What is Malassezia?
Malassezia (Psoriasis and Malassezia) is a pseudo-yeast that can be seen as a normal flora in the body, especially in areas such as the chest, back, head and arms where sebaceous glands are abundant. The role of this fungus in causing diseases such as pityriasis versicolor, seborrheic dermatitis, atopic dermatitis and papillomatosis is known.
Malassezia seems to have an initiating role in inducing the immune mechanisms that initiate psoriasis of the scalp; Based on the results of these studies, Malassezia seems to be very important in the pathogenesis of psoriasis. These factors can aggravate psoriasis through the activation of monocytes and T cells by super antigens and the secretion of various toxins.
The different names of Malassezia mushroom species are as follows:
• Dermatis
• equi
• Malassezia Four Four
• globosa
• Obtuse
• pachydermatis
• restricta
• slooffiae
• sympodialis
ovalis (also known as Pityrosporum ovale)
Cause of Malassezia infection
Malassezia species on the skin about 90% of adults live without causing any damage, but the body’s immune system may suppress this yeast and cause Malassezia to multiply and get sick. Usually, inflammatory responses are part of the complications of this disease. If both diseases of malassezia and dermatitis happen to a person; It is possible that yeast-stimulating metabolites are responsible for these diseases (free fatty acids break down from triglycerides).
The underlying factors of Malassezia skin diseases include the following:
• Humidity
• Sweating (for this reason, it is more likely that people in tropical regions will get pityriasis versicolor disease)
• Oily skin (unusual oiliness of the skin): For this reason, it is more likely that the upper parts of the body, face and scalp will suffer from this disease.
Boils and taking oral antibiotic drugs such as tetracycline to treat them
• Lack of immunity in the body (such as HIV infection), corticosteroids or taking some drugs that lead to suppression of the body’s immune system.
These yeasts produce chemical agents that reduce the amount of skin pigments and create white spots on it. Azelaic acid, pitriacitrin and malacein are among these chemical factors. Administration of azelaic acid is a suitable method for treating disorders such as acne and rosacea.
Malassezia may become nocturnal when exposed to UV light. This condition occurs due to another chemical agent called pitrialactone.
Complications of Malassezia fungal infection
Among the skin diseases that can be caused or aggravated by Malassezia include the following:
• Pityriasis versicolor: in most cases, globosa, M. sympodialis and M. furfur are the cause of this disease.
• Steroid acne
• Pimples under the skin: This disorder is caused by the growth of yeast in the inflamed hair follicles.
• Pustulitis in babies: This disease is associated with the appearance of purulent pimples on the skin of young children and is similar to baby acne.
Seborrheic dermatitis, dandruff, scalp psoriasis and facial psoriasis. In most cases, these diseases are caused by two types of restricta and M. globosa
• Suffering from some facial atopic dermatitis: in this disorder, certain IgE antibodies probably fight against Malassezia and a positive prick test of the organs.
• Convergent and reticular papillomas: In some cases, a person may suffer from converging and reticular papillomas. Such a disorder occurs mostly in teenage girls, and pigmented pimples can usually be seen on their chest, back, and neck.
Aggressive pityrosporosis in people with immunodeficiency diseases (rare case)
Tina Aversikalar
It is a type of chronic and superficial fungal infection of the skin that appears as irregular and scaly spots. These defects may be separate or connected to each other. The disease usually affects the upper parts of the trunk, arms and abdomen. Other areas of the body such as armpits, groin, knees, forearms and genitals are rarely involved.
This disease is only important from a cosmetic point of view. Lesions appear as brown scaly spots, especially on the trunk, neck and arms. In tropical areas, more lesions are seen on the face.
In fair skin, the affected areas are darker than healthy skin, first the lesions are light pink and over time they turn into a pale brown color. In dark skin, colorless or lighter lesions are seen. The shape of the lesions is diverse and it depends on the thickness of the skin, severity of the disease, inflammatory reactions of the skin and especially the amount of contact with sunlight. The symptoms of the disease are aggravated in contact with sunlight and humidity.
folliculitis
This disease is observed in the form of follicular papules on the back, arms, neck and rarely on the face, which are often accompanied by itching.
In this condition, due to the presence of predisposing factors and excessive growth of yeast in hair follicles and local blockage, it may play an important role in causing folliculitis. The disease is common in tropical climates. This disease is seen in people using corticosteroids and immunosuppressive drugs and AIDS patients. Several factors such as sweating, age, sex, race, occupation and consumption of cream can be involved in causing the disease.
The typical lesions are papules and small follicular pustules, which are accompanied by itching and their distribution is clear on the upper body, and the absence of comedones differentiates it from acne.
Diagnosis is based on the clinical manifestations of itchy papules and pustules, direct microscopy, culture and histopathology, as well as the effect of antifungal drugs. In most cases, it responds well to local antifungal treatment. In extensive lesions or in cases that do not respond to local treatment, oral ketoconazole, triazole, fluconazole or itraconazole may have variable effects.
Colonization of Malassezia in hair follicles is not abnormal, therefore, the presence of this fungus in the follicle cannot be the reason for the disease unless quantitative studies determine the increase in yeast growth and also the decrease in the density of skin bacteria.
This disease is mostly seen in people who take antibacterial drugs, in this way the bacterial flora of the skin is destroyed and on the other hand, it weakens the immune defense of the body’s cells. Other factors such as heat, sweating, age, sex, race, occupation, consumption of oil or fatty creams, consumption of corticosteroids and disorders of the immune system can also be considered effective in causing this disease.
Seborrheic dermatitis
It is a chronic and recurrent scaly disease in the head, face and trunk. 2 to 5% of people are affected by this disease and its prevalence is higher in men than women.
The high prevalence of seborrhoeic dermatitis in immunocompromised patients makes the relationship between Malassezia and the immune system important. The prevalence of seborrhoeic dermatitis increases in HIV-positive patients, Parkinson’s disease, multiple sclerosis, stroke, and even depressed patients. It is the mildest form of dendrof disease.
Lesions appear on the head, eyebrows, cheeks, ears, shoulder, sternum, armpit and groin. And their color is red with greasy skins and they are mistaken for the condition of keratinization of the skin caused by secondary bacterial infections and otitis externa. The disease appears more in temperate climates during hot seasons and in physical stress, menopause.
Clinical manifestations and distribution of lesions are completely typical and there is no need to perform mycological tests. Topical azoles and corticosteroids are effective in improving the disease, ketoconazole shampoo twice a week for 2 to 4 weeks is effective in treating seborrheic dermatitis and dendrophy. After the treatment, intermittent use of the drug for 1 or 2 weeks prevents the recurrence of the disease. In case of failure to respond to local treatments, oral ketoconazole is used.
Atopic dermatitis
It is a chronic inflammatory skin disease that is associated with high levels of total IgE and specific IgE against allergens and type I reactions with many allergens.
The pathogenic role of Malassezia furfur in atopic dermatitis is determined by the high prevalence of type I skin reaction (40 to 65%) and the presence of IgE against Malassezia furfur in the serum of patients. About 78% of atopic patients have a positive skin test with Malassezia protein extract. Pterosporum oval extract increases interleukin 4 and interleukin 10 production and IgE production in patients with atopic dermatitis. Among the seven species of Malassezia, two species of Malassezia globosa and Malassezia restricta are the most common isolates associated with atopic dermatitis. In a study, many patients with atopic dermatitis were cured by using oral ketoconazole.
Systemic disease
Most cases of systemic infections have been observed in infants and people with immune system disorders who receive intravenous fat emulsions through venous catheters.
This fungus was isolated from the peritoneal fluid of patients with peritonitis who were exposed to peritoneal dialysis for a long time. In this type of disease, the epidermis of the patient’s skin can be considered as a source of infection.
Malassezia phangemia in infants usually manifests as fever, with or without respiratory disorder and bradycardia. Interstitial pneumonia and thrombocytopenia are common clinical findings. Fever, respiratory failure with or without shortness of breath are the most common clinical symptoms of visceral diseases. Poor nutrition and enlarged liver and spleen are unusual symptoms of the disease. There are no signs of infection at the catheter injection site or skin rashes in infants with Malassezia visceral infection.
There are limited reports of Malassezia furfur associated with infected catheters in adults with underlying diseases. All patients have a history of using intravenous catheters and receiving fat supplements. Fever is one of the most persistent clinical symptoms. Heart and respiratory system dysfunction is one of the most obvious pathological changes in the visceral diseases of Malassezia. These symptoms include; Fungal thrombosis near the catheter, endocardial involvement, vascular vasculitis, alveolar inflammation and bronchitis.
In order to diagnose systemic infections, it is possible to search for yeast cells by taking a blood sample from the catheter. Definite diagnosis is confirmed by blood culture taken from the catheter. Amphotrecin B and miconazole are commonly used to treat systemic Malassezia infections.
psoriasis
The role of Malassezia in psoriasis has not yet been clarified, but there have been several reports regarding the relationship between this lipophilic yeast and the spread of psoriasis lesions. There are reasons that psoriasis is basically a skin disease mediated by T cells. There is little information regarding the initial stimulation that leads to abnormal T cell activities. Streptococcal infections can be a trigger for psoriasis and there is a possibility of releasing superantigenic bacterial toxins. Specific lymphocytes of group A streptococci have been found in psoriasis lesions. Also, T cells with different reactions to morphological types of Malassezia yeasts were found in psoriasis lesions, but they were not specific for the disease. The positive effect of topical or oral ketoconazole followed by the reduction of yeasts shows that Malassezia yeasts may be another antigenic stimulus in psoriasis.
Isolation of Malassezia yeasts in psoriasis lesions alone cannot be the reason of its pathogenicity, but their role in the severity and spread of lesions cannot be ignored.
Eliminate Malassezia fungus
Malassezia infections can generally be treated with oral or topical antifungal medications such as ketoconazole shampoo and oral fluconazole. It is also possible to treat seborrheic dermatitis with topical steroids.
If Malassezia causes dandruff, people can also control Malassezia dandruff at home using the following natural remedies:
• Tea tree oil
• Lemon grass oil
• Aloe vera gel
• Omega 3 fatty acids
• Aspirin
• baking soda
• Zinc
• coconut oil