Production of cytolethal distending toxin and other virulence characteristics of Escherichia coli strains of serogroup O86

Genetic and phenotypic virulence markers of different categories of diarrhoeagenic Escherichia coli were investigated in 106 strains of enteropathogenic E. coli (EPEC) serogroup O86. The most frequent serotype found was O86:H34 (86%). Strains of this serotype and the non motile ones behaved as EPEC i.e., carried eae, bfpA and EAF DNA sequences and presented localised adherence to HeLa cells. Serotypes O86:H2, O86:H6, O86:H10, O86:H18, O86:H27 and O86:H non determined, belonged to other categories. The majority of the strains of serotype O86:H34 and non motile strains produced cytolethal-distending toxin (CDT). The ribotyping analysis showed a correlation among ribotypes, virulence markers and serotypes, thus suggesting that CDT production might be a property associated with a universal clone represented by the O86:H34 serotype.

Effect of irrigation water and processing on the microbial quality of lettuces produced and sold on markets in Dakar (Senegal)

The aim of this survey is to assess the microbiological impact of irrigation water on lettuces produced on two urban agricultural sites and sold on markets; 6 and 7%, respectively, of lettuces coming from the sites of Pikine and Patte d'Oie were Salmonella spp. positive. Lettuces irrigated with shallow groundwater (''Ceanes'' water) were more contaminated (8% at both Pikine and Patte d'Oie sites) compared to those irrigated with wastewater (4% at Pikine) or well water (5% at Patte d'Oie). As for the lettuces in marketplaces, their contamination seems to depend on the type of treatment occurring before sale. Lettuces previously washed in the ``Ceanes'' were more contaminated than those rinsed with tap water at the marketplace. Salmonella spp. have been isolated from all marketplaces. However, the rates of contamination in markets surrounding Patte d'Oie are higher (9 and 11% at Grand Yoff and Dalifort) than those surrounding Pikine (4 and 2% at Zinc and Sham) or Rufisque, the control (2%). Our results confirm that the reuse of wastewater in irrigation is an alternative to animal manure. Its risk of microbial contamination can be significantly reduced by washing the vegetables with tap water before they are sold. Copyright (C) 2010 John Wiley & Sons, Ltd.

Treatment of severe infectious purpura in children with human plasma from donors immunized with Escherichia coli J5: a prospective double-blind study. J5 study Group.

To evaluate the efficacy of anti-J5 serum in the treatment of severe infectious purpura, 73 children were randomized to receive either anti-J5 (40) or control (33) plasma. Age, blood pressure, and biologic risk factors were similar in both groups. At admission, however, tumor necrosis factor serum concentrations were 974 +/- 173 pg/ml compared with 473 +/- 85 pg/ml (P = .023) and interleukin-6 serum concentrations were 129 +/- 45 compared with 19 +/- 5 ng/ml (P = .005) in the control and treated groups, respectively. The duration of shock and the occurrence of complications were similar in both groups. The mortality rate was 36% in the control group and 25% in the treated group (P = .317; odds ratio, 0.76; 95% confidence interval, 0.46-1.26). This trend disappeared after correction for unbalances in risk factors at randomization using a logistic regression model. These results suggest that anti-j5 plasma did not affect the course or mortality of severe infectious purpura in children.

Lesion bypass by the Escherichia coli DNA polymerase V requires assembly of a RecA nucleoprotein filament.

Translesion replication is carried out in Escherichia coli by the SOS-inducible DNA polymerase V (UmuC), an error-prone polymerase, which is specialized for replicating through lesions in DNA, leading to the formation of mutations. Lesion bypass by pol V requires the SOS-regulated proteins UmuD' and RecA and the single-strand DNA-binding protein (SSB). Using an in vitro assay system for translesion replication based on a gapped plasmid carrying a site-specific synthetic abasic site, we show that the assembly of a RecA nucleoprotein filament is required for lesion bypass by pol V. This is based on the reaction requirements for stoichiometric amounts of RecA and for single-stranded gaps longer than 100 nucleotides and on direct visualization of RecA-DNA filaments by electron microscopy. SSB is likely to facilitate the assembly of the RecA nucleoprotein filament; however, it has at least one additional role in lesion bypass. ATPgammaS, which is known to strongly increase binding of RecA to DNA, caused a drastic inhibition of pol V activity. Lesion bypass does not require stoichiometric binding of UmuD' along RecA filaments. In summary, the RecA nucleoprotein filament, previously known to be required for SOS induction and homologous recombination, is also a critical intermediate in translesion replication.

Enterocytozoon bieneusi (microsporidia) in faecal samples from domestic animals from Galicia, Spain

In this survey we examined 87 domestic animal stool samples in order to detect the possible presence of microsporidia in animals in close contact with humans in Galicia (NW, Spain). The detection of Enterocytozoon bieneusi spores was confirmed in faecal samples from two dogs and one goat by polymerase chain reaction. None of the positive samples for microsporidia in the staining method were amplified with species-specific primers for Encephalitozoon intestinalis, E. hellem and E. cuniculi. Four rabbits faecal samples reacted with anti-E. cuniculi serum. Our results could indicate the importance of domestic animals as zoonotic reservoirs of microsporidial human infections.

Phenotypic and genotypic characteristics of shiga toxin-producing Escherichia coli strains isolated from children in São Paulo, Brazil

The biochemical and serological characteristics, virulence properties, and genetic relatedness of Shiga toxin-producing Escherichia coli (STEC) strains isolated in São Paulo, from April 1989 through March 1990, were determined. This is also the first report on clinic findings of human STEC infections in Brazil. The only three STEC strains identified in that period were lysine decarboxylase negative, belonged to serotype O111ac: non-motile, were Stx1 producers, carried the eae and astA genes, and 2 of them also presented the EHEC-hly sequence. The children carrying STEC were all boys, with less than two years old, and had no previous history of hospitalization. None of them presented blood in stools. Vomiting, cough and coryza were the most common clinical manifestations observed. Although the STEC strains were isolated during summer months, and presented similar phenotypic and genotypic characteristics, carbohydrate fermentation patterns and PFGE analysis suggested that these diarrheal episodes were not caused by a single clone.

Eye tracking for on-screen reading

A medida que avanza la tecnolog a, cada vez son m as comunes los libros digitales. Por eso, existen varias formas de mejorar la experiencia de lectura del usuario, como mostrar la de nici on de una palabra que resulte dif cil, o resaltar lo importante del texto cuando se pasa la vista por encima. En este proyecto, se ha investigado la base de esto con la ayuda de un Eye Tracker. Se ha implementado una clasi caci on en palabras f aciles y dif ciles dependiendo de c omo una persona lee, y una forma de saber si se est a leyendo el texto o pasando la vista por encima.

The E.coli RuvAB proteins branch migrate Holliday junctions through heterologous DNA sequences in a reaction facilitated by SSB.

During genetic recombination a heteroduplex joint is formed between two homologous DNA molecules. The heteroduplex joint plays an important role in recombination since it accommodates sequence heterogeneities (mismatches, insertions or deletions) that lead to genetic variation. Two Escherichia coli proteins, RuvA and RuvB, promote the formation of heteroduplex DNA by catalysing the branch migration of crossovers, or Holliday junctions, which link recombining chromosomes. We show that RuvA and RuvB can promote branch migration through 1800 bp of heterologous DNA, in a reaction facilitated by the presence of E.coli single-stranded DNA binding (SSB) protein. Reaction intermediates, containing unpaired heteroduplex regions bound by SSB, were directly visualized by electron microscopy. In the absence of SSB, or when SSB was replaced by a single-strand binding protein from bacteriophage T4 (gene 32 protein), only limited heterologous branch migration was observed. These results show that the RuvAB proteins, which are induced as part of the SOS response to DNA damage, allow genetic recombination and the recombinational repair of DNA to occur in the presence of extensive lengths of heterology.

Influence of the blood meal source on the biology of Meccus picturatus Usinger 1939 (Hemiptera: Reduviidae: Triatominae) under laboratory conditions

Aspects related to hatching, time-lapse between presenting the blood meal and beginning of feeding, feeding time, postfeed defecation delay,life time, mortality and fecundity for each stage of Meccus picturatus, life-cycle were evaluated and compared in two cohorts of M. picturatus fed on hens or rabbits. The hatching rate observed for each of the two studied groups of eggs was 78.1% (n = 2298) on the group fed on hens and 82.1% (n = 2704) on that fed on rabbits, and the average time of hatching was 20 days. Mean time-lapse for beginning feeding was under 3 min in nymphal stages and postfeed defecation delay was under 10 min in all stages, in both cohorts. Mean feeding time was significantly (P < 0.05) shorter in triatomines fed on hens than on rabbits. A similar number of nymphs of each cohort, 69 fed on hens (34.5%) and 68 fed on rabbits (34%), completed the cycle. No significantly (P > 0.05) differences were recorded among the average times from NI to adult in the cohort fed on hens (196.8 ± 15.8 days) and the average time in the cohort fed on rabbits (189.5 ± 22.9). The average span in days for each stage fed on hens was not significantly different to the average span for each stage fed on rabbits. The number of blood meals at each nymphal stage varied from 1 to 6 in both cohorts. The mortality rates were higher on fifth nymphal stage, in both cohorts. No significant (P > 0.05) differences were recorded on mortality rates on most nymphal stages of both cohorts. The average number of eggs laid per female from the cohort fed on hens in a 9-month period was 791.1, whereas the average number of eggs in the cohort fed on rabbits was 928.3.

Professional information factsheet: E. coli O157

This factsheet for health professionals contains information on E. coli O157, a strain of bacteria that can cause severe disease in humans. Information on prevention is included.

Health matters: what you need to know - E. coli O157

This factsheet for general publiccontains information on E. coli O157, a strain of bacteria that can cause severe disease in humans. Information on prevention is included.

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

The enteropathogenic role of cytotoxic necrotizing factor (CNF)-producing Escherichia coli was investigated by searching cnf genes among 2074 isolates from 200 children with and 200 without acute diarrhea in Brazil. Fourteen (7%) cases versus 10 (5%) control children carried at least one cnf positive isolate (P = 0.50) and most isolates expressed CNF type 1. DNA sequences of virulence factors of extraintestinal pathogenic E. coli (ExPEC) were detected in 78.6% of CNF1-producing isolates. Besides not being associated with human acute diarrhea, the CNF1-producing isolates here identified may represent potential ExPEC transitorily composing the normal intestinal flora.