Project description:Previous studies have documented the diversity of genetic background of methicillin-resistant S. aureus (MRSA) strains associated with healthcare (HA-MRSA), community (CA-MRSA) and livestock (LA-MRSA). The accessory and core-variable genome content of those strains remain largely unknown. To compare the composition of accessory and core-variable genome of Belgian MRSA strains according to host, population setting and genetic background, representative strains of HA- (n=21), CA- (n = 13) and ST398 LA-MRSA (n = 18) were characterized by a DNA-microarray (StaphVar Array) composed of oligonucleotide probes targeting ~400 resistance, adhesion and virulence associated genes.ST398 strains displayed very homogenous hybridization profiles (>94% gene content homology) irrespective of their host origin. This “ST398-specific” genomic profile was not distantly demarked from those of certain human-associated lineages but lacked several virulence- and colonization-associated genes harbored by strains of human origin, such as genes encoding proteases, haemolysins or adhesins. No enterotoxin gene was found among ST398 strains. In conclusion, our findings are consistent with a non-human origin of this ST398 lineage but suggest that it might have the potential to adapt further to the human host.
Project description:Studies on S. aureus sub-populations revealed that genomes are well conserved between isolates from the same lineages despite geographic, temporal and selective diversity. However, variation of hundreds of genes can occur between isolates from different lineages and these genes could be involved in interaction with host components. In this study, we aimed to investigate the diversity of secreted virulence factors in human and zoonotic S. aureus isolates from different clonal complexes. We focused on the S. aureus clonal complexes (CC) 8 and CC22 as dominant human lineages, and CC398 as dominant livestock-associated MRSA (LA-MRSA) which is disseminating rapidly. To study the diversity of secreted virulence factors, we compared their extracellular proteomes using label-free LC-MS/MS analysis. A common protein database was created based on DNA sequencing data and PAN genome IDs.
