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[SANET-MG] E coli 0157 and its transducing viruses that transduce virotoxin in polluted water



The ready transmission of E coli 0157 and the transducing viruses that spread toxin gene appear in polluted waters in EU as well as in USA.Our experience in Ontario was that water pollution leads to deadly outbreaks in cities. Irrigations systems may as well spread the bacteria and its viruses to vegetables and fruits.

Gesundheitswesen. 2005 Dec;67(12):858-61.  Links
[Risk factors for abundance of shiga toxin producing Escherichia coli in sewage water][Article in German] Burckhardt F, Heissenhuber A, Morlock G, Busch U, Schindler P, Fruth A, Ammon A, Wildner M. Bayerisches Landesamt fur Gesundheit und Lebensmittelsicherheit, Oberschleissheim. florian.burckhardt@lgl.bayern.de

Shiga toxin producing Escherichia coli (STEC) in sewage influent into surface water are a potential source of human infections with STEC. Eight sewage treatment plants in Bavaria, Germany, were sampled at regular intervals from 2003 to 2004 in order to estimate STEC load and quantify risk factors. 95 of 378 samples (25 %) were tested positive for stx1and/or stx2 with PCR after enrichment culture. STEC elimination after treatment was 44 %. The following risk factors were analysed with logistic regression: location of sewage plant (rural vs. urban), treatment plant technology (two stage vs. three stage treatment) and sampling location (sewage input vs. sewage output). Rural plants had odds-ratios of 1,7 (95 % CI 1.03 - 2.69; p = 0.038) for a positive stx1 and/ or stx2 PCR result, sampling at sewage input of 2.1 (95 %CI 1.28 - 3.36; p = 0.003) and three stage plants of 1.51 (95 % CI 0.94 - 2.44; p = 0.087, not significant). Sampling after rain and after dry spells had no impact on STEC abundance (univariate Chi-square test = 0.01; df1; p = 0.920). Rural sewage plants had higher odds of STEC content. The influence of the sewage plant technology on the STEC load requires further clarification.
Letters in Applied Microbiology
Volume 42 Page 48  - January 2006
doi:10.1111/j.1472-765X.2005.01809.x
Volume 42 Issue 1 Detection of phages carrying the Shiga toxin 1 and 2 genes in waste water and river water samples
R. Dumke1, U. Schröter-Bobsin1, E. Jacobs1 and I. Röske2
Abstract
Aims: To evaluate the occurrence and abundance of phages that carry the stx1 and stx2 gene in water samples of different quality.

Methods and Results: Phages growing on the Shiga toxin-negative Escherichia coli O157:H7 (ATCC 43888) strain were enumerated by a plaque assay in concentrated raw and treated waste water samples and river water samples. Plaques were investigated for the presence of stx1 and stx2 genes by a multiplex/nested PCR procedure. An overall number of 805 plaques were tested for the presence of stx-carrying phages. Stx genes could be demonstrated in 2% (stx1) and 16% (stx2) of the plaques. Stx-phages were eliminated with approximately the same efficiency in comparison with somatic coliphages during the waste water treatment process.

Conclusions: Due to the low numbers of phages carrying the stx genes 1 and 2 in treated waste water and river water, the dilution and inactivation of host bacteria and the unsuitable conditions for the transduction of host organisms in aquatic environments, it is difficult to derive from the data the direct evidence for a public health problem.

Significance and Impact of the Study: The results show the quantitative occurrence of stx-carrying phages in waste and river water and confirm the frequent circulation of these viruses in the aquatic environment.

FEMS Microbiology Letters
Volume 258 Page 127  - May 2006
doi:10.1111/j.1574-6968.2006.00213.x
Volume 258 Issue 1


Newly identified bacteriophages carrying the stx2g Shiga toxin gene isolated from Escherichia coli strains in polluted waters
Cristina García-Aljaro, Maite Muniesa, Juan Jofre & Anicet R. Blanch
Abstract

Shiga toxin-converting bacteriophages are the main vehicle involved in horizontal transmission of stx1 and stx2 genes, which has led to the current spread of stx genes among a high number of Escherichia coli serotypes and other enterobacteria. Several stx gene variants have been described, although some of the variants have never been isolated from inducible bacteriophages. In this study, two stx2g-carrying bacteriophages induced from two different E. coli O2:H25 strains isolated from different wastewater samples were characterized. These bacteriophages when transduced into Shigella sonnei retained their ability to produce Stx2 protein. They had similar but not identical DNA restriction patterns, and similar host ranges. Electron microscopy studies showed that they had isometric capsids with short tails, which resembled phage 933W. However, DNA cross-hybridization studies showed that phage 933W was not closely related to stx2g bacteriophages. This first description of stx2g-carrying bacteriophages enlarges the list of stx-carrying bacteriophages involved in horizontal transmission of stx genes in the environm





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