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Shiga toxin-producing Escherichia coli (STEC) infection can cause clinical manifestations ranging from diarrhea to potentially fatal hemolytic uremic syndrome (HUS). This study is aimed at identifying STEC genetic factors associated with the development of HUS in Sweden. A total of 238 STEC genomes from STEC-infected patients with and without HUS between 1994 and 2018 in Sweden were included in this study. Serotypes, Shiga toxin gene (stx) subtypes, and virulence genes were characterized in correlation to clinical symptoms (HUS and non-HUS), and pan-genome wide association study was performed. Sixty-five strains belonged to O157:H7, and 173 belonged to non-O157 serotypes. Our study revealed that strains of O157:H7 serotype especially clade 8 were most commonly found in patients with HUS in Sweden. stx2a and stx2a + stx2c subtypes were significantly associated with HUS. Other virulence factors associated with HUS mainly included intimin (eae) and its receptor (tir), adhesion factors, toxins, and secretion system proteins. Pangenome wide-association study identified numbers of accessory genes significantly overrepresented in HUS-STEC strains, including genes encoding outer membrane proteins, transcriptional regulators, phage-related proteins, and numerous genes related to hypothetical proteins. Whole-genome phylogeny and multiple correspondence analysis of pangenomes could not differentiate HUS-STEC from non-HUS-STEC strains. In O157:H7 cluster, strains from HUS patients clustered closely; however, no significant difference in virulence genes was found in O157 strains from patients with and without HUS. These results suggest that STEC strains from different phylogenetic backgrounds may independently acquire genes determining their pathogenicity and confirm that other non-bacterial factors and/or bacteria-host interaction may affect STEC pathogenesis.

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 stx2a + stx2c (p &lt, 0.001) and eae (p &lt, 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 Ⅰ (ehxA subtype A), group Ⅱ (ehxA subtype B, C, and F), and group Ⅲ (ehxA subtype D). Most BD- and HUS-associated isolates were clustered into ehxA group Ⅱ, while ehxA group Ⅰ was associated with non-bloody stool and individuals &ge, 10 years of age. The presence of ehxA + eae and ehxA + eae + stx2 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.

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 stx2a + stx2c (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 Ⅰ (ehxA subtype A), group Ⅱ (ehxA subtype B, C, and F), and group Ⅲ (ehxA subtype D). Most BD- and HUS-associated isolates were clustered into ehxA group Ⅱ, while ehxA group Ⅰ was associated with non-bloody stool and individuals ≥10 years of age. The presence of ehxA + eae and ehxA + eae + stx2 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.

Type 2 T-helper cell (Th2)-skewed immunity is associated with successful pregnancy and the ability to easily direct immune responses to a Th2-polarised profile may be an evolutionary benefit. The Th2-like immunity associated with allergic disease might generate favourable effects for the maintenance of pregnancy, but could also promote development of Th2-like immune responses and allergic disease in the offspring. The aim of this study was to explore, by using IgE as a stable proxy for Th2, the Th1/Th2 balance in allergic and non-allergic women by measuring allergen-specific and total IgE antibody levels in plasma during pregnancy and after delivery. Specific and total IgE antibody levels were determined by ImmunoCAP technology at five occasions during pregnancy (gestational weeks 10-12, 15-16, 25, 35 and 39), as well as at 2 and 12 months after delivery. Thirty-six women without and 20 women with allergic symptoms were included, of whom 13 were sensitised with allergic symptoms and 30 were non-sensitised without allergic symptoms. The levels of total IgE, but not allergen-specific IgE, were increased during early pregnancy when compared to 12 months after delivery in the sensitised women with allergic symptoms, but not in the non-sensitised women without allergic symptoms (pandlt;0.01). This increase in total IgE levels during early pregnancy only in the sensitised women with allergic symptoms indicates that allergy is associated with an enhanced Th2 deviation during pregnancy. Original Publication: Martina Sandberg, Anne Frykman, Yvonne Jonsson, Marie Persson, Jan Ernerudh, Göran Berg, Leif Matthiesen, Christina Ekerfelt and Maria Jenmalm, Total and allergen-specific IgE levels during and after pregnancy in relation to maternal allergy, 2009, JOURNAL OF REPRODUCTIVE IMMUNOLOGY, (81), 1, 82-88. http://dx.doi.org/10.1016/j.jri.2009.04.003 Copyright: Elsevier Science B.V., Amsterdam. http://www.elsevier.com/

Exposure to ubiquitous allergens early in life, even before birth, may influence the incidence of allergic diseases later in life. During pregnancy, the fetomaternal interface is surrounded by high levels of T-helper (Th)2-like cytokines, possibly favouring the development of Th2-like immune responses in the offspring. The aim of this study was to evaluate the relation between cord blood (CB) IgE antibodies, Th1- and Th2-like cytokines and chemokines, maternal allergy and development of allergic disease during the first 2 yr of life in the offspring. The CB cytokine and chemokine levels from children of 20 allergic and 36 non-allergic women were determined by a multiplexed Luminex assay and ELISA. Total CB and maternal IgE antibody concentrations were quantified using ImmunoCAP technology. The maternal IgE levels during and after pregnancy correlated with CB IgE and Th2-associated macrophage-derived chemokine [MDC (CCL22)] levels. Development of allergic disease and sensitization was associated with increased CB IgE and MDC (CCL22) levels, as well as high ratios of MDC (CCL22) to Th1-associated interferon-gamma inducible protein 10 [IP-10 (CXCL10)] and interferon-gamma inducible T-cell alpha-chemoattractant [I-TAC (CXCL11) (n = 7 allergic vs. n = 25 non-allergic)]. The correlations between maternal IgE and CB IgE and MDC (CCL22) levels possibly indicate that the maternal immunity can affect the Th1/Th2 profile in the neonate. Development of allergic disease is associated with a more marked Th2-like deviation already at birth, shown as increased levels of CB IgE and MDC (CCL22) and higher ratios of MDC (CCL22) to IP-10 (CXCL10) and I-TAC (CXCL11). This is the pre-reviewed version of the following article: Martina Sandberg, Anne Frykman, Jan Ernerudh, Göran Berg, Leif Matthiesen, Christina Ekerfelt, Lennart Nilsson and Maria Jenmalm, Cord blood cytokines and chemokines and development of allergic disease, 2009, PEDIATRIC ALLERGY AND IMMUNOLOGY, (20), 6, 519-527. which has been published in final form at: http://dx.doi.org/10.1111/j.1399-3038.2008.00794.x Copyright: Blackwell Publishing Ltd http://www.blackwellpublishing.com/