Z-018. Antimicrobial Susceptibility among MRSA Isolates from People and Companion Animals from the Same Geographical Region and its Implications for Empiric Antimicrobial Treatment

S. Sanchez, C. Smith, B. Wheeler, M. A. Jensen;
The Univ. of Georgia, Athens, GA.

MRSA these days in people is one of the most common and dreaded pathogens in outpatient care. This organism has shown increased in prevalence among the community and so it is the number of people affected. It was estimated that 94,360 invasive MRSA cases occurred in the US in 2005, with 18,650, or about 1 in 5, of those cases resulting in death. The GA-Public Health Office confirms that there were 13 deaths due to invasive MRSA in 2005, eight of them involving young previously healthy individuals. Most interestingly, we have seen that this increase in MRSA among people in Georgia was mirrored by an increase in MRSA in its animal population. Antibiograms were obtained following the CLSI disk diffusion and MIC protocols. mecA characterization was performed by PCR. Fifty human and sixty animal isolates in from, dogs (n=43), cats (n=2), horses (n=13) and pet birds (n=2) were obtained from the same geographical area. Isolates were confirmed to carry mecA and typed by PCR. Typing of the mecA gene in human isolates showed that 78% were type IV and 22% were type II. Among the animal isolates 40% were type IV and 60% were type II. The prevalence of mecA types among the animal groups varied with 28% of canine isolates being type IV and 82% type II. Among the equine isolates 18% were type II and 82% were type IV. All feline and avian isolates were type II. 100% of the human type II and type IV isolates were susceptible to tetracycline and vancomycin, with all type II being also susceptible to gentamycin and thrimethoprim sulfa. 100% of the animal type II isolates shared the same sensitivity with the human isolates while among the type IV animal isolates only vancomycin showed 100% susceptibility. These data highlights the difficulty of empiric treatment of MRSA both in people and animals, as well as, the importance of mecA typing and its epidemiology. Furthermore, it seems to indicate that this reverse zoonosis is currently evolving in the animal communities in a separate way acquiring more resistance elements or at least, evolving faster than the human community MRSA population.