Antimicrobial susceptibility of Group B streptococci and isolation rate of Group B streptococci with reduced penicillin susceptibility (PRGBS) isolated at our hospital

Abstract

Streptococcus agalactiae (Group B Streptococci; GBS) is known as a causative agent of infections in susceptible hosts such as the elderly and diabetic patients, and also causes severe invasive infections such as neonatal meningitis and sepsis. Because GBS has been sensitive to β-lactams, β-lactams, especially penicillins, have been used as first-line antimicrobial for GBS infection. Recently, however, the existence of GBS with reduced penicillin susceptibility (PRGBS) has been reported. Therefore, we investigated the antimicrobial susceptibility of 2,987 GBS strains isolated in our hospital from 2012 to 2022 and isolation rate of PRGBS. The PCG non-sensitivity rate for GBS declined after 2019 and remained around 2%. Respiratory specimens had the highest isolation rate of PRGBS at 22.1%. By age, the majority of isolates of PRGBS were from older persons in the 70s and above, regardless of specimen type. PRGBS was not isolated from genital specimens in the 10–40 age range or from newborns. PRGBS was isolated more frequently from hospitalized patients than from outpatients, especially from older hospitalized patients aged 70 years or older, who accounted for about 20% of isolates. In addition, PRGBS were nonsusceptible to penicillins, as well as to cephalosporins, macrolides, and fluoroquinolones, indicating that they tended to be multidrug-resistant. We consider it necessary to continue to monitor trends in GBS antimicrobial susceptibility for appropriate selection of antimicrobial agents for GBS infections.