Uropathogenic Escherichia coli (UPEC) are the causative organisms in more than 80% of urinary tract infections. The bacteria are introduced to the urinary tract that, except for the external part of the urethra, is free from microbial colonization, and thus can cause acute, potentially life-threatening infections with possible progression to chronic disease. The course of such infection depends not only on the agent involved but also on the activation of protective mechanisms. The recently described Toll-like receptor family and antimicrobial peptide cathelicidin appear to play an important role in the recognition and activation functions.

        Key words: urinary tract infections – uropathogenic Escherichia coli – Toll-like receptor 4 – cathelicidin.