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LOW PREVALENCE OF COMPLETE O ISLAND 122 AMONG NON-O157 VEROCYTOTOXIN-PRODUCING ESCHERICHIA COLI IN BELGIUM
Book Contribution - Book Chapter Conference Contribution
Accumulating evidence suggests that differences in pathogenic potential of Verocytotoxin-producing Escherichia coli (VTEC) are due to specific virulence characteristics encoded on horizontally acquired pathogenicity islands such as the locus of enterocyte effacement (LEE), and O Island 122 (OI 122). Whereas intimin and enterohemolysin are used in VTEC diagnostics for many years, the prevalence of OI 122 genes in VTEC associated with human disease in Belgium is unknown. In addition to the characterization of a limited number of VTEC O157, we compared the distribution of OI 122 and other virulence genes in non-O157 VTEC isolated from patients with and without the hemolytic uremic syndrome (HUS).
One hundred and twenty-nine non-O157 VTEC consecutively isolated from routinely submitted stool samples (2 from HUS patients), seventeen non-O157 VTEC isolates from HUS patients, and twenty-one O157 VTEC (of which 10 from HUS patients) were included in this study. PCR was used for the detection of VT1, VT2, eae, multiple plasmid genes (ehx, saa, espP, katP, and etpD), and 9 ORFs of OI 122.
All O157 VTEC isolates (16 O157:H7 and 5 O157:H-) carried VT2, eae, and all plasmid genes, except one sorbitol-fermenting O157:H- isolate which lacked espP and katP. Four isolates were carrying both VT1 and VT2. All O157 VTEC possessed a complete OI 122 (COI 122) with all nine ORFs present.
The virulence factors present in 19 non-O157 VTEC isolates recovered from HUS patients were compared to those present in the 127 isolates from patients without HUS. While VT1 was significantly more present in VTEC not associated with HUS (pTwenty-seven out of 146 (18.5%) non-O157 isolates carried a COI 122, 81 (55.5%) had an incomplete OI 122, and in 38 (26%) isolates OI 122 was not detected. Isolates associated with HUS (7/19; 36.8%) carried significantly more often a COI 122 than non-HUS isolates (20/127; 15.7%) (pOur study confirms the association of OI 122 with O157 and with severe disease induced by non-O157. This genomic island could be considered in addition to the toxin type and other virulence factors for determining the pathogenicity of non-O157 clinical isolates. Our data show that the prevalence of COI 122 in non-O157 VTEC in Belgium is lower compared to other reports.
* research supported by Brussels-Capital Region grant PRFB 2007-29 allowed to G Buvens
One hundred and twenty-nine non-O157 VTEC consecutively isolated from routinely submitted stool samples (2 from HUS patients), seventeen non-O157 VTEC isolates from HUS patients, and twenty-one O157 VTEC (of which 10 from HUS patients) were included in this study. PCR was used for the detection of VT1, VT2, eae, multiple plasmid genes (ehx, saa, espP, katP, and etpD), and 9 ORFs of OI 122.
All O157 VTEC isolates (16 O157:H7 and 5 O157:H-) carried VT2, eae, and all plasmid genes, except one sorbitol-fermenting O157:H- isolate which lacked espP and katP. Four isolates were carrying both VT1 and VT2. All O157 VTEC possessed a complete OI 122 (COI 122) with all nine ORFs present.
The virulence factors present in 19 non-O157 VTEC isolates recovered from HUS patients were compared to those present in the 127 isolates from patients without HUS. While VT1 was significantly more present in VTEC not associated with HUS (pTwenty-seven out of 146 (18.5%) non-O157 isolates carried a COI 122, 81 (55.5%) had an incomplete OI 122, and in 38 (26%) isolates OI 122 was not detected. Isolates associated with HUS (7/19; 36.8%) carried significantly more often a COI 122 than non-HUS isolates (20/127; 15.7%) (pOur study confirms the association of OI 122 with O157 and with severe disease induced by non-O157. This genomic island could be considered in addition to the toxin type and other virulence factors for determining the pathogenicity of non-O157 clinical isolates. Our data show that the prevalence of COI 122 in non-O157 VTEC in Belgium is lower compared to other reports.
* research supported by Brussels-Capital Region grant PRFB 2007-29 allowed to G Buvens
Book: 7th International Symposium on Shiga Toxin (Verocytotoxin) – producing Escherichia coli infections (VTEC2009), 10-14 May 2009, Buenos Aires, Argentina
Publication year:2009
Keywords:VTEC, virulence factors, O Island 122