Occurrence of multidrug-resistant extended-spectrum β-lactamase (ESBL)-producing <i>Escherichia coli</i> in fecal and environmental samples from Belgian livestock farms

ABSTRACT Antimicrobial resistance is a major global health concern, with extended-spectrum β-lactamase (ESBL)-producing bacteria posing a significant threat. Food production animals have been indicated as an important source of ESBL-producing bacteria. This study examined the occurrence of ESBL Escherichia coli in Belgian livestock (cattle, calves, pigs feces, and broiler ceca) and farm environments. Antimicrobial susceptibility of E. coli isolates ( n = 1,219) was screened using microbroth dilution (EUVSEC), and bla TEM/SHV/CTX-M genes were further identified by PCR and sequencing. ESBL-producing E. coli isolates were more common in broiler samples (10% ceca, 2.5% environment) compared to those of pigs (1% feces, 2% environment), cattle (1% feces), and calves (1% feces). Among the 67 ESBL isolates, 63% carried bla CTX-M genes, and 55% bla TEM genes. bla SHV genes (13%) appeared only in isolates from broiler origin (ceca and farm environment). All ESBL-producing E. coli isolates were resistant to between 3 and 13 out of the 19 antimicrobials tested. In addition, a rapid PCR-based screening method in manure DNA extracts was evaluated for its ability to detect bla TEM/SHV/CTX-M genes compared to the conventional culture-based approach. These β-lactamase genes were detected in 98% of the samples ( bla TEM : 95/101, bla CTX-M : 6/101, bla SHV : 0/101). The low prevalence of bla CTX-M and bla SHV in manure DNA extracts compared to the corresponding E. coli isolates may be due to PCR sensitivity issues or matrix inhibitory effects. The presence of ESBL-producing E. coli in broiler ceca, livestock feces, and manure raises concerns about the potential transmission of resistance genes in agriculture, highlighting the need for ongoing surveillance and responsible antibiotic use. IMPORTANCE This research addresses the pressing global health concern of antimicrobial resistance, focusing on extended-spectrum β-lactamase (ESBL)-producing bacteria. The study investigates the occurrence and distribution of ESBL-producing Escherichia coli in Belgian livestock, including cattle, calves, pigs, and broiler chickens, as well as in their farm environments. The findings provide valuable data to inform farmers, veterinarians, and policymakers to raise awareness and support evidence-based antimicrobial stewardship.