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

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

Infections due to streptococcus agalactiae in adluts : emergence and impact of lysogeny

Streptococcus Agalactiae est depuis les années 1990, responsable d'infections invasives émergentes chez l'adulte. Nous montrons queles souches responsables de ces infections appartiennent majoritairement aux sérotypes V et Ia et aux deux clones phylogénétiquement éloignés, CC1 et CC23. L'étude du contenu prophagique montre une lysogénie fréquente suggérant l'importance de la lysogénie dans la spécialisation de ces souches particulièrement aptes à infecter l'adulte. Dans un deuxième temps, nous avons isolé sept phages tempérés de souches associées à des infections cutanées et ostéo-articulaires. Ces phages appartiennent à la famille des SIPHOVIRIDAE. L’analyse par restriction enzymatique de l’ADN phagique et l’amplification par PCR de fragments d’ADN prophagique a montré la diversité de ces phages et leurdifférence des phages isolés de souches associées aux infections materno-foetales. Les phagesisolés de souches lysogènes de CC1 ont présenté un spectre lytique étendu aux souches de tous les clones intra-species.Streptococcus agalactiae has emerged since 1990 in infections in nonpregnant adults, We showed that the strains isolated from adult infections were mainly of serotypes V and Ia., and mainly belonged to the two phylogenetically distant clones, CC1 and CC23. The prophagic content study showed a frequent lysogeny, suggesting a role of lysegeny in the specialization of these strains able to infect adult. Also, we isolated seven phages from strains associated with cutaneous and osteoarticular infections in adult. Ces phages classified among SIPHOVIRIDAE. Restriction analysis of phagic DNA and PCR for prophagic DNA showed genetiacally diverse phages, distinct from the phages isolated from strains responsible for materno-foetal infections. Phages isolated from lysogenic strains of CC1 had a wide lytic spectrum and were able to lyse strains belonging to all clones intra-species

Infections due to streptococcus agalactiae in adluts : emergence and impact of lysogeny

Streptococcus Agalactiae est depuis les années 1990, responsable d'infections invasives émergentes chez l'adulte. Nous montrons queles souches responsables de ces infections appartiennent majoritairement aux sérotypes V et Ia et aux deux clones phylogénétiquement éloignés, CC1 et CC23. L'étude du contenu prophagique montre une lysogénie fréquente suggérant l'importance de la lysogénie dans la spécialisation de ces souches particulièrement aptes à infecter l'adulte. Dans un deuxième temps, nous avons isolé sept phages tempérés de souches associées à des infections cutanées et ostéo-articulaires. Ces phages appartiennent à la famille des SIPHOVIRIDAE. L’analyse par restriction enzymatique de l’ADN phagique et l’amplification par PCR de fragments d’ADN prophagique a montré la diversité de ces phages et leurdifférence des phages isolés de souches associées aux infections materno-foetales. Les phagesisolés de souches lysogènes de CC1 ont présenté un spectre lytique étendu aux souches de tous les clones intra-species.Streptococcus agalactiae has emerged since 1990 in infections in nonpregnant adults, We showed that the strains isolated from adult infections were mainly of serotypes V and Ia., and mainly belonged to the two phylogenetically distant clones, CC1 and CC23. The prophagic content study showed a frequent lysogeny, suggesting a role of lysegeny in the specialization of these strains able to infect adult. Also, we isolated seven phages from strains associated with cutaneous and osteoarticular infections in adult. Ces phages classified among SIPHOVIRIDAE. Restriction analysis of phagic DNA and PCR for prophagic DNA showed genetiacally diverse phages, distinct from the phages isolated from strains responsible for materno-foetal infections. Phages isolated from lysogenic strains of CC1 had a wide lytic spectrum and were able to lyse strains belonging to all clones intra-species

Les infections à "Streptococus agalactiae" chez l'adulte (emergence et impact de la lysogénie.)

Streptococcus Agalactiae est depuis les années 1990, responsable d'infections invasives émergentes chez l'adulte. Nous montrons queles souches responsables de ces infections appartiennent majoritairement aux sérotypes V et Ia et aux deux clones phylogénétiquement éloignés, CC1 et CC23. L'étude du contenu prophagique montre une lysogénie fréquente suggérant l'importance de la lysogénie dans la spécialisation de ces souches particulièrement aptes à infecter l'adulte. Dans un deuxième temps, nous avons isolé sept phages tempérés de souches associées à des infections cutanées et ostéo-articulaires. Ces phages appartiennent à la famille des SIPHOVIRIDAE. L analyse par restriction enzymatique de l ADN phagique et l amplification par PCR de fragments d ADN prophagique a montré la diversité de ces phages et leurdifférence des phages isolés de souches associées aux infections materno-foetales. Les phagesisolés de souches lysogènes de CC1 ont présenté un spectre lytique étendu aux souches de tous les clones intra-species.Streptococcus agalactiae has emerged since 1990 in infections in nonpregnant adults, We showed that the strains isolated from adult infections were mainly of serotypes V and Ia., and mainly belonged to the two phylogenetically distant clones, CC1 and CC23. The prophagic content study showed a frequent lysogeny, suggesting a role of lysegeny in the specialization of these strains able to infect adult. Also, we isolated seven phages from strains associated with cutaneous and osteoarticular infections in adult. Ces phages classified among SIPHOVIRIDAE. Restriction analysis of phagic DNA and PCR for prophagic DNA showed genetiacally diverse phages, distinct from the phages isolated from strains responsible for materno-foetal infections. Phages isolated from lysogenic strains of CC1 had a wide lytic spectrum and were able to lyse strains belonging to all clones intra-species.TOURS-Bibl.électronique (372610011) / SudocSudocFranceF

Two-component system RgfA/C activates the fbsB gene encoding major fibrinogen-binding protein in highly virulent CC17 clone group B Streptococcus.

Group B streptococcus (GBS) strains with the highest ability to bind to human fibrinogen belong to the highly invasive clonal complex (CC) 17. To investigate the fibrinogen-binding mechanisms of CC17 strains, we determined the prevalence of fibrinogen-binding genes (fbsA and fbsB), and fbs regulator genes (rogB encoding an fbsA activator, rovS encoding an fbsA repressor and rgf encoding a two-component system [TCS] whose role on fbs genes was not determined yet) in a collection of 134 strains representing the major CCs of the species. We showed that specific gene combinations were related to particular CCs; only CC17 strains contained the fbsA, fbsB, and rgf genes combination. Non polar rgfAC deletion mutants of three CC17 serotype III strains were constructed. They showed a 3.2- to 5.1-fold increase of fbsA transcripts, a 4.8- to 6.7-fold decrease of fbsB transcripts, and a 52% to 68% decreased fibrinogen-binding ability, demonstrating that the RgfA/RgfC TCS inhibits the fbsA gene and activates the fbsB gene. The relative contribution of the two fbs genes in fibrinogen-binding ability was determined by constructing isogenic fbsA, fbsB, deletion mutants of the three CC17 strains. The ability to bind to fibrinogen was reduced by 49% to 57% in ΔfbsA mutants, and by 78% to 80% in ΔfbsB mutants, suggesting that FbsB protein plays a greater role in the fibrinogen-binding ability of CC17 strains. Moreover, the relative transcription level of fbsB gene was 9.2- to 12.7-fold higher than that of fbsA gene for the three wild type strains. Fibrinogen-binding ability could be restored by plasmid-mediated expression of rgfAC, fbsA, and fbsB genes in the corresponding deletion mutants. Thus, our results demonstrate that a specific combination of fbs genes and fbs regulator genes account for the high fibrinogen-binding ability of CC17 strains that may participate to their enhanced invasiveness for neonates as compared to strains of other CCs

Distribution of the <i>S. agalactiae</i> isolates of various origins, serotypes, sequence types, and clonal complexes between prophage DNA groups, as displayed by SYSTAT 12 software^a.

a<p>NP no prophage amplification; NT, nontypable.</p

CC, ST of <i>S. agalactiae</i> isolates from adult and neonatal invasive infections.

<p>CC, ST of <i>S. agalactiae</i> isolates from adult and neonatal invasive infections.</p

Distribution of 141 <i>S. agalactiae</i> isolates from adult (ACSF and AB) and neonatal (NCFS and NB) patients with invasive disease between prophage DNA groups, on the basis of PCR evaluations of the prophage content of isolates.

<p>Jaccard analysis generated a dendrogram of similarity values for the 10 prophage sequences described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0020256#pone-0020256-t001" target="_blank">table 1</a> (SYSTAT 12 software). Five major prophage DNA groups were defined (groups A to E). The mean number of prophage DNA fragments amplified from strains by PCR and the mean number of absolute deviations (Avedev) were calculated for each prophage DNA group. ^a anatomic origin of isolates; ^b serotype of isolates; ST, sequence-type; CC, clonal complex; NT, nontypeable.</p

Distribution of the SLVs of the major clonal complexes as a function of difference in the number of nucleotides (one or more) with respect to the sequence of the founder sequence type.

<p>Distribution of the SLVs of the major clonal complexes as a function of difference in the number of nucleotides (one or more) with respect to the sequence of the founder sequence type.</p