Nasal carriage of Staphylococcus aureus in livestock in North of Morocco

Background : In Morocco, data of LA-MRSA nasal carriage are still limited. The objectives of this study were to determine for the first time the nasal carriage rate, antimicrobial susceptibility profiles and virulence genes of S aureus isolated from animals and breeders in close contact. Methods : From 2015 to 2016, 480 nasal swab samples were collected from 27 different Livestock areas in Tangier. The antimicrobial susceptibility phenotypes were determined by disk diffusion according to EUCAST 2016. The presence of nuc , mec A and his homologue mec C, lukS/F-PV, and tst genes were determined by 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 = 14.321; 95% CI = 7.484- 27.405; p< 0.0001). In general, S. aureus strains were susceptible to the majority of antibiotics and the higher resistance rates were found against tetracycline (16.7% in animals and 10% in breeders). No MRSA was detected in animals and breeders. A high rate of tst and lukS/F-PV genes has been found only in animals (11.9% and 16.7%, respectively). Conclusion : Despite the lower colonization rate 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 of virulence genes, which is associated to an increased risk of infection dissemination in humans. This highlights the need for implementing adequate approaches for prevention. Further larger and multi-center studies are needed to validate and confirm our findings. Keywords: Staphylococcus aureus , nasal carriage, animals, breeders, MRSA, Morocco