DNA microarray-based characterization and antimicrobial resistance phenotypes of clinical MRSA strains from animal hosts.

Abstract

BACKGROUND: Methicillin-resistant(MRSA) is a leading cause of severe infections in humans and animals worldwide. Studies elucidating the population structure, staphylococcal cassette chromosometypes, resistance phenotypes, and virulence gene profiles of animal-associated MRSA are needed to understand spread and transmission. OBJECTIVES: The objective of this study was to determine 1) clonal complexes andtypes, 2) resistance phenotypes, and 3) virulence/resistance gene profiles of MRSA isolated from animals in Switzerland. METHODS: We analyzed 31 presumptive MRSA isolates collected from clinical infections in horses, dogs, cattle, sheep, and pigs, which had tested positive in the Staphaurex Latex Agglutination Test. The isolates were characterized bytyping and DNA microarray profiling. In addition, we performed antimicrobial susceptibility testing using the VITEK 2 Compact system. RESULTS: Characterization of the 31 presumptive MRSA isolates revealed 3 methicillin-resistantisolates, which were able to grow on MRSA2 Brilliance agar. Of the 28 MRSA isolates, the majority was assigned to CC398 (86%), but CC8 (11%) and CC1 (4%) were also detected. The predominanttype was t011 (n = 23), followed by t009 (n = 2), t034 (n = 1), t008 (n = 1), and t127 (n = 1). CONCLUSIONS: The results of this study extend the current body of knowledge on the population structure, resistance phenotypes, and virulence and resistance gene profiles of MRSA from livestock and companion animals.