Antimicrobial Resistance, FlaA Sequencing, and Phylogenetic Analysis of Campylobacter Isolates from Broiler Chicken Flocks in Greece

Abstract

Human campylobacteriosis caused by thermophilic Campylobacter species is the most commonly reported foodborne zoonosis. Consumption of contaminated poultry meat is regarded as the main source of human infection. This study was undertaken to determine the antimicrobial susceptibility and the molecular epidemiology of 205 Campylobacter isolates derived from Greek flocks slaughtered in three different slaughterhouses over a 14-month period. A total of 98.5% of the isolates were resistant to at least one antimicrobial agent. In terms of multidrug resistance, 11.7% of isolates were resistant to three or more groups of antimicrobials. Extremely high resistance to fluoroquinolones (89%), very high resistance to tetracycline (69%), and low resistance to macrolides (7%) were detected. FlaA sequencing was performed for the subtyping of 64 C. jejuni and 58 C. coli isolates. No prevalence of a specific flaA type was observed, indicating the genetic diversity of the isolates, while some flaA types were found to share similar antimicrobial resistance patterns. Phylogenetic trees were constructed using the neighbor-joining method. Seven clusters of the C. jejuni phylogenetic tree and three clusters of the C. coli tree were considered significant with bootstrap values >75%. Some isolates clustered together were originated from the same or adjacent farms, indicating transmission via personnel or shared equipment. These results are important and help further the understanding of the molecular epidemiology and antimicrobial resistance of Campylobacter spp. derived from poultry in Greece.

Genomic diversity, virulence and source of Campylobacter jejuni contamination in Irish poultry slaughterhouses by whole genome sequencing

“…The use of other molecular biology techniques including pulsed‐field gel electrophoresis (PFGE) and fla A sequencing has been previously documented (Iannetti et al, 2020 ; Natsos et al, 2021 ), with some observations on cross‐contamination during processing and persistence on farms reported. An Italian study (Iannetti et al, 2020 ) used PFGE to investigate cross‐contamination in a poultry slaughterhouse and it observed similar profiles in isolates recovered at both the early and later stages of processing, which was attributed to survival and contamination by flock‐specific strains along the processing line.…”

“…This study however did not estimate the proportion of carcass isolates directly attributed to contamination from Campylobacter derived from caecal carriage in broilers from within the same batch. A more recent study by Natsos et al ( 2021 ) used fla A sequencing to look at the molecular diversity of Campylobacter spp. isolated from broiler flocks in Greece, and showed the presence of the same fla types and antimicrobial resistance profiles in isolates collected from the same farm at different times, adjacent houses of the same farm and different farms and concluded persistence of strains with further contamination of subsequent batches and/or contamination via equipment, working clothes and vehicles.…”

“…This study however did not estimate the proportion of carcass isolates directly attributed to contamination from Campylobacter derived from caecal carriage in broilers from within the same batch. A more recent study by Natsos et al (2021) used flaA sequencing to look at the molecular diversity of Campylobacter spp. isolated from broiler flocks in Greece, and showed the presence of the F I G U R E 4 Heat map showing the distribution of virulence genes amongst different sequence types of Campylobacter jejuni.…”

Transmission of antimicrobial resistance (AMR) during animal transport

“…High total microbial counts remain after standard washing procedures and ineffectively cleaned crates and modules have been shown to be a source of Campylobacter spp., including resistant strains (Natsos et al., 2021 ), for birds to be slaughtered (Herman et al., 2003 ; Sibanda et al., 2018 ; Rasschaert et al., 2020 ; Hertogs et al., 2021 ; Moazzami et al., 2021 ). Campylobacter genotyping supports contaminated crates as being a source of flock and carcass contamination (Hastings et al., 2011 ).…”