Surveillance of susceptibility of Streptococcus agalactiae (GBS) to antimicrobial agents and isolation rates of Group B Streptococci with reduced penicillin susceptibility (PRGBS) in Okinawa

Abstract

We investigated the antimicrobial susceptibility of Streptococcus agalactiae (GBS) isolated from patients living in Okinawa Prefecture, particularly the isolation rates of Group B Streptococci with reduced penicillin susceptibility (PRGBS) and multidrug-resistant GBS. A total of 10,870 GBS isolates were derived from various clinical samples between 2014 and 2016. We found that the susceptibility rates (%) to benzylpenicillin (PCG) were significantly lower than those reported by JANIS, 78.9 vs. 94.3 in 2014, 78.1 vs. 93.1 in 2015, and 81.0 vs. 94.2 in 2016 (p < 0.01). PRGBS were frequently isolated from respiratory samples (2016: 56.3%) and patients aged ≥ 60 years old (p < 0.01). Furthermore, the isolation rates of PRGBS differed among various facilities, and PRGBS were resistant to multiple antimicrobial agents including cephalosporins, erythromycin, and levofloxacin. In 2016, 94.4% of PRGBS were multidrug-resistant. In this study, the GBS isolated in clinical settings in Okinawa showed low sensitivity to PCG, and PRGBS showed multidrug resistance. Additional analyses using serological and genetic methods are required to obtain more detailed information of GBS in Okinawa.