At the beginning of 2007, the incidence of MRSA on pig farms stood at 30 per cent, but by the end of 2008 it had gone up to 75 per cent, Dr Brons reports. Large pig farms (with more than 500 sows) were particularly likely to be MRSA-positive. The bacterium is transported from farm to farm in livestock trucks. Many pigs also become infected on the way to the abattoir because the MRSA bacterium is present in other pigs in the truck. Pig farmers and abattoir workers can become infected with the bacterium too, if they come into contact with live pigs. Abattoir staff who only work with dead pigs do not run any risk, says Dr Broens.

In order to cut the transmission of MRSA from pigs to humans, the bacterium needs to be combatted at source: on the farm. Only reducing antibiotic use will not solve the problem says Dr Broens because the resistant bacteria can spread and thrive among pigs that have not had any antibiotics. Besides reducing antibiotic use, she argues for hygiene measures in order to prevent the spread of resistant bacteria on and between pig farms. This requires a joint plan by farmers, politicians, supermarkets and vets, says the Wageningen University PhD candidate.

Els Broens received her PhD on 28 October from Mart de Jong, professor of Quantitative Veterinary Epidemiology at Wageningen University.