A global increase in Escherichia coli (E. coli) resistant to cephalosporins (extended-spectrum β-lactamases (ESβLs) and AmpC β-lactamases) has been recorded in the last 20 years. Similarly, several studies have reported the spread of colistin resistance in Enterobacteriaceae isolated from food and the environment. The aim of the present study was to evaluate the prevalence of ESβL, AmpC and colistin-resistant E. coli isolated from pork and wild boar meat products in the Emilia Romagna region (North Italy). The isolates were analysed phenotypically (considering both resistant and intermediate profiles) and genotypically. The prevalence of genotypically confirmed ESβL and AmpC E. coli was higher in pork meat products (ESβL = 11.1% vs. AmpC = 0.3%) compared to wild boar meat (ESβL = 6.5% vs. AmpC = 0%). Intermediate profiles for cefotaxime (CTX) and ceftazidime (CAZ) were genotypically confirmed as ESβL in pork meat isolates but not for wild boar. Four E. coli from wild boar meat were resistant to colistin but did not harbour the mcr-1 gene. E. coli isolated from wild boar meat seem to show aspecific antimicrobial resistance mechanisms for cephalosporins and colistin. The prevalence of resistant isolates found in wild boar is less alarming than in pork from farmed domestic pigs. However, the potential risk to consumers of these meat products will require further investigations.
Keywords: AmpC; E. coli; ESβL; blaCTX-M1; colistin; mcr-1; meat; pork; wild boar.