Competitive exclusion products as an antimicrobial alternative to control Salmonella Heidelberg in broilers.

Intestinal infections caused by non-typhoidal Salmonella spp., along with antimicrobial resistance spread are a major food safety concern worldwide. Here, we evaluate the potential of competitive exclusion products developed by anaerobic or aerobic conditions to control systemic infection, cecal colonization, fecal excretion, and improve the intestinal health in broilers challenged by Salmonella Heidelberg (SH). A total of 105 day-old chickens were randomly distributed into three experimental groups: A (untreated control), B (treated with anaerobic culture), and C (treated with aerobic culture). During 21 days, morphometric parameters of the small intestine were analyzed using microscopy, fecal excretions by cloacal swabs, systemic infection, and cecal colonization by colony-forming unit counts (CFU/g). The results indicated the lowest number of positive swabs (45.33%) recovered from Group C, followed by Group B (71.8%) and Group A (85.33%). The bacterial enumeration revealed the lowest amounts in Group C at the necropsy realized in 5-, 7-, and 14-days post-infection (DPI) (P = 0.0010, P = 0.0048, and P = 0.0094, respectively). Statistical differences between intestinal morphometrics were observed in the Group C at 21 DPI. Our results suggest that the product developed under aerobic conditions can improve intestinal health, protecting birds against SH.

Low temperatures do not impair the bacterial plasmid conjugation on poultry meat.

Conjugation plays an important role in the dissemination of antimicrobial resistance genes. Besides, this process is influenced by many biotic and abiotic factors, especially temperature. This study aimed to investigate the effect of different conditions of temperature and storage (time and recipient) of poultry meat, intended for the final consumer, affect the plasmid transfer between pathogenic (harboring the IncB/O-plasmid) and non-pathogenic Escherichia coli organisms. The determination of minimal inhibitory concentrations (MIC) of ampicillin, cephalexin, cefotaxime, and ceftazidime was performed before and after the conjugation assay. It was possible to recover transconjugants in the poultry meat at all the treatments, also these bacteria showed a significant increase of the MIC for all antimicrobials tested. Our results show that a non-pathogenic E. coli can acquire an IncB/O-plasmid through a conjugation process in poultry meat, even stored at low temperatures. Once acquired, the resistance genes endanger public health especially when it is about critically and highly important antimicrobials to human medicine.