Clonal transmission of a colistin-resistant Escherichia coli from a domesticated pig to a human in Laos.

therapy without antibiotics. Finally, the hypothesis for MRSA being selected by the use of cefquinome in those horses cannot be excluded. In this study, two CCs with no geographical clustering were characterized. Indeed, three MRSA strains belonged to CC130, the most prevalent CC among mecC-positive MRSA in animals, whereas the fourth one belonged to ST49, which was recently described in mecC-positive humans. Among the CC130 isolates, two different STs (ST1245 and ST130) and three divergent— though related—spa types were found. This finding might be due either to microevolutions of a common ancestor or to successive introduction of distinct strains. Considering the nosocomial and zoonotic potential of MRSA isolated from horses, equine veterinarians and riders should pay specific attention to hygiene measures in both veterinary clinics and equestrian centres in order to limit MRSA spread. Prudent and responsible use of antibiotics by veterinarians is also of major importance to avoid selection and dissemination of such resistant strains.