Analysis of genetic signatures of virulence and resistance in foodborne Staphylococcus aureus isolates from Algeria

Staphylococcus aureus, a frequent commensal of the human microbiota, also frequently associated with various infections. This study aimed to genetically characterize foodborne methicillin resistant S. aureus (MRSA) in Oran, Algeria. From a total of 474 food matrices, 30 MRSA strains were isolated and characterized using whole genome sequencing (WGS) and bioinformatics. The genomes were assessed for antimicrobial resistance and virulence genes, sequence and spa types and single nucleotide polymorphism (SNP) to establish their relationship. The prevalence of S. aureus was 34.38% with MRSA accounting for 18.40%. MRSA strains showed high resistance to penicillinG, ampicillin and tetracycline. However, inconsistencies were noted between phenotypic and genotypic resistance for methicillin, aminoglycosides, and phenicolates, with mecA gene identified in three isolates. The isolates revealed eight different sequence types (predominantly ST97 and ST45) and eleven spa types (mainly t230 and t8503), correlating with SNP clusters except for isolates belonging to ST7200.86.66% of isolates harboured at least one enterotoxin gene underscores their potential public health threat. This investigation highlights the genetic heterogeneity among S. aureus regarding virulence and antimicrobial resistance, shedding light into food safety in Algeria and the ease of using WGS approach to rapidly characterize bacterial pathogens in community environments.