A Comparison of Methods of MRSA Detection in Dutch Pig Farms

Abstract

Layman’s summary:

Methicillin Resistant Staphylococcus aureus (MRSA) is a S. aureus bacterium which is resistant to most -lactam antibiotics. Antibiotics in this class make up a majority of the antibiotics prescribed to humans and include groups such as Penicillins and Cephalosporins. livestock associated MRSA (LA-MRSA) can be traced back to contact with animals and is genetically distinct from both hospital and community acquired MRSA. Pigs are an important reservoir of LA-MRSA, and close contact between pigs and humans on farms can lead to MRSA carriage by workers. This is a concern as MRSA carriage can lead to active MRSA infection in vulnerable populations, such as those who are hospitalized, possibly resulting in serious skin infections and even sepsis. There is a growing body of research which seeks to understand the link between MRSA found in the environment on farms and its implication on human health. An important part of this is a thorough understanding of the occurrence of MRSA in that setting and the ability to measure it in a reproducible and robust way. This study aims to compare two different sampling methods for measuring airborne MRSA in the farm environment, passive dust sampling with electrostatic dust fall collectors (EDCs), and active sampling air pumps. The study described here is part of a larger study called Exclude MRSA whose objective is to reduce MRSA carriage in pigs by introducing benign bacteria into the noses of piglets which could competitively exclude MRSA. Additionally, the data collected may improve understanding of the ways that MRSA exists in the farm environment and make it easier to compare existing studies which used different sampling methods. Dust samples were taken from 7 Dutch pig farms, with measurements taken in multiple compartments housing pigs of varying ages. These samples were then analyzed for MRSA presence as well as total bacterial count. There was a strong positive relationship between the paired MRSA levels found in EDCs and those measured by pumps. This suggests that in the future EDCs can be used as the primary method for measuring MRSA presence in the pig farm setting.