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Title: Diversity of plasmids and antimicrobial resistance genes in multidrug-resistant Escherichia coli isolated from healthy companion animals

Author
item Jackson, Charlene
item DAVIS, JOHNNIE - Former ARS Employee
item Frye, Jonathan
item Barrett, John
item Hiott, Lari

Submitted to: Zoonoses and Public Health
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/21/2014
Publication Date: 9/1/2015
Citation: Jackson, C.R., Davis, J.A., Frye, J.G., Barrett, J.B., Hiott, L.M. 2015. Diversity of plasmids and antimicrobial resistance genes in multidrug-resistant Escherichia coli isolated from healthy companion animals. Zoonoses and Public Health. 62(6)479-488.

Interpretive Summary: The presence and transfer of antimicrobial resistance genes from commensal bacteria from companion animals to more pathogenic bacteria may contribute to dissemination of antimicrobial resistance. The purpose of this study was to determine antimicrobial resistance gene content and the presence of genetic elements (plasmid replicon types and class I integrons) in antimicrobial resistant Escherichia coli from healthy companion animals. From May to August, 2007, healthy companion animals from three veterinary clinics in the Athens, GA, USA area were sampled and multi-drug resistant E. coli (MDR, resistance to 2 or more antimicrobial classes) were obtained. From the analysis, at least one plasmid replicon type was detected in 94% of the MDR E. coli; four isolates contained as many as five different plasmid replicons. The presence of class I integrons was detected in 61% of the isolates with eight isolates containing aminoglycoside and/or trimethoprim resistance genes in the variable cassette region of the integron. Microarray analysis of a subset of the MDR E. coli identified the presence of genes conferring resistance to antimicrobials including aminoglycosides, Beta-lactams, chloramphenicol, sulfonamides, tetracycline, and trimethoprim. Antimicrobial resistance to eight antimicrobials and five plasmid replicons were transferred via conjugation. The presence of antimicrobial resistance genes and genetic elements indicate that E. coli from companion animals may play an important role in the dissemination of antimicrobial resistance particularly to human hosts during contact. This study is useful for veterinarians and pet owners demonstrating that dogs and cats are a common source of antimicrobial resistant E. coli which may be transferred to humans.

Technical Abstract: The presence and transfer of antimicrobial resistance genes from commensal bacteria in companion animals to more pathogenic bacteria may contribute to dissemination of antimicrobial resistance. The purpose of this study was to determine antimicrobial resistance gene content and the presence of genetic elements in antimicrobial resistant Escherichia coli from healthy companion animals. 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 and multi-drug resistant E. coli (n=36; MDR, resistance to 2 or more antimicrobial classes) were obtained. Of the 25 different plasmid replicon types tested by PCR, at least one plasmid replicon type was detected in 94% (34/36) of the MDR E. coli; four isolates contained as many as five different plasmid replicons. Nine replicon types (FIA, FIB, FII, I2, A/C, U, P, I1, and HI2) were identified with FIB, FII, I2 as the most common pattern. The presence of class I integrons (intI) was detected in 61% (22/36) of the isolates with eight isolates containing aminoglycoside and/or trimethoprim resistance genes in the variable cassette region of intI. Microarray analysis of a subset of the MDR E. coli (n=9) identified the presence of genes conferring resistance to aminoglycosides (aac, aad, aph, and strA/B), Beta-lactams (ampC, cmy, tem, and vim), chloramphenicol (cat), sulfonamides (sulI and sulII), tetracycline [tet(A), tet(B), tet(C), tet(D), and regulator, tetR] and trimethoprim (dfrA). Antimicrobial resistance to eight antimicrobials (ampicillin, cefoxitin, ceftiofur, amoxicillin-clavulanic acid, streptomycin, gentamicin, sulfisoxazole, and trimethoprim-sulfamethoxazole) and five plasmid replicons (FIA, FIB, FII, I1, and I2) were transferred via conjugation. The presence of antimicrobial resistance genes, intI, and transferable plasmid replicons indicate that E. coli from companion animals may play an important role in the dissemination of antimicrobial resistance particularly to human hosts during contact.