Yes because diarrhea is caused by an infection as well and it could be caused by the same issue. Also you can sometimes get diarrhea from nervousness or from eating the wrong foods.
Diarrhea and urinary infection are two very unrelated conditions. Diarrhea usually results from problems in the gastrointestinal tract while that of urinary infection arises from problems in the urinary system.
the better phrase would be that it is common to have UTI with diarrhea. UTI is commonly caused by the E. Coli bacteria, a normal flora of the large intestine.
