inhibited at 4(th) level (8µg/ml) and 20% at 5(th) level (10µg/ml). The last three levels are above the therapeutic index and not recommended in actual clinical practice. It is thus conceivable to explore some other more effective chemotherapeutic agents, modify combinations or find more effective procedures to stop morbidity and mortality due to ethambutol resistant Mycobacterium tuberculosis.