Use of phage applications to combat MRSA at the sow-piglet interface to reduce exposure of staff and contamination of the environment

The biggest risk for human transmission of methicillin-resistant Staphylococcus aureus (MRSA) from livestock is direct contact with infected animals or contaminated surroundings, including exposure to the air. In pig farming, sows (female pigs) are at the top of the production chain and, when infected, can continuously pass MRSA down to other pigs. However, a strategy of completely cleaning and disinfecting pig breeding facilities is too costly to be practical. This study focuses on breaking the MRSA cycle by successfully raising piglets that are free of MRSA from infected sows. This approach aims to lower the spread of the infection in the production chain and reduce risks to humans and the environment. To achieve this, we are testing specific phage cocktails (bacterial viruses that target MRSA) applied at the mother-piglet level, and then regularly testing both sows and piglets to track MRSA reduction. Additionally, the study will examine how the treatment affects the overall microbial environment (including MRSA) in animals, their surroundings, and even the air farmworkers breathe. The potential benefits of this treatment will also be evaluated by computer models to see how it impacts MRSA levels in breeding pigs, herds, farmworkers, and public health overall. The goal is to explore whether phage treatments can help reduce MRSA in animals, lowering the risk for human and environmental contamination. This is part of a "One Health" approach, which links human, animal, and environmental health.

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The main risk factor for human carriage of livestock associated methicillin-resistant Staphylococcus aureus is direct contact with colonised animals or contaminated environmental materials, along with airborne exposure. Sows are at the top of the pig production pyramid, when colonised, constitute a permanent source of MRSA further down the production pyramid. An all-in all-out strategy with efficient cleaning and disinfection is economically not feasible in pig breeding units. This study aims at breaking the cycle through successfully raising MRSA-negative piglets from positive sows to reduce the infection pressure in the production chain and the associated human and environmental exposure. Interventions will be applied to reduce MRSA directly on the mother-offspring interface by using farm-specific phage-cocktails at the sow-piglet interface. MRSA reduction will be studied through repeated sampling of sows and piglets. Likewise, the impact of the phage treatment on the microbiome dynamics and specifically on MRSA in animals, their environment and in bioaerosols including the exposure of farm staff will be investigated by meta-omics approaches. The impact of the phage application on the prevalence of MRSA in breeding pigs, herds receiving breeding pigs and the effect on the colonisation of farm staff and public health will be investigated by modelling. Phage application is expected support “one health” by reducing MRSA in the animal population and consequently reducing exposure of farm staff and environmental contamination.