A 27-year-old female who is known to have Crohn's disease
affecting the terminal ileum and caecum presents with a one-week history of
diarrhoea. She complains of passing green watery stools. There is no history
of abdominal pain, passage of blood or mucous. She has no fever and there has
been no loss of weight.
She is on long-term azathioprine for Crohn's disease.
There is no recent travel history and she has not eaten meals that may have
been contaminated. She gives a history of swimming in the local swimming pool,
which is frequented by many schoolchildren.
On examination she does not look unwell and she is not
tachycardic or dehydrated. She is afebrile and on examination of her abdomen
there are no significant findings.
Routine haematology and biochemistry are unremarkable.
Stools are sent of for microscopy, culture and
Which of the following organisms is likely to be detected
in the stools ?
a) E coli O 157