Humoral immune response to Shiga Toxin 2 (Stx2) among Brazilian urban children with hemolytic uremic syndrome and healthy controls

Abstract

BackgroundShiga toxin (Stx)-producing Escherichia coli (STEC) infection is associated with hemolytic uremic syndrome (HUS), the main cause of acute renal failure in early childhood. Stx is essential in the pathogenesis of HUS, which has been mostly related to Stx2-producing isolates. Very limited data exist on the immune response to STEC in the Brazilian population. In this study, the prevalence of immunoglobulin G (IgG) antibodies to Stx2 was investigated in sera of children diagnosed with HUS and of healthy children in the city of São Paulo, Brazil.MethodsIgG-antibody reactivity to Stx2 was determined by immunoblotting (WB) and enzyme-linked immunosorbent assay (ELISA) in sera from 13 children with HUS aged 8 months to 6 years and 54 healthy urban children aged 5 months to 7 years.ResultsA positive immune response to the A and B subunits of Stx2 was observed in 46.1% HUS patients and in 16.6% healthy individuals by WB. All HUS patients and 62.9% healthy children showed IgG antibodies to the Stx2 A subunit. The frequency of antibodies to both subunits or only to the A subunit of Stx2 was significantly higher in HUS patients than controls (p < 0.05). Also, the mean OD value obtained by ELISA was higher in that group. Considering children’s age, the frequency of reactivity to either the A subunit or both subunits of Stx2 was considerably higher in HUS children up to three years old compared to controls in the same age range. Moreover, in almost 37% of healthy children, no immune response to Stx2 was detected independently of the child’s age.ConclusionsThe seroepidemiolgy of anti-Stx2 antibodies was described for the first time in healthy children and children with HUS in Brazil. The percentage of individuals showing antibodies against Stx2 was higher among HUS patients than controls, and in spite of the low number of notified HUS cases, STEC strains are circulating in our settings. In addition, the results obtained also corroborated previous data on the increased sensitivity and specificity of WB compared to toxin-based enzyme immunoassays.

Diarrheagenic Escherichia coli

“…In an attempt to overcome this gap, prevalence of anti-Stx2 antibodies in sera of children diagnosed with HUS and of healthy children was recently determined 176 . The percentage of individuals showing antibodies against Stx2 was higher among HUS patients than controls, and the results also confirmed that STEC strains are circulating in our settings despite the low number of identified HUS cases.…”

Antibody response to lipopolysaccharides and recombinant proteins of Shiga toxin (STX)‐producing Escherichia coli (STEC) in children with haemolytic uraemic syndrome in Poland

“…Similar observations were also confirmed by other investigators. Antibodies IgG to protein Stx2b were diagnosed by ELISA in 76·9% Brazilian urban children with HUS (Guirro et al 2014) and in 71% of the patients infected by an Stx2b‐producing strain (Ludwig et al 2001). In another study, conducted in Canada, 13 (93%) out of 14 paediatric patients with HUS were tested positive for Stx2b Abs (7 out of 13 were positive for both Stx1 Abs and Stx2b Abs, and 6 of the 13 were positive for Stx2b Abs only; Karmali et al 2003).…”

Comment on “Shiga-Toxin Producing Escherichia coli in Brazil: A Systematic Review. Microorganisms 2019, 7, 137”

“…Furthermore, due to the importance of STEC infections in public health, HUS surveillance is compulsorily notified at a national level, and surveillance is based on a sentinel system [5]. Possible explanations on the low incidence of STEC outbreaks in Brazil is beyond the revision made by Castro et al [1], and has been explored in other publications [6,7].…”