Z-013. Prevalence of Methicillin Resistant Staphylococcus aureus and Staphylococcus intermedius in Domesticated Pets from Southern Louisiana

T. Rachal1, K. Ghislain1, A. Corbin1, B. Melius2, P. Seeman3, R. Nathaniel1;
1Nicholls State Univ., Thibodaux, LA, 2Metairie Small Animal Hosp., Metairie, LA, 3Ridgefield Animal Hosp., Thibodaux, LA.

Methicillin resistant Staphylococcus aureus (MRSA) and methicillin resistant Staphylococcus intermedius (MRSI) can both cause skin and wound infections in the domesticated animal population. Both of these Staphylococcal species are gram positive, coagulase positive, and highly resistant to most antibiotics. The prevalence of these two Staphylococcal species in domesticated pets is important because MRSA is a major human pathogen causing significant nosocomial public health problems, while MRSI has zoonotic capabilities and has been reported to cause human infections. Species identification is not routinely carried out clinically and is difficult to perform due to very few biochemical differences between these two organisms. In order to investigate the colonization rates in domesticated pets, nose and mouth swabs were taken from 115 animals at two regional small animal hospitals and cultured for these organisms. The samples were cultured for Staphylococcus on mannitol salt agar. Catalase and coagulase positive strains were tested for resistance to oxacillin. The methicillin resistant Staphylococcus species were then tested for resistance to polymixin B, presence of L-pyrroglutamyl-aminopeptidase (PYR) and the ability to produce acetoin (Voges-Proskauer test) to differentiate between S.aureus and S.intermedius. In addition, a PCR product corresponding to the thermonuclease gene nuc was amplified from each strain by species specific primers and used to confirm species differentiation. Our results show a 70% (81/115) rate of colonization of pets by coagulase positive Staphylococcus species of which 39.5% (32/81) were also resistant to oxacillin. Additionally, 62.5% (20/32) of MRS were identified as Staphylococcus aureus and 37.5% (12/32) were identified as Staphylococcus intermedius. Overall, 46% (53/115) of animals tested carried Staphylococcus aureus, while 24% (28/115) harbored Staphylococcus intermedius. These results indicate that pets could serve as reservoirs for MRSA and MRSI, as well as suggest that during recurrent episodes of human infection, screening strategies should include all household animals.