Mingling of human and veterinary strains of Staphylococcus aureus : an emerging issue in health-care systems

Aim: Methicillin-resistant Staphylococcus aureus remains a leading cause of hospital and community infections. We report a retrospective molecular characterization of S. aureus strains from different settings: hospital workers and patients, and veterinarian surgeons and pets. Materials and Methods: Eighty-nine S. aureus isolates obtained from nasal swabs of 10 patients, 17 health-care workers (HCWs), 9 pets, and 53 veterinarians were genotypically characterized by means of repetitive extragenic palindromic polymerase chain reaction (Rep PCR) and whole-genome sequencing. Results: Thirteen different sequence types (STs) were detected: ST398, ST22, ST8, ST30, ST15, ST5, ST121, ST45, ST10, ST6, ST34, ST97, and ST1. Two new STs differing from ST22 and ST5 for a single multilocus sequence typing gene were also identified. Rep PCR documented a genetic relationship among isolates obtained from 5 veterinarians and 10 HCWs. Conclusion: The large diversity of S. aureus strains detected may reflect a larger epidemiology within the hospital and community, in which companion animals likely act as a reservoir. We identified the circulation of ST5, ST8, ST15, ST22, ST30, ST45, and ST121 both in the hospital and veterinarian environment. Starting from the idea of a unique setting where our population lives, we consider the relationship between community- and hospital-acquired S. aureus.