Putative connection between zoonotic multiresistant extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli in dog feces from a veterinary campus and clinical isolates from dogs

Abstract

Introduction: To contribute to the understanding of multiresistant bacteria, a 'One Health' approach in estimating the rate of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli and getting insights into the transmission from clinical settings to the surrounding environment was employed by collecting fecal samples of dogs in a public area. Isolates were compared to those from samples of diseased dogs from a nearby small-animal clinic.

Materials and methods: One hundred fecal samples of dogs were collected on a single day in the public area of a veterinary faculty with a small-animal clinic and adjacent residential neighborhoods. All identified ESBL-producing strains were isolated by selective plating, genotypically analyzed by DNA microarray, polymerase chain reaction, sequence analysis, and pulsed-field gel electrophoresis and compared to 11 clinical ESBL/AmpC-producing E. coli isolated from diseased dogs treated in the small-animal clinic 2 months before and 2 months following the environmental sampling collection.

Results and discussion: Fourteen percent (14/100) of the extra-clinical samples harbored phenotypic ESBL/putative AmpC-producing E. coli with additional resistances against other antimicrobials. One ESBL-strain displayed an identical macrorestriction pattern to one clinical, another one to three clinical clonal ESBL-producing strains. The genotypic ESBL-determinants (blaCTX-M-1 and blaCTX-M-15) and detection rates (10%) in dog feces collected outside of the small-animal clinic are comparable to the rates and ESBL-types in the healthy human population in Germany and to clinical and non-clinical samples of humans and companion animals in Europe. The occurrence of identical strains detected both outside and inside the clinical setting suggests a connection between the small-animal clinic and the surrounding environment. In conclusion, dog feces collected in proximity to veterinary facilities should be considered as a non-point infection source of zoonotic ESBL-producing E. coli for both animals and humans. The common sniffing behavior of dogs further urges hygienic measures on the part of dog-patient owners, who should be educated to remove their pet's feces immediately and effectively.

Keywords: antimicrobial resistance; clonality; environmental spread; shared ESBL-STs; urban environments.

Fig. 1

(a) Phenotypic and genotypic typing results of ESBL- and AmpC-producing E. coli isolates based on a dendrogram (>XbaI-generated PFGE profiles after exclusion of double clones). Software: BioNumerics 6.6, Applied Maths, Belgium, cluster analysis of dice similarity indices based on the unweighted pair group method with arithmetic mean (UPGMA). (b) Comparison of clones from clinical dog isolates and extra-clinical fecal samples. CEF: cefotaxime; AMP: ampicillin; AMC: amoxicillin–clavulanic acid; GEN: gentamicin; KAN: kanamycin; DOX: doxycycline; SXT: sulfamethoxazole–trimethoprim; CAP: chloramphenicol; NAL: nalidixic acid; ENRO: enrofloxacin; R: resistant; I: intermediate.