oa Southern African Journal of Epidemiology and Infection - Molecular characterisation of resistant Mycobacterium tuberculosis isolates from Dr George Mukhari Hospital, Pretoria, South Africa : original research
Drug-resistant tuberculosis is a serious problem throughout the world. Resistance to rifampicin (RIF) and isoniazid (INH) is due to mutations in the rpoB and katG genes, respectively. The distribution of rpoB and katG gene mutations in RIF- and INH-resistant clinical Mycobacterium tuberculosis (MTB) isolates from Dr George Mukhari Hospital, Garankuwa, South Africa was determined. The rpoB and katG genes were amplified using PCR and sequenced. Among the 240 resistant MTB isolates obtained, 143/240 (59.6%) were multidrug-resistant (MDR), defined as resistance to INH and RIF, 44/240 (18.3%) were resistant to INH and 4.6% (11/240) to RIF while 17.5% (42/240) isolates were resistant to a combination of drugs. A total of 67.1% (161/240) isolates had mutations in the rpoB region. The most frequent mutations encountered were at codon 516 GAC to GTC 42.2% (68/161), codon 526 CAC to GAC 37.3% (60/161), and the least, at codon 531 TCG to TTG 0.6% (1/161). Codon 315 in the katG gene showed mutations in 70% (168/240) isolates resistant to INH. Of these, 58.3% (98/168) isolates showed a mutational change from AGC to ACC, 23.8% (40/168) from AGC to AAC, AGC to ATC in 10.1% (17/168), AGC to CGC in 4.8% (8/168) and AGC to ACA 3% (5/168) while mutations in codon 314 contributed 9.6% (20/209) with the change from ACC to CCC. This study provided information on the genetic diversity of multidrug-resistant MTB strains as well as the effects it can take on the clinical management of patients.
Article metrics loading...