Shiga toxin-producingEscherichia coliO157 associated with human infections in Switzerland, 2000–2009

Abstract

SUMMARYShiga toxin-producingEscherichia coli(STEC), an important foodborne pathogen, can cause mild to severe bloody diarrhoea (BD), sometimes followed by life-threatening complications such as haemolytic uraemic syndrome (HUS). A total of 44 O157 strains isolated from different patients from 2000 through 2009 in Switzerland were further characterized and linked to medical history data. Non-bloody diarrhoea was experienced by 15·9%, BD by 61·4% of the patients, and 29·5% developed HUS. All strains belonged to MLST type 11, were positive forstx2 variants (stx2 and/orstx2c),eaeandehxA, and only two strains showed antibiotic resistance. Of the 44 strains, nine phage types (PTs) were detected the most frequent being PT32 (43·2%) and PT8 (18·2%). By PFGE, 39 different patterns were found. This high genetic diversity within the strains leads to the conclusion that STEC O157 infections in Switzerland most often occur as sporadic cases.