Clinical Microbiology and Antimicrobial Chemotherapy. 2024; 26(2):194-200
To study the dynamics and molecular mechanisms of resistance of Streptococcus agalactiae strains isolated from pregnant women and newborns in St. Petersburg in 2010–2022.
The strains of S. agalactiae (n = 248) were obtained by analyzing the clinical material of pregnant women and newborns who were hospitalized at Research Institute of Obstetrics, Gynecology and Reproductology named after D.O. Ott in 2010–2011 and 2020–2022. Determination of susceptibility to antibacterial drugs was evaluated by disk diffusion method. The detection of resistance genes to macrolides and lincosamides (mef and ermB) was performed by real-time PCR using reagents «Resistom MLSB-Streptococcus» (Litech, Russia).
All isolates S. agalactiae (n = 248) were sensitive to penicillin and vancomycin. Compared to 2010–2011, the resistance of S. agalactiae to erythromycin increased from 18.4% to 42.1% and to clindamycin from 15.6% to 39.3%. Among S. agalactiae strains (n = 71) resistant to erythromycin and clindamycin, cMLSB phenotype was predominant (59.1%); iMLSB (31%) and M-phenotype (9.9%) were less common. The results of detection of genes encoding resistance to erythromycin and clindamycin showed that in 38 (53.5%) and 9 (12.7%) isolates of S. agalactiae resistance genes ermB and mefA were detected as one resistance determinant, respectively, association of two ermB/mefA genes was detected in 2 (2.8%) strains; resistance genes were not detected in 22 (31%) isolates.
Penicillin and vancomycin are effective drugs for the treatment and prevention of infections caused by S. agalactiae. The increase in resistance to macrolides and lincosamides reflects the global trend of increasing resistance to these antibiotics. Regular monitoring of antibiotic resistance of the pathogen is necessary to update the clinical recommendations.