Journal Article

<i>mef</i>(A), <i>mef</i>(E) and a new <i>mef</i> allele in macrolide-resistant <i>Streptococcus</i> spp. isolates from Norway

Maria Sangvik, Pia Littauer, Gunnar Skov Simonsen, Arnfinn Sundsfjord and Kristin Hegstad Dahl

in Journal of Antimicrobial Chemotherapy

Published on behalf of British Society for Antimicrobial Chemotherapy

Volume 56, issue 5, pages 841-846
Published in print November 2005 | ISSN: 0305-7453
Published online September 2005 | e-ISSN: 1460-2091 | DOI:
mef(A), mef(E) and a new mef allele in macrolide-resistant Streptococcus spp. isolates from Norway

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  • Medical Oncology
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Objectives: To type mef genes in a nationwide collection of clinical isolates of Streptococcus pneumoniae and Streptococcus pyogenes as well as pharyngeal carrier strains of viridans streptococci in Norway.

Methods: Erythromycin-resistant mef-positive multilocus sequence-typed (MLST) clinical isolates of S. pneumoniae (n = 36) and S. pyogenes (n = 12) from the National Surveillance Program for Antimicrobial Resistance (NORM) as well as viridans streptococci (n = 20) from healthy adults were included. PCR-amplified mef genes were initially discriminated by BamHI digestion. Selected mef genes from representatives of different sequence types (STs) of S. pneumoniae (n = 11) and S. pyogenes (n = 4), and viridans group streptococcal species (n = 8) were typed by sequencing and their strains examined for co-resistances. Hydropathy plots of different mef-encoded proteins were performed.

Results: A predominance of mef(A) was detected in S. pneumoniae (23/36) and S. pyogenes (9/12) due to the clonal spread of ST9 and ST39, respectively. mef(E) was the most widely distributed mef determinant occurring in nine different STs of S. pneumoniae and in four different viridans species. A new mef allele was identified in two STs of S. pyogenes.

Conclusions: mef(E) is the most widely distributed mef determinant in Norwegian clinical strains of S. pneumoniae and pharyngeal carrier strains of various viridans streptococci. However, mef(A) is more prevalent in S. pneumoniae and S. pyogenes due to clonal spread. A new mef allele was found in two different STs of S. pyogenes.

Keywords: macrolide efflux; erythromycin; M-type resistance; Major Facilitator Superfamily

Journal Article.  3879 words.  Illustrated.

Subjects: Medical Oncology ; Critical Care

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