Abstract: Objective To study the relationship between psoriasis and Streptococcus, Mycobacterium,and scale proteins from psoriatic patients(SPPs). Methods The throat swabs of patients with psoriasis vulgaris were cultured. Antibodies against streptococcal antigens,SPPs and crude lipids from M.tuberculosis were detected by ELISA for both psoriatic patients and healthy controls. Results ① Beta-hemolytic streptococci were the most common flora isolated from the throat swabs in the patients with psoriasis vulgaris.② The titres of antibodies against streptococcal antigens increased significantly in all types of psoriasis. The level of IgG antibody was the highest in guttate type of psoriasis while IgM antibody was the highest in plaque type of psoriasis.③ No antibody against crude lipids extracted from M.tuberculosis was detected in all types of psoriasis.④ Patients with psoriasis arthropathica had a significantly higher titre of antibody against SPPs than that in patients with other types of psoriasis and healthy controls. The titres of antibodies against SPPs2 and SPPs14 were 2.8 and 2.0 times higher respectively in the patient group than those in the control group. Conclusions ① The predominant bacterial flora is Streptococcus in the throat swabs from patients with psoriasis vulgaris.② There are different kinds of antibodies against Streptococcus in the patients with different types of psoriasis, which suggests that the immunoreaction to the Streptococcus varies with different types and stages of psoriasis.③ No antibody against crude lipids from M.tuberculosis is detected in all types of psoriasis.④ SPPs2 and SPPs14 may play a role in the pathogenesis of psoriasis arthropathica.

Key words: Psoriasis, Mycobacterium tuberculosis, Streptococcus agalactiae