An uncommon occurrence of bicavitary effusion due to mast cell neoplasia in a 12-year-old mixed breed dog.

A case of bicavitary effusion affecting a 12-year-old female spayed mixed breed dog that was presented to Tuskegee University College of Veterinary Medicine's Emergency Service for abdominal distension and vomiting. Upon physical exam, the patient exhibited signs of pain and sensitivity to touch and pain on abdominal palpation with a positive fluid wave. The patient also had dull mentation and increased respiratory effort with an abdominal component. On labwork, there was a leukocytosis characterized by a mature neutrophilia, monocytosis, and basophilia. A mild thrombocytopenia with low numbers of poorly granulated mast cells were also noted on peripheral blood smear review. Serum biochemistry revealed a mild azotemia and abnormal SNAP cPL test. The patient received a full abdominal ultrasound, which detected bicavitary effusion, hepatomegaly, and splenomegaly. Cytology of the cavitary effusions was moderately cellular with significant numbers of mast cells. The patient was euthanized following a tentative diagnosis of systemic mastocytosis. The clinical signs, in this case, are consistent with published data for systemic mastocytosis, which include organomegaly, abdominal pain, gastrointestinal signs, and hematologic abnormalities. However, this is the first report of bicavitary effusion due to presumed systemic mastocytosis.

Frequency of resistance to methicillin and other antimicrobial agents among Staphylococcus aureus strains isolated from pigs and their human handlers in Trinidad.

BACKGROUND: Methicillin-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. METHODS: Isolation 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. RESULTS: The 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. CONCLUSIONS: The 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.