Molecular characterization of Staphylococcus aureus from nasal samples of healthy pet cats.

The objective of this study was to characterize Staphylococcus aureus isolates recovered from the nasal samples of healthy pet cats in Algiers province. A total of 138 nasal swabs were collected. Antimicrobial susceptibility was conducted using the disk-diffusion method and the VITEK-2 susceptibility system. Whole genome sequencing was performed to identify multiple-locus sequence typing, antimicrobial and virulence genes. Staphylococcus aureus isolates were detected in 23 cats. Among these, 11 were methicillin-resistant S. aureus (MRSA) (one isolate/sample). Three sequence types (ST6, ST5, and ST1) were identified in MRSA, with the predominance of ST6 (n = 7). Seven distinct STs [ST398, ST97, ST15, ST7, ST291, ST5043, and a new ST, (ST9219)] were detected in methicillin-sensitive S. aureus. All MRSA isolates harbored the mecA gene and SCCmec-type-IVa. MRSA exhibited resistance to tetracycline [n = 3/tet(L) and tet(M); n = 1/tet(K)], kanamycin-tobramycin [n = 3/ant(4')-Ia), amikacin-kanamycin (n = 1/aph(3')-IIIa], and erythromycin-clindamycin [n = 1/erm(C)]. Seven S. aureus isolates were multidrug resistant. All the isolates were negative for lukS/lukF-PV and tst-1 genes, while 20 isolates were IEC-positive. This study revealed a diversity of genetic lineages in S. aureus strains isolated from nasal samples of pet cats, including multidrug-resistant and toxigenic strains. The presence of IEC-positive S. aureus suggests possible human-animal transmission.