<i>Escherichia coli</i>Strains Belonging to Phylogenetic Group B2 Have Superior Capacity to Persist in the Intestinal Microflora of Infants

Nowrouzian, Forough L.; Wold, Agnes E.; Adlerberth, Ingegerd

doi:10.1086/427996

Cited by 155 publications

(178 citation statements)

References 35 publications

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“…Moreover, the latter predominate among E. coli strains with the ability to survive in the environment (Walk et al, 2007). By contrast, group B2 are more likely to be host-adapted, 'specialists' (Gordon & Cowling, 2003;Nowrouzian et al, 2005;White et al, 2011), and at least some B2 strains appear to be regular human commensals (Clermont et al, 2008;Carlos et al, 2010). Therefore, a larger number of TA loci in groups A and B1 may reflect their higher stress tolerance, and hence adaptation to various ecological niches (Pandey & Gerdes, 2005;Wang & Wood, 2011).…”

Section: Discussionmentioning

confidence: 99%

Type II toxin–antitoxin systems are unevenly distributed among Escherichia coli phylogroups

et al. 2015

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Type II toxin-antitoxin systems (TAs) are bicistronic operons ubiquitous in prokaryotic genomes, displaying multilevel association with cell physiology. Various possible functions have been assigned to TAs, ranging from beneficial for their hosts, such as a stress response, dormancy and protection against genomic parasites, to detrimental or useless functions, such as selfish alleles. As there is a link between several Escherichia coli features (e.g. virulence, lifestyle) and the phylogeny of this species, we hypothesized a similar association with TAs. Using PCR we studied the distribution of 15 chromosomal and plasmidic type II TA loci in 84 clinical E. coli isolates in relation to their main phylogenetic groups (A, B1, B2 and D). In addition, we performed in silico searching of these TA loci in 60 completely sequenced E. coli genomes deposited in GenBank. The highest number of TA loci per strain was observed in group A (mean 8.2, range 5-12) and the lowest in group B2 (mean 4.2, range 2-8). Moreover, significant differences in the prevalence of nine chromosomal TAs among E. coli phylogroups were noted. In conclusion, the presence of some chromosomal TAs in E. coli is phylogroup-related rather than a universal feature of the species. In addition, their limited collection in group B2 clearly distinguish it from the other E. coli phylogroups.

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Section: Discussionmentioning

confidence: 99%

Type II toxin–antitoxin systems are unevenly distributed among Escherichia coli phylogroups

et al. 2015

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“…Over the last decade, a number of authors have sought to establish the prevalence of E. coli with ExPEC potential colonising the gut by performing microbiological screening studies on the stool of healthy individuals that delineate resident E. coli strains based on their phylogroup (58)(59)(60)(61)(62)(63). Results of these studies have demonstrated that 11-48% of healthy individuals are colonised with E. coli belonging to phylogroup B2, which is traditionally associated with virulence and ExPEC infections.…”

Section: Expec As An Intestinal Colonistmentioning

confidence: 99%

Extra-intestinal pathogenic Escherichia coli (ExPEC): Disease, carriage and clones

Dale

Woodford

2015

Journal of Infection

158

132

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Extra-intestinal pathogenic E. coli (ExPEC) have a complex phylogeny, broad virulence factor (VF) armament and significant genomic plasticity, and are associated with a spectrum of host infective syndromes ranging from simple urinary tract infection to life-threatening bacteraemia. Their importance as pathogens has come to the fore in recent years, particularly in the context of the global emergence of hyper-virulent and antibiotic resistant strains.Despite this, the mechanisms underlying ExPEC transmission dynamics and clonal selection remain poorly understood. Large-scale epidemiological and clinical studies are urgently required to ascertain the mechanisms underlying these processes to enable the development of novel evidence-based preventative and therapeutic strategies. In the current review, we provide a concise summary of the methods utilised for ExPEC phylogenetic genetic delineation before exploring in detail the associations between ExPEC VFs and site-specific disease. We then consider the role of ExPEC as an intestinal colonist before outlining known associations between ExPEC clonal variation, specific disease syndromes and antibiotic resistance.

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“…This collection could provide information on the occurrence and prevalence of integrons before the misuse and overuse of antimicrobials -major contributors to the development and spread of resistance [17]. Another set (40) was isolated in 2009 from urine of women with clinical and laboratory diagnoses of community-acquired urinary tract infections in Belo Horizonte, Brazil [18]. This study was approved by Ethics Committee UFMG (178/09).…”

Section: Bacterial Strainsmentioning

confidence: 99%

Occurrence and characterization of class 1 integrons in Escherichia coli from healthy individuals and those with urinary infection

Oliveira-Pinto

Diamantino

Oliveira

et al. 2017

Journal of Medical Microbiology

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Purpose. Class 1 integrons are among the main vehicles that facilitate the spread of antibiotic-resistance genes, with serious public health consequences. The aim of this cross-sectional study was to investigate the presence of class 1 integrons and to characterize their variable regions, as well as the antimicrobial resistance profiles and phylogenetic groups of a collection of Escherichia coli isolates recovered from healthy subjects (n=42) and those with urinary infection (n=40).Methodology. The methods used included PCR, sequencing and antimicrobial susceptibility testing.Results. PCR screening for the integrase gene (intI1) revealed a higher incidence of class 1 integrons in uropathogenic E. coli (65 %, UPEC) than in commensal isolates (11.9 %). Eight of 31 intI1-positive isolates, all of them UPEC, harboured empty integrons. The variable regions of the other 23 contained gene cassettes encoding resistance to b-lactams (blaOXA-1), aminoglycosides (aadA1 and aadA5), trimethoprim (dfrA1 and dfrA17) and an ORF. To our knowledge this is the first report of an ORF identified as a putative phage tail protein associated with a class 1 integron. The aadA1 and dfrA17-addA5 arrays prevailed in commensal E. coli and UPEC, respectively. UPEC isolates were highly resistant to the antimicrobials tested, in contrast to commensal isolates. The E. coli isolates carrying gene cassettes associated with class 1 integrons were found to be unrelated to any phylogroup or multiresistance.Conclusion. Co-resistance to clinically relevant fluoroquinolone and trimethoprim-sulfamethazole in all UPEC isolates is a cause for concern. These results expand the current knowledge of gene cassettes in both commensal and pathogenic E. coli.

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Escherichia coliStrains Belonging to Phylogenetic Group B2 Have Superior Capacity to Persist in the Intestinal Microflora of Infants

Cited by 155 publications

References 35 publications

Type II toxin–antitoxin systems are unevenly distributed among Escherichia coli phylogroups

Type II toxin–antitoxin systems are unevenly distributed among Escherichia coli phylogroups

Extra-intestinal pathogenic Escherichia coli (ExPEC): Disease, carriage and clones

Occurrence and characterization of class 1 integrons in Escherichia coli from healthy individuals and those with urinary infection

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