Molecular and phenotypic typing of Staphylococcus aureus isolates from rabbit meat

Twenty-six Staphylococcus aureus isolates were recovered from rabbit carcasses and cuts during a period of seven months. Samples from 51 different animals, flocks and farms were obtained from five establishments in four Spanish provinces. To determine their diversity and possible origin, isolates were typed by three molecular and three phenotypic methods. PFGE, with the highest discrimination index (D=0.966), identified 19 patterns (more than one band difference) and 10 types (more than three band differences). Based on > or = 90% similarity, RAPD (D=0.877) produced nine patterns while ribotyping (D=0.786) produced seven types. On the basis of biotyping (D=0.644), 11 isolates belonged to human ecovars and 15 to the non-host-specific crystal violet type C (NHS CV:C) biotypes. By direct phage typing (D=0.761), 17 isolates were lysed by human phages into groups II (8 isolates), III (5 isolates), I/III (2 isolates) and V (2 isolates). The overall resistance to antimicrobials (D=0.783) was 76.9%, with most isolates being resistant to tetracycline (61.5%) and penicillin G (26.9%). PFGE showed that samples from each processing plant carried different S. aureus types, some of them persisting over time. There also was evidence of interestablishment dissemination of genetically related clones, most of them belonging to the PFGE type A and phenotype "NHS CV:C biotypes-3A/3C/55/71 phage type", which is highly virulent for European commercial rabbitries. The ubiquity of the virulent phenotype, as well as the high incidence of resistance to antibiotics with application in human medicine, is a matter of concern in public and animal health.