Trichomoniasis is an bacterial std, and you get it through unprotected sex. If she has it, you should also be tested, and treated, and your husband should be as well.
Its hard to find in men, so even if his test is negative, he should be treated.
You can read more about it here -
http://www.medhelp.org/Medical-Dictionary/Terms/1/001331.htm
AJ