Serotypes and antibiotic resistance patterns in beta-hemolytic Streptococcus agalactiae isolates in colonized mothers and newborns with invasive disease

Introduction: Current preventive measures against neonatal disease caused by Streptococcus agalactiae (GBS) are prenatal screening and intrapartum antibiotic prophylaxis with appropriate antimicrobials. An alternative to this strategy would be the administration of a polysaccharide vaccine as the distribution of capsular serotypes of circulating strains needs to be known. Methods: A study was made of 188 strains from pregnant women carrying GBS and 24 newborns with neonatal disease. Susceptibility testing was performed with penicillin, erythromycin and clindamycin following CLSI standards, and capsular serotype was determined by two methods: latex agglutination and PCR. Results: Of the 188 strains of S. agalactiae from the pregnant women, there was 80.8% agreement in the results between the two techniques. Resistant to erythromycin and clindamycin was found in 16.5% and 10.1%, respectively. For neonatal strains, 95.8% of the results obtained by the two techniques were identical. The rates of resistance to erythromycin and clindamycin were 8.3% and 4.1%, respectively. In both groups, most frequently isolated serotype was III, and the most related to antimicrobial resistance serotype was v. Conclusion: Epidemiological studies are necessary to continue surveillance of serotypes causing invasive disease and its antibiotic sensitivity patterns using sensitive and specific methods. (C) 2013 Elsevier Espana, S.L.U. and Sociedad Espanola de Enfermedades Infecciosas y Microbiologia Clinica. All rights reserved.