As shown by the data of the annual national monitoring on antimicrobial resistance, the prevalence of MRSA in Swiss slaughter pigs increased in the period from 2009 to 2012 from 2.0% to 18.1%. This rapid increase is primarily due to the proliferation of a specific clone of the genotype MRSA ST398 t034, which is characterized by a broad resistance to therapeutically important antibiotics. A first study, designed as a master's thesis at the center for zoonoses, bacterial animal diseases and antimicrobial resistance (ZOBA), shows, that no potential common farm as source of this clone could be identified. Effective measures to combat further spread of MRSA in the Swiss pig population can only be developed, if detailed insights into the specific factors, such as entry way, dissemination of this agent within the herd up to slaughter are known. Thus, the aim of this project is to track the MRSA status of selected Swiss fattening farm throughout the entire process from fattening to slaughter, including transport of the animals and as well as MRSA carriage by farmers. Thereby, critical control points and potential intervention measures could be identified (part A).
Also, the suitability of oral fluid samples for determining flock prevalence of MRSA compared to nasal swabs should be investigated. The ongoing national monitoring on antimicrobial resistance is based on nasal swabs of slaughter pigs for determination of MRSA herd prevalence, while sampling only one animal per herd. With oral fluid sampling much more animals of a herd could be tested and any factors such as transport of animals and contact with animals of other stocks during transport to the slaughterhouse could be avoided with this simple and low-cost way of sampling (part B).
