Biofilm-Producing Ability of Bovine Extraintestinal Pathogenic Escherichia coli and Its Correlation with Attachment Factors

Background: Escherichia coli is recognized as a common cause of infection. Long-lasting presence of bacteria on biotic and abiotic surfaces and failure of bacterial eradication are predicted by biofilm production. Some extracellular frills of E. coli can be implicated in productive events, leading to biofilm formation by surface colonization. Objectives: In the present study, correlation of csgA (encoding curli fimbriae) and fimA (encoding a large subunit of type I fimberiae) gene expression with biofilm formation of extraintestinal bovine pathogenic E. coli strains was evaluated in different enrichment media. Methods: The microtiter plate-based crystal violet method was applied to examine the biofilm production of 30 E. coli strains in Luria-Bertani (LB) and Brain-Heart Infusion (BHI) broth with 1% sucrose. PCR assay was performed to determine the presence of the studied genes. Results: According to the results, 100% of isolates contained csgA genes, and 96.7% contained fimA genes. Using the BHI medium with 1% sucrose, 53.3% and 16.6% of strains were average and strong biofilm producers, respectively. On the other hand, by using the LB medium, 66.6% of isolates were poor biofilm producers, whereas none were strong biofilm producers. Conclusions: The BHI medium containing 1% sucrose was better detected in biofilm production, compared to the LB medium. Since the studied genes were present in non-biofilm producing isolates, the correlation of these genes with biofilm-producing ability is questioned.