Human infection with Shiga toxin-producing Escherichia coli (STEC) is a major cause of postdiarrheal hemolytic-uremic syndrome (HUS), a life-threatening condition characterized by hemolytic anemia, thrombocytopenia, and acute renal failure. E. coli O157:H7 is the dominant STEC serotype associated with HUS worldwide, although non-O157 STEC serogroups can cause a similar disease. The detection of anti-O157 E. coli lipopolysaccharide (LPS) antibodies in combination with stool culture and detection of free fecal Shiga toxin considerably improves the diagnosis of STEC infections. In the present study, we exploited a bacterial glycoengineering technology to develop recombinant glycoproteins consisting of the O157, O145, or O121 polysaccharide attached to a carrier protein as serogroup-specific antigens for the serological diagnosis of STEC-associated HUS. Our results demonstrate that using these antigens in indirect ELISAs (glyco-iELISAs), it is possible to clearly discriminate between STEC O157-, O145-, and O121-infected patients and healthy children, as well as to confirm the diagnosis in HUS patients for whom the classical diagnostic procedures failed. Interestingly, a specific IgM response was detected in almost all the analyzed samples, indicating that it is possible to detect the infection in the early stages of the disease. Additionally, in all the culture-positive HUS patients, the serotype identified by glyco-iELISAs was in accordance with the serotype of the isolated strain, indicating that these antigens are valuable not only for diagnosing HUS caused by the O157, O145, and O121 serogroups but also for serotyping and guiding the subsequent steps to confirm diagnosis.
Shiga toxin-producing Escherichia coli (STEC) is an important food-borne pathogen associated with sporadic cases and outbreaks of diarrhea, bloody diarrhea (BD), and hemolytic-uremic syndrome (HUS), a life-threatening condition characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure (1). Postdiarrheal HUS is caused by particular serotypes of STEC or, in regions, such as South Asia, by Shigella dysenteriae serotype 1 (2). STEC strains are characterized by the production of Shiga toxin 1 (Stx1) and/or Shiga toxin 2 (Stx2), and the production of these toxins is central in the pathogenesis of BD and HUS (3). E. coli O157:H7 is the dominant STEC serotype associated with sporadic cases and outbreaks of BD and HUS in different parts of the world (4); however, a subset of non-O157:H7 STEC serotypes (O26:H11, O103:H2, O111:NM, O121:H19, O145:NM, and O45:H2, among others) can cause a similar disease (5, 6).STEC-associated HUS is the most common cause of acute renal failure in children worldwide and constitutes 90% of all HUS cases in this population. Five to 10 percent of children with STEC infection develop HUS, for which the only treatment is supportive care. The incidence rate of postdiarrheal HUS varies according to country, and Argentina shows the highest HUS incidence worldwide, with 12 to 14 cases per 100,000 ...