Adhesive threads of extraintestinal pathogenic Escherichia coli

Abstract

The ability to adhere to host surfaces is by far the most vital step in the successful colonization by microbial pathogens. Colonization begins with the attachment of the bacterium to receptors expressed by cells forming the lining of the mucosa. Long hair like extracellular appendages called fimbriae, produced by most Gram-negative pathogens, mediate specific attachment to the epithelial cell surface. Associated with the fimbriae is a protein called an adhesin, which directs high-affinity binding to specific cell surface components. In the last couple of years, an enormous amount of research has been undertaken that deals with understanding how bacterial pathogens adhere to host cells. E. coli in all probability is one of the best studied free-living organisms. A group of E. coli called Extraintestinal pathogenic E. coli (ExPEC) including both human and animal pathogens like Uropathogenic E. coli (UPEC), Newborn meningitic E. coli (NMEC) and Avian pathogenic E. coli (APEC), have been found to harbour many fimbriae including Type 1 fimbriae, P fimbriae, curli fibres, S fimbriae, F1C fimbriae, Dr fimbriae, afimbrial adhesins, temperature-sensitive haemagglutinin and many novel adhesin gene clusters that have not yet been characterized. Each of these adhesins is unique due to the recognition of an adhesin-specific receptor, though as a group these adhesins share common genomic organization. A newly identified putative adhesin temporarily termed ExPEC Adhesin I, encoded by gene yqi, has been recently found to play a significant role in the pathogenesis of APEC infection, thus making it an interesting candidate for future research. The aim of this review is to describe the role of ExPEC adhesins during extraintestinal infections known till date, and to suggest the idea of investigating their potential role in the colonization of the host gut which is said to be a reservoir for ExPEC.

The Type VI Secretion System Plays a Role in Type 1 Fimbria Expression and Pathogenesis of an Avian Pathogenic Escherichia coli Strain

“…The interaction between a bacterial pathogen and eukaryotic cells depends on signaling through proteins and the delivery of toxins, bacterial effectors, chemicals, and cell surface adhesins to mediate specific attachment to the host membrane (2). Bacterial adherence to host cells is generally the first step in infections caused by E. coli and is important during the initial stages of host colonization (2).…”

The irp2 and fyuA genes in High Pathogenicity Islands are involved in the pathogenesis of infections caused by avian pathogenic Escherichia coli (APEC)

“…Adhesion, an important virulence factor of pathogens, is localized on the bacterial surface. Adhesin can bind to the surface receptors of the host cell to escape scavenging, and it is thus very important in the pathogenic process (Antao et al 2009). The fimC and ompA genes encode adherence factors that influence E. coli adherence to host cells (Jones et al 1993).…”

Ag43 Promotes Persistence of Uropathogenic E scherichia coli Isolates in the Urinary Tract

“…Adhesion factors of E. coli, facilitating the initial colonization of epithelia and eventually leading to invasion of the host cell, have been described extensively elsewhere (2,3). More recently, factors supporting E. coli persistence have also attracted increasing interest (6,7,11).…”