Spread of an emerging Mycobacterium tuberculosis drug-resistant strain in the Western Cape of South Africa
METHODS: Routine drug susceptibility testing was performed prospectively over a 2-year period on Mycobacterium tuberculosis isolates in two health districts of the Western Province, South Africa. A cluster of drug-resistant strains that shared a rare mutation in katG315 was found in 64 of the 450 cases identified as having been infected with drug-resistant TB. Isolates belonging to this cluster were phenotypically and genotypically characterised. Epidemiological and clinical characteristics were used to identify mechanisms leading to the acquisition and spread of this drug-resistant strain.
RESULTS: An outbreak of an emerging non-Beijing drug-resistant strain infecting 64 pulmonary tuberculosis (PTB) cases was identified. This previously undetected genotype (now designated DRF150) is characterised by five IS6110. insertions, specific spoligotypes and high levels of resistance to the first-line TB medications isoniazid, streptomycin and rifampicin. In 45% of the cases it is also resistant to ethambutol and pyrazinamide. Key factors leading to the development and spread of this drug-resistant genotype were inappropriate chemotherapy, poor adherence to treatment and prolonged periods of infectiousness due to delays in susceptibility testing.
CONCLUSIONS: Molecular markers allowed early identification of an emerging non-Beijing drug-resistant strain.
Document Type: Regular Paper
Affiliations: 1: Department of Science and Technology/National Research Foundation (DST/NRF) Centre for Biomedical TB Research/Medical Research Council (MRC) Centre for Molecular and Cellular Biology, Stellenbosch University, Tygerberg, South Africa 2: Department of Health, Worcester, South Africa 3: National Health Laboratory Services, Cape Town, South Africa 4: Department of Health, George, South Africa 5: Harvard School of Public Health, Boston, Massachusetts, USA 6: Imperial College, London, UK
Publication date: 01 February 2007
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