Effects of Zeolite on Virulence Gene Content in Avian Pathogenic Escherichia coli

Avian pathogenic Escherichia coli (APEC) continues to be a major concern for public health and animal farming due to its diverse virulence factors that support iron uptake, adherence, toxin release, and resistance to host defenses. While natural zeolites are commonly incorporated into animal feed for their detoxifying, buffering, and adsorption capabilities, little is known about how they affect the presence of pathogenic genes in gut bacteria. This study explored whether feeding broiler chickens with natural zeolite could affect the virulence gene profiles of E. coli found in their ceca. One hundred fifty chicks were divided into five groups receiving 0%, 5%, 10%, 15%, or 30% zeolite. Eleven genes were screened using PCR. Results showed that zeolite levels significantly affected the virulence-associated gene carriage of E. coli, with the 10% zeolite group showing no isolates that met the APEC classification criteria (≥ 5 virulence genes) and the lowest presence of minimal predictor virulence genes (iroN, ompT, iutA, hlyF, and iss), indicating that 10% zeolite was the most effective level under the conditions of this study. These findings mark the first report that natural zeolite can reduce virulence gene carriage in E. coli within a live animal model, supporting its potential as a nonantibiotic method to reduce APEC risk and for modulating pathogenic bacterial populations. Further investigation, including gene expression and challenge trials, is needed to better understand the underlying mechanisms and validate its protective benefits.