Multilocus Sequence Typing of Swedish Invasive Group B Streptococcus Isolates Indicates a Neonatally Associated Genetic Lineage and Capsule Switching

Abstract

Streptococcus agalactiae, also designated group B streptococcus (GBS), is an important pathogen in neonates, pregnant women, and nonpregnant adults with predisposing conditions. We used multilocus sequence typing (MLST) to characterize 158 GBS isolates that were associated with neonatal and adult invasive disease and that were collected in northern and western Sweden from 1988 to 1997. Five major genetic lineages (sequence type [ST] 19, ST-17, ST-1, ST-23, and ST-9 complexes) were identified among the isolates, including serotype Ia, Ib, and II to V isolates, indicating a highly clonal population structure among invasive GBS isolates. A number of STs were found to contain isolates of different serotypes, which indicates that capsule switching occurred rather frequently. Two distantly related genetic lineages were identified among isolates of serotype III, namely, clonal complex 19 (CC19), and CC17. CC19 was equally common among isolates from adult and neonatal disease (accounting for 10.3% of GBS isolates from adult disease and 18.7% from neonatal disease), whereas CC17 significantly appeared to be associated with neonatal invasive disease (isolated from 21.9% of neonatal isolates but only 2.6% of adult isolates). The distribution of the mobile elements GBSi1 and IS1548 reveals that they can act as genetic markers for lineages CC17 and CC19, respectively.

Multilocus sequence typing analysis of Streptococcus mutans strains with the cnm gene encoding collagen-binding adhesin

“…sing high collagen-binding rates (TLJ11-2, TLJ85-4, TLJ137-4 and TLJ9-1) ( A lack of correlation between serotypes and STs has been demonstrated in many bacterial species, such as Streptococcus pneumoniae, Neisseria meningitidis and Streptococcus agalactiae, and the horizontal transfer of capsular biosynthesis genes related to serotyping is speculated to be the reason (Coffey et al, 1991;Luan et al, 2005;Pettigrew et al, 2006;Swartley et al, 1997). In fact, we also reported the association of one ST with two serotypes in our previous work (Lapirattanakul et al, 2008;Nakano et al, 2007).…”

Antimicrobial resistance in colonizing group B Streptococci before the implementation of a Swedish intrapartum antibiotic prophylaxis program

“…Since the surface cultures of the infants were taken immediately after birth, the vaginal samples in these mothers were assumed to be false negative. All GBS isolates were serotyped (types Ia, Ib, II-VIII) by co-agglutination (Essum AB, Umeå, Sweden) In non-typable isolates a PCR-based typing method was used (16 (17). Serotype III isolates of the study were further characterized by PCR for the presence of these mobile genetic elements.…”

Physiological impact of transposable elements encoding DDE transposases in the environmental adaptation of Streptococcus agalactiae

“…IS1548 is significantly linked to the S. agalactiae phylogenetic subdivision A1a that corresponds to the clonal complex 19 (CC19), which is associated with strains responsible for neonatal meningitis and endocarditis (Héry-Arnaud et al, 2005). Based on this association, Luan and collaborators proposed to use IS1548 as a genetic marker for the identification of serotype III strains belonging to the CC19 (Luan et al, 2005). IS1548 is not frequently found among S. agalactiae isolates of bovine origin (prevalence of 9 to 16 %), and when present in these strains, this insertion element was never found to target the hylB gene (Dmitriev et al, 2003;Shakleina et al, 2004;Sukhnanand et al, 2005).…”