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- Hua, Y., et al.
(author)
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Molecular Characterization of the Enterohemolysin Gene (ehxA) in Clinical Shiga Toxin-Producing Escherichia coli Isolates
- 2021
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In: Toxins. - : MDPI AG. - 2072-6651. ; 13:1
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Journal article (peer-reviewed)abstract
- Shiga toxin (Stx)-producing Escherichia coli (STEC) is an important foodborne pathogen with the ability to cause bloody diarrhea (BD) and hemolytic uremic syndrome (HUS). Little is known about enterohemolysin-encoded by ehxA. Here we investigated the prevalence and diversity of ehxA in 239 STEC isolates from human clinical samples. In total, 199 out of 239 isolates (83.26%) were ehxA positive, and ehxA was significantly overrepresented in isolates carrying stx(2a) + stx(2c) (p < 0.001) and eae (p < 0.001). The presence of ehxA was significantly associated with BD and serotype O157:H7. Five ehxA subtypes were identified, among which, ehxA subtypes B, C, and F were overrepresented in eae-positive isolates. All O157:H7 isolates carried ehxA subtype B, which was related to BD and HUS. Three ehxA groups were observed in the phylogenetic analysis, namely, group ? (ehxA subtype A), group II (ehxA subtype B, C, and F), and group (ehxA subtype D). Most BD- and HUS-associated isolates were clustered into ehxA group II, while ehxA group ? was associated with non-bloody stool and individuals >= 10 years of age. The presence of ehxA + eae and ehxA + eae + stx(2) was significantly associated with HUS and O157:H7 isolates. In summary, this study showed a high prevalence and the considerable genetic diversity of ehxA among clinical STEC isolates. The ehxA genotypes (subtype B and phylogenetic group II) could be used as risk predictors, as they were associated with severe clinical symptoms, such as BD and HUS. Furthermore, ehxA, together with stx and eae, can be used as a risk predictor for HUS in STEC infections.
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| 2. |
- Hua, Y., et al.
(author)
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Whole-genome characterization of hemolytic uremic syndrome-causing Shiga toxin-producing Escherichia coli in Sweden
- 2021
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In: Virulence. - : Informa UK Limited. - 2150-5594 .- 2150-5608. ; 12:1, s. 1296-1305
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Journal article (peer-reviewed)abstract
- Shiga toxin-producing Escherichia coli, a foodborne bacterial pathogen, has been linked to a broad spectrum of clinical outcomes ranging from asymptomatic carriage to fatal hemolytic uremic syndrome (HUS). Here, we collected clinical data and STEC strains from HUS patients from 1994 through 2018, whole-genome sequencing was performed to molecularly characterize HUS-associated STEC strains, statistical analysis was conducted to identify bacterial genetic factors associated with severe outcomes in HUS patients. O157:H7 was the most predominant serotype (57%) among 54 HUS-associated STEC strains, followed by O121:H19 (19%) and O26:H11 (7%). Notably, some non-predominant serotypes such as O59:H17 (2%) and O109:H21 (2%) also caused HUS. All O157:H7 strains with one exception belonged to clade 8. During follow-up at a median of 4years, 41% of the patients had renal sequelae. Fifty-nine virulence genes were found to be statistically associated with severe renal sequelae, these genes encoded type II and type III secretion system effectors, chaperones, and other factors. Notably, virulence genes associated with severe clinical outcomes were significantly more prevalent in O157:H7 strains. In contrast, genes related to mild symptoms were evenly distributed across all serotypes. The whole-genome phylogeny indicated high genomic diversity among HUS-STEC strains. No distinct cluster was found between HUS and non-HUS STEC strains. The current study showed that O157:H7 remains the main cause of STEC-associated HUS, despite the rising importance of other non-O157 serotypes. Besides, O157:H7 is associated with severe renal sequelae in the follow-up, which could be a risk factor for long-term prognosis in HUS patients. © 2021 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.
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