Diversity of Prophage DNA Regions of Streptococcus agalactiae Clonal Lineages from Adults and Neonates with Invasive Infectious Disease

Abstract

The phylogenetic position and prophage DNA content of the genomes of 142 S. agalactiae (group-B streptococcus, GBS) isolates responsible for bacteremia and meningitis in adults and neonates were studied and compared. The distribution of the invasive isolates between the various serotypes, sequence types (STs) and clonal complexes (CCs) differed significantly between adult and neonatal isolates. Use of the neighbor-net algorithm with the PHI test revealed evidence for recombination in the population studied (PHI, P = 2.01×10−6), and the recombination-mutation ratio (R/M) was 6∶7. Nevertheless, the estimated R/M ratio differed between CCs. Analysis of the prophage DNA regions of the genomes of the isolates assigned 90% of the isolates to five major prophage DNA groups: A to E. The mean number of prophage DNA fragments amplified per isolate varied from 2.6 for the isolates of prophage DNA group E to 4.0 for the isolates of prophage DNA group C. The isolates from adults and neonates with invasive diseases were distributed differently between the various prophage DNA groups (P<0.00001). Group C prophage DNA fragments were found in 52% of adult invasive isolates, whereas 74% of neonatal invasive isolates had prophage DNA fragments of groups A and B. Differences in prophage DNA content were also found between serotypes, STs and CCs (P<0.00001). All the ST-1 and CC1 isolates, mostly of serotype V, belonged to the prophage DNA group C, whereas 84% of the ST-17 and CC17 isolates, all of serotype III, belonged to prophage DNA groups A and B. These data indicate that the transduction mechanisms, i.e., gene transfer from one bacterium to another by a bacteriophage, underlying genetic recombination in S. agalactiae species, are specific to each intraspecies lineage and population of strains responsible for invasive diseases in adults and neonates.

Emergence of Serotype IV Group B Streptococcus Adult Invasive Disease in Manitoba and Saskatchewan, Canada, Is Driven by Clonal Sequence Type 459 Strains

“…Strains of serotype V have been associated with the marked increase of adult invasive infections observed in North America since the 1990s (3,(10)(11)(12). Strains of this serotype, particularly those identified by multilocus sequence typing (MLST) as sequence type 1 (ST1), reportedly cause more invasive disease and have reduced susceptibility to macrolide and lincosamide antibiotics (13)(14)(15).…”

Molecular characterization of Streptococcus agalactiae in diseased farmed tilapia in China

“…Additionally, human GBS isolates carrying identical genotypes as those of the tilapia GBS isolates (IS1381-IS861-ISSag2-GBSil) were not found (Salloum et al, 2011). GBS isolates with genotype bac…”

“…Lysogeny plays an important role in the virulence and evolution of S. agalactiae species as well as contributes to intraspecies genomic diversity. The relationships between temperate phages and S. agalactiae strains depend on the phage type and/or bacterial lineage (Salloum et al, 2011).…”

“…The primer pairs (Table 2) used to detect 10 prophage DNA gene fragments of GBS and the amplification conditions were described by Salloum et al (2011). The final volume of the reaction mixture was 50 μl, containing 1 μl genomic DNA, 0.2 μM of each primer, 0.2 mM each of dATP, dTTP, dCTP, and dGTP, 0.25 U rTaq polymerase [TaKaRa Biotechnology (Dalian) Co. Ltd., China], and 1 × PCR buffer.…”

“…Recently, phage typing was used in epidemiological investigations because lysogeny was specific to each intraspecific lineage of GBS strain (Salloum et al, 2011). In addition, numerous mobile genetic elements (MGEs), including six insertion sequences (IS) and a group II intron, were employed to detect the diversity of GBS isolates.…”