Pig-manure fertilizer linked to human MRSA infections

People living near pig farms or agricultural fields fertilized with pig manure are more likely to become infected with methicillin-resistant Staphylococcus aureus (MRSA) bacteria, new research suggests.

The link between pig manure and MRSA follows on from previous research, highlighted by the Digital Journal, that found that livestock workers are at high risk of carrying MRSA, compared to the general population.

MRSA is a strain of staphylococcus bacteria that is resistant to methicillin and certain first-line antibiotics called beta-lactams. The bacteria can cause serious infections of the skin, blood, lungs and bones. Infections with drug-resistant strains, like MRSA, can be particularly difficult to treat.

For the new research, scientists examined the incidence of infections in Pennsylvania. In Pennsylvania manure from pig farms is often spread on crop fields to comply with state regulations for manure disposal.

In undertaking the study, researchers reviewed electronic health-care records from patients who sought care from the Pennsylvania-based Geisinger Health System. The researchers examined whether infected people lived near pig farms or agricultural land where pig manure was spread. They found that people who had the highest exposure to manure (calculated on the basis of how close they lived to farms, how large the farms were and how much manure was used) were 38% more likely to contract MRSA. The finding was based on analysis of skin, blood, and sputum samples.

This is not the only connection between farm animals and MRSA. Some parallel research has suggested that Human MRSA originated from cattle. Some researchers are of the view that the widespread use of antibiotics to encourage growth in farm animals fuels the proliferation of MRSA and other drug-resistant bacteria

The pig-manure / MRSA research has been published in the journal JAMA Internal Medicine. The title of the paper is "High-Density Livestock Operations, Crop Field Application of Manure, and Risk of Community-Associated Methicillin-Resistant Staphylococcus aureus Infection in Pennsylvania."

Posted by Tim Sandle