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.
All Science Journal Classification (ASJC) codes
- Microbiology (medical)