Assessment of Cefotaxime Susceptibility and Resistance Gene Transfer Risk between Bacillus Strains and Escherichia coli Ec457
Year: 2026
Type: article
Abstract: Antibiotic resistance in husbandry remains a major global challenge due to the extensive use of antimicrobials in animal production. Probiotics with genetically stable profiles are therefore considered promising alternatives to reduce antibiotic reliance and limit resistance dissemination. This study evaluated the susceptibility of three Bacillus strains: P4QN11, BAD7, and S2.5, and Escherichia coli Ec457 to cefotaxime, and investigated the potential transfer of the bla-CTX-M resistance gene. Disk diffusion assays showed that Bacillus P4QN11, BAD7, and S2.5 had large inhibition zones of 26 to 27 millimeters, indicating high susceptibility, while E. coli Ec457 exhibited a small inhibition zone of 13 ± 1 millimeters, confirming resistance. Cefotaxime resistance of E. coli Ec457 was evidenced by the presence of the blaCTX-M gene detected by PCR. Co-cultivation experiments under selective pressure with LiCl and cefotaxime tested whether Bacillus strains could acquire resistance genes. After repeated co-culture, Bacillus P4QN11, BAD7, and S2.5 remained phenotypically susceptible in disk diffusion tests, and PCR showed no blaCTX-M amplification, confirming gene transfer was not detected. These results demonstrated that the Bacillus strains do not acquire cefotaxime resistance genes from E. coli Ec457, even under selective conditions. This supports their genetic stability and safety for use as probiotics in food and animal feed, help to reduce the spread of antibiotic resistance. Further research should explore longer co-culture periods and genomic analysis to confirm these findings under diverse environmental conditions.
Language: English
Subfield: Microbiology (medical)
Field: Medicine
Domain: Health Sciences
Open Access status: bronze
OpenAlex ID: W7160486607