Clonal spread of methicillin-resistant coagulase-negative staphylococci among horses, personnel and environmental sites at equine facilities.

A cross-sectional study was carried out to investigate species distribution and clonality of methicillin-resistant coagulase-negative staphylococci (MRCoNS) isolated from the nasal cavity of 39 horses and 32 veterinary or caretaker staff, and from 76 environmental surfaces at three equine facilities in Denmark. MRCoNS obtained by selective isolation were characterised by 16S rDNA sequencing, PCR detection of mecA, and pulsed-field gel electrophoresis (PFGE). MRCoNS were found in 32 (82%) horses, 20 (63%) humans and 50 (66%) environmental samples. The most common species was S. vitulinus (n=56), followed by S. sciuri (n=25), S. haemolyticus (n=14). Undistinguishable PFGE patterns were observed in MRCoNS of equine, human and environmental origin. A S. vitulinus clone and a S. haemolyticus clone were isolated from multiple horses, staff members and environmental sites within a farm and a veterinary hospital, respectively. The results indicated that methicillin-resistant strains of these two species can be shared by and possibly exchanged between horses and personnel, either directly or through contaminated environments.