Staphylococcus aureus (S. aureus) is an important opportunistic pathogen that can colonizes the nasal mucosa of humans and cats. This study aimed to investigate the prevalence, genetic diversity, antimicrobial resistance, and virulence factors of S. aureus isolated from healthy domestic cats in Algiers. A total of 138 Nasal swabs were collected from cats. The isolates were identified using conventional and molecular methods. Antimicrobial susceptibility testing was performed using the disk-diffusion method and VITEK-2 susceptibility system. Whole genome sequencing (WGS) was performed for all recovered isolates in order to detect MLST, antimicrobial and virulence genes. The prevalence of S. aureus carriage in healthy cats was 16.66% (23 isolates), out of theme 7.97% were MRSA (11 isolates). Antimicrobial susceptibility testing revealed a diverse resistance profile in S. aureus isolates. Upon WGS, MLST revealed the presence of three STs (ST6, ST5 and ST1) in MRSA, With the predominance of ST6 (n=7), and six different STs in MSSA, with the detection of ST398 (n=3). All MRSA harbored mecA and SCCmec type IV. This study revealed significant carriage rate of S. aureus and a high rate of MRSA, with a variety of genetic lineage detected. MRSA isolates belonged to CA-MRSA and the emergent MSSA-ST398 animal-independent clad were detected, which is responsible for invasive human infections. Twenty out of 23 S. aureus were IEC positive suggesting possible transmission from humans to cats. Multi-resistant and toxigenic S. aureus strains were found in the nasal cavities of cats, which could have serious implications for cat and human health.
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