Comparison of the Staphylococcal Chromosome Cassette (SCC) in Methicillin-Resistant (MRSA) and Non- Staphylococci (MRNAS) from Animals and Humans.

Methicillin-resistant (MRSA) and non- staphylococci (MRNAS) cause different infections in animals, including mastitis, in livestock and humans. This study aimed to identify and compare the staphylococcal chromosome cassette (SCC) types of MRSA or MRNAS isolated from several animal species and humans in different countries. Of 1462 and non- staphylococci, 68 grew on Chrom MRSA ID agar, were phenotypically resistant to cefoxitin and tested positive with the PCR for the gene. These 60 MRSA and 8 MRNAS were isolated in Belgium mainly from cows (livestock-associated (LA) MRS) and humans (community-acquired (CA) MRS) and in Japan from dogs and cats. The SCC cassettes were identified by multiplex PCR in 52 MRSA and 7 MRNAS and by whole genome sequencing (WGS) in 8 additional MRSA. The SCC types IV and V were the most frequent in Belgian LA-MRS and CA-MRS, while the SCC type II was identified in four of the five Japanese MRSA. The remaining isolate was a bovine in which no SCC was identified. These results confirm the high prevalence of the SCC types IV and V in LA-MRS and CA-MRS in Belgium, emphasizing the possible public health hazard of the former, and the absence of SCC in some MRNAS.