Nasal carriage of Staphylococcus aureus in farm animals and breeders in north of Morocco

BACKGROUND: The objectives of this study were to determine for the first time, in Morocco, the nasal carriage rate, antimicrobial susceptibility profiles and virulence genes of Staphylococcus. aureus isolated from animals and breeders in close contact. METHODS: From 2015 to 2016, 421 nasal swab samples were collected from 26 different livestock areas in Tangier. Antimicrobial susceptibility phenotypes were determined by disk diffusion according to EUCAST 2015. The presence of nuc, mecA, mecC, lukS/F-PV, and tst genes were determined by Polymerase Chain Reaction (PCR) for all isolates. RESULTS: The overall S. aureus nasal carriage rate was low in animals (9.97%) and high in breeders (60%) with a statistically significant difference, (OR = 13.536; 95% CI = 7.070-25.912; p < 0.001). In general, S. aureus strains were susceptible to the majority of antibiotics and the highest resistance rates were found against tetracycline (16.7% in animals and 10% in breeders). No Methicillin-Resistant S. aureus (MRSA) was detected in animals and breeders. A high rate of tst and lukS/F-PV genes has been recovered only from animals (11.9 and 16.7%, respectively). CONCLUSION: Despite the lower rate of nasal carriage of S. aureus and the absence of MRSA strains in our study, S. aureus strains harbored a higher frequency of tst and lukS/F-PV virulence genes, which is associated to an increased risk of infection dissemination in humans. This highlights the need for further larger and multi-center studies to better define the transmission of the pathogenic S. aureus between livestock, environment, and humans.