Multi-drug resistant (MDR) and extended-spectrum β-lactamase (ESBL) producing Escherichia coli isolated from slaughtered pigs and slaughterhouse workers in Yaoundé, Cameroon

Abstract

Antimicrobial resistance (AMR) in the food chain remains a global public health concern for both humans and animals. This study aimed to determine the prevalence, resistance profiles, and clonal relatedness of multidrug-resistant (MDR) and extended-spectrum β-lactamases- producing Escherichia coli (ESBL-Ec) isolated from slaughtered pigs and slaughterhouse workers in Yaoundé, Cameroon. A cross-sectional study was conducted over four months, from February to May 2023 in two selected pig's slaughterhouse markets in Yaoundé. Rectal swabs were collected from 375 pigs at four time points and pooled per three according to gender, origin, and abattoirs leading to 125 pooled samples. Seven faecal samples from 60 contacted exposed workers were collected. Samples were cultured on CHROMagar™ ESBL medium, dark pink to reddish colonies were considered E. coli. Resistance genes including bla _CTX-M, bla _SHV and bla _TEM were detected using the polymerase chain reaction (PCR) while ERIC-PCR was used to assess the genetic relatedness between isolates. The prevalence of ESBL-Ec was elevated among exposed workers (71.4 %; n = 5/7) and pigs (70.4 %; n = 88/125). Overall, ESBL-Ec exhibited high resistance to cefuroxime (100 %, n = 105/105), cefotaxime (100 %, n = 105/105), amoxicillin-clavulanic acid (98.1 %, n = 103/105), cefixime (92.4 %, n = 97/105), tetracycline (86.7 %, n = 91/105) and sulfamethoxazole-trimethoprim (81.9 %, n = 86/105). However, these isolates showed good susceptibility to gentamicin (3.8 %, n = 4/105), chloramphenicol (8.6 %, n = 9/105), and fosfomycin (14.3 %, n = 15/105). All human isolates and 75.8 % (n = 75/99) of pig isolates were multi-drug resistant. The bla _CTX-M was the most prevalent resistance gene among exposed workers (100 %, n = 6/6) and pigs (80.8 %, n = 80/99) followed by bla _TEM (33.3 % each). High clonal relatedness of ESBL-Ec strains was observed among pig and human isolates across slaughterhouses. This study showed that the gastrointestinal tract of pigs might be an important reservoir of MDR and ESBL-Ec in Yaoundé, Cameroon and these resistant bacteria might be circulating between sources, especially humans. Heightening awareness on appropriate antibiotic use in humans and animals as well as implementing stringent biosecurity and food safety measures are imperative to prevent the emergence and spread of AMR in the country.

Keywords: ESBL; Escherichia coli; Exposed workers; Multidrug resistance; Pigs.

Fig. 1

Geographical representation of study sites and surrounding areas.

Fig. 2

Flowchart of the human and pig isolates. AST: Antimicrobial Susceptibility Testing; ESBL-Ec: Extended Spectrum β-Lactamase producing Escherichia coli; SH: Slaughterhouse.

Fig. 3

Prevalence of ESBL-Ec carriage in humans and pigs across slaughterhouse.

Fig. 4

Distribution of multi-drug resistant ESBL-Ec.

Fig. 5

Distribution of resistance genes among ESBL-Ec isolated from humans and pigs.

Fig. 6

Genetic relatedness of ESBL-E. coli (n = 88) isolated from pigs (n = 82) and exposed workers (n = 06) in Cameroon. Dendogram generated by GelJ software (version 2.1) using UPGMA and Dice similarity coefficient. The clusters were obtained by similarities of the ERIC genes according to the same genetic pools.