What is the role of streptococcal infection in the etiology of guttate psoriasis?

Updated: Oct 16, 2020
  • Author: Kirstin Altman, MD; Chief Editor: Dirk M Elston, MD  more...
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The association of guttate psoriasis with streptococcal infection has been recognized for more than 50 years. As many as 80% of patients with guttate psoriasis have clinical or laboratory evidence of streptococcal infection, usually in the form of tonsillopharyngitis. [38]

The streptococcal serotypes in these patients are similar to those seen in the general population. Aside from group A streptococci, Lancefield groups C and G streptococci have also been related to guttate psoriasis. [39, 40] Although specific Lancefield groups have been associated with psoriasis, no association with any specific M serotype has been discovered.

A number of cases in children have also been triggered by streptococcal perianal cellulitis. Presumably, absorption of streptococcal by-products occurs across the mucosa, as with pharyngeal infections.

Unfortunately, although the association is definite, details regarding the exact mechanism by which streptococcal infection influences the formation of the psoriatic lesions are still largely theoretical.

Lotus et al demonstrated that guttate psoriasis patients expressing the HLA-Cw*0602 allele were twice as likely to have positive streptococcal throat cultures. [17]

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