Study of Bacterial Distribution on the Skin of Psoriasis by Tape Method

Ryu, Ji Hun; Lee, Jeung; Son, Sook Ja; Won, Young Ho; Oh, Jong Seok

Abstract

BACKGROUND
Psoriasis is one of the relatively common chronic relapsing cutaneous disorders. The etiology and pathogenesis of the psoriatic skin lesion are still unknown. A colonization of microbacterial organisms especially Staphylococcus aureus (S. aureus) have been considered as a factor for development and exacerbation of psoriatic skin lesion. OBJECTIVES: The purpose of this study was to observe the bacteria on the skin of the patients with psoriasis and healthy normal persons, and evaluate the relations between bacterial density, S. aureus colonization, and severity of psoriatic skin lesions. MATERIALS & METHODS: Twenty two psoriasis patients and 25 healthy normal persons were involved for this study. Psoriasis patients were classified according to a severity estimated by PASI (Psoriasis Area and Severity Index) and activity of psoriatic skin lesions. Microbial sampling by tape method (3M, 5x5 cm) were performed on the psoriatic skin lesion and uninvolved skin in the patients of psoriasis, and on the inner forearm of the normal healthy person. Microbial sampling by a swab were also carried out from nasal mucosa. The tapes were gently contacted on the blood agar plate, and cultured in aerobic condition(30 degrees C) during 2-5 days and the numbers of colony forming unit (CFU) were estimated. RESULTS: The results were as follows; Total numbers of CFU in the lesion and uninvolved skin of psoriasis patients were significantly higher than those of the healthy controls (p<0.05). Total numbers of CFU relatively were correlated with PASI score (p<0.05), but they were not correlated with duration of the disease (p>0.05). The activity of psoriasis was relatively correlated with PASI score and total number of CFU (p<0.05). The number of S. aureus in the psoriatic plaque was not significantly higher than number of uninvolved skin in psoriasis, and number of healthy normal persons (p>0.05). There was a significant correlation between the numbers of S. aureus on the lesional and uninvolved skin and that on the nasal mucosa. (p<0.05). CONCLUSION: This study demonstrates that bacterial density is significantly higher on the psoriatic skin lesions, which suggests that bacterial colonization on the skin has a role in the development and exacerbation of the psoriatic lesion.