title: Polyclonal spread of erythromycin-resistant Streptococcus agalactiae in southern Taiwan.
abstract: Resistance to erythromycin is common among Streptococcus agalactiae in Taiwan, however the genetic relatedness of erythromycin-resistant isolates has not yet been reported. From 1991 to 2001, 629 clinical isolates of S. agalactiae were collected in a medical center at Tainan in southern Taiwan, of which 189 (30.0%) were resistant to erythromycin. The isolation rate of erythromycin-resistant group B streptococcus (GBS) was stable, irrespective of the clinical sources or study period. Among them, 145 (76.7%) isolates showed the macrolide-lincosamide-streptogramin B (MLS)-resistant phenotype, and 44 (23.3%) had the macrolide (M)- resistant phenotype. Of the isolates with MLS phenotype, 141 (97.2%) isolates harbored the ermB gene alone and only three (2.1%) the ermTR gene, whereas 41 (93.2%) of 44 isolates with M phenotype harbored the mefA/E gene. Of 177 typeable isolates, there were 26 unrelated pulsed-field gel electrophoresis (PFGE) patterns. PFGE type 1 accounted for 17.8% (24/135) of MLS phenotype isolates with the ermB gene and 48.7% (18/37) of M phenotype isolates with the mefA/E gene. During the study period, the proportion of PFGE type 6 decreased significantly, whereas that of type 8 increased. Our results suggest that erythromycin resistance is not uncommon among clinical isolates of S. agalactiae and is, at least, partially related to polyclonal spread in southern Taiwan.
authors.affiliation: Department of Internal Medicine, National Cheng Kung University Hospital, Tainan, Taiwan.
authors.forename: Wen-Chien
authors.initials: WC
authors.lastname: Ko
authors.forename: Jing-Jou
authors.initials: JJ
authors.lastname: Yan
authors.forename: Nan-Yao
authors.initials: NY
authors.lastname: Lee
authors.forename: Hsiu-Mei
authors.initials: HM
authors.lastname: Wu
authors.forename: Jiunn-Jong
authors.initials: JJ
authors.lastname: Wu
mesh_terms: D024881:Drug Resistance, Bacterial / Q000235:genetics*; D004352:Drug Resistance, Microbial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D004917:Erythromycin / Q000494:pharmacology*; D006801:Humans; D018942:Macrolides / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D013290:Streptococcal Infections / Q000453:epidemiology* / Q000382:microbiology; D013292:Streptococcus agalactiae / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D013624:Taiwan / Q000453:epidemiology
chemical_list: D018942:Macrolides; D004917:Erythromycin