Molecular characterization of Chilean isolates of streptococcus agalactiae

Abstract

Streptococcus agalactiae is the main causing organism of invasive infections such as sepsis and meningitis in the newborn. To perform a genotype characterization of Streptococcus agalactiae strains coming form invasive infections of newborns and colonized pregnant women. A group of 58 strains not related epidemiologically isolated from colonized pregnant women and invasive infections in newborns, were studied. Pulsed field electrophoresis (PFGE) and polymerase chain reaction amplification of hylB and IS 1,548 genes, as possible virulence markers, were performed. Among the studied strains, 37 genetic subtypes were observed. There were nine groups of identical PFGE patterns. Three corresponded to serotype la and six to serotype III. An erythromycin and clindamycin resistant clone was identified in three colonized women and a newborn with sepsis, which were not epidemiologically related. The hylB gene was equally present in cases of neonatal meningitis or colonized pregnant women. There was a great degree of polymorphism among the studied strains. The ample presence of hylB gene and the absence of the insertion element IS1548 in the hylB gene in invasive and colonizing strains, indicates that both groups of strains are potentially pathogenic.