Preliminary results on detection of Extended-Spectrum Beta-Lactamase (ESBL)-producing Escherichia coli from red foxes, corvids, and waterfowl in the Emilia-Romagna region, Northern Italy

In the context of the One Health approach, antimicrobial resistance (AMR) is considered one of the main challenges. Various studies have reported how wildlife populations may act as sentinels for AMR in the environment, especially in highly anthropized landscape or where zootechnical activities are intensive. Furthermore, predators may acquire AMR bacteria through consumption of prey. Escherichia coli can acquire AMR genes, including those encoding resistance to Highest Priority Critically Important Antimicrobials (HPCIAs) for human medicine as Extended-spectrum β-lactamases (ESBL) genes, thus representing a good bioindicator for AMR (1-3). In the study period January 2020-April 2022, 370 E. coli strains were isolated from faecal samples of 347 wild animals (115 red foxes, 183 corvids, and 49 waterfowl) in the Emilia-Romagna region (Northern Italy) to assess the prevalence of ESBL E. coli faecal shedders. Following Decision (EU) 2020/1729 (4), the isolates were tested for AMR towards 15 antimicrobials, most of them ranked as Critically Important Antimicrobials (CIAs) by the WHO. By MIC test, 31/370 (8.4%) phenotypically ESBL-producing E. coli were detected as resistant to cefotaxime and/or ceftazidime. ESBL E. coli were isolated from red foxes (n= 13), corvids (n= 11) and waterfowl (n= 7). By PCR, phenotypically-resistant E. coli harboured ESBL-plasmidic related genes; in particular, blaSHV, blaTEM and blaCTX genes were carried by 2 (6.5%), 12 (38.7%) and 30 (96.8%) isolates, respectively. The co-presence of all genes was never found, but 38.7% of ESBL-producing E. coli harboured blaTEM and blaCTX –genes simultaneously. Overall, the genotypically-confirmed ESBL E. coli tested by MIC test were found resistant to cefotaxime (100%), ampicillin (96.9%), sulfamethoxazole (87.1%), ceftazidime (87.1%), ciprofloxacin (51.6%), tetracycline (48.4%), trimethoprim (35.5%), nalidixic acid (16.1%), chloramphenicol (16.1%), gentamycin (6.5%), colistin (3.2%). All isolates were susceptible to amikacin, meropenem, tigecycline and azithromycin. The prevalence of ESBL-producing E. coli found in our study shows the potential role of wild animals, especially waterfowl (7/49; 28.6%) and red foxes (13/115; 11.3%), as carriers of MDR isolates. This phenomenon is worsened by co-resistances to CIAs, thus representing a potential public health risk and suggesting the use of wild animals as sentinels for the analysis of the AMR spread in the environment.