Virulence Profiling, Multidrug Resistance and Molecular Mechanisms of Campylobacter Strains from Chicken Carcasses in Tunisia

Abstract

Antibiotic resistance in foodborne pathogens is an emergent global health concern. The objectives of this study were to assess antimicrobial resistance (AMR) in Campylobacter isolates from chicken carcasses and to investigate the AMR molecular mechanisms as well as the presence of virulence determinants. The study was performed on 257 samples collected from abattoirs and retail shops in northeastern Tunisia. Forty-eight Campylobacter isolates were recovered and identified as C. jejuni (n = 33) and C. coli (n = 15). Antibiotic resistance was tested against eight antibiotics and high resistance rates were observed against tetracycline (100%), erythromycin (97.9%), ciprofloxacin (73%), nalidixic acid (85.4%), ampicillin (83.3%), amoxicillin/clavulanic acid (22.9%), chloramphenicol (75%), and gentamicin (27.1%). All isolates were multidrug-resistant, and 22 resistance patterns were found. All isolates were screened for AMR genes (tet(O), tet(A), tet(B), tet(L), cmeB, ermB, blaOXA-61, and aphA-3), and for point mutations in gyrA (C257T substitution) and 23SrRNA (A2075G/A2074C) genes. All screened AMR genes, as well as the C257T and the A2075G mutations, were detected. The virulence genotypes were also determined, and all isolates carried the motility (flaA) and invasion (cadF) genes. Most of them also harbored the cdtA, cdtB, and cdtC genes, encoding the Campylobacter toxin. The screening of the cgtB and the wlaN genes, involved in Guillain-Barré Syndrome expression, revealed the presence of the cgtB in 21.2% of C. jejuni strains, whereas none of them carried the wlaN gene. Our findings highlight the emergence of Campylobacter strains simultaneously harboring several virulence and AMR determinants, which emphasizes the risk of transmission of MDR strains to humans via the food chain. Hence, controlling the dissemination of foodborne pathogens “from the farm to the fork” as well as restricting the use of antimicrobials in husbandry are mandatory to prevent the risk for consumers and to mitigate the dissemination of MDR pathogens.

The European Union Summary Report on Antimicrobial Resistance in zoonotic and indicator bacteria from humans, animals and food in 2020/2021

“…An increase of the tested concentrations of erythromycin (up to 512 mg/L instead of 128 mg/L) has been implemented since 2021 according to Decision (EU) 2020/1729, allowing for 2021 a better screening of isolates which may carry erm (B), as it enables differentiation of isolates with an MIC < 128 mg/L, which are likely to only have mutations or alterations in target genes (L4, L22 CmeABC, CmeR genes and the binding site of CmeR) from those with a higher MIC (≥ 512 mg/L) that have an erythromycin resistance phenotype more likely associated with possession of transferable erm (B), even though mutational resistance cannot be ruled out (Wang et al, 2014 ). Point mutations in 23SrRNA might also confer similar levels of high resistance against erythromycin as ermB‐mediated resistance in Campylobacter (Wei and Kang, 2018 ; Béjaoui et al, 2022 ).…”

The rise of antibiotic resistance in Campylobacter

“…In an intensive pig farm in South Africa, the MDR rates of C. jejuni and C. coli were 94.0% and 85.2%, respectively [24]. C. jejuni and C. coli from livestock, including poultry, pigs, and ruminants, and their feed have shown high rates of antibiotic resistance, while C. coli appears to be better adapted for MDR [25]. Worldwide, Campylobacter has been isolated from various wild bird species and wild boars, with a MDR rate of 67.0% for C. coli from wild boars [1,26 ▪ ].…”

Broiler house environment and litter management practices impose selective pressures on antimicrobial resistance genes and virulence factors ofCampylobacter

“…This may lead to their persistence through pre-harvest and post-harvest, thereby posing a risk to the public (Ghatak et al ., 2017; Al Hakeem et al ., 2022). Furthermore, strains carrying ARGs conferring resistance to critically important antibiotics for humans, as well as possessing VFs that increase their ability to colonize host tissues, will be harder to treat in the event contaminated food products reach consumers (Montgomery et al ., 2018; Liu et al ., 2019; Béjaoui et al ., 2022).…”