Investigation of antimicrobial susceptibility of Group B streptococci with reduced penicillin susceptibility during the past five years from 2010 to 2014

Abstract

Penicillins are the first-line drugs for the treatment of Streptococcus agalactiae (GBS) infections. Recently, GBS strains with reduced penicillin susceptibility (PRGBS) have been reported. We studied the annual trend of the antimicrobial susceptibility of about 1,465 GBS strains isolated from clinical specimens in 5 general hospitals during the past five years from 2010 to 2014 and also investigated the medical records of the patients from whom PRGBS strains were isolated. Of 51 PRGBS strains, 43 were from respiratory specimens, 5 from urogenital specimens, and 3 from decubitus ulcer. The susceptibilities of these strains were tested by the broth microdilution method. The MICs of penicillin G, erythromycin, levofloxacin, cefepime, and vancomycin were determined. The susceptibilities of these PRGBS strains were 0, 24, 27, 22, and 100%, respectively. Of the 43 patients whose respiratory specimens showed PRGBS strains, 38 were 60 years old or older and 39 were bedridden. These results suggest that PRGBS might cause a nosocomial infection via respiratory secretion.