Open AccessPhenotypic and Genotypic Characterization of Streptococcus pyogenes Isolates Displaying the MLS B Phenotype of Macrolide Resistance in Spain, 1999 to 2005
Author(s) -
Emilio Pérez-Trallero,
Milagrosa Montes,
Beatriz Orden,
Esther Tamayo,
José María García-Arenzana,
José María Marimón
Publication year - 2007
Publication title -
antimicrobial agents and chemotherapy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.07
H-Index - 259
eISSN - 1070-6283
pISSN - 0066-4804
DOI - 10.1128/aac.01054-06
Subject(s) - phenotype , genotype , streptococcus pyogenes , biology , microbiology and biotechnology , genetics , streptococcaceae , antibacterial agent , antibiotics , gene , bacteria , staphylococcus aureus
The aim of this study was to describe the genetic characteristics ofStreptococcus pyogenes showing the MLSB phenotype of macrolide resistance from 1999 to 2005 in Spain and to highlight the substantial increase in these isolates in the last few years. The antimicrobial susceptibilities of 17,232 group A streptococci isolated from Madrid and Gipuzkoa from 1999 to 2005 were studied. The presence of the resistance genesermA ,ermB ,mef ,tetM , andtetO and the presence of theintTn andxis genes of the Tn916 -Tn1545 transposon family were studied in a sample of 739 MLSB -resistant isolates. The epidemiological relationships among these isolates were analyzed byemm typing, T typing, and multilocus sequence typing. Erythromycin resistance was found in 21.3% of the isolates analyzed (annual variation of 14.3% to 28.9%). Until 2003, most erythromycin-resistant isolates showed the M phenotype, but in 2004 and 2005, about 50% of isolates showed the MLSB phenotype. Among the MLSB -resistant isolates studied, 16 clones were identified. The most prevalent clone was a strangeemm 11/T11/ST403 clone with a nullyqiL allele. All but one of the 463emm 11/T11/ST403 isolates carried theermB ,tetM ,intTn , andxis genes. The second most prevalent MLSB -resistant clone wasemm 28/T28/ST52, which comprised two subclones: one bacitracin-resistant, tetracycline-susceptible subclone carrying theermB gene (n = 115) and another bacitracin-susceptible, tetracycline-resistant subclone carrying theermB andtetM genes (n = 33). The rapid diffusion of these two clones, and especially ofemm 11/T11/ST403, caused the large increase in MLSB -resistantS. pyogenes isolates in Spain, suggesting a potential ability for international dissemination.