Prevalence of methicillin-resistant Staphylococcus spp. in Lithuanian dogs – a cross sectional study

Objectives: To investigate methicillin-resistant Staphylococcus spp. (MRS) occurrence in dogs from Lithuania. Methods: Between April 2012 and September 2013 samples from skin, ears and nose were taken from 300 dogs kept as companion animals in private households (n=220) as well as in 5 kennels of pure-breed dogs (n=80). Healthy (n=50) as well as diseased animals (160 pyoderma, 40 otitis and 50 reproductive disorders, such as infertility and abortions) were involved in the study. MRS were screened on Brilliance MRSA 2 Agar (Thermo Scientific) and Mannitol Salt Agar (Liofilchem) supplemented with 4 mg/L cefoxitin (Sigma-Aldrich). Species identification was performed using RapID Staph Plus (Thermo Scientific) biochemical identification system, species-specific nuc genes PCR and 16S rRNA sequencing for confirmation. Susceptibility testing to beta-lactams was done using the disc diffusion method and interpreted according to EUCAST guidelines. The presence of mecA and mecC genes was studied by PCR. Statistical analysis was performed using "R 1.8.1" package (http://www.r-project.org/). Comparison between categorical variables was calculated by the chi-square test and Fisher"s exact test. Results were considered statistically significant if p<0.05. Results: Twenty-seven MRS isolates were obtained from 23 dogs out of 300 (7.6%). The most prevalent species were S. pseudintermedius (n=15), S. haemolyticus (n=4) and S. lentus (n=3). The remain species included S. chromogenes (n=2), S. schleiferi (n=1), S. aureus (n=1) and S. xylosus (n=1). All isolates harboured the mecA gene while mecC gene was not detected. Twenty two isolates were detected in dogs within 3 large kennels from which 20 were obtained from vaginal samples of bitches. Anamnesis demonstrated inappropriate usage of fluoroquinolones in two kennels, 2-4 weeks before sampling. The prevalence of MRS in dogs kept in households was 2.3% i.e. significantly lower (p<0.01)