BackgroundMethicillin-resistant Staphylococcus aureus (MRSA) has emerged recently worldwide in production animals, particularly pigs and veal calves, which act as reservoirs for MRSA strains for human infection. The study determined the prevalence of MRSA and other resistant strains of S. aureus isolated from the anterior nares of pigs and human handlers on pig farms in Trinidad.MethodsIsolation of S. aureus was done by concurrently inoculating Baird-Parker agar (BPA) and Chromagar MRSA (CHROM) with swab samples and isolates were identified using standard methods. Suspect MRSA isolates from Chromagar and BPA were subjected to confirmatory test using Oxoid PBP2 latex agglutination test. The disc diffusion method was used to determine resistance to antimicrobial agents.ResultsThe frequency of isolation of MRSA was 2.1% (15 of 723) for pigs but 0.0% (0 of 72) for humans. Generally, for isolates of S. aureus from humans there was a high frequency of resistance compared with those from pigs, which had moderate resistance to the following antimicrobials: penicillin G (54.5%, 51.5%), ampicillin (59.1%, 49.5%), and streptomycin (59.1%, 37.1%), respectively. There was moderate resistance to tetracycline (36.4%, 41.2%) and gentamycin (27.2%, 23.7%) for human and pig S. aureus isolates, respectively, and low resistance to sulfamethoxazole-trimethoprim (4.5%, 6.2%) and norfloxacin (9.1%, 12.4%), respectively. The frequency of resistance to oxacillin by the disc method was 36.4 and 34.0% from S. aureus isolates from humans and pigs, respectively. Out of a total of 78 isolates of S. aureus from both human and pig sources that were resistant to oxacillin by the disc diffusion method, only 15 (19.2%) were confirmed as MRSA by the PBP'2 latex test kit.ConclusionsThe detection of MRSA strains in pigs, albeit at a low frequency, coupled with a high frequency of resistance to commonly used antimicrobial agents in pig and humans could have zoonotic and therapeutic implications. Finally, the diagnostic limitation of using CHROMagar and testing for oxacillin resistance by the disc diffusion method alone to determine MRSA strains without performing confirmatory tests cannot be overemphasized because the possibility of overdiagnosis of MRSA infections cannot be ignored.

Medicine (TUCVM) for abdominal distention and vomiting. The dog previously presented to the Community Practice (CP) Service at TUCVM 4 days prior for yelping after the owner picked her up that morning. The owner reported instances where when barely touched, the dog would cry out and yelp in pain. On Surgery Service (SS) consult, the patient was found to have crepitus in the right carpus, left elbow, and both shoulders. Pain was elicited on extension of the right shoulder and in the region of the left medial thigh.Radiographs and bloodwork were performed following an orthopedic exam by the SS. There was also evidence of organomegaly on the radiographs, and an abdominal ultrasound was scheduled for later in the week. The medications prescribed by CP were Gabapentin 100 mg orally twice daily, Galliprant 30 mg orally once daily, and Denamarin 225 mg orally once daily for elevated liver enzymes (ALT and ALP) seen on serum biochemistry.The owner reported that 2 days following the CP visit, the patient vomited clear liquid with brown bits in it (coffee ground appearance) six times. The owners reported that although the