Introduction: Psoriasis is a lifelong inflammatory disease that involves the skin, joints, cardiovascular system, and CNS. Its outward symptoms include redness, peeling, and itching. One of the important aspects in understanding this disease is to examine the changes in the skin microbiome of psoriasis patients. Staphylococcus aureus usually exists on the skin and mucous membranes of humans, and approximately 10-20% of people carry it without symptoms. S.aureus acts as an opportunistic pathogen and contributes to the inflammatory processes associated with psoriasis by affecting the Th1/Th17 axis. The aim of this study is to investigate the colonization rate of S.aureus on the skin of patients with psoriasis compared to healthy control subjects.
Methods: This cross-sectional study was designed with the aim of investigating the colonization rate of S.aureus bacteria on the skin of patients compared to control subjects. The participants in this study included 21 patients with psoriasis who visited the skin clinic of Tajrish Hospital located in Tehran. 21 healthy individuals who did not have psoriasis and matched the patient group in terms of age and sex. A skin sample was taken from the forearm of a person using a sterile swab from 5 square centimeter and inoculated into liquid BHI culture medium and incubated for 48 hours at 37°C. After DNA extraction by boiling method and with the help of specific primers, PCR reaction was performed to detect the presence or absence of S.aureus. The samples that were positive for the presence of S.aureus were cultured in the special mannitol salt agar culture medium after preparation of serial dilutions. The obtained data were analyzed using SPSS version 26 software.
Results: In microbial cultures, 38% (8 out of 21 patients) of the samples of psoriasis patients led to the growth of S.aureus, while this figure was only 5.9% (2 out of 21 healthy people) in the control group. The Mann-Whitney test showed that the number of S.aureus clones in the skin of patients with psoriasis was significantly higher than that of the control group (p<0.05). This increase in the number of clones was observed especially in the inflamed areas of the patients' skin.
Conclusion: The results showed that patients with psoriasis have significant changes in the frequency of S.aureus compared to the control group. A better understanding of the interactions of S.aureus on the skin microbiome and the immune system may lead to the development of new therapeutic strategies. This study emphasizes the importance of investigating the increase in S.aureus colonization on the skin in order to better understand the pathogenesis of psoriasis and improve the quality of life of patients.