Does the Bordetella pertussis inhibit adenylyl cyclase?

Hi, I'm currently revising for my USMLE Step 1, and in Lippincott's Illustrated Biochemistry, it says the pertussis toxin does inhibit, but Clinical Microbiology MRS says the opposite and so does First Aid. I thought Lippincott's was reliable, they even draw attention to the pertussis toxin inhibiting adenylyl cyclase statement with some sort of underlining. I'm very confused :(