Background: Ethiopia is among the high-burden countries of tuberculosis (TB) in the world Since mycobacterial culture and susceptibility testing are not routinely performed in Ethiopia, recent data on susceptibility patterns and the mycobacterial species cultured from sputum smear positive patients are limited.
Objectives: The aim was to determine first line anti-TB drug susceptibility of Mycobacterium tuberculosis isolates obtained from consecutive newly diagnosed smear positive pulmonary TB patients in north west Ethiopia.
Methodology: A retrospective cross sectional study was conducted using previously collected sputum samples (n=180) kept at the referral hospital of the University of Gondar at -20 degrees C. Sputum samples were cultured on Lowenstein Jensen (LJ) medium. Conventional Polymerase Chain Reaction (PCR) using RD4 primers to identify the M. tuberculosis complex was performed on cultured isolates. Ninety eight (84.4%) of the 116 isolates identified as M. tuberculosis were tested for their drug susceptibility pattern using the proportion method Clinical baseline data including body mass index, body temperature, clinical symptoms and erythrocyte sedimentation rate were obtained.
Results: The culture retrieval rate of previously frozen sputum samples was 64.4% (116/180). All the isolated mycobacterial species (n=116) were confirmed as belonging to the M. tuberculosis complex by PCR. Of 98 isolates for which the drug susceptibility test was done, 15.3% (15/98) were found to be resistant to one or more antimycobacterial drugs, and resistance to isoniazid and streptomycin was most common with 8.2% (8/98) and 6.1% (6/98) respectively. TB patients co infected with HIV had increased erythrocyte sedimentation rate, higher age and lower sputum smear grade than HIV negative TB patients.
Conclusions: No mycobacteria other than M. tuberculosis were detected in sputum smear positive TB-patients. Although no multi drug resistant strain was observed, relatively high rates of INH resistance were found in this region. Culture facilities are urgently needed in regional centers to increase diagnostic sensitivity and monitor developing trends of drug resistance in Ethiopia.