Enteroaggregative Escherichia coli and Salmonella associated with nondysenteric persistent diarrhea

Bhan, Maharaj Kishan; Khoshoo, Vikram; Sommerfelt, Halvor; Raj, P.; Sazawal, Sunil; Srivastava, Ram

doi:10.1097/00006454-198908000-00005

Cited by 96 publications

(64 citation statements)

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“…At pH 5.5, the aggR deletion mutant expressed the aggA fusion to a significantly greater degree than it did at pH 7.5, suggesting that aggA was responsive to pH by aggRdependent and aggR-independent mechanisms. DISCUSSION EAggEC strains have been shown to be diarrheal pathogens in both epidemiologic and volunteer studies (2,3,12,33,34), yet the basic features of EAggEC pathogenesis are unknown. We have previously shown that the AA phenotype in EAggEC 17-2 is associated with the presence of a ca.…”

Section: Properties Of Aggr Deletion Mutants 17-2aaggr Was Testedmentioning

confidence: 99%

“…Enteroaggregative Escherichia coli (EAggEC) is a class of diarrheagenic E. coli associated with diarrhea in both epidemiologic and volunteer studies (2,3,13,33,34). EAggEC is defined by its characteristic aggregative adherence (AA) to HEp-2 cells in cell culture (33).…”

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confidence: 99%

“…Here, we report the complete sequencing of the 3.0-kb region 2 and the identification of several potential ORFs. One of these encodes a predicted protein of 29.4 kDa which bears homology to the AraC family of DNA binding proteins.…”

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AggR, a transcriptional activator of aggregative adherence fimbria I expression in enteroaggregative Escherichia coli

et al. 1994

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Enteroaggregative Escherichia coli (EAggEC) has been associated with persistent pediatric diarrhea in the developing world, yet the pathogenetic mechanisms of EAggEC infection are unknown. Our previous data have suggested that aggregative adherence of some EAggEC strains to HEp-2 cells is mediated by flexible, bundle-forming fimbriae, which we have termed aggregative adherence fimbriae I (AAF/I). Genes sufficient to confer expression of AAF/I are located on the 60-MDa plasmid of EAggEC 17-2; AAF/I genes are present as two unlinked plasmid regions (regions 1 and 2), separated by 9 kb of DNA. Here we report the complete DNA sequencing of region 2 and the identification of an open reading frame which is involved in the expression of AAF/I. One open reading frame of 794 bp encodes a protein (designated AggR) with a predicted molecular size of 29.4 kDa, which shows a high degree of amino acid sequence identity to CfaR and other members of the AraC class of gene regulators. The cloned aggR gene (or, alternatively, a cloned cfaR gene) was sufficient to complement a region 1 clone to confer AAF/I expression. To further substantiate the role of aggR in the regulation of AAF/I, we constructed a 289-bp in-frame aggR deletion and replaced the native gene in 17-2 by allelic exchange, using the temperature-sensitive vector pIB307. The resulting aggR deletions were negative for AAF/I expression, but expression was restored when the aggR gene (cloned into pBluescript II SK) was reintroduced into the aggR mutant. RNA slot blot experiments using a probe for the putative AAF/I pilin subunit (aggA) revealed that aggR operates as a transcriptional activator of aggA expression. aggA::phoA fusions were constructed in 17-2 and in 17-2 delta aggR. AggR was found to promote expression of the aggA gene under a variety of conditions of temperature, osmolarity, oxygen tension, and medium. At acid pH, aggA expression was maximal and was regulated by both AggR-dependent and AggR-independent mechanisms.

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Section: Properties Of Aggr Deletion Mutants 17-2aaggr Was Testedmentioning

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AggR, a transcriptional activator of aggregative adherence fimbria I expression in enteroaggregative Escherichia coli

et al. 1994

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“…In Brazil, intestinal infectious processes seem to play an important role in triggering the syndrome. The presence of bacteria in patients with protracted diarrhea, especially classic enteropathogenic E. coli, has been reported (1,2). The serotypes detected have the property of adhering to the epithelium and provoking important morphological and functional changes in the small intestine.…”

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confidence: 99%

Morphological changes of the jejunal mucosa in protracted diarrhea and their correlation with disease duration, weight loss and serum albumin levels

La¹,

Fj³

1997

Braz J Med Biol Res

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The pathogenesis of protracted diarrhea is multifactorial. In developing countries, intestinal infectious processes seem to play an important role in triggering the syndrome. Thirty-four children aged 1 to 14 months, mean 6.5 months, with protracted diarrhea were studied clinically and in terms of small intestinal mucosal morphology. Mild, moderate or severe hypotrophy of the jejunal mucosa was detected in 82% of cases, and mucosal atrophy was observed in 12%. The intensity of the morphological changes of the jejunal mucosa correlated negatively with serum albumin levels. No correlation was detected between mucosal grading and duration of diarrhea or between mucosal grading and weight reported as percentile. After nutritional support was instituted, serial jejunal biopsies were obtained from 12 patients: five patients submitted to parenteral nutrition for 7 to 38 days, mean 17 days, and 7 patients receiving a hypoallergenic oral diet (semi-elemental formula, 3; chicken formula, 3; human milk, 1). In seven cases (58%) a progressive increase in villus height and a decrease in the number of inflammatory cells were noted. Recovery of the morphologic pattern was accompanied by clinical improvement in all patients.

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“…Man usually acquires this infection through the ingestion of contaminated food or drink (4). The microbial factors that contribute to virulence in S. enteritidis are not clearly understood, however, adherence is believed to be an important first step in the process of infection (2,3,2,22).…”

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Adherence and Pathogenesis of Salmonella enteritidis in Mice

Aslanzadeh

Paulissen

1990

Microbiology and Immunology

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Enteroaggregative Escherichia coli and Salmonella associated with nondysenteric persistent diarrhea

Cited by 96 publications

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AggR, a transcriptional activator of aggregative adherence fimbria I expression in enteroaggregative Escherichia coli

AggR, a transcriptional activator of aggregative adherence fimbria I expression in enteroaggregative Escherichia coli

Morphological changes of the jejunal mucosa in protracted diarrhea and their correlation with disease duration, weight loss and serum albumin levels

Adherence and Pathogenesis of Salmonella enteritidis in Mice

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