Persistence of nasal colonisation with methicillin resistant Staphylococcus aureus CC398 among participants of veterinary conferences and occurrence among their household members: A prospective cohort study, Germany 2008-2014.

There are only few data on the persistence and transmission of methicillin resistant Staphylococcus aureus (MRSA) of the clonal complex (CC) 398 among veterinarians and their household members. We therefore investigated the long-term colonisation with MRSA CC398 among participants of veterinary conferences in Germany in 2008/2009 and their household members. Forty-five initially MRSA CC398 positive and 180 initially MRSA CC398 negative conference participants were included in a longitudinal study. These persons and their household members were tested for nasal colonisation in 2011, 2012 and 2014. Of 31 continuously tested and initially MRSA CC398 positive participants only 8 (26%) were colonized with MRSA CC398at all 4 time points, 4 (13%) of them consistently with the same spa type. Among initially MRSA CC398 negative participants, 13 (7%) were tested MRSA CC398 positive at least once during the follow-up period. Data for household members at least at one time point were available for 185 households. Of these 21 (11%) households had one or more household member who tested positive for MRSA CC398at least once. The odds of household members to be MRSA CC398 positive was 12 times higher (95% confidence interval 4-37) when the conference participant tested MRSA CC398 positive in 2008/2009. This association remained strong when household members working in veterinary medicine or livestock farms were excluded. In summary, these data suggest that colonisation with MRSA CC398 is partially transient and that household members of MRSA CC398 colonized persons are at an increased risk of colonisation with MRSA CC398.