Journal Article

Characterization of the MacA–MacB efflux system in <i>Neisseria gonorrhoeae</i>

Corinne E. Rouquette-Loughlin, Jacqueline T. Balthazar and William M. Shafer

in Journal of Antimicrobial Chemotherapy

Published on behalf of British Society for Antimicrobial Chemotherapy

Volume 56, issue 5, pages 856-860
Published in print November 2005 | ISSN: 0305-7453
Published online September 2005 | e-ISSN: 1460-2091 | DOI:
Characterization of the MacA–MacB efflux system in Neisseria gonorrhoeae

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  • Medical Oncology
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Objectives: A homologue of the MacA–MacB ABC transporter of Escherichia coli, which recognizes and exports macrolides, was identified in Neisseria gonorrhoeae. This study was undertaken to determine whether gonococci could use the MacA–MacB homologue to express decreased susceptibility to macrolides.

Methods: Techniques of DNA sequencing, gene cloning and expression of recombinant proteins in E. coli, gene mutation construction, transcriptional analysis and antimicrobial susceptibility testing were used in the study.

Results: Although the gonococcal MacA–MacB efflux pump enhanced bacterial resistance to macrolides when overexpressed in an E. coli background, its loss in a gonococcal clinical isolate only slightly decreased bacterial resistance to azithromycin and erythromycin. However, a mutation in the −10 sequence of the promoter used in macAB expression enhanced the macrolide resistance of gonococci that produced a defective MtrC–MtrD–MtrE pump, which also recognizes macrolides.

Conclusions: The results from this study indicate that gonococci can employ both the MacA–MacB and MtrC–MtrD–MtrE efflux pumps to develop resistance to macrolides, particularly if mutations develop in the promoter that drives transcription of macAB.

Keywords: gonococci; macrolides; resistance; efflux; regulation

Journal Article.  4010 words.  Illustrated.

Subjects: Medical Oncology ; Critical Care

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