The role of short journey transportation in the spreading of swine pathogens and antimicrobial-resistant bacteria

Background: The transport of live pigs poses a risk to on-farm biosecurity. Trucks can carry pathogens with significant economic and health impacts, including antimicrobial-resistant (AMR) bacteria. This study aimed to investigate the microbiological contamination of trucks before and after loading, focusing on AMR bacteria and other major pathogens transmissible through faeces. Samples were collected by swabbing the internal surface of disinfected empty trucks at farm entry (‘clean’) and after loading (‘dirty’), and were tested for total plate count (TPC), specific bacteria and viruses. Escherichia coli isolates were also phenotypically and molecularly tested for the presence of extended-spectrum β-lactamase (ESBL), other β-lactamases (AmpC) and carbapenemase. Results: Bacterial counts (both TPC and Enterobacteriaceae count) and the probability of testing positive for E. coli, ESBL/AmpC-producing E. coli and Rotavirus A varied significantly depending on the truck condition, being significantly higher in “dirty” than in “clean” trucks. Despite a non-significant difference, positivity to Rotavirus B showed the same tendency. Conversely, the truck condition had no effect on Rotavirus C. Salmonella spp., PRRSV, and carbapenemase-producing E. coli were detected only in samples collected on “dirty” trucks. Conclusions: Although the prevalence of most agents in ‘clean’ samples was close to zero, the relatively frequent occurrence of E. coli and some rotaviruses highlights the importance of improving sanitisation procedures. The detection of ESBL/AmpC- and carbapenemase-producing E. coli was of particular concern. These findings confirm the role of trucks in spreading pathogens of concern and AMR, highlighting the importance of effective monitoring and proper sanitisation procedures.