About this Research Topic
The gram-negative bacilli Escherichia coli comprise the main facultative anaerobes living as commensals in the intestines of humans and warm-blooded animals; most of these strains rarely cause disease in healthy individuals. Nevertheless, in healthy and immunocompromised individuals, pathogenic E. coli strains can cause a wide range of human diseases in the gastrointestinal tract or in extraintestinal sites. Such a variety of behaviors is due to the occurrence of virulence genes in mobile genetic elements and to the extreme permissiveness of E. coli to acquire DNA via horizontal gene transfer. Therefore, although clinical outcomes may vary in severity, pathogenic E. coli remains a public health concern as these strains continue to gain novel traits, sometimes resulting in more virulent strains.
E. coli acquisition of specific combinations of virulence genes defined the currently recognized diarrheagenic E. coli (DEC) pathotypes, which constitute the most important contributors to cases of diarrhea especially in infants and young children in low- and middle-income countries, in South Asia, sub-Saharan Africa, and Latin America. These pathotypes, which differ in relation to their virulence mechanisms, preferential sites of host colonization, symptoms, and clinical consequences, are classified as enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC), enteroinvasive E. coli (EIEC), enterohemorrhagic E. coli (EHEC)/Shiga toxin-producing E. coli (STEC), diffusely adherent E. coli (DAEC), enteroaggregative E. coli (EAEC), and the most recently defined adherent invasive E. coli (AIEC).
Pathogenic E. coli strains involved in extraintestinal infections are collectively known as extraintestinal pathogenic E. coli (ExPEC), as they can spread to and multiply in extraintestinal organs, leading to signs and symptoms mainly in the urinary tract, blood and meninges. To this end, ExPEC strains express virulence factors such as adhesins, toxins, capsules, invasins, and iron uptake systems that support bacteria in colonization and survival at these sites.
The E. coli genetic plasticity also contributed to the emergence and spread of antimicrobial resistance among strains, including multidrug resistance clones, thus comprising a very serious global matter. To overcome this, resistant strains should be identified, and the development of alternative prophylaxis and treatment options, such as vaccines and other antimicrobial compounds, is extremely necessary.
Recent studies using genomic and metagenomic data obtained from high throughput technologies have revealed that certain pathogenic E. coli strains combine the main virulence characteristics of different pathotypes, comprising potentially more virulent hybrid strains. Therefore, studies that contribute to the understanding of the E. coli diversity, as well as their interaction with the host in various disease conditions are needed to provide a deeper understanding of how they have emerged and how they associate and affect their hosts. In addition, there is an urgent need to develop new tools and uncover novel therapeutic targets and prophylactic strategies to prevent the economic burden of E. coli infections on public health globally.
This Research Topic aims to contribute to a better understanding of the genetic E. coli diversity and to advance the knowledge about their different virulence strategies. Reviews, mini-reviews, and original research articles that provide an in-depth understanding of the molecular mechanisms involved in their relationship with the host, genetic differences, phenotypic variations, typing, diagnosis, and antimicrobial resistance, revealing potential new targets for disease prevention and treatment, are welcome.
Keywords: Escherichia coli, Virulence Factors, Genome, Antibiotic Resistance
Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.