Cat losing hair

Question
Hi!
My 16 year old short-haired, spayed female cat has been developing bald spots over the last couple weeks.  She has a large one on her back between her shoulder blades and two smaller spots -- one behind her ear and one on her leg.  The spot on her back feels hot to touch, but maybe that's just how her skin feels with no hair insulating it?  The one behind her ear looks a little crusty.

I took her to the vet and the vet didn't know what to make of it.  She looked at the large spot with a blue light and also took a fungal culture which may take another week or two to come back.  Then she sent us home with antibiotics.

My cat had her senior bloodwork done two months ago and all was well except for a low white blood count which she has shown on many of the previous tests.  Her thyroid was comfortably below 2.0.

I haven't given her the antibiotics yet because if she has a fungal infection, this would make things worse.  I feel like I should wait for those results.  On the other hand, I'm very worried about her and am concerned that if it's a bacterial infection, I shouldn't be waiting to treat her.

Basically what I'd like to know is: how likely is it that her hair loss is caused by a bacterial infection?  Is there anything else I can do/have checked to have a better idea of the actual cause of her problem before just randomly giving her antibiotics?

She doesn't seem to feel well, but I haven't noticed her scratching excessively.  She also seems hungrier than usual. She does not go outside, but she does occasionally tussle with my other cat.  The bald spots do not seem sensitive when I touch them, not can I feel any lumps there.  I've posted pictures of them on Flickr in case that will help:  http://www.flickr.com/photos/34278353@N07/ (Click on the picture to make it bigger.  To make it bigger again, click on "All Sizes" right above the photo.)

The vet we saw was substituting for my regular vet, and she didn't seem to have much experience with this kind of thing, so I'm hoping you don't mind offering an expert second opinion.  Thank you so much!

Answer
The photos don't really indicate a bacterial skin infection.  THat is very rare in cats.  It does resemble a fungal disease and a drug called fluconazole can be prescribed along with a miconazole creme.  I have had success with a few of these fungal cats using a new product called MAlacetic Ultra Conditioner Spray, which contains Ketoconazole.