High Incidence of Erythromycin Resistance among Clinical Isolates of Streptococcus agalactiae in Taiwan

The in vitro susceptibilities of 266 isolates of Streptococcus agalactiae determined by the agar dilution method showed that 6% of isolates were nonsusceptible to penicillin and 46% was resistant to erythromycin. Of the erythromycin-resistant isolates, 86.3% had the macrolide-lincosamide-streptogramin (MLS) resistance phenotype (constitutive MLS, 85.5%; inducible MLS, 0.8%) and 13.7% had the M phenotype.