Antibiotic Resistance and Virulence of Arcobacter butzleri in the Large-Scale Poultry Slaughtering Chain

Arcobacter butzleri is a Gram-negative bacterium identified as a zoonotic pathogen worldwide. The ingestion of contaminated food is considered the main route of transmission to humans. A. butzleri has been isolated from several meat supply chains, including poultry industry. Therefore, poultry products and their production chain represent the main transmission routes of this microorganism. The present study aimed to assess the antibiotic resistance and to characterize the virulence capacity of A. butzleri isolated from broiler carcasses during slaughtering and from the slaughterhouse surfaces. One-hundred and seventeen isolates were examined for their antimicrobial resistance to different antibiotics concentration. After selection of the most resistant and susceptible isolates, infectiveness on mucus-secreting human cells (HT29-MTX-E12) was tested, as well as their capability on forming biofilm. All isolates showed resistance to at least one antibiotic, highlighting a multi-resistance phenomenon. The greatest resistance was found to ampicillin (98/117 isolates). The 73% of the isolates were resistant to more classes of antibiotics. The results showed that A. butzleri from slaughterhouse surfaces were more resistant to antibiotics than those from broiler. All the isolates were able to infect the HT29-MTX-E12 cells and displayed a moderate biofilm production. The colonization and the biofilm production abilities were not correlated to the isolation sources. The antibiotic resistance detected is of remarkable relevance considering the possible transmission of resistance factors to humans. Subsequent WGS analyses will be conducted to understand the genomic traits correlated to the high antibiotic resistance of strains and to their persistence. The results obtained highlight the importance of increasing optimization actions in slaughter processes to reduce the incidence A. butzleri considering the risk to which the population is subjected.