Ethidium bromide transport across Mycobacterium smegmatiscell-wall: correlation with antibiotic resistance

BMC Microbiology

Research Article

Jorge Ramos¹  Isabel Couto²  Miguel Viveiros³  Liliana Rodrigues⁴  Leonard Amaral⁵ 

[1] Unit of Mycobacteriology, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Rua da Junqueira 100, 1349-008, Lisboa, Portugal;Unit of Mycobacteriology, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Rua da Junqueira 100, 1349-008, Lisboa, Portugal;Centro de Recursos Microbiológicos (CREM), Faculdade de Ciências e Tecnologia, UNL, 2829-516, Caparica, Portugal;Unit of Mycobacteriology, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Rua da Junqueira 100, 1349-008, Lisboa, Portugal;Cost Action, BM0701, (ATENS;Unit of Mycobacteriology, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Rua da Junqueira 100, 1349-008, Lisboa, Portugal;UPMM, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Rua da Junqueira 100, 1349-008, Lisboa, Portugal;Unit of Mycobacteriology, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Rua da Junqueira 100, 1349-008, Lisboa, Portugal;UPMM, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Rua da Junqueira 100, 1349-008, Lisboa, Portugal;Cost Action, BM0701, (ATENS;

关键词: Verapamil;    Efflux Pump;    Ethambutol;    EtBr;    Thioridazine;   

DOI  :  10.1186/1471-2180-11-35

 received in 2010-09-22, accepted in 2011-02-18,  发布年份 2011

来源: Springer

【 摘 要 】

BackgroundActive efflux systems and reduced cell-wall permeability are considered to be the main causes of mycobacterial intrinsic resistance to many antimicrobials. In this study, we have compared the Mycobacterium smegmatis wild-type strain mc2155 with knockout mutants for porins MspA (the main porin of M. smegmatis) and MspC, the efflux pump LfrA (the main efflux pump system of M. smegmatis) and its repressor LfrR for their ability to transport ethidium bromide (EtBr) on a real-time basis. This information was then correlated with minimum inhibitory concentrations (MICs) of several antibiotics in the presence or absence of the efflux inhibitors chlorpromazine, thioridazine and verapamil.ResultsIn the absence of porins MspA and MspC, accumulation of ethidium bromide decreased and the cells became more resistant to several antibiotics, whereas the knockout mutant for the LfrA pump showed increased accumulation of EtBr and increased susceptibility to EtBr, rifampicin, ethambutol and ciprofloxacin. Moreover, the efflux inhibitors caused a reduction of the MICs of streptomycin, rifampicin, amikacin, ciprofloxacin, clarithromycin and erythromycin in most of the strains tested.ConclusionsThe methodology used in this study demonstrated that porin MspA plays an important role in the influx of quaternary ammonium compounds and antibiotics and that efflux via the LfrA pump is involved in low-level resistance to several antimicrobial drugs in M. smegmatis. The results obtained with this non-pathogenic mycobacterium will be used in future studies as a model for the evaluation of the activity of the same efflux inhibitors on the susceptibility of multidrug resistant strains of Mycobacterium tuberculosis to isoniazid and rifampicin.

【 授权许可】

Unknown   
© Rodrigues et al; licensee BioMed Central Ltd. 2011. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.