Characterization of four Escherichia coli clonal groups

Abstract

(1991)(1992) that involved an unusual multi-resistant E. coli O78:H10 strain. Surprisingly, the isolates qualified as enteroaggregative E. coli (EAEC), a diarrheagenic pathotype, making this the first reported involvement of EAEC in an extraintestinal disease outbreak. Paper IV reports an analysis of 51 archived E. coli O78:H10 isolates (1956 2000) that showed E. coli O78:H10 to be clonally heterogeneous, comprising one dominant clonal group (61% of isolates, including all 19 Copenhagen outbreak isolates) from ST10 (phylogenetic group A), plus several minor clonal groups (phylogenetic groups A and D). The outbreak clone exhibited both extraintestinal pathogenic E. coli (ExPEC) and EAEC characteristics. Paper V reports evidence that the outbreak strain adhered more extensively to human bladder epithelial cells than did prototype uropathogenic (ExPEC) strains thanks to its aggregative adherence fimbriae, the principal adhesins of EAEC, and was capable of extensive biofilm formation on urethral catheters. These findings suggest that certain EAEC-specific virulence factors increase uropathogenicity.Paper VI reports a search for ST131, a globally disseminated, recently emerged multiresistant ExPEC clonal group, among 115 extended-spectrum beta-lactamase (ESBL)-producing E. coli clinical isolates from Danish patients (2008 -2009), to assess ST131's prevalence in Copenhagen among ESBL-producing isolates. ST131 was the most prevalent clonal group (38% of isolates) and compared with other ESBL isolates was more often community-associated and exhibited distinctive and extensive virulence profiles.Paper VII reports temporal trends in antimicrobial resistance and virulence genes among historical E. coli ST131 isolates (1968 -2011). Antimicrobial resistance increased over time due to emergence of the (resistance-associated) H30 and H30-Rx ST131 subclones. Distinctive characteristics of the ST131 H30-Rx subclone including specific virulence factors (iutA, afa/dra, kpsM II), K100 capsule, multidrug resistance, and ESBL production possibly contributed to this lineage's epidemiologic success. These findings confirm that ST131 represents a group of distinctive subclones, not a unitary entity.In conclusion, all four clonal groups were multiresistant and demonstrated the potential to spread locally or globally. A combination of antimicrobial resistance and specific virulence genes likely contributed to their epidemiologic success. Future implementation of rapid methods to screen for such multiresistant high-risk clones and their cardinal virulence genes conceivably could assist in clinical management and prevention efforts.

Diet-mediated gut microbial community modulation and signature metabolites as potential biomarkers for early diagnosis, prognosis, prevention and stage-specific treatment of colorectal cancer

“…This facultative gram-negative anaerobic bacterium symbiotically colonizes the human gut. The bacterium has four major phylogenetic groups i.e., A, B1, B2, and D [105] ; however, strains from groups D and B2 are known to be pathogenic. B2 group strains associated with CRC carcinogenesis via different mechanisms are an excellent example.…”

Virulence-Associated Genes and Genetic Diversity of Avian Pathogenic (APEC) and Fecal (AFEC) E. Coli Isolates From Chickens

“…These VAGs are involved in different steps of infection and/or adaptation, and their functions can be classi ed as adhesins, invasins, toxins, iron acquisition systems, and protectins/serum resistance [7][8], thereby protecting the pathogen from the host immune response and enabling its extraintestinal existence [7]. The nature and the combination of the VAGs of APEC could determine the degree of virulence and their potential to cause speci c diseases in speci c hosts.…”