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Please use this identifier to cite or link to this item: http://hdl.handle.net/1807/1991

Title: Antimicrobial Susceptibility Determined by the E Test, Löwenstein-Jensen Proportion, and DNA Sequencing Methods among Mycobacterium tuberculosis Isolates – Discrepancies, Preliminary Results
Authors: Freixo, Maria Inês Moura
Caldas, Paulo C. S.
Said, Abbadi
Martins, Fátima
Brito, Rossana Coimbra
Fonseca, Leila de Souza
Saad, Maria Helena Féres
Keywords: Tropical Diseases
Mycobacterium tuberculosis - susceptibility test - DNA sequencing - E test oc04019
Issue Date: Feb-2004
Publisher: Fundação Oswaldo Cruz, Fiocruz
Citation: Memórias do Instituto Oswaldo Cruz 99(1)
Abstract: Mycobacterium tuberculosis strains resistant to streptomycin (SM), isoniazid (INH), and/or rifampin (RIF) as determined by the conventional Löwenstein-Jensen proportion method (LJPM) were compared with the E test, a minimum inhibitory concentration susceptibility method. Discrepant isolates were further evaluated by BACTEC and by DNA sequence analyses for mutations in genes most often associated with resistance to these drugs (rpsL, katG, inhA, and rpoB). Preliminary discordant E test results were seen in 75% of isolates resistant to SM and in 11% to INH. Discordance improved for these two drugs (63%) for SM and none for INH when isolates were re-tested but worsened for RIF (30%). Despite good agreement between phenotypic results and sequencing analyses, wild type profiles were detected on resistant strains mainly for SM and INH. It should be aware that susceptible isolates according to molecular methods might contain other mechanisms of resistance. Although reproducibility of the LJPM susceptibility method has been established, variable E test results for some M. tuberculosis isolates poses questions regarding its reproducibility particularly the impact of E test performance which may vary among laboratories despite adherence to recommended protocols. Further studies must be done to enlarge the evaluated samples and looked possible mutations outside of the hot spot sequenced gene among discrepant strains.
URI: http://bioline.utsc.utoronto.ca/archive/00000989/01/oc04019.pdf
Appears in Collections:Bioline International Legacy Collection

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