Ulcerative colitis cases, possible cause? (1,4)

I believe the answer is:

e coli

I'm a little stuck... Click here to teach me more about this clue!

'possible cause?' is the definition.
The definition suggests a singular noun which matches the answer.

'ulcerative colitis cases' is the wordplay.
'cases' indicates the answer is hidden within the clue.
'E COLI' is hidden in the letters of 'ulcerative colitis'.

Can you help me to learn more?

(Other definitions for e coli that I've seen before include "Bug that causes food poisoning" , "Cause of internal problem" , "Bacterium found in the gut" , "Type of bacteria causing food poisoning" , "cause of ill-feeling" .)

I've seen this clue in The Guardian.

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