High prevalence of avian adapted CC5 Staphylococcus aureus isolates in poultry meat in Spain: food chain as vehicle of MRSA and MSSA CC398-t1451

Staphylococcus aureus can cause food poisoning and human infections and CC5 and CC398 are relevant lineages in the animal-human interface. The objective was to determine the S. aureus prevalence in chicken-derived food, and to study the diversity of lineages, and their antimicrobial resistance and virulence genotypes. Sixty poultry-food samples were processed, and the S. aureus isolates obtained were characterised. Antibiotic susceptibility was performed and the presence of resistance/virulence genes, and avian mobile genetic elements (MGEs) was studied. Forty-four non-repetitive S. aureus isolates were obtained of 28/60 samples (46.7%), and 43 methicillin-susceptible (MSSA) and one methicillin-resistant S. aureus (MRSA) isolates were detected. Five S. aureus isolates were multidrug-resistant and 50% of isolates showed susceptibility to all tested antibiotics. Eighteen spa-types, 11 sequence-types and 8 clonal-complexes were identified in the S. aureus collection. Three CC398 isolates (2 MSSA/1 MRSA) of spa-type-t1451 were detected, and MSSA-CC398 isolates harboured the scn-gene (absent in MRSA-CC398). CC5 was the most frequent lineage identified (56.8%), all MSSA, and 56.7% of them contained avian-MGEs. A high prevalence of avian-adapted MSSA-CC5 isolates was detected. Poultry meat has been shown to be a vehicle for CC398-t1451 isolates, both MRSA and MSSA, showing characteristics of the animal and human clades, respectively.