Abstract

Escherichia coli (E. coli), Staphylococcus aureus, and Salmonella enteritidis are virulent bacterial pathogens that cause serious infections on dairy farms. Nano-based disinfectants are a promising area for antibacterial applications, including chitosan nanoparticles (ChNPs) and silver nanoparticles (AgNPs). This study aimed to evaluate the antimicrobial activity of two commercial disinfectants, ChNPs and AgNPs, against Escherichia coli O26 (E. coli O26), Staphylococcus aureus, and Salmonella enteritidis isolated from three dairy farms in the Sharqia governorate, Egypt. After applying 5% hydrogen peroxide, 10% iodine, 5% silver-hydrogen peroxide nanoparticles (Ag-H2O2 NPs), 5% chitosan-hydrogen peroxide nanoparticles (Ch-H2O2 NPs), 10% silver iodide nanoparticles (Ag-I NPs), and 10% chitosan iodide nanoparticles (Ch-I NPs) individually and in combination, the viability of fifty-three strains—comprising 7 E. coli O26, 43 Staphylococcus aureus, and 2 Salmonella enteritidis—was tested using a quantitative suspension method in the presence or absence of organic matter at varying contact times. The tested strains of E. coli O26, Staphylococcus aureus, and Salmonella enteritidis predominated in the samples at 17.07%, 39.45%, and 50%, respectively. Additionally, the in vitro experiments revealed that the most effective (100%) and fastest (less than a minute) bactericidal effect was achieved by the combination of H2O2-Iodine, loaded AgNPs, ChNPs, and their complexes. The results indicated that bactericidal efficacy depended on factors such as organic matter presence, contact time, and disinfectant concentration. Nano-based disinfectants combining silver, chitosan, and the H2O2-Iodine complex proved to be highly effective biocidal agents against pathogenic E. coli O26, Staphylococcus aureus, and Salmonella enteritidis. When two or more antimicrobial agents are combined, they can offer a valuable tool for controlling pathogenic bacteria.