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Open Access Research article

Possible role of Escherichia coli in propagation and perpetuation of chronic inflammation in ulcerative colitis

Magdalena Pilarczyk-Zurek1, Agnieszka Chmielarczyk1, Tomasz Gosiewski1, Anna Tomusiak1, Pawel Adamski2, Malgorzata Zwolinska-Wcislo3, Tomasz Mach3, Piotr B Heczko1 and Magdalena Strus1*

Author Affiliations

1 Department of Microbiology, Jagiellonian University Medical College, Czysta 18 Street, Cracow, 31-121, Poland

2 Polish Academy of Sciences, Institute of Nature Conservation, 33 Mickiewicza Avenue, Cracow, 31-120, Poland

3 Department of Gastroenterology, Hepatology and Infectious Diseases, Jagiellonian University Medical College, Śniadeckich 5 Street, Cracow, 31-531, Poland

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BMC Gastroenterology 2013, 13:61  doi:10.1186/1471-230X-13-61

Published: 8 April 2013

Abstract

Background

This study investigated a possible role of Escherichia coli in propagation and perpetuation of the chronic inflammation in ulcerative colitis (UC). The lesions of UC are located superficially on the rectal and/or colonic mucosa. It is suggested that the commensal bacteria of the digestive tract may play a role in the pathogenesis of UC. Several studies have demonstrated proliferation of E. coli in the gut of UC patients. An increase in the number of E. coli in the inflamed tissue is most probably related to the abundance of iron ions produced by the bacteria.

Methods

Colon mucosal biopsies were collected from 30 patients with acute-phase UC, both from tissues with inflammatory changes (n = 30) and unchanged tissue with no inflammatory changes (n = 30) from the same patient. Biopsies were also taken from 16 patients with irritable bowel syndrome diarrhea who comprised the control group. Quantitative and qualitative analysis of the biopsy specimens was performed using culture methods and real-time polymerase chain reaction (PCR). Genotyping of the E. coli isolates was done using pulsed-field gel electrophoresis. Multiplex PCR was used to compare the E. coli strains for the presence of genes responsible for synthesis of iron acquisition proteins: iroN, iutA, iha, ireA, chuA, and hlyA.

Results

We demonstrated that there was a significant increase in the number of E. coli at the sites of inflammation in patients with UC compared to the control group (P = 0.031). Comparative analysis of the restriction patterns of E. coli isolated from inflammatory and unchanged tissues showed that the local inflammatory changes did not promote specific E. coli strains. There was a significant difference in the frequency of the iroN gene in E. coli isolated from patients with UC as compared to the control group.

Conclusions

The increase in the numbers of E. coli in the inflammatory tissues is related to the presence of chuA and iutA genes, which facilitate iron acquisition during chronic intestinal inflammatory processes.

Keywords:
Ulcerative colitis; Escherichia coli; Iron acquisition