Escherichia coli harboring shiga toxin 2 gene variants: frequency and association with clinical symptoms

Shiga toxin (Stx)-producing Escherichia coli (STEC) from patients with hemolytic-uremic syndrome (HUS), patients with diarrhea without HUS, or asymptomatic subjects were genotyped to assess associations between stx(2) variants and clinical manifestations of infection. Neither stx(2d) nor stx(2e) was found in 268 STEC isolates from patients with HUS. Of 262 STEC isolates from patients with diarrhea, stx(2d) was found in 41 (15.6%; P<.000001), and stx(2e) was found in 12( 4.6%; P=.0004). The stx(2c) genotype frequency was similar among isolates from patients with HUS (3.7%) and diarrhea (5.0%). The frequencies of stx(2c), stx(2d), and stx(2e) among 96 STEC isolates from asymptomatic subjects were comparable to those among isolates from patients with diarrhea. None of the 626 STEC isolates contained stx(2f). All stx(2d)-positive or stx(2e)-positive STEC isolates were eae negative and originated from subjects older than those with STEC isolates with stx(2c). stx(2c)-positive STEC isolates can cause HUS, but the presence of stx(2d) or stx(2e) may predict a milder disease with a minimal risk of HUS.