Experimental exposure of farmed mink (Neovison vison) to livestock-associated methicillin-resistant Staphylococcus aureus contaminated feed

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) is widely distributed in the Danish pig production. Spillover to the mink production is hypothesized to occur via contaminated pig by-products used in the production of mink feed. The aim of the present longitudinal experimental cohort study was to confirm the potential of LA-MRSA being transmitted to naïve mink after exposure to contaminated feed, and to study the persistence of the bacterium on the animals after ceased exposure to contaminated feed. LA-MRSA-negative mink (n = 28) were housed in pairs in 14 mesh cages. Twenty-four mink (12 cages) received around 5.1 × 10 ⁸ cfu/mink in the feed for five days, while four mink (two cages) were kept as negative controls and fed with LA-MRSA negative feed. Twenty-four hours after initiation of spike, all 28 min. were tested LA-MRSA-positive by paw swabs. After cease of the spiking period, one mink per cage were moved to a clean housing facility to study the potential effect of environmental contamination in persistence of the LA-MRSA. All mink were re-tested three times per week for the subsequent 26 days to study whether the mink cleared off the bacterium. The results showed that LA-MRSA can be transmitted to paws and pharynx on mink after exposure to contaminated feed and that LA-MRSA may spread indirectly through contaminated environmental sites. Mink tend to clear off LA-MRSA, however, the bacterium may persist on mink for more than 26 days.