In this issue of the Archives, Telfer et al1 examine the role of Streptococcus in psoriasis with specific reference to serologic subtypes. This study fails to show that patients whose psoriasis was triggered or aggravated by streptococci harbored specific subtypes (as has been demonstrated for patients with acute glomerulonephritis and those with acute rheumatic fever), but it again focuses our attention on the important role of this organism in psoriasis, especially acute guttate psoriasis (AGP). In 1964, Whyte and Baughman2 ventured that "the question of what mechanism could be responsible for the production of AGP as a sequel to Streptococcus infection invites speculation." Telfer et al surpass the antiquated speculation on "toxic" vs "allergic" mechanisms to integrate current knowledge on genetic, immunologic, and toxic properties of Streptococcus with modern information on pathogenetic mechanisms of psoriasis.
The M protein, of which more than 80 serotypes have been identified, is important
Baughman RD. Search for Streptococcus. Arch Dermatol. 1992;128(1):103. doi:10.1001/archderm.1992.01680110113019