Qom University of Medical Sciences Journal

Psoriasis is a common T-lymphocyte-associated immune disorder characterized by red and thick plaques and silver scales, and is the most common autoimmune disease with a high economic burden due to the long duration of involvement. Recent studies have shown the important role of bacteria in the onset and progression of this disease. Staphylococcus aureus as a gram-positive bacterium, is the most important cause of skin infection and colonizes more than 80% in the nose and skin. Studies have shown a significant relationship between the amount of Staphylococcus aureus colonization in people with psoriasis and healthy people, and the amount of Staphylococcus aureus colonization in the skin lesions of people with psoriasis is more than in people without skin lesions. On the other hand, due to the spread of antibiotic-resistant strains, Methicillin-resistant Staphylococcus aureus (MRSA) strains are the main cause of colonization and infection in acute and chronic soft tissue wounds. Patients infected with MRSA during hospitalization can transmit this organism to others, which can increase the risk of infection. Vancomycin is one of the antibiotics that is widely used in hospitals, especially in treatment of MRSA infection, and currently is the only effective antibiotic against MRSA strains. Drug resistance, side effects of chemical drugs and environmental requirements have gradually increased the tendency to use effective herbal compounds for treatment of skin diseases. This study aims to investigate the antimicrobial effect of Cinnamomum zeylanicum essential oil on MRSA strains isolated from skin lesions of patients with psoriasis.
Methods
In this study, 140 patients with psoriasis referred to Shariati Hospital in Tehran, Iran participated. The inclusion criterion was the definite diagnosis of psoriasis by a dermatologist (clinically or by biopsy). Sampling were mostly done from the head and neck, head of the knees, nails, palms and feet. After collection, the samples were cultured on blood agar medium. After transfer to the laboratory, they were identified and isolated using differential biochemical tests including gram staining, catalase test, tube coagulase test, mannitol fermentation test, and deoxyribonuclease test.
The sensitivity of S. aureus strains to antibiotics was determined using Kirby-Bauer disk diffusion method based on the Clinical and Laboratory Standards Institute instructions. The susceptibility patterns were interpreted by the inhibition zone diameter. Staphylococcus aureus was considered as MRSA when inhibition zone diameter of cefoxitin (30 µg) was ≤21 mm.  To prepare the essential oil, the bark of the Cinnamomum zeylanicum plant was extracted by Clevenger apparatus and the compounds in the essential oil were identified by gas chromatography-mass spectrometry (GC-MS) method. The minimum inhibitory concentration (MIC) of the Cinnamomum zeylanicum essential oil and vancomycin was evaluated by polystyrene 96-well microplates with Mueller Hinton broth. The collected data were analyzed in SPSS v. 21 software using chi-square and t-test. The significance level was set at 0.05.
Results
Of 140 participants, after diagnostic tests, it was found that 61 (43.57%) had infection with Staphylococcus aureus bacteria. After performing the cefoxitin disc sensitivity test, 20 (14.28%) were found to have infection with MRSA, of whom 11 were women and 9 were men, aged 14-59 years. In terms of contamination with MRSA bacteria, the highest contamination was found in the head and neck areas (30%), but the results of statistical tests showed no significant relationship between gender, sampling area, and age in patients infected with MRSA. The highest and lowest antibiotic resistance of the staphylococcus aureus strains were related to penicillin (85.71%) and chloramphenicol (2.85%), respectively. After identifying the MRSA strains, the MIC of Cinnamomum zeylanicum essential oil against them was investigated and compared with the MIC of vancomycin. All MRSA strains were sensitive to Vancomycin and their MIC was less than 2 μg/mL. The MIC of Cinnamomum zeylanicum essential oil against the strains was 0.5-8 μl/mL
Discussion
One of the microbial factors that can be effective in the progression of psoriasis is Staphylococcus aureus. The presence of MRSA strains in patients with skin infections caused by this bacterium in hospitals increases the risk of severe skin infections caused by MRSA in hospitalized patients. Although the use of vancomycin antibiotic is currently the only treatment option for MRSA infection, the inappropriate use of this antibiotic may cause an increase in microbial resistance to it. One of the promising solutions to eliminate drug-resistant microorganisms is the use of effective herbal compounds. In this study, the antibacterial effects of Cinnamomum zeylanicum essential oil against MRSA strains were investigated and confirmed. The effective compounds of this essential oil were tested using the GC-MS method which showed that the most compound was cinnamaldehyde. The molecular mechanism of the antimicrobial effect of cinnamaldehyde is the disruption of the biosynthesis pathways of phosphatidylglycerol and phosphatidylethanolamine, which leads to disturbance in the integrity of the Staphylococcus aureus cell membrane. The study of the compounds of Cinnamomum zeylanicum essential oil showed that this plant had strong antioxidant and anti-inflammatory properties due to the presence of cinnamaldehyde and terpene compounds. Herbal medicines, especially those extracted from the plants whose extracts contain anti-inflammatory, antimicrobial and antioxidant compounds, are useful in the treatment of diseases such as atopic dermatitis and psoriasis. In addition to removing antimicrobial effects, Cinnamomum zeylanicum essential oil can control and treat skin lesions and infections caused by psoriasis due to its anti-inflammatory effects, and it can be used as a part of pharmaceutical formulation in topical ointments and gels. Clinical studies are recommended to confirm the therapeutic effect of Cinnamomum zeylanicum essential oil.
Ethical Considerations
Compliance with ethical guidelines
This study is approved by the ethics committee of Islamic Azad University, Varamin-Pishva Branch (Ethics Code: IR.IAU.VARAMIN.REC.1396.3).
Funding
This article is taken from the thesis of Mrs. Maryam Nilqaz, a master's student in the field of microbiology, which was done at the Faculty of Biological Sciences, Islamic Azad University, Varamin-Pishwa branch, and was done at the personal expense of the first author.
Authors contributions
Writing-review and editing, conceptualization, sources and supervision: Masoumeh Mahdavi-Ourtakand; Writing-main draft, methodology and funding: Maryam Nilghaz; Research: Masoumeh Mahdavi-Ourtakand and Fatemeh Noorbakhsh.
Conflicts of interest
The authors declared no conflict of interest.