ARS | Publication request: Anatomical Distribution and Genetic Relatedness of Antimicrobial Resistant E. coli from Healthy Companion Animals

Submitted to: Journal of Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 9, 2010
Publication Date: February 1, 2011
Citation: Davis, J.A., Jackson, C.R., Cray, P.J., Barrett, J.B., Brousse,Jr, J.H., Gutafson, J., Kucher, M. 2011. Anatomical Distribution and Genetic Relatedness of Antimicrobial Resistant E. coli from Healthy Companion Animals. Journal of Applied Microbiology. 110(2):597-604.

Interpretive Summary: The contribution of dogs and cats as reservoirs of antimicrobial resistant Escherichia coli remains largely undefined. This is increasingly important considering the possibility of transfer of bacteria from companion animals to the human host. In this study, dogs and cats from veterinary clinics were screened for the presence of E. coli. From May to August, 2007, healthy companion animals (155 dogs and 121 cats) from three veterinary clinics in the Athens, GA, USA area were sampled. E. coli was isolated from swabs of nasal, oral, rectal, abdomen, and hindquarter areas and tested for antimicrobial susceptibility against a panel of 16 antimicrobials and genetic relatedness using Pulsed-Field Gel Electrophoresis (PFGE) analysis. Although rectal swabs yielded the most E. coli (165/317; 52%) from dogs and cats, the organism was distributed evenly among the other body sites sampled. E. coli isolates from both dogs and cats exhibited resistance to all antimicrobials tested with the exception of amikacin, cephalothin, and kanamycin. Resistance to ampicillin was the most prevalent resistant phenotype detected. Among the resistant isolates, 21 resistance patterns were observed, where 18 patterns represented multidrug resistance (MDR; resistance is equal to 2 antimicrobial classes). Also among the resistant isolates, 33 unique clonal types were detected, where each clonal type contained isolates from various sampling sites. This data suggests that dogs and cats could be a common source of antimicrobial resistant E. coli which may be transferred to humans from various sites on the animal’s body.

Technical Abstract: Aims: Escherichia coli have been targeted for studying antimicrobial resistance in companion animals due to opportunistic infections and as a surrogate for resistance patterns in zoonotic organisms. The aim of our study examined antimicrobial resistance in E. coli isolated from various anatomical sites on healthy dogs and cats and identified genetic relatedness. Methods and Results: From May to August, 2007, healthy companion animals (155 dogs and 121 cats) from three veterinary clinics in the Athens, GA, USA area were sampled. E. coli was isolated from swabs of nasal, oral, rectal, abdomen, and hindquarter areas. Antimicrobial susceptibility testing against 16 antimicrobials was performed using broth microdilution with the SensititreTM system. Clonal types were determined by a standardized pulsed-field gel electrophoresis protocol. Although rectal swabs yielded the most E. coli (165/317; 52%) from dogs and cats, the organism was distributed evenly among the other body sites sampled. E. coli isolates from both dogs and cats exhibited resistance to all antimicrobials tested with the exception of amikacin, cephalothin, and kanamycin. Resistance to ampicillin was the most prevalent resistant phenotype detected (dogs, 33/199; 17% and cats, 27/118; 23%). Among the resistant isolates, 21 resistance patterns were observed, where 18 patterns represented multidrug resistance (MDR; resistance is equal to 2 antimicrobial classes). Also among the resistant isolates, 33 unique clonal types were detected, where each clonal type contained isolates from various sampling sites. Similar resistance phenotypes were exhibited among clonal types and three clonal types were from both dogs and cats. Conclusions: Healthy companion animals can harbor antimicrobial resistant E. coli on body sites that routinely come in contact with human handlers. Significance and Impact of the Study: This study is the first report that demonstrates a diverse antimicrobial resistant E. coli population distributed over various sites of a companion animal’s body, thereby suggesting potential transfer of resistant microflora to human hosts during contact.