Background: Resistance to first line anti-tuberculosis (TB) drugs is an increasing concern. Drug sensitivity of mycobacterial isolates from patients who failed treatment may indicate the potential sources of spread and the emerging patterns of resistance.
Objective: To determine the prevalence of resistance to the main anti TB drugs among re-treatment cases who had previously received loose drugs or the 3FDC regimen in the intensive phase.
Methods: Mycobacteria were isolated on Lowenstein-Jensen media from sputum of smear positive pulmonary TB patients who visited the St Peter's TB Specialized Hospital, a referral TB Hospital in Addis Ababa, for retreatment between December 2001 and October 2002. The susceptibility of isolates to rifampicin, isoniazid ethambutol and streptomycin was tested using the standard modified proportion method
Result: Of the 84 Mycobacterium tuberculosis isolates, resistance to at least one drug was observed in 53.6% and 26.2% of the isolates were multi drug resistant (MDR). MDR was more frequent among patients who had previously been treated with the 3FDC regimen than among patients previously treated with loose drugs (p < 0.05). The proportion of strains resistant to rifampicin and ethambutol was significantly higher than in an earlier report from Addis Ababa.
Conclusion: MDR is an emerging problem among re-treatment cases of pulmonary TB in Addis Ababa. The problem of drug resistance should be addressed by operational research on drug regimens, effectiveness and delivery.