Typical and atypical enteropathogenic Escherichia coli bacterial translocation associated with tissue hypoperfusion in rats

A.M.A Liberatore,F.C Moreira,I.H.J Koh,T.A.T Gomes,J.L Menchaca-Diaz

doi:10.1590/s0100-879x2011007500105

A.M.A Liberatore, F.C Moreira + Show 3 more

Open Access

https://doi.org/10.1590/s0100-879x2011007500105

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Abstract

Although enteropathogenic Escherichia coli (EPEC) are well-recognized diarrheal agents, their ability to translocate and cause extraintestinal alterations is not known. We investigated whether a typical EPEC (tEPEC) and an atypical EPEC (aEPEC) strain translocate and cause microcirculation injury under conditions of intestinal bacterial overgrowth. Bacterial translocation (BT) was induced in female Wistar-EPM rats (200-250 g) by oroduodenal catheterization and inoculation of 10 mL 10(10) colony forming unit (CFU)/mL, with the bacteria being confined between the duodenum and ileum with ligatures. After 2 h, mesenteric lymph nodes (MLN), liver and spleen were cultured for translocated bacteria and BT-related microcirculation changes were monitored in mesenteric and abdominal organs by intravital microscopy and laser Doppler flow, respectively. tEPEC (N = 11) and aEPEC (N = 11) were recovered from MLN (100%), spleen (36.4 and 45.5%), and liver (45.5 and 72.7%) of the animals, respectively. Recovery of the positive control E. coli R-6 (N = 6) was 100% for all compartments. Bacteria were not recovered from extraintestinal sites of controls inoculated with non-pathogenic E. coli strains HB101 (N = 6) and HS (N = 10), or saline. Mesenteric microcirculation injuries were detected with both EPEC strains, but only aEPEC was similar to E. coli R-6 with regard to systemic tissue hypoperfusion. In conclusion, overgrowth of certain aEPEC strains may lead to BT and impairment of the microcirculation in systemic organs.

Highlights

Bacterial translocation (BT) is defined as the migration of indigenous bacteria as well as their products from the intestinal lumen to the mesenteric lymph nodes and to other extraintestinal sites [1]
Results typical EPEC (tEPEC) and atypical EPEC (aEPEC) can translocate through the intestinal mucosa under overgrowth conditions Like the positive control strain R-6, the tEPEC and aEPEC strains were recovered from the mesenteric lymph nodes (MLN) of all 11 animals (100%), whereas the HS strain was recovered from 8 of 10 animals (80%)
Bacteria were not found to be in the extraintestinal organs of any of the animals tested with the non-pathogenic strains E. coli HB101 and www.bjournal.com.br were negative in all groups

Summary

Introduction

Bacterial translocation (BT) is defined as the migration of indigenous bacteria as well as their products from the intestinal lumen to the mesenteric lymph nodes and to other extraintestinal sites [1]. Intestinal barrier disruption, and immune deficiency conditions have been proposed as the three major BT-inducing factors [2]. According to a growing consensus, under physiological conditions, BT occurs regularly for intestinal microbe presentation and this event has been referred to as the gut immune enhancing mechanism [3]. The experimental and clinical demonstrations of this phenomenon are based on mesenteric lymph nodes (MLN) showing positive culture. We have previously identified an indigenous naturally tetracycline-resistant Escherichia coli strain (E. coli R-6, serotype ONT:H2) in the mesenteric lymph nodes and Peyer’s patches of a rat, after 10 days of antibiotic therapy [6].

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