Primary drug resistance in newly diagnosed smear positive tuberculosis patients in Addis Ababa, Ethiopia.

BACKGROUND

Drug resistance monitoring is an important aspect of tuberculosis (TB) control.

OBJECTIVE

To determine the sensitivity of mycobacterial isolates from newly diagnosed pulmonary TB patients to first line anti-TB drugs in Addis Ababa.

METHODS

A survey on primary anti-tuberculosis drug resistance was conducted on smear positive pulmonary TB patients visiting 19 health centers and 3 hospitals in Addis Ababa from September 2004 to December 2005. Sputum was digested and decontaminated using Petroff's method and inoculated on Lowenstein-Jensen (LJ) media. Mycobacterial isolates were tested for sensitivity to isoniazid, rifampicin, ethambutol and streptomycin on Middlebrook 7H10 media using the standard indirect proportion method.

RESULTS

Among the M. tuberculosis strains isolated from 173 patients, 21.4% were resistant to at least one drug. Single drug resistance to streptomycin was observed in 16.2%, to isoniazid in 13.3%, to rifampicin in 1.2% and to ethambutol in 3.5% of the isolates. The prevalence of resistance to at least one drug was 15.7% and 23.7% among patients with and without HIV co-infection, respectively (p > 0.05). Only one patient (0.6%) had a multidrug resistant (MDR) strain. However, the prevalence of resistance to more than one drug was 10.4%.

CONCLUSION

Although the prevalence of MDR was low in this study, the precursors of MDR are accumulating in Addis Ababa.