Drug resistance patterns of mycobacterium tuberculosis complex and associated factors among retreatment cases at jimma university specialized hospital, south west Ethiopia

Abstract

Background: The global burden of tuberculosis(TB) has been accompanied with the emergence of multidrug-resistant tuberculosis(MDR-TB).The rate of MDR-TB is five times higher among previously treated tuberculosis cases than new cases. There is a need to determine the level of drug resistant TB among these patients. Objective: The objective of this study was to determine drug resistance patterns of Mycobacterium tuberculosis complex isolates among previously treated TB cases at Jimma University specialized Hospital, south west Ethiopia. Methods: A prospective cross-sectional study was conducted from March 2012 to April 2013. A total of 79 smear positive previously treated TB cases were enrolled in to the study. Structured questionnaire and patients medical records were used to collect participant‟s socio-demographic and clinical data. Sputum specimens were collected and cultured in to the modified middlebrook 7H9 broth media. Identification of Mycobacterium tuberculosis complex was done by paranitrobenzoic acid (500 μg/ml) inhibition test. Drug susceptibility testing was done to four first line drugs ( streptomycin 1μg/ml , isoniazid 0.1μg/ml , rifampicin 1μg/ml and ethambutol 5μg/ml) in modified middlebrook 7H9 broth media by BACTEC /MGIT 960 system using indirect proportion method. Data were analyzed using SSPS version20. Results: 70 Mycobacterium tuberculosis complex isolates were tested for drug susceptibility patterns. Out of these 41/70 (58.6%) isolates were resistant to one or more drugs. Any drug resistance to isoniazid 36/70 (51.4%) was found to be the most common. Factors associated with any drug resistance were, residence place (AOR: 3.44, 95%: CI 1.11, 10.60, p=0.032), duration of illness (AOR: 3.4, 95%: CI 1.10, 10.62, p=0.035) and number of treatment before this episode (AOR: 2.99, 95%: CI 1.01, 8.86, p=0.048). The prevalence of MDR-TB was 22/70(31.4%). Patients with the history of treatment failures were 3.4 times more likely to have MDR-TB than relapse cases (AOR: 3.43, 95% CI: 1.14, 10.28, p=0.028). All of the MDR-TB isolates were resistant to either streptomycin or ethambutol. A total of 12/70(17.1%) MDR-TB isolates were resistant to all four first-line drugs. About 97.5% of rifampicin resistant isolates were MDR-TB. Conclusion and recommendation: In this study, the prevalence of any drug resistance and MDR-TB were high. MDR-TB showed statistically significant association treatment failures. Patients‟ compliance to full course therapy should be supervised .Treatment failures should timely be identified and referred for culture and drug susceptibility testing.