Detection of serum anti-lipopolysaccharides (lps) antibodies from enterohemorrhagic e. coli (ehec) in asymptomatic kindergarten teachers of buenos aires province

Abstract

EHEC is responsible for developing typical Hemolytic Uremic Syndrome (HUS) and Argentina has the highest incidence in the world. The endemo-epidemic behavior that HUS presents in our countrywas associated with person-to-person transmission. Since children below 5 years old are the most affected, our objective was to determine the frequency of kindergarten teachers with anti-LPS-EHECantibodies in serum. One hundred and fifty teachers from J.C. Paz district from Buenos Aires Province participated in an informative talk given by LuSUH, a non-governmental association, about good practices to reduce HUS transmission. Then, 63 of them voluntarily gave, under a signedwritten informed consent, a sample of blood obtained by finger puncture. A commercial ELISA (Chemtest, Arg) was used to detect specific IgM and IgG isotypes against 4 types of LPS-EHEC: O157, O145, O121 and O103. These variants represent approximately 87% of the EHEC serotypes associated with HUS in Argentina. The IgM finding was considered as indirect evidence of current infection with the EHEC specific serotype. Forty-two samples were evaluated, 60% (25/42) of them were positive for at least one type of LPS. Fifty-six percent of them (14/25) were IgM positive. Fifty percent of the positive samples were reactive for LPS O157, 26% for LPS O121, 12% for LPS O145 and 2% for LPS O103. Among the samples positive for LPS O157, 5% belonged to IgM isotype, 31% to IgG and 14% had both. The IgG isotype was the unique detected for LPS O145 and O103 (12 and2%, respectively). For LPS O121, the IgM isotype was detected in 2%, IgG in 12% and both isotypes in 12% of the samples. The elevated frequency of LPS-EHEC reactive samples (60%) reflects the high circulation of EHEC strains in our country. This agrees with the prevalence of anti-Stx2 antibodies reported in our population previously. Very strikingly, nearly half of these individuals carry IgM, suggesting that they would be in the active phase of infection.