Erythromycin Resistance and Genetic Elements Carrying Macrolide Efflux Genes in Streptococcus agalactiae

Abstract

The macrolide resistance determinants and genetic elements carrying the mef(A) and mef(E) subclasses of the mef gene were studied with Streptococcus agalactiae isolated in 2003 and 2004 from 7,084 vaginorectal cultures performed to detect carrier pregnant women. The prevalence of carriage was 18% (1,276 isolates), and that of erythromycin resistance 11.0% (129 of the 1,171 isolates studied). erm(B), erm(A) subclass erm(TR), and the mef gene, either subclass mef(A) or mef(E), were found in 72 (55.8%), 41 (31.8%), and 12 (9.3%) erythromycin-resistant isolates, while 4 isolates had more than 1 erythromycin resistance gene. Of the 13 M-phenotype mef-containing erythromycin-resistant S. agalactiae isolates, 11 had the mef(E) subclass gene alone, one had both the mef(E) and the erm(TR) subclass genes, and one had the mef(A) subclass gene. mef(E) subclass genes were associated with the carrying element mega in 10 of the 12 mef(E)-containing strains, while the single mef(A) subclass gene found was associated with the genetic element Tn1207.3. The nonconjugative nature of the mega element and the clonal diversity of mef(E)-containing strains determined by pulsed-field gel electrophoresis suggest that transformation is the main mechanism through which this resistance gene is acquired.

Diversity and Mobility of Integrative and Conjugative Elements in Bovine Isolates of S treptococcus agalactiae , S. dysgalactiae subsp. dysgalactiae , and S. uberis

“…The predominance of erm(B) resistance genes in S. agalactiae was already reported by several authors (35,38,53). All of the macrolide-resistant strains of S. uberis and S. dysgalactiae also carry an erm(B) gene.…”

Characterization of Multidrug-Resistant Group B Streptococci with Reduced Penicillin Susceptibility Forming Small Non-Beta-Hemolytic Colonies on Sheep Blood Agar Plates

“…In addition, these isolates harbored several amino acid substitutions in the quinolone resistance-determining regions of GyrA, GyrB, and ParC, which were reported to be responsible for fluoroquinolone resistance in GBS (8,11). Furthermore, an erm(B) gene, which confers resistance to macrolides and lincosamides (12,13), was detected by PCR (see Table S1 in the supplemental material). Therefore, these isolates were characterized as multidrug-resistant PRGBS.…”

Antimicrobial resistance and virulence-related genes ofStreptococcusobtained from dairy cows with mastitis in Inner Mongolia, China

“…PCR was used to amplify mefA and ermB genes encoding resistance to erythromycin (Marimón et al, 2005), tetM, tetO, tetL, and tetK conferring resistance to tetracycline (Lopardo et al, 2003), pbp2b gene contributing to penicillin resistance (Charpentier & Tuomanen, 2000). Primers, amplicon size, and annealing temperatures are listed in Table 1; PCR was performed using the same conditions as used to identify Streptococcus species.…”