Assessment of the antimicrobial efficacy of probiotics, biosynthesized silver nanoparticles, and their combination with physical irradiations against cattle endometritis pathogens

Abstract

Abstract Endometritis is a postpartum uterine inflammation caused by bacterial infection often linked to complications such as abortion. The current study aims to manage microbial endometritis in cattle using the antimicrobial effects of probiotics, biosynthesized silver nanoparticles (AgNPs), and biophysical factors. The antimicrobial effects of some selected commercial Bacillus probiotic strains -divided into seven groups and biosynthesized AgNPs (1–5 mM) against various pathogenic strains were investigated. Experiments included AgNPs characterization (SEM/EDX, UV–Vis, and FTIR), and disc diffusion assays. The impact of UV, IR, and 50 Hz sinusoidal EMF at 5 mT on pathogen viability; both alone and in combination with AgNPs; was assessed followed by ultrastructural analysis (TEM). Group 1 (G1) probiotics showed the highest inhibition (16.57 ± 5.59 mm), especially against E. coli and P. aeruginosa. AgNPs (5 mM) synthesized from G1 achieved maximum antimicrobial activity (up to 52 mm for E. coli), with IR + AgNPs reducing bacterial counts by over 75%. In contrast, UV and EMF treatments, especially when combined with AgNPs, unexpectedly increased fungal growth. This study highlights the potent antimicrobial effects of probiotics and biosynthesized AgNPs, with the combination of IR and AgNPs demonstrating the strongest inhibitory activity, particularly against bacteria. In contrast, UV and EMF treatments were less effective and, in some cases, appeared to promote fungal growth.