Occurrence and Survival of Livestock-Associated MRSA in Pig Manure and on Agriculture Fields.

Lӕrke Boye Astrup,Karl Pedersen,Julie Elvekjӕr Hansen

doi:10.3390/antibiotics10040448

Abstract

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) is widespread in European pig production, and an increasing number of humans attract infections with this bacterium. Although most infections occur in humans with direct livestock contact, an increasing number of infections occur in humans without any established livestock contact. There have been speculations that at least some of these infections may be connected to the exposure of liquid pig manure for example spread as fertilizers. The present study therefore undertook to measure the presence of LA-MRSA in liquid pig manure and on the surface of soils fertilized with liquid manure and investigate the survival of the bacterium in manure. The results showed that LA-MRSA could be detected in 7 out of 20 liquid manure samples and in 12 out of 186 soil samples. However, the bacterium was not more frequently detected in samples collected after compared to before the spreading of liquid manure on the fields, thus suggesting that other sources of LA-MRSA on agriculture fields likely exist. The decimation time in liquid manure was >32 days at 5 °C in vitro but decreased with increasing temperature. Based on these results, liquid manure does not appear to be an important risk factor for human exposure to LA-MRSA.

Highlights

While previous investigations foremost have focused on Escherichia coli or enterococci, or applied metagenomics, few studies have so far to our knowledge investigated the occurrence of methicillin-resistant Staphylococcus aureus (MRSA) in pig manure, and none have addressed the survival of this bacterium in manure
Studies on the survival of Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) in dust in pig farms indicated a half-life of 5 days at room temperature, corresponding to a decimation time of approximately 17 days [25], which is somewhat longer than the decimation time (2.5–6.5 days, Table 2) we found in liquid manure at 25 ◦ C
LA-MRSA can be found in liquid pig manure, in modest concentrations

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Several studies have investigated the occurrence of antibiotic residues and antibioticresistant bacteria in manure from farms, in pig manure, and it has been shown that both are common in manure [1]. A German study demonstrated that liquid pig manure generally contained more bacteria that were resistant to several antibiotics than urban sewage sludge [2]. Similar results were demonstrated in a study conducted in Korea [3]. While previous investigations foremost have focused on Escherichia coli or enterococci, or applied metagenomics, few studies have so far to our knowledge investigated the occurrence of methicillin-resistant Staphylococcus aureus (MRSA) in pig manure, and none have addressed the survival of this bacterium in manure

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Conclusion