Wildlife as a reservoir of multidrug resistant Escherichia coli and Klebsiella spp. strains: an over 2-year monitoring in the Emilia Romagna region (Italy).

INTRODUCTION Antimicrobial resistance (AMR) is a health challenge worldwide. Wildlife is considered an indicator of AMR pollution, spreading from human related environments to the natural ones. Here we present an AMR monitoring in wildlife, investigating foxes (F), corvids (C) and aquatic birds (AB) as AMR sentinels and focusing on multidrug resistant (MDR) Enterobacteriaceae. MATERIALS AND METHODS Between August 2020 and February 2023, in the context of the project funded by the Italian Ministry of Health (PRC2019002), 495 faecal samples were collected from 184 foxes (F), 210 corvids (C) and 101 aquatic birds (AB) as part of the infectious disease surveillance program of the Emilia Romagna region (Italy). The samples were also tested for MDR Enterobacteriaceae, identified by MALDI-TOF. The AMR profiles were evaluated determining the Minimal Inhibitory Concentration, interpreted according to the EUCAST breakpoints (2020). MDR was assessed according to Magiorakos et al. (2012) (1). RESULTS Of main interest was the isolation of 467 Escherichia coli and 36 Klebsiella spp. strains. 98/467 (21%) E. coli and 17/36 (47%) Klebsiella spp. isolates were resistant from 3 to 10 antimicrobial classes. Overall, the most common resistance rates in the MDR isolates (115) were to sulfamethoxazole (102; 89%), ampicillin (99; 86%), ciprofloxacin (78; 68%) and tetracycline (75; 65%), followed by cefotaxime (67; 58%), ceftazidime (62; 54%), trimethoprim (64; 56%), nalidixic acid (50; 43%), chloramphenicol (29; 25%%), azithromycin (24; 21%), colistin (23; 20%), gentamicin (20; 17%), tigecycline (15; 13%) and amikacin (2; 2%) (Figure 1, Figure 2). MDR was mostly related to F (n=51; 44%), followed by AB (n=40; 35%) and C (n=24%; 29%) (Table 1). Notably, 17/28 strains (61%), isolated from AB, were found resistant to ≥8 antimicrobial classes. DISCUSSION AND CONCLUSION Our study underlines the important role of wildlife in monitoring the spread of AMR from anthropogenic drivers to the natural environment. Aquatic birds, foxes and corvids were all effective AMR indicators, which can be used for future AMR surveillance programs. REFERENCES 1. Magiorakos, A. P. et al., 2012. Clin Microbiol Infect, 18(3), 268-281.