Didn't your Dr check your urine??? How strange!
I would also be annoyed but they do take UTI's very seriously in preg as they can bring on early labour. I had a mild attack of one a few weeks ago and the hospital wanted to admit me for a week on IV AB's ( i insisted on going home as my DD had just had surgery and needed her mummy with her). They eventually agreed and allowed me to take oral AB's and within a week it was all gone.

I guess your Dr was playing it safe - but still should have had your urine tested!