Isolierung und Charakterisierung von Shigatoxin-produzierendenE. coli-Stämmen aus Stuhlproben: Ergebnisse einer Sentinel-Studie

Abstract

SummaryIsolation and characterization of shigatoxin producing E. coli strains isolated from stool samples: results of a Sentinel-study In order to record the incidence and clonal types of shigatoxin-producing E. coli of human origin (EHEC) and to evaluate the feasibility, sensitivity and specificity of a protocol for screening and isolation of EHEC under conditions clinical stool diagnostics a pilot study (Sentinel-study) was carried out with private clinical laboratory (covering 1.1 Mio. inhabitants). 3 % EHEC bacteria were detected among 3835 stool samples investigated from patients suffering with watery and bloody diarrhoea. These isolates belong to a broad range of serovars and clones with a spectrum of various virulence factors. Thus, about 10 % of the isolates have been identified as E. coil O157:H7/-, only, but with the same frequency E. coli O103:H2, O26:Hll/-, O8:H or Ont. The protocol of combined bacterial enrichment and molecular methods turned out to be valuable and feasible under conditions and economic requests of private diagnostic laboratories covering ca. 85 % of primary diagnostics.

A chromogenic plating medium for isolatingEscherichia coliO157:H7 from beef

“…In the present study, under conditions of increased sensitivity (presumptively-positive samples of uninoculated raw beef also exposed to IMS), the percentage of false-positive samples with the BCM ® O157:H7(¦) plating medium was only 15·8%, but was two and a half times greater with the MacConkey sorbitol-based MSA-BCIG. Even in the presence of high numbers of false-positive colonies, however, BCM ® O157:H7(¦) plating medium has been effective in rapidly isolating E. coli O157:H7 from the stools of patients with watery and bloody diarrhoea with no false negatives detected after 3835 samples (Prager et al 1998). Additionally, this plating medium has been used as an integral part of a protocol for the rapid identification of E. coli O157:H7 from human stool samples (Reissbrodt 1998).…”

Enterohaemorrhagic Escherichia coli O157 and non-O157 serovars differ in their mechanisms for iron supply

“…The EHEC strains used in this study, all clinical isolates from diarrhoea patients, were analysed for the presence of the intimin gene eae and for Shiga toxin expression using the methods described by Prager et al (1998). The prevalence of eae was significantly lower among non-O157 isolates (27% of strains tested, primarily O26 and O103) than among O157 isolates, among which all strains tested were eae + , as has been reported previously (Nataro and Kaper, 1998).…”

“…Determination of virulence markers (Shiga toxin by ELISA and PCR; enterohaemolysin phenotypically and by PCR; intimin by PCR), as well as biochemical and serological characterisation of strains were performed as previously described (Prager et al, 1998).…”

Zur Verbesserung der gegenwärtigen bakteriologischen Diagnostik von enterohämorrhagischen Escherichia coli (EHEC)

“…Shiga-Toxin-ELISA • Klinisch-mikrobiologische Diagnostik • EHEC-Infektionen • Epidemiologische Überwachung Enterohämorrhagische Escherichia coli (EHEC) sind humanpathogene Varianten des Darmbakteriums Escherichia coli [1,2], die weltweit [3,4,5,6,7], so auch in Deutschland [8,9,10,11,12], häufig vorkommen. Sie lassen sich im Wesentlichen durch ihre Fähigkeit zur Bildung verschiedener Zelltoxine definieren, der sog.…”

“…Sie lassen sich im Wesentlichen durch ihre Fähigkeit zur Bildung verschiedener Zelltoxine definieren, der sog. Für die mikrobiologische Diagnostik der EHEC-Bakterien ist jedoch der Nachweis ihrer Shigatoxinbildungsfähigkeit obligatorisch [11,13,14]. Zusätzlich können sie weitere Virulenzfaktoren aufweisen, die eine virulenzsteigernde oder klinisch-potenzierende Wirkung ausüben und für die epidemiologische Diagnostik (Stammdifferenzierung, Subtypisierung) wichtig sind (s. Diskussion und Tabelle 4).…”