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.
