Virulence factors and phenotypical traits of verotoxigenic strains of Escherichia coli isolated from human patients in Germany

Abstract

Fecal isolates of Escherichia coli which were collected from human patients in different parts of Germany between 1985 and 1992 were examined for production of verotoxins (VT). Among 2165 isolates 54 (2.5%) verotoxigenic E. coli (VTEC) were found. The 54 VTEC belonged to 13 different serotypes, 46 (85.2%) of these were enterohemorrhagic E. coli (EHEC) types as O157:H7, O157:H-, O145:H-, O111:[H8] and O26:[H11]. Of the 54 VTEC 50 (92.6%) hybridized with one or both of the DNA probes specific for VT1 and VT2. The 4 VTEC strains which were negative for VT1 and VT2 differed from all other VTEC by many phenotypical trains such as serotype, production of alpha-hemolysin and absence of EHEC-plasmid and "attaching and effacing" (eae)-specific DNA sequences. In contrast, VTEC which were positive for VT1, VT2 or both were frequently positive for eae sequences (92.0%), EHEC-plasmids (90.0%) and for production of enterohemolysin (88.0%). With enterohemolysin as an epidemiological marker more VTEC strains (81.5%) could be identified than with others such as the absence of beta-glucuronidase activity (61.1%) or non-fermentation of sorbitol (48.1%). Case reports were available for 42 of the 54 VTEC strains. The clinical presentation of 42 cases with VTEC ranged from uncomplicated diarrhea to severe diseases as hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS). However, bloody diarrhea, HC and HUS were more associated with the O157 group than with other VTEC groups.

The prevalence and characterization of verotoxin-producing Escherichia coli isolated from cattle and pigs in an abattoir in Hong Kong

“…The O157 : H7 serotype was not isolated from pigs and the predominant genotype of the porcine VTEC was t2e + eaeA − EHEC-hlyA − . The role of VTEC in human diarrhoea in Hong Kong is lower than that in other countries [6,31]. One reason may be the absence of eaeA in porcine and the majority of the bovine VTEC.…”

Effect of non‐target cells on the sensitivity of the PCR for Escherichia coli O157 : H7

“…increased as observed is reassuring since a high percentage of VTEC strains associated with disease carry the eaeA gene Ten millilitres of each VTEC/non-target and VTEC-only test dilutions were centrifuged at 3000 g for 20 min at 4°C (Beutin et al 1994 ;Schmidt et al 1994). The sensitivity of the multiplex PCR for the VT1 gene and the pellet resuspended in 100 ml of sterile distilled water.…”

Thiol-independent activity of a cholesterol-binding enterohemolysin produced by enteropathogenic Escherichia coli

“…Since the first report of EHly in E. coli strains isolated from children with diarrhea (3), EHly has been investigated intensively in enterohemorrhagic E. coli strains that produce verotoxin and have caused outbreaks of diarrhea, especially in Germany and the United States (19,20). The biochemical and structural aspects of EHly have not yet been investigated as thoroughly as those of E. coli α-hemolysin.…”