Characterisation of methicillin-resistant <i>Staphylococcus aureus</i> clinical isolates from animals in New Zealand, 2012–2013, and subclinical colonisation in dogs and cats in Auckland
Creators: name: Karkaba, A
name: Benschop, J
name: Hill, KE
name: Grinberg, A
Publisher: name: Taylor & Francis
Year: 2016
Subjects: subject: Space Science
subject: Medicine
subject: Microbiology
subject: FOS: Biological sciences
subject: Biotechnology
subject: Environmental Sciences not elsewhere classified
subject: Chemical Sciences not elsewhere classified
subject: Cancer
subject: Infectious Diseases
subject: FOS: Health sciences
subject: Virology
subject: Computational Biology

description: AIMS: To characterise methicillin-resistant <i>Staphylococcus aureus</i> (MRSA) isolates from infection sites in animals in New Zealand and assess the prevalence of subclinical MRSA colonisation in dogs and cats attending veterinary clinics in Auckland. METHODS: MRSA isolates from clinical specimens obtained by the main New Zealand veterinary diagnostic laboratories between June 2012 and June 2013, were genotypically characterised by DNA microarray hybridisation analysis and <i>spa</i> typing. In addition, nasal or perineal skin swabs collected from a cross-sectional sample of dogs (n=361) and cats (n=225) attending 29 veterinary clinics in Auckland during the same period were analysed for MRSA by culture. RESULTS: Eight MRSA clinical isolates were submitted for characterisation by the participating laboratories. The isolates originated from five dogs, including two isolates from the same dog, one foal, and one isolate had no identification of the source. The strain-types identified were AK3 (ST-5 SCC<i>mec</i>IV t045; n=1), USA500 (ST8 SCC<i>mec</i>IV t064; n=1), WSPP (ST30 SCC<i>mec</i>IV t019; n=1), Rhine Hesse (ST5 SCC<i>mec</i>II t002; n=2), and EMRSA-15 (ST22 SCC<i>mec</i>IV t032; n=3). No MRSA were isolated from 586 cultured swabs. Methicillin-susceptible <i>S. aureus</i> were detected in 9/257 (3.5%) swabs and non-<i>aureus</i> staphylococci in 22/257 (8.5%) swabs. The estimated true MRSA subclinical colonisation prevalence was 0%, with an upper 95% CI boundary of 1.9% for cats and 1.4% for dogs. CONCLUSIONS: The modest number of MRSA isolates submitted for this study by the participating laboratories suggests clinical MRSA infection in animals in New Zealand continues to be sporadic. The wide variety of strain-types found mirrored the evolving strain-type diversity observed in humans. We cannot rule out bias due to the non-random sampling of dogs and cats, but the apparent colonisation prevalence of 0% was consistent with the low prevalence of subclinical colonisation in humans in New Zealand. These similarities indicate the epidemiology of animal and human MRSA infections are linked. CLINICAL RELEVANCE: In the last decade, the prevalence of human MRSA infections in New Zealand has steadily increased. This is the second published study of MRSA in animals in New Zealand. The results indicate clinical MRSA infection in animals remains sporadic, but the diversification of the strain-types may pose new therapeutic challenges to veterinarians, due to their diverse resistome.