Survival of livestock-associated methicillin-resistant Staphylococcus aureus CC398 on different surface materials

Abstract

Background: Zoonotic livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) is widely spread in pig herds in many countries. However, the knowledge regarding the survival of LA-MRSA in the pig farm environment is currently limited. The aim of this study was to assess the survival of LA-MRSA on different surface materials found in the farm environment. The study investigated the survival of two different LA-MRSA strains belonging to the clonal complex (CC) 398 on four different surfaces: stainless steel, polypropylene plastic, K30 concrete and commercial concrete disk coupons. The survival of the bacteria over time was determined by the viable count method and, where possible, fitting a model to the observed data by using nonlinear least squares method to calculate the half-life (t1 / 2) for different strain and material combinations. Results: The study showed that the half-life of the bacteria was longer on polypropylene plastic (t1 / 2=11.08–15.78 days) than on stainless steel (t1 / 2=2.45–7.83 days). On these materials, both LA-MRSA strains survived through the 14 week observation period. The bacterial decay was fastest on the concrete surfaces, where LA-MRSA became undetectable after 3–9 weeks. Conclusions: The survival of LA-MRSA in the pig farm environment may be affected by different surface materials. A more frequent sampling protocol (< 7 days) is needed to determine the half-life on concrete surfaces.