Dutch Consumer research body finds 11% of pork is contaminated with MRSA bacteria

The Dutch Food and Consumer Product Safety Authority (VWA) has undertaken a study of the incidence of nt-MRSA (non-typable MRSA), which affects pigs, calves and livestock farmers and found the bacteria in 84% of cases studied.

Furthermore they have reported that 11% of meat products in the retail sector are contaminated with the hospital bacteria MRSA. The tests consisted of 1293 samples of unheated meat taken in the retail trade (supermarkets, butchers, poulterers, etc.),throughout Holland.

MRSA is the name given to a group of bacteria that belong to the Staphylococcus aureus (SA) family of bacteria. The people who are most at risk of becoming either colonised or infected with MRSA are those in close contact with people who may be carrying the bacteria, for example in hospital wards that care for ill people. Nt-MRSA is a clone of MRSA.

According to the Authority, meat does not contribute to the spread of the bacteria, which is resistant to most antibiotics.

However, nt-MRSA can be spread where livestock is kept.

Suprisingly, most nt-MRSA is found in dead turkey and chicken (31 and 27% respectively).

With live animals, the bacteria has only been found (so far) in pigs and calves. The animal health authority has confirmed that 50% of animals on pig farms are infected with the bacteria the level of infection in cattle isn't known.

Arie van Nes, from the Faculty of Animal Health in Utrecht said "The figures surprised me. My first thoughts were that it can be spread through processing."

He published a report Methicillin-resistant Staphylococcus aureus in Veterinary Doctors and Students, the Netherlands in Emerging Infectious Diseases Volume 12, Number 12–December 2006

"The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in the Netherlands, at 1.0%, is among the lowest in Europe. In 2004, a relationship between pig farming and a high risk for MRSA carriage was found. To investigate if those in professional contact with livestock are at higher risk for MRSA carriage, we screened 80 veterinary students and 99 veterinarians and questioned them about animal contacts and known MRSA risk factors. Of these, 27 students who did not have livestock contact were excluded from further analysis. We found 7 carriers of MRSA, a prevalence of 4.6%, which is similar to that found in patients who had previously been treated at foreign hospitals."

Here are the test results ;



Their conclusions :

· MRSA generally occurs in most types of unheated meat of farm animals and poultry sampled in retail outlets in 2007. On average, MRSA was present in around 11% of some 1300 samples. The highest prevalences were found in turkey, chicken and veal. The numbers of MRSA bacteria found were very low. In a subset of about half of
the positive samples, there were less than 10 colony-forming units per gram of meat present in each sample.
· The relative contribution of Dutch products and products from other EU Member States seems to be of the same order of magnitude, but the low numbers in the second category do not permit any reliable conclusion, and must be further investigated.
· The MRSA strains isolated from the different meat types were mostly (84%) of the Spa-type of NT-MRSA, that has recently been found also in Dutch in pigs and other species.
· A not inconsiderable percentage (16%), however, was of Spa-types, which have not been associated with livestock farming previously. Further research is required to determine whether there is a hitherto unknown reservoir in domestic (farm) animals and whether there is transmission to humans.
· The relative contribution to contamination of products, for example through the contamination of carcases, from the slaughter and processing environment or due to processors carrying the bacteria, requires further investigation to determine where effective intervention could take place in the chain. This needs to involve a comparison of the typing results and resistance patterns of MRSA bacteria in the various links of the chain.