Trichosporon beigelii is a species of yeast-like fungus broadly distributed in the natural world, found in soil, water, and decomposing wood. It is also a normal inhabitant of the human body, existing as part of the microbiota on the skin and in the gastrointestinal tract. In healthy individuals, the immune system and resident microbiome keep this organism in check, but changes in a person’s health can allow it to cause infections ranging from minor to systemic.
Associated Infections
Trichosporon beigelii is responsible for two distinct types of infections, categorized as either superficial or invasive. The most common is a superficial condition known as white piedra, which is confined to the hair shaft and does not invade living tissue. It manifests as soft, white to light-brown nodules attached to hairs, most frequently affecting the scalp, beard, and pubic region. The nodules are composed of fungal elements that encase the hair.
A far more serious condition is the invasive infection trichosporonosis, which occurs when the fungus enters the bloodstream and disseminates throughout the body. This systemic disease can affect multiple organs, including the lungs, kidneys, liver, and spleen, leading to the formation of abscesses. The ability of Trichosporon to adhere to medical devices and form biofilms contributes to its capacity to cause these dangerous infections.
Symptoms and Identification
The signs of a Trichosporon beigelii infection differ depending on whether it is superficial or invasive. For white piedra, the primary symptom is the visible presence of small, soft, white or tan nodules clinging to the hair shafts. These nodules can feel gritty and are numerous, but the condition is asymptomatic and does not cause itching or inflammation.
In contrast, the symptoms of invasive trichosporonosis are severe and reflect a systemic illness. Patients develop a persistent fever that does not resolve with standard antibiotic treatment. Another common sign is the appearance of skin lesions, which may present as reddish or purplish papules that can become necrotic. If the infection spreads to the lungs, it can cause respiratory distress and pneumonia-like symptoms.
Medical confirmation is achieved through laboratory analysis. To diagnose white piedra, a sample of the affected hair is examined under a microscope to reveal the fungal structures. For suspected invasive trichosporonosis, blood cultures are drawn to detect the yeast in the bloodstream, and tissue biopsies from affected organs may also be taken for microscopic examination and fungal culture.
Risk Factors for Infection
The risk factors for a Trichosporon beigelii infection vary between its superficial and invasive forms. Invasive trichosporonosis is almost exclusively a disease of immunocompromised individuals. The most significant risk factor is neutropenia, a condition with an abnormally low count of white blood cells, frequently seen in patients with hematologic cancers like leukemia after receiving chemotherapy.
Other major risk factors for invasive disease include:
- Being an organ transplant recipient taking immunosuppressive drugs to prevent rejection.
- The use of long-term corticosteroid therapy, which suppresses the immune system.
- The presence of indwelling medical devices, such as central venous catheters, which provide a route into the bloodstream.
In contrast, white piedra can occur in healthy individuals. The primary risk factors are environmental, as it is most common in tropical and subtropical regions with high heat and humidity. Poor personal hygiene can also contribute to the development of the infection.
Medical Treatment and Management
The approach to treating Trichosporon beigelii infections is determined by the nature of the disease. For white piedra, treatment is straightforward. The most direct method is to shave the hair in the affected area, which physically removes the fungal nodules. Topical antifungal agents, such as medicated shampoos or creams containing azoles, are also applied to eliminate any remaining fungal elements.
Treating invasive trichosporonosis is a more complex medical challenge requiring aggressive therapy with systemic antifungal medications, administered intravenously. The class of drugs known as triazoles, particularly voriconazole, has been found to be effective against Trichosporon species. This medication works by inhibiting an enzyme the fungus needs to build its cell membrane.
A challenge in managing invasive trichosporonosis is the organism’s resistance to certain antifungal drugs like amphotericin B. Therefore, it is important for laboratories to perform antifungal susceptibility testing. This testing helps guide doctors in selecting the most effective medication for the specific strain, improving the chances of a successful outcome.