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Mutations Prevalent among Rifampin- and Isoniazid-Resistant Mycobacterium tuberculosis Isolates from a Hospital in Vietnam

By M. Caws, Phan Minh Duy, Dau Quang Tho, Nguyen Thi Ngoc Lan, Dai Viet Hoa and Jeremy Farrar

Abstract

Vietnam is ranked 13th among the WHO list of 22 high-burden countries, based upon estimated total number of tuberculosis cases. Despite having a model national tuberculosis program, consistently achieving and exceeding WHO targets for detection and cure, drug-resistant and multidrug-resistant tuberculosis cases continue to rise. Rapid multidrug-resistant tests applicable in this setting, coupled with effective treatment regimens, would be a useful tool in reversing this trend, allowing early identification of patients with multidrug-resistant tuberculosis and avoiding resistance-amplifying regimens. Sequencing of consecutive isolates identified by the National Tuberculosis Program showed 89% of isoniazid-resistant isolates could be detected by targeting just 2 codons, katG 315 and −15C→T in the inhA promoter, while rifampin resistance will be more complex to detect, with many different mutation and insertion events in rpoB. The most prevalent rifampin resistance-conferring mutations, as in other countries, were in rpoB codons 531 (43%), 526 (31%), and 516 (15%). However, a hybridization-based resistance test with probes targeting the 5 most common mutations would only detect 78% of rifampin-resistant isolates. Overall, these data suggest that rifampin resistance may be used as a surrogate marker for multidrug-resistant tuberculosis and that a sensitivity of between 70 to 80% may be possible for rapid molecular detection of multidrug-resistant tuberculosis in this setting

Topics: Mycobacteriology and Aerobic Actinomycetes
Publisher: American Society for Microbiology
OAI identifier: oai:pubmedcentral.nih.gov:1489476
Provided by: PubMed Central
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