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

Dissemination of Methicillin-Susceptible CC398 Staphylococcus aureus Strains in a Rural Greek Area

A large collection of Staphylococcus aureus including a. 745 clinically significant isolates that were consecutively recovered from human infections during 2012-2013, b. 19 methicillin- susceptible (MSSA), randomly selected between 2006-2011 from our Staphylococcal Collection, c. 16 human colonizing isolates, and d. 10 strains from colonized animals was investigated for the presence and the molecular characteristics of CC398. The study was conducted in Thessaly, a rural region in Greece. The differentiation of livestock-associated clade from the human clade was based on canSNPs combined with the presence of the phi 3 bacteriophage and the tetM, scn, sak, and chp genes. Among the 745 isolates, two MRSA (0.8% of total MRSA) and thirteen MSSA (2.65% of total MSSA) were found to belong to CC398, while, between MSSA of our Staphylococcal Collection, one CC398, isolated in 2010, was detected. One human individual, without prior contact with animals, was found to be colonized by a MSSA CC398. No CC398 was identified among the 10 S. aureus isolated from animals. Based on the molecular markers, the 17 CC398 strains were equally placed in the livestock-associated and in the human clades. This is the first report for the dissemination of S. aureus CC398 among humans in Greece