Methicillin-resistant coagulase positive staphylococcal colonization in veterinary professionals, owners and companion animals

Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a significant pathogen in both human and veterinary medicine. This thesis presents the results of investigation into the prevalence of MRSA and other methicillin-resistant coagulase positive staphylococcal colonization, and potential for interspecies transmission between companion animals and contacting humans such as pet owners and veterinary professionals.;In the second study, the goal was to determine the prevalence of MRSA colonization in veterinary personnel, and to evaluate potential risk factors for colonization. MRSA was isolated from 27/417 (6.5%) volunteers attending an international conference including 23/345 (7.0%) veterinarians, 4/34 (12.0%) technicians and 0/38 others. Colonization was more common among large animal personnel (15/96, 15.6%) compared to small animal personnel (12/271, 4.4%) and personnel without patient contact (0/50) (P<0.001). Large animal practice was the only variable significantly associated with colonization (OR = 2.9; 95% CI 1.2 --- 6.6). Canadian epidemic MRSA-5 (CMRSA-5) was isolated exclusively from large animal personnel (P <0.001) from the US (n-10), UK (n=2) and Demnark (n=1). CMRSA-2 was isolated from 11 small animal and two large animal personnel from the US (n=12) and Germany (n=1).;The objective of the third study was to investigate the prevalence of methicillin-resistant coagulase positive staphylococcal colonization in humans and companion animals residing within a common household, and to examine the occurrence of concurrent colonization. Staphylococcus aureus was isolated from 27.6% (67/242) humans, 14.3% (19/132) dogs and 4.3% (7/161) cats. The prevalence of MRSA colonization was 3.3% in humans and 1.5% in dogs. Staphylococcus intermedius was isolated from 4.1% humans, 46.2% dogs and 6.8% cats. Isolates from 0.4% humans, 4.5% dogs and 1.2% cats were MRSI, and MRSS was isolated from 0.8% dogs. Lack of hand washing was significantly associated with S. intermedius colonization (P=0.045, OR 1.97; 95% CI 1.05-3.69). Concurrent human-pet colonization with S. aureus was present in 10 (8.3%) households and with S. intermedius in four (3.3%) households. Indistinguishable S. aureus isolates between people and their pets were present in five households, whereas all S. intermedius isolates were distinct on pulsed-field gel electrophoresis.;These results are consistent with low level methicillin-resistant coagulase positive staphylococcal colonization in the Ontario dog and cat populations. Identification of higher colonization rates in veterinary professionals compared to community rates and evidence of concurrent colonization with indistinguishable staphylococci between pet owners and their dogs and cats suggests that interspecies transmission of methicillin-resistant staphylococci may represent a potential health risk to humans in close contact with animals and to companion animals through contact with humans, particularly their owners.;The objective of the first study was to investigate the prevalence of methicillin-resistant staphylococcal colonization in dogs upon admission to a veterinary teaching hospital, and to identify possible risk factors for colonization and the most frequent sites of colonization. Methicillin-resistant Staphylococcus pseudintermedius was isolated from the nasal passages of 4/193 (2.1%) dogs. MRSA and methicillin-resistant S. schleiferi subsp coagulans (MRSS) were isolated from the rectum and nasal passage respectively, of one dog each (0.5%). Methicillin-resistant S. intermedius (MRSI) was not identified in any of the dogs. Risk factor analyses could not be performed due to the low prevalence.