The Collaborative International Dictionary of English v.0.48:

Pathogenic \Path`o*gen"ic\, a. [Gr. pa`qos disease + the root of
   ge`nos birth.] (Med. & Biol.)
   Of or pertaining to pathogeny; producting disease; as, a
   pathogenic organism; a pathogenic bacterium.
   [1913 Webster]

WordNet (r) 3.0 (2006):

pathogenic
    adj 1: able to cause disease; "infective agents"; "pathogenic
           bacteria" [syn: infective, morbific, pathogenic]

Moby Thesaurus II by Grady Ward, 1.0:

21 Moby Thesaurus words for "pathogenic":
   bad, bad for, contaminated, foul, harmful, injurious, insalubrious,
   insanitary, morbific, noisome, noxious, peccant, pestiferous,
   polluted, septic, tainted, unhealthful, unhealthy, unhygienic,
   unsanitary, unwholesome