Journal Article

Molecular epidemiology of macrolide resistance in β-haemolytic streptococci of Lancefield groups A, B, C and G and evidence for a new <i>mef</i> element in group G streptococci that carries allelic variants of <i>mef</i> and <i>msr</i>(D)

Maria Rosario Amezaga and Hamish McKenzie

in Journal of Antimicrobial Chemotherapy

Published on behalf of British Society for Antimicrobial Chemotherapy

Volume 57, issue 3, pages 443-449
Published in print March 2006 | ISSN: 0305-7453
Published online January 2006 | e-ISSN: 1460-2091 | DOI: http://dx.doi.org/10.1093/jac/dki490
Molecular epidemiology of macrolide resistance in β-haemolytic streptococci of Lancefield groups A, B, C and G and evidence for a new mef element in group G streptococci that carries allelic variants of mef and msr(D)

More Like This

Show all results sharing these subjects:

  • Medical Oncology
  • Critical Care

GO

Show Summary Details

Preview

Objectives: To study the molecular mechanisms of erythromycin resistance in β-haemolytic streptococci of Lancefield groups A, B, C and G.

Methods: Erythromycin-resistant clinical isolates from North East Scotland were collected over 2 years. Resistance phenotypes were determined by disc diffusion and MICs by Etest. Resistance genes mef, msr(D), erm(B) and erm(TR) were identified by PCR and mef and msr(D) were sequenced.

Results: Erythromycin resistance prevalence was 1.9% in group A streptococci (31 of 1625), 4.3% in group B (53 of 1233), 3.8% in group C (18 of 479) and 6.2% in group G (64 of 1034). The numbers of resistant isolates available were 26, 42, 9 and 52 in each group respectively. The majority of resistant isolates in groups A (57.7%, 15 of 26), B (88.1%, 37 of 42) and G (90.4%, 47 of 52) were MLSB. The contribution of M phenotype was significant in groups C (77.8%, 7 of 9) and A (42.3%, 11 of 26). Group A isolates carried mef(A) and group B carried mef(E) exclusively. A mef sequence distinct from mef(A) and mef(E) was identified in group G and was associated with a new msr(D) sequence. These sequence variants appear to be part of a new genetic element that is inserted in the comEC gene. A bimodal distribution of erythromycin MICs was noted in erm(TR) isolates.

Conclusions: The results demonstrate significant differences in the mechanisms of macrolide resistance amongst different Lancefield groups in the same geographical area. New sequences show that resistance mechanisms are still evolving.

Keywords: M phenotype; MLSB phenotype; erm(B); erm(TR)

Journal Article.  5300 words.  Illustrated.

Subjects: Medical Oncology ; Critical Care

Full text: subscription required

How to subscribe Recommend to my Librarian

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.