Emergence of methicillin-resistant Staphylococcus pseudintermedius (MRSP) in dogs in the island nation of Grenada, West Indies

Background: Staphylococcus pseudintermedius (SP) is a commensal bacterium of the skin and mucosae of dogs, and an opportunistic pathogen associated with various conditions. Emergence of methicillin resistant SP (MRSP) that are multidrug resistant complicates treatment of clinical conditions. Furthermore, environmental contamination in veterinary clinical settings, nosocomial infections, and zoonotic infections are of concern to animal and public health. By 2014, only methicillin susceptible SP were reported from canine pyoderma cases in Grenada. Given reports of global dissemination of MRSP, we hypothesized visitor dogs to Grenada would introduce MRSP to Grenadian dogs. Between 2017 and 2018, oral and perianal swabs were collected from all dogs in the study, while skin swabs were obtained from dogs with cutaneous lesions consistent with pyoderma. Environmental swabs were obtained to assess contamination at a small animal clinic. Samples were processed using routine microbiological and molecular techniques. A questionnaire was administered to dog owners to evaluate risk factors for MRSP infection. Results: Study subjects comprised 193 clinically healthy dogs representing 119 local dogs and 74 visitor dogs. SP carriage was 58% (69/119) in local dogs and 64.9% (48/74) in visitor dogs. MRSP prevalence was 1.7% (2/119) in local dogs and 8.1% (6/74) in visitor dogs. The study also included dogs with clinical dermatitis and 80% (4/5) had SP and 20% (1/5) had MRSP. Overall, SP antimicrobial resistance (AMR) levels were higher in visitor dogs compared to local dogs with statistically significant differences in resistances to chloramphenicol, clindamycin, oxacillin and fluoroquinolone. MRSP was found in the veterinary clinic environment and the strain was identical to that found in some visitor dogs. Genotypic, AMR, and epidemiologic data are compatible with visitor dogs introducing MRSP to local dogs. Conclusions: MRSP was documented for the first time in dogs in Grenada and was associated with antimicrobial use. These findings are consistent with reports of international MRSP dissemination via dog movements. Resistance to critically important antimicrobials emphasizes the need for AMR surveillance for making informed animal health decisions. Environmental contamination at the veterinary clinic supports the plausibility of nosocomial transmission and highlights the importance of implementing strict hygiene and disinfection procedures.