Bicillin L-A vs Placebo for the Treatment of Chronic, Plaque-Type Psoriasis Unresponsive to Topical Medications

Psoriasis is a chronic, inflammatory skin disorder most commonly manifested by well-demarcated, erythematous and/or scaling plaques on the elbows, knees, scalp, and trunk. Psoriasis is a common disease with overall incidence of 1-3% of the general population. The estimated prevalence varies from 1-2%. There is significant geographical variability with the lowest incidence of the disease around the equator and increasing towards the poles.

Psoriasis is now considered an autoimmune disease mediated by activated T-cells, releasing proinflammatory cytokines, predominately TNF-a and IFN-y. The key role for T-cells in the pathogenesis of psoriasis was supported by reported beneficial effects of specific T cell targeted therapies including cyclosporin A and certain recently marketed immune response modifiers.

While disease pathogenesis is still not completely understood, the factors that may trigger or worsen psoriasis have been systematically studied and well described in the medical literature. Psychological stress, mechanical trauma to the skin, certain medications and Streptococcus strains are the most common disease triggers.

It was first reported in 1916 that the onset of psoriasis is often preceded by throat infections with hemolytic streptococci and the role of M-protein positive beta hemolytic streptococci in triggering guttate psoriasis has been confirmed in subsequent studies. Exacerbation of chronic plaque type psoriasis has been reported in association with tonsillitis in retrospective studies. Moreover, high frequency of remission after tonsillectomy or antibiotic treatment has been documented.