The two most common isolation sites in humans are respiratory and genital tracts, although isolation from synovial fluid and other anatomical sites have also been reported. Mycoplasma orale can cause infections in leukaemic or immunosuppressed patients. Mycoplasma faucium, Mycoplasma lipophilum and Mycoplasma buccale have been implicated in diseases of the gingival crevices and respiratory tract. Mycoplasmas could also be playing a key role. Montagnier's proposal has met with varying degrees of skepticism.
Mycoplasma infection introduces an uncontrollable variable into the experiment.
Optimal media for culturing these organisms and the antisera for identification are not available commercially.