Methods for the Detection of Antimicrobial Resistance and the Characterization of Staphylococcus aureus Isolates from Food-Producing Animals and Food of Animal Origin

Antimicrobial resistance is an important issue not only in human and veterinary medicine, but also in food safety. Resistant bacteria, including meticillin-susceptible and meticillin-resistant Staphylococcus aureus, which originate either from food-producing animals or from contaminations along the food chain, can reach the consumer and cause foodborne infections and intoxications. The current chapter provides basic knowledge about the methods to assess the antimicrobial susceptibility/resistance of S. aureus and the correct evaluation of the corresponding results. In food safety, it is of utmost relevance to trace back resistant bacteria and to identify their sources. Therefore, typing to strain level is necessary. Various—primarily genotypic—typing methods applicable to S. aureus, such as spa and dru typing, multi-locus sequence typing, pulsed-field gel electrophoresis, and analysis by DNA microarray among others, are presented and examples for their successful use in typing of S. aureus from food of animal origin are given.