Differential Expression of fimH, ihf, upaB, and upaH Genes in Biofilms- and Suspension-Grown Bacteria From Samples of Different Uropathogenic Strains of Escherichia coli.

Abstract

Uropathogenic Escherichia coli (UPEC) strains are the main bacteria that cause urinary tract infections (UTIs). UPEC are a significant public health hazard due to their high proliferation, antibiotic resistance, and infection recurrence. The ability to form biofilms is a mechanism of antibiotic resistance, which requires the expression of different genes such as fimH, ihf, upaB, and upaH. Despite the relevance of biofilm formation in bacterial pathogenicity, differences in the expression level of these genes among bacterial growth conditions have been little studied. Here, we have characterized the expression of fimH, ihf, upaB, and upaH genes in biofilms and suspension-grown bacteria of different E. coli strains. These included the UPEC CFT073, the multidrug-resistant strain CDC-AR-0346, and clinical isolates obtained from UTI patients. The expression of fimH, ihf, upaB, and upaH was markedly heterogeneous in clinical isolates, both in terms of transcript levels and response to suspension or biofilm conditions. That expression pattern was distinct from the one in UPEC CFT073, where upaB and upaH were upregulated and ihf and fimH were slightly downregulated in biofilm. In conclusion, the data presented here show that the pattern of biofilm-associated genes in the clinical isolates from UTI patients is not fully related to the reference strain of UPEC CFT073. However, analysis of a larger number of samples is required.