Moonbeam, humidity, I'm sure you know, will encourage the spores to grow even more.
There are A/C maintenance companies that will flush out ducts if you have a central air conditioning system.
Also, I used to see a product at the Family Food Center in the cleaning section (where they have Harpic, Windex, etc) made by a German company I believe. The packaging isn't attractive but they have products that clean grout and other things.