Staphylococcus aureus and MRSA colonization rates among personnel and dogs in a small animal hospital: association with nosocomial infections

The genetic relationship of thirty Methicillin-resistant S. aureus (MRSA) isolates derived from the nasal cavities of canine patients hospitalized (n = 7), veterinary personnel (n = 20), and environmental sources (n = 3) sampled during a 20-month investigation period, were analyzed in this study. Genetic relatedness of all MRSA isolates was investigated involving commonly used typing techniques: Pulsed-field gel electrophoresis (PFGE), Multilocus sequence typing (MLST), spa typing, PCR for detection of Panton-Valentine leukocidine (PVL) genes and staphylococcal cassette chromosome mec-typing (SCCmec). Analysis of typing results revealed a certain predominant (72%) genotype: PFGE type IMT-A, ST22, spa type t032, SCCmecIV. This genotype has been reported previously (Walter et al., 2008c) being the predominant PFGE type associated with MRSA-positive clinical specimens, mostly from wound infections, derived from small and exotic animals of that facility. Furthermore, occasionally high rates in nasal colonization of veterinary personnel (18 of 88: 20%) in one of three personal screening periods were accompanied by a sudden rise of MRSA infections in small animals. Our data strongly indicate that high rates of colonized veterinary staff lead to an increase of nosocomial infections in small animal hospitals. We therefore recommend the introduction of surveillance of nosocomial infections especially in surgical veterinary hospitals.