Four strains from seafood, six from beef and one from a clinical case of bloody diarrhoea were positive for Shiga toxins Stx1 and Stx2 and also for stx1and stx2 genes.
Non-O157:H7 STEC less frequently contained stx1 (P=.046), stx2 (P<.001), iha (P<.001), eae, and espA (P=.039 for both), were isolated less often from patients treated in emergency departments (P=.022), and tended to be associated less frequently with bloody diarrhea (P=.061).
Severe disease in the form of bloody diarrhea and the hemolytic uremic syndrome is attributable to Shiga toxin (Stx), which exists as 2 major types, Stx1 and Stx2.
The detected STEC included two isolates (serotypes O26:H(-) and O111:H(-)) of Shiga toxin type 1 (Stx1-only) STEC from a child with non-bloody diarrhea, two isolates (Stx1-Stx2 STEC and Stx1-only STEC) from an adult with bloody diarrhea, and one isolate of Stx1-Stx2v STEC (O157:H7) from normal child.
Virulence gene profiles were as follows: 61% stx(1) but not stx(2); 22% stx(2) but not stx(1); 17% both stx(1) and stx(2); 84% intimin (eae); and 86% enterohemolysin (E-hly). stx(2) was strongly associated with an increased risk of HUS, and eae was strongly associated with an increased risk of bloody diarrhea.