You are the specialist registrar in paediatrics doing the ward rounds. There has been a recent outbreak of Escherichia coli (E coli) O157:H7 gastroenteritis in the community. A 5-year old girl was admitted 3 days ago with bloody diarrhoea, abdominal cramps and vomiting. Her stool has grown E coli O157:H7. She is now stable and her parents are keen to take her home but are understandably anxious and ask you about possible complications. You are aware of the risk for progression to haemolytic uraemic syndrome (HUS). However, you are not sure if all such patients should be closely monitored. You note that the patient now has a normal platelet count and renal function and wonder if there are any simple parameters to predict the risk of HUS, which may take up to 2 weeks to develop.

You talk to the consultant in public health medicine, who kindly directs to you to the national guidelines by the Health Protection Agency (HPA) on the management of E coli O157:H7 infections.1 Unfortunately, the guidelines do not answer your question. Your consultant has come across anecdotal evidence that leukocytosis may be a predictor for HUS in such children.

You decide to do a literature search and critically appraise the evidence.

Structured clinical question

In a child with Escherichia coli O157:H7 infection [patient], does a high white blood cell count [risk factor] predict progression to haemolytic uraemic syndrome [outcome]?

Search strategy

Secondary sources

Cochrane library, Best Evidence, Clinical Evidence

No relevant articles were found

Primary sources

MEDLINE (1966 to date) and OLDMEDLINE (1950–1965) searched by the PubMed interface on 29/10/2006.

Search terms

“Hemolytic uremic syndrome” AND “Escherichia coli O157” with limits (English, Human, All child: 0–18 years) revealed 267 results.

Addition of the …