Table 2: Investigations recommended in the diagnosis of STEC-associated HUS in adults

Microbiology	Comments
Stool culture	Indicate bloody diarrhoea and/or suspicion of E. coli O157/STEC on request form
PCR	If stool culture negative
Rectal swab (HUS only)	Submit directly to SERL from cases of HUS who are unable to produce a stool sample. Please discuss a suitable swab type with SERL prior to taking sample
Urine	Features of HUS
Dipstick	Haematuria and proteinuria
Blood	Features of HUS
FBC and film film WBC haemoglobin platelets	fragmented RBC Neutrophilia^5,21 anaemia or a falling Hb (may be falsely elevated because of haemoconcentration) low or falling platelet count
Urea and electrolytes	Rising urea or creatinine
Lactate	Elevation may indicate alternative diagnosis such as severe sepsis or ischaemic colitis
Liver function tests	Bilirubin elevated because of haemolysis. Transaminitis is not uncommon
Lactate dehydrogenase	Elevated because of haemolysis and tissue hypoxia¹³
C-Reactive protein	Any increase in CRP is associated with increased risk of HUS^10,11
Coagulation Screen	All adults