Molecular epidemiology, clinical features and significance of Shiga toxin detection from routine testing of gastroenteritis specimens

After introduction of faecal multiplex PCR that includes targets for stx1 and stx2 genes, we found stx genes were detected in 120 specimens from 111 patients over a 31-month period from 2018–2020 from a total of 14,179 separate tests performed. The proportion of stx1 only vs stx2 only vs stx1 and stx2 was 35%, 22% and 42%, respectively. There were 54 specimens which were culture positive, with 33 different serotypes identified, the predominant serotype being O157:H7 (19%). Eighty-two patients had clinical data available; we found a high rate of fever (35%), bloody diarrhoea (34%), acute kidney injury (27%), hospital admission (80%) and detection of faecal co-pathogens (23%). Only one patient developed haemolytic uraemic syndrome. We found no significant association with stx genotype and any particular symptom or complication. We found a significant association of serotypes O157:H7 and O26:H11 with bloody stool, but no significant association with any other symptom or complication.