Detection of cytotoxic necrotizing factor types 1 and 2 among fecal Escherichia coli isolates from brazilian children with and without diarrhea

Tavechio, Ana Terezinha; Marques, L. R. M.; Abe, Cecília M.; Gomes, Tânia A. T.

doi:10.1590/s0074-02762004000100014

Cited by 5 publications

(5 citation statements)

References 19 publications

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“…No cnf2 or cnf3 genes, which were first observed in E. coli strains isolated from animals (12, 45), were detected in our human strains, a finding consistent with the absence or very weak prevalence of these genes observed in previous studies (9,12,32,37,55,63,64). These results suggest that cnf2-and cnf3-positive strains are almost entirely absent in humans and thus are probably involved only in animal diseases.…”

Section: Resultssupporting

confidence: 91%

Cyclomodulins in Urosepsis Strains of Escherichia coli

et al. 2010

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Determinants of urosepsis in Escherichia coli remain incompletely defined. Cyclomodulins (CMs) are a growing functional family of toxins that hijack the eukaryotic cell cycle. Four cyclomodulin types are actually known in E. coli: cytotoxic necrotizing factors (CNFs), cycle-inhibiting factor (Cif), cytolethal distending toxins (CDTs), and the pks-encoded toxin. In the present study, the distribution of CM-encoding genes and the functionality of these toxins were investigated in 197 E. coli strains isolated from patients with communityacquired urosepsis (n ‫؍‬ 146) and from uninfected subjects (n ‫؍‬ 51). This distribution was analyzed in relation to the phylogenetic background, clinical origin, and antibiotic resistance of the strains. It emerged from this study that strains harboring the pks island and the cnf1 gene (i) were strongly associated with the B2 phylogroup (P, <0.001), (ii) frequently harbored both toxin-encoded genes in phylogroup B2 (33%), and (iii) were predictive of a urosepsis origin (P, <0.001 to 0.005). However, the prevalences of the pks island among phylogroup B2 strains, in contrast to those of the cnf1 gene, were not significantly different between fecal and urosepsis groups, suggesting that the pks island is more important for the colonization process and the cnf1 gene for virulence. pks-or cnf1-harboring strains were significantly associated with susceptibility to antibiotics (amoxicillin, cotrimoxazole, and quinolones [P, <0.001 to 0.043]). Otherwise, only 6% and 1% of all strains harbored the cdtB and cif genes, respectively, with no particular distribution by phylogenetic background, antimicrobial susceptibility, or clinical origin.The bacterial species Escherichia coli comprises a wide diversity of strains belonging to the commensal intestinal flora of humans and warm-blooded animals. Among these strains, several pathogenic variants cause intestinal or extraintestinal infections in humans and animals (33). Population genetic studies based on multilocus enzyme electrophoresis and various DNA markers (10,20,44) classify the E. coli strains into four major phylogenetic groups (A, B1, B2, and D). The groups are diversely associated with certain ecological niches and propensities to cause disease.Extraintestinal pathogenic E. coli (ExPEC) strains are facultative pathogens that are not yet fully described. They are reported to belong mainly to phylogroups B2 and D, and they possess high numbers of virulence genes that belong to a flexible gene pool (43, 53). Among ExPEC strains, uropathogenic E. coli (UPEC) strains take advantage of host behavior and susceptibility by employing virulence factors that facilitate bacterial growth and persistence in the urinary tract (5, 28-30). Important virulence mechanisms are adhesion, invasion, subversion of host defenses, and direct interference with host cellular functions via secreted effectors (33,69).These effectors include the cyclomodulins (CMs), a functional class of toxins that hijack the cell cycle, a fundamental host cell process (48). In the ...

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Section: Resultssupporting

confidence: 91%

Cyclomodulins in Urosepsis Strains of Escherichia coli

et al. 2010

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“…15,19 Nevertheless, recent studies did not find an exclusive association with disease and concluded that necrotoxic E. coli may be part of the normal gastrointestinal flora. 24 In the tiger lung, predominantly macrophages were observed in the lesions, which is in contrast with the findings reported in other animals, in which neutrophils were the main inflammatory cell in the alveolar spaces.…”

Section: 17contrasting

confidence: 75%

“…Escherichia coli strains carrying cnf -1 have been isolated from humans with urinary tract infection and, sporadically, from feces of children with diarrhea 15,19 . Nevertheless, recent studies did not find an exclusive association with disease and concluded that necrotoxic E. coli may be part of the normal gastrointestinal flora 24 …”

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confidence: 99%

Necrotizing Pneumonia and Pleuritis Associated with Extraintestinal Pathogenic Escherichia Coli in a Tiger (Panthera Tigris) Cub

Carvallo

DebRoy

Baeza³

et al. 2010

J VET Diagn Invest

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Abstract. Extraintestinal pathogenic Escherichia coli (ExPEC) cause diseases in humans and animals, affecting organs outside the alimentary canal. In recent years, ExPEC have been reported as a cause of fatal pneumonia in dogs, cats, and in a horse. In the current report, a fatal case of pneumonia and pleuritis is described in a 4-week-old tiger (Panthera tigris) cub associated with ExPEC. The cub was presented with a sudden-onset respiratory illness and died after a few hours. Postmortem examination of the cub revealed an acute necrotizing pneumonia. The alveolar spaces were filled with large numbers of inflammatory cells (predominantly macrophages), edema, fibrin strands, and short bacillary bacteria. Escherichia coli O6:H31 was isolated in pure culture from the affected lung. It carried virulence genes cnf-1, sfa, fim, hlyD, and papG allele III, which are known to be associated with ExPEC strains. No evidence of infection by any other agent was detected. This is the first report, to the authors' knowledge, in which ExPEC has been associated with pneumonia in tigers.

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“…CNF1 strains have mostly been isolated from extraintestinal infections from humans with urinary tract infections (UTIs) and occasionally children with diarrhoea. The majority of CNF2 strains have been isolated from calves with septicaemia or diarrhoea [13].…”

Section: Introductionmentioning

confidence: 99%

Occurrence and characteristics of cytotoxic necrotizing factors, cytolethal distending toxins and other virulence factors inEscherichia colifrom human blood and faecal samples

et al. 2007

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Escherichia coli isolates from human blood (n=266) and faecal (n=237) samples were examined for cytotoxic necrotizing factors 1 and 2 (CNF 1 and 2), cytolethal distending toxin (CDT), and putative virulence factors that have been associated with disease conditions in humans and animals. PCR showed that the chromosomally encoded, Rho-activating, CNF1 (68/544, 12.5%) was more common than the transmissible plasmid-borne CNF2 (3/544, 0.6%). The relative risk of having either CNF or CDT toxin genes in blood compared to faecal isolates was 3.88 (95% CI 2.36-6.38). This was highly significant (P<0.0001) and demonstrates the importance of these factors in bloodstream infections. Fifty-one of 65 (78%) E. coli bearing CNF1 and 11 of 21 (52%) of E. coli bearing CDT also carried the pyelonephritis-associated pilus gene, papG. The S fimbrial adhesin gene, sfa, was found in 57 blood (21%) and eight faecal samples (3%). The F17 fimbrial adhesin gene and afimbrial adhesin gene afa did not occur frequently. Haemolysin (hly) was found in all of the isolates tested. Further studies must be designed to identify the clinical significance of these genes and their role in pathogenesis.

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Detection of cytotoxic necrotizing factor types 1 and 2 among fecal Escherichia coli isolates from brazilian children with and without diarrhea

Abstract: The enteropathogenic role of cytotoxic necrotizing factor (CNF)-producing

Cited by 5 publications

References 19 publications

Cyclomodulins in Urosepsis Strains of Escherichia coli

Cyclomodulins in Urosepsis Strains of Escherichia coli

Necrotizing Pneumonia and Pleuritis Associated with Extraintestinal Pathogenic Escherichia Coli in a Tiger (Panthera Tigris) Cub

Occurrence and characteristics of cytotoxic necrotizing factors, cytolethal distending toxins and other virulence factors inEscherichia colifrom human blood and faecal samples

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