All authors read, discussed and approved the final manuscript.”
“Background Streptococcus

agalactiae, one of the group B streptococci (GBS), PSI-7977 clinical trial is a leading cause of bovine mastitis [1] and has been implicated in cases of invasive disease in humans since the 1960s and 1970s [2]. GBS have emerged as major pathogens in neonates [3] and in elderly adults, in whom they cause invasive infections, such as meningitis, soft tissue infections, endocarditis and osteoarticular infections [4, 5]. There is a considerable body of evidence to suggest a genetic link between bovine isolates and the emerging human isolates [6, 7]. GBS isolates were initially distinguished on the basis of differences in capsule polysaccharides, giving rise to 10 different serotypes [8, 9].

Serotype III has been identified as a marker of late-onset neonatal disease isolates [10], but serotyping does not have sufficient discriminatory power to distinguish Belnacasan in vitro between isolates. Molecular methods have therefore been developed to determine the genetic relationships between isolates: multilocus enzyme electrophoresis [11], ribotyping [12], random amplified polymorphism DNA (RAPD) [13, 14] and pulsed-field gel electrophoresis (PFGE) [15]. These methods make it possible to compare isolates and to define particular bacterial genogroups associated with invasive isolates in neonates. These findings either were confirmed by multilocus sequence typing, as described by Jones et al. [16]. Other studies have shown that sequence type 17 (ST-17) isolates are associated with invasive behavior [17, 18]. Two methods are currently used to explore the genetic links between isolates: PFGE for epidemiological studies, and MLST for both epidemiological and phylogenetic studies. Analyses of fully sequenced bacterial genomes have revealed the existence of tandemly repeated

sequences varying in size, location and the type of repetition [19]. Tandem repeats (TR) consist of a direct repetition of between one and more than 200 nucleotides, which may or may not be perfectly identical, located within or between genes. Depending on the size of the unit, the TR may be defined as a microsatellite (up to 9 bp) or a minisatellite (more than 9 bp) [19]. A fraction of these repeated sequences display intraspecies polymorphism and are described as VNTRs (variable number of tandem repeats). The proportion of VNTRs in the genome varies between bacterial species. Indeed, variation in the number of repeats at particular loci is used by some bacteria as a means of rapid genomic and phenotypic adaptation to the environment [20]. A molecular typing method based on VNTRs variability has recently been developed and applied to the typing of several bacterial pathogens [19].