Prevalence and characteristics of methicillin-resistant Staphylococcus aureus in pigs and pig workers in Tenerife, Spain.

Methicillin-resistant Staphylococcus aureus (MRSA) strains belonging to sequence type (ST) 398 are being reported with increasing frequency in Europe and other countries. This MRSA type has been isolated from colonized and infected animals and humans. The aim of this study was to determine the prevalence of nasal MRSA carriage in pigs and pig workers. A total of 300 pigs from 15 different farms were sampled in the slaughterhouse of Tenerife. A total of 54 pig workers were screened for MRSA: 20 belonged to farms whose pigs had been sampled and 34 to the slaughterhouse. The percentage of positive samples of MRSA in pigs was 85.7%. The overall prevalence of nasal MRSA carriage in pig workers was 9.3%. All MRSA isolates from pigs and humans belonged to one clonal group showing multilocus sequence type (MLST) 398. Two types of Staphylococcal Chromosome Cassette (SCCmec) were found, IV and V. In conclusion, the prevalence of MRSA in nasal samples from pigs and pig workers in Tenerife was high. We therefore consider it essential to deepen epidemiological study of this strain of animal origin, as well as to increase surveillance and control measures at all stages of the food chain.