Escherichia coli gene fimA was the most frequent gene that occurred in the intestine of all investigated groups. All subjects with fimA gene had significantly higher values of tumor necrosis factor alpha (TNF-α) and CRP than those with other E. coli genes. There was also a tendency to increased serum interleukin (IL)-6 levels in patients carrying the fimA gene; however, no relation was observed to serum IL-8 and IL-10. Patients with Crohn’s disease had significantly higher IL-6 than those with ulcerative colitis (UC) and controls. The highest levels of TNF-α were detected in the UC group. There were no significant differences in serum IL-8 and IL-10 between all three groups. The presence of E. coli gene fimA in the large bowel of patients with IBD is related to the immunological activity of the disease which may be important from the aspect of therapeutical strategy.
Extraintestinal pathogenic Escherichia coli (ExPEC) is one of the main etiological agents of bloodstream infections caused by Gram-negative bacilli. ExPEC pathogenicity is due to the presence of genes, located on plasmids or chromosomes that encode virulence factors. E. coli virulence factors such as adhesins, toxins, invasins are able to modify the metabolism of host cell, contributing to disease. In this study, 80 strains of E. coli were isolated by hemoculture from septicemic patients and examinated by polymerase chain reaction to identify the virulence factors genes encoding toxins and to determine the phylogenetic group. We characterized genes encoding 3 different types of toxins: α-hemolysin (hlyA), cytotoxic necrotizing factor type 1 (cnf1) and five subtypes of cytolethal distending toxins (cdt-I to cdt-V). 23.75% of E. coli strains contained cnf1 gene and 22.5% hlyA. Genes cdt-I and cdt-IV were detected in 1 of 80 strains. Phylogenetic classification showed that E. coli strains fall into 4 groups (A, B1, B2, D) based on PCR detection (chuA and yjaA genes and DNA fragment TSPE4.C2). Virulent ExPEC belong mostly to groups B2 and D. Our results confirmed this fact: 56% of E. coli strains belonged to group B2 and 24% to group D.
We determined the incidence of enterovirulent E. coli (EVEC; which can to cause gastrointestinal infections) in strains isolated from patients with both of the major inflammatory bowel diseases (IBD), Crohn's disease (CD) and ulcerative colitis (UC) and from patients with noninflammatory bowel diseases (nonIBD). Cell detachment E. coli (CDEC) were detected in 14 % of all strains. A significant difference in the presence of CDEC was found between the groups of strains isolated from UC (24.1 %), nonIBD (11.9 %) and CD (4.7 %). Enteroaggregative E. coli (EAggEC) were detected in 2.5 %, typical enteropathogenic strains (EPEC) in 1.3 % and enterotoxigenic ones (ETEC) in 1.5 %. Enteroinvasive (EIEC) and shigatoxin producing E. coli (STEC) were not detected. Some strains showed a high invasion level in gentamicin-protection assay. These strains could therefore belong to adherent-invasive E. coli (AIEC) because they are free of genes encoding invasins (ipaH, ial) and are equipped with fimA gene. However, complete characterization of these strains and their classification as AIEC will require further tests.
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