Man contracts 'animal' MRSA

on 30/10/2012 00:00:00

It was found in an elderly man living in a nursing home who was once a part-time cattle farmer.

Known as ST398 MRSA or "pig" MRSA, it has only been reported to sporadically cause infections in animals, but can cause serious and life threatening infections in humans. These include endocarditis (damage to the lining of the heart) and bacteraemia (bacterial bloodstream infection).

The case is documented in the October edition of Epi-Insight, the Health Protection Surveillance Centre (HPSC) monthly newsletter.

Microbiologists writing in the publication have warned of implications on screening for MRSA if further cases of this particular strain are identified in Ireland.

Current guidelines recommend that high-risk patients - including those who previously tested positive or are being transferred from another hospital - be screened before being admitted to hospital.

However, the microbiologists say if further cases of pig MRSA are identified, then pre-admission screening may have to be extended to close contacts or family members with close contacts with livestock.

The microbiologists also warn that prompt recognition of this strain in both animals and humans "is of utmost importance… not only because of the risk to animals and food products but also because of the risk of spread to and between humans".

ST398 has been associated with outbreaks in other countries, showing that human-to-human transmission is possible. It has not been reported previously in either animals or humans in Ireland.

The patient in this case was an elderly man living in a rural nursing home. He had previously tested positive for non-livestock associated MRSA and then subsequently negative. However, he tested positive for the ST398 strain in late 2011.

The microbiologists analysing his case said while he could have acquired the ST398 strain during a hospital stay or in the nursing home, he had not had any animal contacts while in the home. However they said it was "impossible to completely rule out a link between the patient and animal sources particularly because of the rural location of the nursing home".

While living or working on a farm is considered a risk factor for the acquisition of MRSA elsewhere in Europe, it is not included in Irish guidelines.

The microbiologists said another possible source of the ST398 MRSA was raw meat products as it has been reported previously in pork, beef, veal, lamb, and chicken, as well as mozzarella cheese.