Attaching-effacing Bacteria in Animals

Abstract

Enteric bacteria with a demonstrable or potential ability to form attaching-effacing lesions, so-called attaching-effacing (AE) bacteria, have been found in the intestinal tracts of a wide variety of warm-blooded animal species, including man. In some host species, for example cattle, pigs, rabbits and human beings, attaching-effacing Escherichia coli (AEEC) have an established role as enteropathogens. In other host species, AE bacteria are of less certain significance. With continuing advances in the detection and typing of AE strains, the importance of these bacteria for many hosts is likely to become clearer. The pathogenic effects of AE bacteria result from adhesion to the intestinal mucosa by a variety of mechanisms, culminating in the formation of the characteristic intimate adhesion of the AE lesion. The ability to induce AE lesions is mediated by the co-ordinated expression of some 40 bacterial genes organized within a so-called pathogenicity island, known as the "Locus for Enterocyte Effacement". It is also believed that the production of bacterial toxins, principally Vero toxins, is a significant virulence factor for some AEEC strains. Recent areas of research into AE bacteria include: the use of Citrobacter rodentium to model human AEEC disease; quorum-sensing mechanisms used by AEEC to modulate virulence gene expression; and the potential role of adhesion in the persistent colonization of the intestine by AE bacteria. This review of AE bacteria covers their molecular biology, their occurrence in various animal species, and the diagnosis, pathology and clinical aspects of animal diseases with which they are associated. Reference is made to human pathogens where appropriate. The focus is mainly on natural colonization and disease, but complementary experimental data are also included.

In Vitro and In Vivo Model Systems for Studying Enteropathogenic Escherichia coli Infections

“…Although much information has been gathered through in vitro analyses with respect to localization and function of T3S effector proteins, in vivo systems are the only way of assessing A/E pathogen virulence within the context of the complete intestinal environment. A/E bacteria are able to infect diverse animal species (Wales et al 2005) from the invertebrate Caenorhabditis elegans to mice, rabbits, pigs, and cattle. As such, the diversity of available animal models has provided the research community with a wealth of potential hosts with which to simulate the various aspects of human infection.…”

Quantitative Proteomic Analysis of Type III Secretome of Enteropathogenic Escherichia coli Reveals an Expanded Effector Repertoire for Attaching/Effacing Bacterial Pathogens

“…EHEC can also infect cattle, and this serves as a reservoir for subsequent food and water contaminations, resulting in significant economic loss. There are numerous EPEC and EHEC serotypes that infect many other mammals (8). C. rodentium is a mouse-specific pathogen that colonizes murine cecum and large intestines (7).…”

The LysR-Type Transcriptional Regulator QseD Alters Type Three Secretion in Enterohemorrhagic Escherichia coli and Motility in K-12 Escherichia coli

“…Of the multiple pathogenic serotypes of clinical importance, O157:H7, a serotype that is believed to have evolved recently from an O55:H7 atypical enteropathogenic E. coli (aEPEC) strain, is by far the most prevalent and virulent (18,34,40). EHEC strains are part of a larger group of enteric pathogens that includes enteropathogenic E. coli (EPEC), a rabbit EPEC strain, and Citrobacter rodentium, all of which are able to cause attaching and effacing (AE) lesions on intestinal epithelial cells (80).…”