Epidemiological features of drug resistant tuberculosis in Harare, 1994 to 1996

To characterise the prevalence, clinical and radiological features of drug resistant tuberculosis in selected patients with pulmonary tuberculosis in Harare between 1994 and 1996.

A retrospective review of medical and microbiological records.

Beatrice Road Infectious Diseases Hospital, Harare, Zimbabwe.

381 smear-positive tuberculosis patients who had samples submitted to the National Tuberculosis Reference Laboratory for culture and susceptibility testing.

Prevalence of resistance of isolated cultures of Mycobacterium tuberculosis to anti-tuberculosis drugs; clinical, radiological and microbiological response to treatment with recommended anti-tuberculosis regimens.

Resistance to one or more drugs was detected in 16 isolates (16/165, 9.7%), single drug resistance in five (3.0%) and resistance to two or more drugs in 11 (6.7%). There were no distinctive clinical or radiological features of drug-resistant tuberculosis, although a higher percent of drug resistant cases had evidence of pleural disease (25% vs 2.5%, p = 0.005). Neither past history of tuberculosis or known or suspected HIV infection was associated with the presence of drug resistance.

In spite of the resurgence of tuberculosis and the high prevalence of HIV infection in Zimbabwe, the rates of drug resistance have remained relatively low, even among a selected population at high risk of resistance. A significant proportion of cases of drug-resistant tuberculosis appear to be due to new transmission of drug resistant strains, which reinforces the importance of maintaining a surveillance system for the monitoring of drug susceptibility. Ongoing prospective studies should provide more reliable estimates of the prevalence and determinants of drug resistance in Zimbabwe.