Antimicrobial and anti-virulent efficacies of melanin, and risk factors associated with Escherichia coli and Salmonella species from broiler farms and humans: integrating a one health approach

Abstract

Introduction Esherishia coli ( E. coli ) and Salmonella species (spp.) pose serious public health threats because of their ability to contaminate poultry products and spread through farm environments. This study assessed the prevalence, antimicrobial resistance, and virulence gene profiles of E. coli and Salmonella spp. Methods A cross-sectional study was conducted, involving the random collection of 400 samples from broilers, drinker’s water, feedstuff, broiler litter, and poultry workers in broiler farms. Furthermore, a structural questionnaire was administered to poultry workers to identify potential risk factors and assess the public health implications associated with pathogen transmission. The antimicrobial and anti-virulence activities of melanin against E. coli and Salmonella enteritidis ( S. enteritidis ) were also assessed. Results E. coli and Salmonella spp. were frequently isolated from broiler farms, with a predominance of. E. coli serotype O111:H2 (25.64%) and S. enteritidis strains (30.4%) among the total examined samples. Multivariate analysis revealed that poultry workers, who had symptoms worsened after starting farm work and those did not use of personal protective equipment (PPE) were strongly associated with E. coli positivity. E. coli isolates exhibited full resistance to ampicillin (AMP) and tetracycline (TET), whereas Salmonella spp. isolates showed full resistance to AMP. Most of the examined E. coli isolates (71.8%) and the Salmonella spp. isolates (60.9%) were multidrug resistant (MDR) strains. In addition, 28.2% of E. coli isolates and 30.4% of Salmonella spp. isolates were -XDR. The stx 1, stx 2, and hyl A virulence genes were respectively detected in 69.2%, 69.2%, and 74.4% of the examined E. coli isolates, whereas the sop B and hil A virulence genes were identified in all Salmonella spp. isolates. One-way repeated-measures analysis of variance (ANOVA) showed that natural melanin treatment significantly reduced the expression of virulence genes in both E. coli and S. enteritidis isolates. Conclusion The predominance of E. coli serotypes O111 and S. enteritidis highlights the need for improved hygiene practices and zoonotic diseases awareness to limit pathogen transmission in poultry farms. The detection of MDR and XDR strains e emphasizes the consequences of antimicrobial misuse and its implications for public health. Melanin has potential antimicrobial and anti-virulence activities against E. coli and S. enteritidis .