Assessing the Load, Virulence and Antibiotic-Resistant Traits of ESBL/Ampc E. coli from Broilers Raised on Conventional, Antibiotic-Free, and Organic Farms

Abstract

Poultry is the most likely source of livestock-associated Extended Spectrum Beta-Lactamase (ESBL) and plasmid-mediated AmpC (pAmpC)-producing E. coli (EC) for humans. We tested the hypothesis that farming methods have an impact on the load of ESBL/pAmpC-EC in the gut of broilers at slaughter. Isolates (n=156) of antibiotic-free (AF), organic (O), and conventional (C) animals were characterized for antibiotic susceptibility and antibiotic resistance genes. Thirteen isolates were whole-genome sequenced. The average loads of ESBL/pAmpC-EC in cecal contents were 4.17 Log CFU/g for AF; 2.85 Log CFU/g for O; and 3.88 Log CFU/g for C type (p < 0.001). ESBL/pAmpC-EC isolates showed resistance to antibiotic classes historically used in poultry, including penicillins, tetracyclines, quinolones, and sulfonamides. Isolates from O and AF farms harbored a lower proportion of resistance to antibiotics than isolates from C farms. Among the determinants for ESBL/pAmpC, CTX-M-1 prevailed (42.7%), followed by TEM-type (29%) and SHV (19.8%). Avian pathogenic E. coli (APEC), belonging to ST117 and ST349, were identified in the collection. These data confirm the possible role of a broiler as an ESBL/AmpC EC and APEC reservoir for humans. Overall, our study suggests that antibiotic-free and organic production may contribute to a reduced exposure to ESBL/AmpC EC for the consumer.

Genome analysis of third-generation cephalosporin-resistant Escherichia coli and Salmonella species recovered from healthy and diseased food-producing animals in Europe

“…coli was 4.0% (109/2712) in 2008–09, 3.3% (100/2993) in 2013–2014, and 1.0% (34/3412) in the present study conducted in 2015–2018. Similar observations were made in ad hoc studies and in several European national surveys [ 14 , 23 , 24 ]. Hence, the French national surveillance network Resapath reported a decreasing proportion of ESBL/AmpC in food-producing animals in the time period 2011–2021 [ 37 ].…”

“…However, recently the proportion of ESBL/AmpC in E . coli has declined in Europe as a possible consequence of the reduction in antibiotic use [ 14 , 23 , 24 ]. Indeed, the overall sales of antimicrobials including cephalosporins in veterinary medicine in Europe have approximately halved from 2010 to 2019 [ 25 ].…”

Intensified livestock farming increases antibiotic resistance genotypes and phenotypes in animal feces

“…For example, the most common genes found in feces from commercial poultry flocks from Italy are those against tetracycline and aminoglycosides 5 . Escherichia coli isolates from antibiotic-free and organic farms exhibit a lower proportion of resistance to antibiotics than isolates from conventional farms, which is of particular concern given the identification of pathogenic Escherichia coli in the latter 6 . Organic systems also represent a protective barrier to conventional systems due to their low prevalence of resistant Escherichia coli isolates, and high cephalosporin resistance has been detected in conventional samples, despite their prohibition in poultry farming 7 .…”

“…However, domestic animals are often reared and treated under very different farming management systems. Fecal resistance and the potential for ARG transmission based on the point of origination have been largely overlooked 6,7 .…”

Foodborne bacteria in slaughterhouses : with focus on cleaning and disinfection

“…This resistance is transferrable to other bacteria (Gekenidis et al 2020;Dorr et al 2022). Extended-spectrum beta-lactamase-producing bacteria have been found in the gut of both humans and animals (Asir et al 2015;Tofani et al 2022). In several European countries, ESBL E. coli has also been detected on the carcasses of pigs, sheep, cattle and chickens (Bardoň et al 2013;Pacholewicz et al 2015;Biasino et al 2018;Tsitsos et al 2022).…”