hey el!
what happens to the body on TNFs is that it poses the risk of you becoming immunosuppressed. the white blood cell count can deminish (that's why it should be checked periodically).
if indeed a person get immunocompromised and WBCs drop too low, a person can develop oral and vaginal fungal infections (thrush and yeast).
have you had recent blood work?
how are your WBCs?
i've had 2 bouts of thrush while on Enbrel.
so yeah, your body's own bacteria can take over and cause infection if you get immunosuppressed.