An investigation of methicillin-resistant Staphylococcus aureus colonization in people and pets in the same household with an infected person or infected pet.

OBJECTIVE To investigate the prevalence of concurrent methicillin-resistant Staphylococcus aureus (MRSA) colonization in people and pets in the same household with a person or pet with an MRSA infection and to compare MRSA isolates by use of molecular techniques. DESIGN 2 cross-sectional evaluations conducted concurrently. SAMPLE POPULATION 24 dogs, 10 cats, and 56 humans in part 1 and 21 dogs, 4 cats, and 16 humans in part 2 of the study. PROCEDURES In both parts of the study, nasal swab specimens were collected from humans and nasal and rectal swab specimens were collected from household pets. Selective culture for MRSA was performed, and isolates were typed via pulsed-field gel electrophoresis (PFGE) and spa typing. Households were defined as positive when MRSA was isolated from at least 1 person (part 1) or 1 pet (part 2). RESULTS In part 1, 6 of 22 (27.3%) households were identified with MRSA colonization in a person. In these households, 10 of 56 (17.9%) humans, 2 of 24 (8.3%) dogs, and 1 of 10 (10%) cats were colonized with MRSA. In part 2, only 1 of 8 households was identified with MRSA colonization in a pet. Most MRSA isolates obtained from humans and pets in the same household were indistinguishable by use of PFGE. CONCLUSIONS AND CLINICAL RELEVANCE The high prevalence of concurrent MRSA colonization as well as identification of indistinguishable strains in humans and pet dogs and cats in the same household suggested that interspecies transmission of MRSA is possible. Longitudinal studies are required to identify factors associated with interspecies transmission.