Antibiotic resistance patterns among group B Streptococcus isolates: implications for antibiotic prophylaxis for early-onset neonatal sepsis.

Study/principles: Antibiotic prophylaxis of Group B Streptococcus (GBS) positive women during labour reduces the risk of early-onset neonatal sepsis. Penicillin is the first choice, and clindamycin and erythromycin are second choices for penicillin-allergic women. Resistance to these antibiotics is rising. The aims of this study were to evaluate the rates of clindamycin and erythromycin resistance among GBS-positive isolates cultures from pregnant women in the University Hospital of Geneva and to evaluate the legitimacy of new Centres for Disease Control and Prevention (CDC) recommendations for our context.

Methods: We collected a vagino-rectal swab from pregnant women at 35-37 weeks gestation. We recovered 124 GBS positive isolates. Identification was based on the characteristic of the colony on the chromogenic agar, the streptococcal agglutination test and confirmation by mass spectrometry. Antimicrobial susceptibility was determined by disk diffusion, according to CLSI guidelines 2010.

Results: The rate of resistance to clindamycin was 28% and to erythromycin was 30%. Only 3 of the 38 erythromycin resistant strains (7.9%) were susceptible to clindamycin, and only 3 out of the 35 clindamycin resistant GBS (8.6%) were identified as "inducible resistance". The rate of co-resistance to clindamycin of erythromycin-resistant strains was 92%. Penicillin remained efficacious in all cases.

Conclusion: Rates of clindamycin and erythromycin resistance are also increasing in our context. These antibiotics should not be used for GBS neonatal sepsis prevention, without adequate antimicrobial susceptibility testing. In case of penicillin allergy and lack of antibiogramm, cephalosporins or vancomycin should be used as recommended in CDC guidelines.