2020 Volume 73 Issue 1 Pages 1-8
We investigated the detection rate of group B streptococci with reduced penicillin susceptibility (PRGBS) in the Kinki region of Japan from 2010 to 2014. We isolated 10,797 samples of group B Streptococcus (GBS; Streptococcus agalactiae) strains from clinical materials submitted to our laboratory by 427 medical institutions for identification of bacteria during this 4-year period. As a result, 506 strains of PRGBS were detected. The detection rates of PRGBS strains in the respiratory tract, blood culture, and GBS screening of vaginal swabs were 5.8% (500/8590), 2.4% (6/250), and 0% (0/1957), respectively. Furthermore, we randomly extracted 125 strains of PRGBS and 307 strains of penicillin-sensitive GBS (PSGBS) and investigated rates of antimicrobial susceptibility, and capsular antigen serotype. The antimicrobial susceptibility rate of PRGBS was low except for vancomycin and meropenem, whereas that for PSGBS was high for all drugs. We also investigated the relation between the capsular antigen serotype by material and detection frequency. From blood cultures, the most frequent serotype in 6 strains of PRGBS was III (50.0%), followed by Ia (33.3%) and Ib (16.7%), and that in 80 strains of PSGBS was Ib (40.5%), followed by III (19.0%) Ia and VI (13.9%). From the respiratory tract, the most frequent serotype in 119 strains of PRGBS was III (53.7%), followed by Ib (25.6%) and Ia (13.2%), and that in 96 strains of PSGBS was VI (34.7%), followed by III (29.5%) and Ib (24.2%). From GBS screening of vaginal swabs, the most frequent serotype in 131 strains of PSGBS was Ib (24.4%), followed by III (22.9%), Ia (22.1%), and II (13.7%), whereas PRGBS was not detected at all. We consider monitoring of future trends to be necessary from the viewpoints of the control of medically related infections and mother-to-child infections.
