Effect of gamma radiation and some antibacterial agents on cyclomodulin associated effects in some uropathogenic E. coli isolates

Abstract

Colibactin and cytotoxic necrotizing factor 1 (Cnf 1) are cyclomodulins produced by extraintestinal pathogenic E. coli and commensal E. coli that colonize colorectal carcinoma patients (CRC). Both toxins contribute to the hypervirulence of E. coli, play role in bacterial colonization and development of chronic infections. Recent studies have proven that both toxins predispose to carcinogenesis since both acquire cell cycle modulating effects that disrupt the normal cellular functions and stimulate mutagenesis. Colibactin is a genotoxin encoded by a 54 kb genomic stretch known as pks island and it causes double strand DNA breaks (dsDNA) and megalocytosis in infected cells. On the other hand, cytotoxic necrotizing factor 1 (Cnf 1) is located downstream to hlyCABD operon in pathogenicity island II of uropathogenic E. coli and it activates the Rho proteins stimulating multinucleation. In this work, the prevalence of Cnf 1 and colibactin was investigated among E. coli isolates recovered from urinary tract infected patients in Egypt. Afterward, the effect of antibacterial agents subMICs and low doses of gamma radiation on the cytotoxicity of an UPEC isolate and expression of colibactin were investigated. Additionally, the pathologic effects associated with the production of both cyclomodulins in an in vivo animal model were examined.

The study was divided into two sections, in vitro and in vivo experimental models. The in vitro experimental model included: (i) Recovery, identification and detection of the hemolytic activity of UPEC isolates, (ii) Detection of Cnf 1 and colibactin characteristic phenotypic features on cultured mammalian cells (HeLa, Hep2, Vero, and Caco2 cells), (iii) Detection of both toxins genotypic features (cnf 1, clbA and clbQ genes) in the test isolates by PCR, (iv) testing the effect of treatment with antibacterial agents subMICs and low doses of gamma radiation on the cytotoxicity of a UPEC isolate producing Cnf1