Methicillin-resistant Staphylococcus aureus (MRSA), first identified in the 1960s, was initially considered to be a nosocomial pathogen (hospital acquired infection). Beginning in the late 20th century, a specific clone of MRSA known as USA300 emerged as a leading cause of community-acquired infection, but doubts remain as to where many cases of MRSA infection originate, and how to break the transmission of this dangerous strain.
A new study finds that 8% of hospital outpatients carrying methicillin-resistant MRSA lived with an MRSA-positive pet. When faced with chronic and or recurrent MRSA cases, physicians should consider the possibility of household pets as MRSA source. Patients should be informed of this possibility. Unnecessary close contact should be avoided and heightened hygiene practices should be instituted. Sampling/swabbing of all the human and animals in a household seems appropriate to identify unrecognized sources and break potential cycles of reinfection especially in cases involving immunocompromised patients.
Transmission of MRSA between Companion Animals and Infected Human Patients Presenting to Outpatient Medical Care Facilities. PLoS ONE 6(11): e26978. doi:10.1371/journal.pone.0026978
Methicillin-resistant Staphylococcus aureus (MRSA) is a significant pathogen in both human and veterinary medicine. The importance of companion animals as reservoirs of human infections is currently unknown. The companion animals of 49 MRSA-infected outpatients (cases) were screened for MRSA carriage, and their bacterial isolates were compared with those of the infected patients using Pulsed-Field Gel Electrophoresis (PFGE). Rates of MRSA among the companion animals of MRSA-infected patients were compared to rates of MRSA among companion animals of pet guardians attending a “veterinary wellness clinic” (controls). MRSA was isolated from at least one companion animal in 4/49 (8.2%) households of MRSA-infected outpatients vs. none of the pets of the 50 uninfected human controls. Using PFGE, patient-pets MRSA isolates were identical for three pairs and discordant for one pair (suggested MRSA inter-specie transmission p-value = 0.1175). These results suggest that companion animals of MRSA-infected patients can be culture-positive for MRSA, representing a potential source of infection or re-infection for humans. Further studies are required to better understand the epidemiology of MRSA human-animal inter-specie transmission.