Background: Drug resistance levels and patterns among Mycobacterium tuberculosis isolates from newly diagnosed and previously treated tuberculosis patients in Mbarara Uganda were investigated.
Methods: We enrolled, consecutively, all newly diagnosed and previously treated smear-positive TB patients aged >/= 18 years. Isolates were tested for drug resistance against rifampicin (RIF) and isoniazid (INH) using the Genotype(R) MDRTBplus assay and results were compared with those obtained by the indirect proportion method on Lowenstein-Jensen media. HIV testing was performed using two rapid HIV tests.
Results: A total of 125 isolates from 167 TB suspects with a mean age 33.7 years and HIV prevalence of 67.9% (55/81) were analysed. A majority (92.8%) of the participants were newly presenting while only 7.2% were retreatment cases. Resistance mutations to either RIF or INH were detected in 6.4% of the total isolates. Multidrug resistance, INH and RIF resistance was 1.6%, 3.2% and 4.8%, respectively. The rpobeta gene mutations seen in the sample were D516V, S531L, H526Y H526 D and D516V, while one strain had a Delta1 mutation in the wild type probes. There were three strains with katG (codon 315) gene mutations while only one strain showed the inhA promoter region gene mutation.
Conclusion: The TB resistance rate in Mbarara is relatively low. The GenoType(R) MTBDRplus assay can be used for rapid screening of MDR-TB in this setting.