Micro-array for the identification of Shiga toxin-producing Escherichia coli (STEC) seropathotypes associated with Hemorrhagic Colitis and Hemolytic Uremic Syndrome in humans

Abstract

A micro-array has been developed, based on the GeneDisc® array, for the genetic identification of 12 O-types and 7 H-types of Shiga toxin-producing Escherichia coli (STEC) including the most clinically relevant enterohemorrhagic E. coli (EHEC) serotypes. The genes selected for determination of the O antigens ( rfbE O157, wzx O26, wzx O103, wbd1 O111, ihp1 O145, wzx O121, wzy O113, wzy O91, wzx O104, wzy O118, wzx O45, and wbgN O55) and H-types ( fliC H2, fliC H7, fliC H8, fliC H11, fliC H19, fliC H21, and fliC H28) showed a high specificity and concordance with serology. The micro-array also had a high specificity for EHEC-associated virulence factors, including Shiga toxins 1 and 2 ( stx1 and stx2), intimin ( eae), enterohemolysin ( ehxA), serine protease ( espP), catalase peroxidase ( katP), the type II secretion system ( etpD), subtilase cytotoxin ( subA), autoagglutinating adhesin ( Saa) and type III secreted effectors encoded in the genomic islands OI-122 ( ent/espL2, nleB, and nleE) and OI-71 ( nleF, nleH1-2, and nleA). The eae gene was detected in all typical EHEC strains, and the pattern of nle genes encoded in OI-71 and OI-122 was found to be closely associated with certain serotypes of typical EHEC and emerging EHEC strains. Virulence plasmid associated genes such as katP, espP, and etpD were more common in EHEC than in STEC strains; this supports their association with virulence. This array constitutes a valuable approach for the identification of STEC strains with a high potential for human virulence.