Analysis of the baseline survey on the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in holdings with breeding pigs, in the EU, 2008 Part A: MRSA prevalence estimates

Methicillin-resistant Staphylococcus aureus (MRSA) is a major concern for public health. The MRSA lineage ST398 has been recognised as an occupational hazard for people in contact with pigs and it can occasionally be introduced into hospitals. This preliminary European Union-wide baseline survey on MRSA was conducted in 2008 in holdings with breeding pigs. A total of 1,421 holdings housing and selling mainly breeding pigs (breeding holdings), and 3,176 holdings housing breeding pigs and selling mainly pigs for fattening or slaughter (production holdings) from 24 European Union Member States were included in the survey. Also, two countries not belonging to the European Union participated in the survey. Pooled dust samples collected from the holdings were tested for MRSA and all isolates were typed by spa-typing and classified in relation to belonging to MRSA ST398. The survey results indicate that MRSA was commonly detected in holdings with breeding pigs in some Member States, while in other Member States prevalence was low. Seven Member States did not detect any MRSA in the surveyed holdings. The European Union prevalence of MRSA positive breeding holdings was 14.0%, and the prevalence varied from 0% to 46.0% among the Member States. The European Union prevalence of MRSA positive production holdings was 26.9%, while in Member States prevalence varied from 0% to 51.2%. MRSA ST398 was the predominant MRSA lineage identified, covering 92.5% of the MRSA isolates. MRSA isolates not belonging to ST398 were detected in six Member States. A varying set of MRSA spa-types was isolated, although the t011 spa-type was by far the most dominant type. MRSA spa-types not belonging to ST398 described in human medicine were also detected among the surveyed pig holdings. Monitoring of MRSA in food producing animal species as well as investigations of human health importance of the non-ST398 MRSA findings in pigs are recommended.