Intestinal bacteria (1,4)

I think it could be either:

Which length description are you looking for?:

1,4

e coli

'intestinal bacteria' is the definition.
(I've seen this in another clue)

This is the entire clue.

(Other definitions for e coli that I've seen before include "Some types of this bacterium are toxic" , "Common species of bacterium" , "An infection found in food and water" , "cause of serious complaint" , "cause of ill-feeling" .)

I've seen this clue in The Guardian.

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