Inhibitory Effects of the Spore-forming Bacillus spp. on the Expression Levels of eae, luxS, flu, and ctxM Genes in E. coli Isolates

Abstract

<jats:title>Abstract</jats:title> <jats:p><jats:bold>Background: </jats:bold><jats:italic>Escherichia coli</jats:italic> antibiotic resistance are one of the major health problems in many countries. Today, researchers are focusing on novel approaches for the treatment of <jats:italic>E. coli</jats:italic> infections, including the use of spore-forming probiotics for their high stability in the harsh gastrointestinal (GIT) environment. <jats:bold>Results: </jats:bold>The presence of resistance genes (<jats:italic>flu</jats:italic>, <jats:italic>eae</jats:italic>, <jats:italic>luxS</jats:italic>, and <jats:italic>ctxM</jats:italic> ) was confirmed by PCR in four out of 40 <jats:italic>E. coli</jats:italic> isolated from 300 fecal samples of patients suffering from diarrhea. Following confirming the ability of broiler-derived <jats:italic>Bacillus</jats:italic> <jats:italic>coagulans</jats:italic> and <jats:italic>Bacillus subtilis</jats:italic> to survive under the simulant gastric environment, they were co-cultured with the four <jats:italic>E. coli</jats:italic> isolates harboring the studied resistance genes. Results of the expression of <jats:italic>flu</jats:italic>, <jats:italic>luxS</jats:italic>, <jats:italic>eae</jats:italic>, and <jats:italic>ctxM</jats:italic> genes<jats:bold> </jats:bold>revealed that the expression levels of these genes decreased significantly (p-value &lt; 0.05) after co-culture of <jats:italic>E. coli</jats:italic> with <jats:italic>B. subtilis</jats:italic> ATCC 6633 and broiler-derived <jats:italic>B. subtilis</jats:italic>. However, the broiler-derived <jats:italic>B. subtilis</jats:italic> showed a greater effect on the expression levels of <jats:italic>eae</jats:italic>, <jats:italic>luxS</jats:italic>, and <jats:italic>ctxM</jats:italic>. <jats:italic>B. coagulans</jats:italic> MTCC 5856 and broiler-derived <jats:italic>B. coagulans</jats:italic> also led to significant decreases in expression levels of all the studied genes (p-value &lt; 0.05), while the standard strain had a greater impact on the expression of <jats:italic>ctxM</jats:italic> than the broiler-derived strains.<jats:bold>Conclusion: </jats:bold>The broiler-derived isolates had a greater capacity to decrease the expression of these genes than the standard strains, proposing their adoption for dietary supplementations. However, further studies are required to study the effects of these spore-forming bacteria on <jats:italic>E. coli</jats:italic> infections <jats:italic>in vivo</jats:italic> and their possible influence on lactose tolerance, nutritional absorption, and reduced cholesterol levels.</jats:p>