Although Streptococcal therapies are thought to have a role in treating certain forms of psoriasis, there is little evidence to demonstrate the efficacy of these treatments, according to a systematic review published in the Cochrane Database of Systematic Reviews.

Researchers included data from 5 randomized controlled trials that included 162 participants with an acute guttate or chronic plaque psoriasis diagnosis. Studies examined the effect of an antistreptococcal antibiotic or tonsillectomy intervention on disease outcomes compared with either placebo or no intervention. Primary outcome measures included time to resolution, with resolution defined as achievement of clear or almost clear skin, and adverse effects. Additional outcomes included the proportion of patients who achieved clear or almost clear skin (ie, Physician Global Assessment [PGA] 0 or 1 or Psoriasis Area and Severity Index [PASI] 90 or 100), the proportion of patients who achieved a PASI 75 or PGA 1-2, and long-term relapse risk (≥1).

Treatment modalities in the guttate psoriasis trials were as follows:

·         trial 1 (n=43): penicillin (50,000 IU/kg/day in 3 doses vs erythromycin (250 mg 4 times daily) vs no treatment (14 days)

·         trial 2 (n=20) penicillin (1.6 million units intramuscularly once daily) vs no treatment

·         trial 3 (n=20) rifampicin (300 mg twice daily) vs placebo

Treatment modalities in the chronic plaque psoriasis trial were as follows:

·         trial 1 (n=50) long-term azithromycin (500 mg/day) vs vitamin C

·         trial 2 (n=29) tonsillectomy vs no treatment with 24-month follow-up after surgery

In the study that compared penicillin with no treatment, a total of 6 events of clearance were reported in the treatment group vs 3 events in the no treatment group at 6-week follow-up (relative risk [RR], 2.00; 95% CI, 0.68-5.85). There was no difference between the 2 groups in 6-week change in mean PASI. In the study that examined erythromycin treatment, there was also no difference between the treatment groups for mean PASI at 6 weeks. Comparatively, azithromycin was associated with a higher proportion of patients who achieved PASI 75 or PGA 1-2 at 48-week follow-up (60% vs 0%, respectively; RR, 25.06; 95% CI, 1.60-393.59).

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The study examining penicillin vs erythromycin also found no difference between the 2 groups at 6 weeks in mean PASI. Among patients who received a tonsillectomy, 1 patient experienced minor bleeding compared with 0 in the no treatment group (RR, 2.81; 95% CI, 0.12-63.83). A greater proportion of patients who received a tonsillectomy achieved 8-week PASI 90 compared with the no intervention group (7% vs 0%, respectively; RR, 2.81; 95% CI, 0.12-63.83). Tonsillectomy was also associated with a greater proportion of patients who achieved PASI 75 by 8 weeks (20% vs 0%; RR, 6.56; 95% CI, 0.37-116.70).

The authors noted several limitations, including small study populations and the high or unclear risk of bias in the “small number” of trials that were included.

“More evidence on the relationship between flares of chronic plaque psoriasis and infection is needed prior to further interventional trials assessing antistreptococcal intervention in this form of psoriasis,” the authors concluded.

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Reference

Dupire G, Droitcourt C, Hughes C, Le Cleach L. Antistreptococcal interventions for guttate and chronic plaque psoriasis. Cochrane Database Syst Rev. 2019;3:CD011571.