Antimicrobial susceptibility determined by the E test, Löwenstein-Jensen proportion, and DNA sequencing methods among Mycobacterium tuberculosis isolates discrepancies, preliminary results
AUTOR(ES)
Freixo, Maria Inês Moura, Caldas, Paulo CS, Said, Abbadi, Martins, Fátima, Brito, Rossana Coimbra, Fonseca, Leila de Souza, Saad, Maria Helena Féres
FONTE
Memórias do Instituto Oswaldo Cruz
DATA DE PUBLICAÇÃO
2004-02
RESUMO
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.
Documentos Relacionados
- Nalidixic Acid as a Decontaminant in Löwenstein-Jensen Medium
- Comparison of Recoveries of Mycobacterium tuberculosis Using the Automated BACTEC MGIT 960 System, the BACTEC 460 TB System, and Löwenstein-Jensen Medium
- BLOOD MEDIA FOR THE CULTIVATION OF MYCOBACTERIUM TUBERCULOSIS VII. : Comparison of Blood Agar-Penicillin and Lowenstein-Jensen Media under Routine Diagnostic Conditions
- Comparison of improved BACTEC and Lowenstein-Jensen media for culture of mycobacteria from clinical specimens.
- Recovery of mycobacteria from blood in mycobacteria growth indicator tube and Lowenstein-Jensen slant after lysis-centrifugation.