ABSTRACT
One hundred and seven group B Streptococcus (GBS) isolates and 344 group A Streptococcus (GAS) isolates were collected between 2005 and 2009 from 2 area hospitals and studied for resistance to erythromycin (ERY) and clindamycin (CLI) and the presence of the erm(T) macrolide resistance gene. The erm(T) gene was found in 5 (8%) of 61 erythromycin nonsusceptible GBS isolates and in 22 (55%) of 40 erythromycin nonsusceptible GAS isolates. The erm(T) gene in all 27 GBS/GAS erm(T) gene-positive isolates was located on a plasmid. Three erm(T) gene-positive plasmids were DNA sequenced. Two plasmids (1 each from GBS and GAS isolates) were both 4967 bp in size, contained the erm(T) gene, and differed by only 2 base pairs, suggesting interspecies horizontal transfer of the erm(T) gene containing plasmid. The third (GBS) plasmid was 6825 bp in size and contained GBSi1, a group II bacterial intron, as well as the erm(T) gene. Pulsed-field gel electrophoresis of all 27 erm(T) gene containing isolates and a selection of erm(T) gene-negative isolates indicated possible clonal expansion among erm(T) gene containing GAS isolates, but not among the 5 erm(T) gene-positive GBS isolates.
Subject(s)
Anti-Bacterial Agents/pharmacology , Bacterial Proteins/genetics , Macrolides/pharmacology , Methyltransferases/genetics , Plasmids , Streptococcus agalactiae/drug effects , Streptococcus pyogenes/drug effects , Base Sequence , Drug Resistance, Bacterial/genetics , Gene Order , Humans , Microbial Sensitivity Tests , Streptococcal Infections/microbiology , Streptococcus agalactiae/genetics , Streptococcus agalactiae/isolation & purification , Streptococcus pyogenes/genetics , Streptococcus pyogenes/isolation & purificationABSTRACT
Among 48 erythromycin-resistant group D streptococci (GDS), 36 had the erm(T) resistance gene. erm(T) was also found in 4 of 31 erythromycin-resistant Enterococcus faecium isolates. This is the first report of the erm(T) gene in U.S. GDS isolates and the first report of the erm(T) gene in enterococci.
Subject(s)
Anti-Bacterial Agents/pharmacology , Enterococcus faecium/drug effects , Erythromycin/pharmacology , Methyltransferases/genetics , Streptococcus/drug effects , Bacterial Proteins , Drug Resistance, Bacterial/genetics , Enterococcus faecium/enzymology , Enterococcus faecium/genetics , Gram-Positive Bacterial Infections/epidemiology , Gram-Positive Bacterial Infections/microbiology , Humans , Microbial Sensitivity Tests , Prevalence , Streptococcal Infections/epidemiology , Streptococcal Infections/microbiology , Streptococcus/enzymology , Streptococcus/geneticsABSTRACT
The emergence of macrolide- and lincosamide-resistant Streptococcus pneumoniae is a worldwide concern. Of particular interest is the increasing prevalence of erythromycin and clindamycin-resistant isolates containing both erm(B) and mef genes. This study determined the prevalence of erythromycin and clindamycin resistance in 596 clinical S. pneumoniae isolates from 2 adult tertiary care hospitals over a 4-year period (2001-2004). Erythromycin resistance increased from 24% to 34%, but S. pneumoniae isolates resistant to clindamycin as well as to erythromycin increased from 3% in 2001 to 15.5% in 2004 (5-fold increase). Among erythromycin-resistant isolates, those also resistant to clindamycin (MLS(B) phenotype) increased 3-fold (12.8-45%). Of forty-one erythromycin/clindamycin-resistant S. pneumoniae isolates tested, 29 (71%) contained both erm(B) and mef(E) genes. Pulsed-field gel electrophoresis performed on 28 erm(B) + mef(E) positive isolates identified 2 predominant and possibly related clones, which made up 64% of the isolates.
