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

Methicillin-Susceptible ST398 Staphylococcus aureus Responsible for Bloodstream Infections: An Emerging Human-Adapted Subclone?

In the course of an annual 3-month bloodstream infections (BSI) survey conducted during a four-year period in 31 healthcare institutions located in three noncontiguous French regions, we report 18 ST398 Staphylococcus aureus BSI. ST398 BSI incidence showed a seven-fold increase during the study period (0.002 per 1,000 patient days in 2007 vs. 0.014 in 2010). ST398 BSI isolates differed from the pig-borne multiresistant clone: 17/18 BSI isolates were methicillin susceptible and none was of t011, t034 or t108 pig-borne spa-types. ST398 BSI isolates had homogenous resistance patterns (15/18 with only Eryr) and prophagic content (all harboured the hlb-converting Sau3int phage). The clustering of BSI and pig-borne isolates by spa-typing and MLVA, the occurrence of Sau3int phage in BSI isolates and the lack of this phage in pig-borne isolates suggest that the emergence of BSI isolates could have arisen from horizontal transfer, at least of the Sau3int phage, in genetically diverse MSSA ST398 isolates. The acquisition of the phage likely plays a role in the increasing ability of the lysogenic ST398 isolates to colonize human. The mode of acquisition of the non pig-borne ST398 isolates by our 18 patients remains unclear. ST398 BSI were diagnosed in patients lacking livestock exposure and were significantly associated with digestive portals of entry (3/18 [16.7%] for ST398 vs. 19/767 [2.5%] for non ST398 BSI; p = .012). This raises the question of possible foodborne human infections. We suggest the need for active surveillance to study and control the spread of this human-adapted subclone increasingly isolated in the hospital setting

Characterization of Streptococcus agalactiae phages in correlation with anatomical origin, phylogeny and metabolic functions of isolates

Notre travail a consisté à rechercher des éléments génétiques nouveaux associés aux souchesde Streptococcus agalactiae (SGB) responsables de méningites néonatales (MNN).L'amplification au hasard des ADN génomiques a identifié 3 fragments prophagiquesassociés aux souches à haut risque de MNN. Trente-six phages ont été isolés à partir desouches invasives et non invasives de SGB. La caractérisation moléculaire a défini sixgroupes moléculaires. L'étude du spectre lytique a montré des particularités pour chacun dessix groupes moléculaires. L'étude des capacités métaboliques de souches de SGB a montréque les souches lysogènes appartenant aux lignées phylogénétiques impliquées dans les MNNet présentent des pertes cataboliques. Les transferts génétiques horizontaux qui marquent lesclones des MNN ne semblent pas jouer un rôle dans la résistance aux macrolides. Desmécanismes de transduction ont joué un rôle important dans l'émergence de lignéesphylogénétiques impliquées dans les MNN.We tried to identify new genetic elements in the genome of Streptotoccus agalactiae (SGB)strains responsible for neonatal meningitis (MNN). Three prophage-related DNA elementswere identified by randomly amplified polymorphie DNA analysis significantly associatedwith SGB strains presented a high risk of causing MNN. Thirty-six phages were isolated from invasive and non invasive SGB strains. Molecular characterization of phage DNA identified six distantly related molecular groups. The various phage groups had specifie lytic activities.The lysogenic strains belonging to phylogenetic lineages most involved in MNN presented catabolic losses. The horizontal gene transfers that mediate mobile genetic elementsrecognized as markers of highly virulent clones do not seem to be have played a role in theemergence of macrolide resistance. Ali our results indicate that transduction may have play arole in the emergence of phylogenetic lineages implicated in MNN

Etude des phages de streptococcus agalactiae en lien avec l'origine anatomique, la phylogénie et les propriétés métaboliques des isolats

Notre travail a consisté à rechercher des éléments génétiques nouveaux associés aux souchesde Streptococcus agalactiae (SGB) responsables de méningites néonatales (MNN).L'amplification au hasard des ADN génomiques a identifié 3 fragments prophagiquesassociés aux souches à haut risque de MNN. Trente-six phages ont été isolés à partir desouches invasives et non invasives de SGB. La caractérisation moléculaire a défini sixgroupes moléculaires. L'étude du spectre lytique a montré des particularités pour chacun dessix groupes moléculaires. L'étude des capacités métaboliques de souches de SGB a montréque les souches lysogènes appartenant aux lignées phylogénétiques impliquées dans les MNNet présentent des pertes cataboliques. Les transferts génétiques horizontaux qui marquent lesclones des MNN ne semblent pas jouer un rôle dans la résistance aux macrolides. Desmécanismes de transduction ont joué un rôle important dans l'émergence de lignéesphylogénétiques impliquées dans les MNN.We tried to identify new genetic elements in the genome of Streptotoccus agalactiae (SGB)strains responsible for neonatal meningitis (MNN). Three prophage-related DNA elementswere identified by randomly amplified polymorphie DNA analysis significantly associatedwith SGB strains presented a high risk of causing MNN. Thirty-six phages were isolated from invasive and non invasive SGB strains. Molecular characterization of phage DNA identified six distantly related molecular groups. The various phage groups had specifie lytic activities.The lysogenic strains belonging to phylogenetic lineages most involved in MNN presented catabolic losses. The horizontal gene transfers that mediate mobile genetic elementsrecognized as markers of highly virulent clones do not seem to be have played a role in theemergence of macrolide resistance. Ali our results indicate that transduction may have play arole in the emergence of phylogenetic lineages implicated in MNN.TOURS-Bibl.électronique (372610011) / SudocSudocFranceF

Contrôles microbiologiques des endoscopes de 2012 à 2014 : validation de la qualité du traitement des endoscopes

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Community-Acquired Clostridium difficile Infection: A Reality in Patient Without Risk Factor

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