Enteroaggregative Escherichia coli (EAEC) are an increasingly important cause of diarrhoea. E. coli belonging to this category cause watery diarrhoea, which is often persistent and can be inflammatory. EAEC have been implicated in sporadic diarrhoea in children and adults, in both developing and developed countries, and have been identified as the cause of several outbreaks worldwide. EAEC are defined by their ability to adhere to epithelial cells in a characteristic "stacked-brick" pattern but are otherwise highly heterogeneous. Genes that could contribute to the pathogenicity of EAEC encode adhesins, toxins, and other factors, all of which are only partially conserved. Practicable tools are needed to improve diagnosis and identify risk factors. EAEC-infected individuals can be treated with fluoroquinolones but there is a need to examine alternative treatment protocols.

https://wwwnc.cdc.gov/eid/article/4/2/pdfs/98-0212.pdf

Enteroaggregative escherichia coli

Enteric Escherichia coli (E. coli) are both natural flora of humans and important pathogens causing significant morbidity and mortality worldwide. Traditionally enteric E. coli have been divided in...

https://www.tandfonline.com/doi/pdf/10.4161/gmic.19182

Infection strategies of enteric pathogenic Escherichia coli

The Escherichia coli strain causing a large outbreak of haemolytic uraemic syndrome and bloody diarrhoea in Germany in May and June 2011 possesses an unusual combination of pathogenic features typical of enteroaggregative E. coli together with the capacity to produce Shiga toxin. Through rapid national and international exchange of information and strains the known occurrence in humans was quickly assessed.We describe simple diagnostic screening tools to detect the outbreak strain in clinical specimens and a novel real-time PCR for its detection in foods.

/pdf/characteristics-of-the-enteroaggregative-shiga-toxin-2kvxlld90b.pdf

Characteristics of the enteroaggregative Shiga toxin/verotoxin-producing Escherichia coli O104:H4 strain causing the outbreak of haemolytic uraemic syndrome in Germany, May to June 2011.

Enteroaggregative Escherichia coli (EAEC) represents a heterogeneous group of E. coli strains. The pathogenicity and clinical relevance of these bacteria are still controversial. In this review, we describe the clinical significance of EAEC regarding patterns of infection in humans, transmission, reservoirs, and symptoms. Manifestations associated with EAEC infection include watery diarrhea, mucoid diarrhea, low-grade fever, nausea, tenesmus, and borborygmi. In early studies, EAEC was considered to be an opportunistic pathogen associated with diarrhea in HIV patients and in malnourished children in developing countries. In recent studies, associations with traveler's diarrhea, the occurrence of diarrhea cases in industrialized countries, and outbreaks of diarrhea in Europe and Asia have been reported. In the spring of 2011, a large outbreak of hemolytic-uremic syndrome (HUS) and hemorrhagic colitis occurred in Germany due to an EAEC O104:H4 strain, causing 54 deaths and 855 cases of HUS. This strain produces the potent Shiga toxin along with the aggregative fimbriae. An outbreak of urinary tract infection associated with EAEC in Copenhagen, Denmark, occurred in 1991; this involved extensive production of biofilm, an important characteristic of the pathogenicity of EAEC. However, the heterogeneity of EAEC continues to complicate diagnostics and also our understanding of pathogenicity.

Epidemiology and Clinical Manifestations of Enteroaggregative Escherichia coli

Background Conflicting studies exist regarding the role of enteroaggregative Escherichia coli (EAEC) as a cause of acute diarrheal illness. The objective of this meta-analysis was to determine whether identification of EAEC in stool samples is associated with acute diarrheal illness among different subpopulations, by geographic area. Methods A comprehensive search of electronic bibliographic databases (Medline and PubMed) from August 1985 to January 2006, as well as a search of conference proceedings, references of articles, and contacts with investigators of EAEC, yielded 354 studies. Results Forty-one studies (12%) that met the selection criteria (i.e., that examined the association between acute diarrheal illness and the excretion of EAEC among different subpopulations) were included. In this meta-analysis, presence of EAEC identified with the HEp-2 cell adherence assay was found to be significantly associated with acute diarrheal illness among children residing in developing regions (odds ratio [OR], 1.58; 95% confidence interval [CI], 1.36-1.83) and industrialized regions (OR, 1.23; 95% CI, 1.03-1.48), adults with human immunodeficiency virus infection residing in developing regions (OR, 6.43; 95% CI, 2.91-14.16), adults residing in developing regions (OR, 7.15; 95% CI, 1.96-26.04), and international travelers to developing regions (OR, 6.72; 95% CI, 2.62-17.20). A limited number of studies were available that examined the role of EAEC identified by its virulence genes by a DNA probe. Conclusions On the basis of this meta-analysis, we conclude that EAEC is a cause of acute diarrheal illness among many different subpopulations in both developing and industrialized regions, that EAEC strains are very heterogeneous and that additional studies that examine the role of EAEC in acute diarrheal illness are needed.

/pdf/enteroaggregative-escherichia-coli-is-a-cause-of-acute-1lclkxk8my.pdf

Enteroaggregative Escherichia coli is a cause of acute diarrheal illness: a meta-analysis.

The importance of enteroaggregative Escherichia coli (EAggEC) as a possible aetiological agent of acute diarrhoea among children in Calcutta, India, was investigated. Simultaneously the use of a previously described PCR diagnostic system was assessed for its ability to identify EAggEC infection. E. coli strains isolated during a 1-year case-control study from faecal samples of 388 children aged <5 years, with or without diarrhoea, were examined for EAggEC by HeLa cell adherence assay in parallel with a PCR assay with primers generated from an EAggEC DNA probe. A blind comparison was made between the two methods to determine their diagnostic potential. E. coli isolates that adhered to HeLa cells in an aggregative pattern were the sole isolates significantly more often in 254 cases (9%) than in 134 control (2%) children. Age stratification showed that EAggEC were isolated more frequently from children aged <36 months. The EAggEC isolates belonged to several O serogroups and showed multiple drug resistance. Both methods were positive for 26 samples, nine samples were positive by PCR alone and seven samples were positive by culture alone, thus indicating a 78% sensitivity and 97% specificity for the PCR assay. EAggEC is an important aetiological agent of acute diarrhoea among infants in and around Calcutta, and the PCR diagnostic system may be useful to identify such infection in epidemiological studies.

Use of PCR to identify enteroaggregative Escherichia coli as an important cause of acute diarrhoea among children living in Calcutta, india

Characterization of polynomially complete quasigroups based on Latin squares for cryptographic transformations

Visual Cryptography Scheme (VCS) for general access structure was developed by Ateniese, Blundo, Santis and Stinson in 1996 for black and white image and subsequently different schemes have been developed. In this paper, we propose a new model for Steiner Triple Systems (STS) based access structures by using “stacking” i.e. “superimposition” and “machine operation” which are mathematically equivalent to “OR” and “XOR” respectively. The concept of qualified set is extended. The technique to construct the VCS is developed for the model. The structure of the VCS is analysed. The contrast of the reconstructed secret image (SI) under the two operations is studied. Finally we introduce STS based (3, n)-Visual Threshold Scheme (VTS) and derive the ratio of its pixel expansion and the number of qualified sets.

/pdf/a-new-visual-cryptography-scheme-for-sts-based-access-57ay2pj0gu.pdf

A new visual cryptography scheme for STS based access structures

Ateniese, Blundo, De Santis and Stinson introduced Visual Cryptography Schemes (VCS) and Extended Visual Cryptography Schemes (EVCS) for general access structures. In [3] we developed a new VCS for...

A new online extended visual cryptography scheme for STS access structures

Corrigendum to “Characterization of polynomially complete quasigroups based on latin squares for cryptographic transformations” [Discrete Appl. Math. 200 (2016) 5–17]

Sucheta Chakrabarti

Papers

Use of PCR to identify enteroaggregative Escherichia coli as an important cause of acute diarrhoea among children living in Calcutta, india

Characterization of polynomially complete quasigroups based on Latin squares for cryptographic transformations

A new visual cryptography scheme for STS based access structures

A new online extended visual cryptography scheme for STS access structures

Corrigendum to “Characterization of polynomially complete quasigroups based on latin squares for cryptographic transformations” [Discrete Appl. Math. 200 (2016) 5–17]