Characterization and risk assessment of MRSA from food

Livestock-associated Methicillin-resistant Staphylococcus aureus (la-MRSA) have been described with varying prevalences at primary production and along the different food chains in several countries, including Germany. Working or living on a farm was proven to be a risk factor for acquiring MRSA, whereas the exposure risk decreases from farm to fork and was considered to be low for food. Since 2009, more than 1.500 MRSA isolates from various food samples (raw meat from pork, veal, beef, game, turkey and chicken) and taken in the course of the national monitoring of zoonotic agents were intensively characterized at the National Reference Laboratory for staphylococci including Staphylococcus aureus at the BfR. All isolates were multiresistant against at least 3 different classes of antimicrobials. The majority of MRSA (85.2 %) belonged to clonal complex CC398, with t011 and t034 being the predominant spa types. Among isolates from poultry, non-CC398 MRSA of spa types t1430 (chicken) resp. t002 (turkey) were more frequently detected. Only few isolates carried genes encoding for one of the well described virulence determinants (e.g. enterotoxins, leukocidins etc.). Nevertheless, findings of Panton-Valentine leukocidin (PVL) positive MRSA in food warrant special attention and need to be considered in risk assessment.