Antimicrobial Resistance in Generic Escherichia coli Isolates from Wild Small Mammals Living in Swine Farm, Residential, Landfill, and Natural Environments in Southern Ontario, Canada

Abstract

To assess the impacts of different types of human activity on the development of resistant bacteria in the feces of wild small mammals, we compared the prevalences and patterns of antimicrobial resistance and resistance genes in generic Escherichia coli and Salmonella enterica isolates from fecal samples collected from wild small mammals living in four environments: swine farms, residential areas, landfills, and natural habitats. Resistance to antimicrobials was observed in E. coli isolates from animals in all environments: 25/52 (48%) animals trapped at swine farms, 6/69 (9%) animals trapped in residential areas, 3/20 (15%) animals trapped at landfills, and 1/22 (5%) animals trapped in natural habitats. Animals trapped on farms were significantly more likely to carry E. coli isolates with resistance to tetracycline, ampicillin, sulfisoxazole, and streptomycin than animals trapped in residential areas. The resistance genes sul2, aadA, and tet(A) were significantly more likely to be detected in E. coli isolates from animals trapped on farms than from those trapped in residential areas. Three S. enterica serotypes (Give, Typhimurium, and Newport) were recovered from the feces of 4/302 (1%) wild small mammals. All Salmonella isolates were pansusceptible. Our results show that swine farm origin is significantly associated with the presence of resistant bacteria and resistance genes in wild small mammals in southern Ontario, Canada. However, resistant fecal bacteria were found in small mammals living in all environments studied, indicating that environmental exposure to antimicrobials, antimicrobial residues, resistant bacteria, or resistance genes is widespread.

Antimicrobial Resistance in Escherichia coli Isolates from Raccoons (Procyon lotor) in Southern Ontario, Canada

“…These values are consistent with previous studies looking at the prevalences of AMR in wildlife in Ontario and around the world (5% to 48% in Ontario, Canada [2,12], 13.7% in the Czech Republic [14], and 20.1% in the United Kingdom [28]). We found that the prevalence of AMR in fecal E. coli isolates from raccoons in rural areas was lower than what has been reported for small mammals (e.g., mice, rats, and chipmunks) living on swine farms (48%) and in contrast with previous studies, and we detected no significant difference in the prevalences of resistance between urban and rural environments (2).…”

“…Small wild mammals, such as mice and voles, are often targeted for studies investigating the impact of human activity on the development of antimicrobial resistance the environment and associated wildlife (2,8,12); however, because of the limited home range of these species, they are unlikely to be involved in the widespread dissemination of resistant bacteria. For this study, we targeted raccoons (Procyon lotor), which are common, midsized mammals that live in close association with humans in both urban and agricultural areas.…”

“…Wild animals, particularly species that live in close association with humans, may be exposed to resistant bacteria in their environment, and antimicrobial resistance has been detected in fecal bacteria from a variety of wild animals, including birds, reptiles, mammals, and fish, throughout the world (2,15,17,24). Wild animals have been implicated as potential reservoirs of resistant bacteria, and it has been hypothesized that wild animals might act as vehicles for the dissemination of resistant bacteria throughout the environment (4).…”

Escherichia coli from clinical mastitis

“…34 Similar reports of high levels of resistance to antimicrobials exist. 1,27,37 The findings of the present study suggest that, on the properties sampled, there may not have been selective pressure caused by antibiotic use.…”

High Levels of Antimicrobial Resistance among Escherichia coli Isolates from Livestock Farms and Synanthropic Rats and Shrews in the Mekong Delta of Vietnam

“…The prevalence of ampicillin resistance among E. coli isolates from bank voles and wood mice from forest sites in England was also very high (90.0%) (36). Furthermore, in a Canadian study, the prevalence of ampicillin resistance was higher among wild mammals trapped in a natural environment than among those trapped on swine farms (8.0% versus 2.0%, respectively) (31). Further molecular studies are needed to elucidate the molecular basis of this.…”