Transmission of MRSA between humans and animals on duck and turkey farms

The objectives of this study were to estimate the prevalence of MRSA on duck and turkey farms, identify risk factors for human carriage and study transmission between animals and humans.

On 10 duck and 10 turkey farms, samples were taken from animals, poultry houses, home residences and humans and cultured using pre-enrichment and selective enrichment. MRSA isolates were typed by spa typing and multiple-locus variable number tandem repeat analysis (MLVA) typing. A subset of isolates from animals and humans was investigated using whole-genome mapping.

MRSA was found on one duck farm and three turkey farms. On duck farms, all humans were MRSA negative. On turkey farms, 5 of 11 farmers, 2 of 32 family members and 15 of 49 samples from the home residences were MRSA positive. Individuals with daily contact with turkeys were significantly more often MRSA positive than individuals without daily contact. All MRSA isolates belonged to livestock-associated MLVA complex 398, belonged to spa type t011, were negative for Panton-Valentine leucocidin, were mecC negative and were mecA positive. Whole-genome mapping proved a valuable tool to study the transmission of livestock-associated MRSA and showed that on two turkey farms the isolates from the animals and humans were indistinguishable or closely related, indicating transmission.

MRSA carriage in individuals in daily contact with turkeys was significantly higher than that in individuals only living on the farms or than in the general Dutch population. Therefore, persons with a high degree of contact with turkeys have an increased risk of MRSA carriage, and we propose that they should be screened prior to hospitalization in order to decrease the risk of nosocomial transmission.