CHRONIC PLAQUE PSORIASIS: STREPTOCOCCUS PYOGENES THROAT CARRIAGE RATE AND THERAPEUTIC RESPONSE TO ORAL ANTIBIOTICS IN COMPARISON WITH ORAL METHOTREXATE

Objective: To determine the throat carriage rate of Streptococcus pyogenes in patients having chronic plaque psoriasis and the effect of antibiotics as compared with that of oral methotrexate. Design: Quasi-experimental study. Place and Duration of Study: Dermatology Department, Combined Military Hospital, Abbottabad, from January to December 2006. Patients and Methods: Forty patients and 40 age and gender-matched controls were selected. Throat swab for culture of Streptococcus pyogenes was taken from each patient and control. All patients were treated with oral Penicillin V 250 mg, 6 hourly, and oral Rifampicin, 600 mg daily, for 10 days. Pre- and posttherapy 'Psoriasis Area and Severity Index' (PASI) were compared. Thirty of these 40 patients were later given oral methotrexate, 5-10 mg weekly, for 04 weeks and pre- and post-therapy PASI were compared. Chi-square and paired-samples t-test were used for data analysis. Results: Throat swab cultures were positive for Streptococcus pyogenes in 05 (12.5%) patients and none (0%) of the controls (p=0.02). Mean pre- and postantibiotic therapy PASI were 15.92 +/- 05.94 and 15.19 +/- 06.17 respectively (p=0.078). Mean pre- and postmethotrexate PASI were 15.81 +/- 5.55 and 8.79 +/- 4.19 respectively (p <0.01). Conclusion: Throat carriage of Streptococcus pyogenes is common in patients with chronic plaque psoriasis. Short-term antibiotic treatment has no role in routine treatment of chronic plaque psoriasis. However, it would be worthwhile to consider the effects of long-term antibiotics on chronic plaque psoriasis.