Sorbitol-fermenting Shiga toxin-producing Escherichia coli O157:H(-) strains: epidemiology, phenotypic and molecular characteristics, and microbiological diagnosis.

The significance of Shiga toxin (Stx)-producing Escherichia coli (STEC) O157:H7 as the major cause of hemorrhagic colitis and the hemolytic-uremic syndrome (HUS) worldwide has been well established (for reviews, see references 21, 31, 41, and 60). The recognition of this pathogen has been facilitated by the availability of classical microbiological diagnostic procedures that are based on the characteristic phenotypic feature of this pathogen, in particular, its inability to ferment sorbitol after overnight incubation (40). However, in addition to E. coli O157:H7, STEC strains of serotype O157:H (nonmotile) which do ferment sorbitol rapidly have emerged as important causes of human diseases in continental Europe during the past decade (7, 8, 9–12, 16, 22, 27, 35, 39). Such strains are missed by diagnostic procedures recommended for the detection of E. coli O157:H7, and their significance in other parts of the world might thus be underestimated. This review summarizes the current knowledge on the significance of sorbitolfermenting (SF) STEC O157:H strains as causes of human diseases, the epidemiology of the infection, phenotypic and molecular characteristics of these pathogens, and strategies that are available for their microbiological diagnosis.