Wild boars carry extended-spectrum β-lactamase- and AmpC-producing Escherichia coli
Extended-spectrum β-lactamase (ESBL)-producing <i>Escherichia coli</i> and methicillin-resistant <i>Staphylococcus aureus</i> (MRSA) represent major healthcare concerns. The role of wildlife in the epidemiology of these bacteria is unclear. The purpose of this study was to determine their prevalence in wild boars in Germany and to characterize individual isolates. A total of 375 fecal samples and 439 nasal swabs were screened for the presence of ESBL-/AmpC-<i>E. coli</i> and MRSA, respectively. The associations of seven demographic and anthropogenic variables with the occurrence of ESBL-/AmpC-<i>E. coli</i> were statistically evaluated. Collected isolates were subjected to antimicrobial susceptibility testing, molecular typing methods, and gene detection by PCR and genome sequencing. ESBL-/AmpC-<i>E. coli</i> were detected in 22 fecal samples (5.9%) whereas no MRSA were detected. The occurrence of ESBL-/AmpC-<i>E. coli</i> in wild boars was significantly and positively associated with human population density. Of the 22 <i>E. coli</i>, 19 were confirmed as ESBL-producers and carried genes belonging to <i>bla</i><sub>CTX-M</sub> group 1 or <i>bla</i><sub>SHV-12</sub>. The remaining three isolates carried the AmpC-β-lactamase gene <i>bla</i><sub>CMY-2</sub>. Several isolates showed additional antimicrobial resistances. All four major phylogenetic groups were represented with group B1 being the most common. This study demonstrates that wild boars can serve as a reservoir for ESBL-/AmpC-producing and multidrug-resistant <i>E. coli</i>.