Detection of methicillin-resistant Staphylococcus aureus ST398 in food samples of animal origin in Spain

Sir, Methicillin-resistant Staphylococcus aureus (MRSA) strains belonging to clonal lineage sequence type (ST) 398 are being reported at an increasing frequency in Europe.1 This new MRSA type has been isolated from colonized and infected animals and humans, and also from meat in some countries,1,2 representing a risk to human health; nevertheless, so far, no data about detection of MRSA ST398 in food in Spain have been published. A total of 318 raw food samples of food-producing animals (148 chicken, 55 pork, 46 veal, 19 lamb, 10 turkey, 8 rabbit and 12 minced-meat samples) and of wild animals (8 game bird, 4 wild boar, 4 deer and 4 hare samples) were collected from November 2007 to March 2009 in La Rioja (Spain). Samples were suspended in saline solution and 100 µL was inoculated in brain heart infusion (BHI) broth containing 6.5% NaCl, and incubated at 35°C for 24 h. Then, 300 µL was seeded on ORSAB plates (Oxoid) with oxacillin (2 mg/L), and incubated at 35°C for 36 h. One blue presumptive MRSA colony per sample was selected and identified by DNase assay and by PCRs of the mecA and nuc genes.3,4