What is Trichosporonosis?
Trichosporon species are types of yeast-like organisms that belong to the group of yeasts known as basidiomycetes. They are commonly found in warm and tropical climates, in various environments such as soil, water bodies like rivers and lakes, decomposing wood, and even in certain foods like cheese. They are also found living in insects like scarab beetles, and in the feces of birds, pigeons, bats, and cattle. In humans, these organisms can be found in the mouth and digestive system and can temporarily live on the skin, in the respiratory tract, and in the vagina.
The Trichosporon genus was first described in 1865 by Beigel, who discovered that it could cause a harmless infection of the hair shaft. For a long time, due to the lack of simple methods to tell the different species apart in the laboratory, many species of Trichosporon were all grouped together under the name T. beigelii. However, the development of modern molecular technology enabled scientists to discover several variations which belonged to other fungal groups. As a result, the species classification of Trichosporon was updated. Now, more than 50 different subspecies and around 16 different strains capable of causing disease in humans have been identified.
While Trichosporon species have mostly been grown in labs, the fungus is now known to cause infections, particularly in individuals with weakened immune systems. These infections are often opportunistic, meaning they take advantage of the reduced defenses of these individuals to establish an infection.
What Causes Trichosporonosis?
Invasive trichosporonosis is a type of infection that is mostly found in people who have blood disorders or diseases that weaken the immune system. In contrast, skin infections and allergic pneumonia caused by trichosporonosis are more common in people with healthy immune systems.
In 2005, a large study looked back at patients with blood disorders who had experienced invasive trichosporonosis. The research involved data gathered over 20 years and included 287 cases. This study showed that about 75% of the patients had trichosporonosis in their bloodstream, while around 50% had trichosporonosis that had spread throughout their body.
The study also found that there are several factors which increase the risk of having a more severe form of this disease. These include:
* Undergoing chemotherapy
* Having a kind of disease that causes tumors to form
* Having a weakened immune system
* Having low levels of a certain type of white blood cell (neutropenia)
* Having a kidney disease that is in its final stages (end-stage renal disease)
* Having severe burn injuries
* Having cystic fibrosis, which is a disease that affects your lungs and digestive system.
Risk Factors and Frequency for Trichosporonosis
Trichosporon infections, which cause diseases like white piedra, are found across the world but are evenly distributed between tropical and temperate areas. These include regions like South America, Middle East, India, Southeast Asia, Africa, Europe, Japan and parts of southeastern USA.
- White piedra, a kind of Trichosporon infection, is mostly seen in children and young adults, especially females.
- In hospitals, up to 3% of patients can have Trichosporon, whereas in outpatient settings, its presence on skin in those without symptoms can be as high as 12.4%.
- The way Trichosporon is spread is currently unclear, but poor hygiene habits, close contact, long hair, and humid conditions seem to be risk factors. There have been some documented cases of sexual transmission, particularly for pubic white piedra.
- In Houston, Texas, a higher number of black men were reported to have this infection, with 40% of young infected males showing genital symptoms.
An invasive form of Trichosporon infection presents differently, primarily causing problems in patients with blood cell deficiencies or cancers. It’s been reported to be the second most common yeast infection in patients with blood cancers and has a very high mortality rate of 80%, even with antifungal therapy.
- Other groups at increased risk include babies born early or with low birth weight, people with AIDS, patients on steroids, those with an intravascular catheter, or those on dialysis, and people who’ve had heart valve surgery or a liver transplant.
Signs and Symptoms of Trichosporonosis
White piedra is a superficial hair infection that usually doesn’t cause any symptoms. However, patients may notice visible nodules on the hair or experience itching or pain at the site of infection. These nodules are soft, paste-like, and ivory-colored. They can be as small as 0.5 millimeters, but can combine and cover several millimeters of a hair strand. This condition is more common on facial and genital hair compared to hair on the scalp or torso.
A more severe infection caused by the same fungus, known as invasive infection or disseminated trichosporonosis, can lead to serious symptoms that typically don’t improve with broad-spectrum antibiotics. Patients may experience a high fever and symptoms of sepsis, and in severe cases, this can progress to multi-organ failure. The patient might have a fungal bloodstream infection in over 70% of cases. The condition can be fatal, with a mortality rate varying from 30% to 77% in documented cases.
Patients with disseminated trichosporonosis may see red bumps on the skin of the trunk and limbs, and in some cases, these bumps can form blisters. Should the infection affect the central nervous system, symptoms can include:
- Headache
- Nausea
- Vomiting
- Fever
If the lungs are infected, it can present symptoms like difficulty breathing, coughing, and even bloody sputum. Chest x-rays may show diffuse infiltrates with an alveolar pattern, as well as other abnormalities such as reticulonodular infiltrates, lobar infiltrates, and cavitations. If the kidneys are involved, one might experience protein in the urine, blood in the urine, and kidney failure.
In rare cases, this infection can also cause peritonitis (inflammation of the inner wall of the abdomen), pacemaker lead endocarditis (a type of heart infection), and pneumonia. Other rare manifestations include sinusitis in someone with a healthy immune system, bloodstream and urinary tract infections in diabetic patients, and hospital-acquired infections in patients with severe burns.
Testing for Trichosporonosis
White piedra is a condition that is typically diagnosed based on physical signs and then confirmed using various testing methods. This might include looking at a small sample under a microscope, blood tests to check your overall health, or even urine tests.
For more serious cases, doctors will look for a specific type of fungus called Trichosporon. This fungus has some unique characteristics, like being able to produce an enzyme called urease, and it tends to grow in a unique patterning on test plates. It also prefers certain sugars, and it can grow at human body temperature. Finding all of these things can help confirm that Trichosporon is present, meaning that white piedra is the right diagnosis.
Sometimes, the doctor might find Trichosporon in a urine sample, especially if the infection has spread throughout the body. In these serious cases, the doctor might also use something called a latex agglutination test to look for signs of widespread infection.
There are also some newer testing methods that might be used for faster diagnosis. These involve looking at the DNA of the fungus, and can deliver results quicker than traditional methods.
If the infection has spread to certain organs, your doctor might want to use imaging tests to get a better look. This could include X-rays or CT scans for areas like the chest or abdomen, or an ultrasound of the heart if the doctor suspects a condition called endocarditis. If lung involvement is suspected, a procedure called a bronchoscopy might be done to examine the insides of the lungs.
Treatment Options for Trichosporonosis
White Piedra, a condition caused by a fungal infection that leads to small, soft, white nodules on your hair, is usually treated by removing these nodules and the infected hair. Using antifungal creams, like miconazole or ketoconazole, can also help eliminate the fungus. For those who do not wish to cut their hair, a medication called itraconazole can be effective when taken orally. If a person is allergic to these types of medications, sulfur in white petrolatum or selenium sulfide foam are other treatment alternatives.
In more severe cases where the disease has spread throughout the body and the patient’s immune system is weak (neutropenic), a drug called voriconazole has been found to be highly effective. Other options may include itraconazole, fluconazole, or a combination of amphotericin and voriconazole or 5-flucytosine (another type of antifungal medication).
If the infection continues to be resistant, then amphotericin B may be used together with voriconazole or micafungin. There’s one important thing to note: a group of compounds named echinocandins, typically used in treating certain other kinds of fungal infections, are not effective against this particular fungus.
Curing severe cases of the disease often depends on how long the patient’s immune system has been weak (the duration of neutropenia) and the success of any necessary surgical procedures.
What else can Trichosporonosis be?
Trichosporonosis is a condition that can often look like other invasive fungal infections such as invasive candidiasis, aspergillosis, and cryptococcosis. This is particularly true in individuals with weakened immune systems, where Trichosporon infection can happen at the same time as other fungal, bacterial, or viral infections. This makes it difficult to correctly identify the disease based on the symptoms alone, and laboratory testing becomes crucial.
Usually, a blood culture that results positive is used to confirm the diagnosis. A method known as Grocott’s method can be used to tell Trichosporon apart from Candida, another type of fungus. The process involves using periodic acid methenamine silver (PAS), a way of staining cells that makes Trichosporon easily distinguishable. Other stains that have a strong reaction with Trichosporon are colloidal iron and alcian blue.
Other tools for diagnosing trichosporonosis include using patterns from histopathological staining – this involves marking tissues for examination – and electron microscopic findings. The way their hypha (branching filaments on the fungus) and granules appear under electron microscopy is also different. Candida displays similar-looking pseudohyphae with fine granules, whereas Trichosporon shows different sizes and silver granules.
What to expect with Trichosporonosis
Generally speaking, shallow skin infections tend to improve fairly easily. Most people experience little to no symptoms. Although it’s possible for the infection to come back, removing the affected hair usually solves the problem. White piedra, a fungal infection that affects hair, does not increase the risk of getting serious Trichosporon infections.
The outcome of a severe infection largely depends on the patient’s overall health condition and immune system strength. In many documented cases, there has been a high rate of death. The possibility of full recovery from a widely spread infection has been seen in patients who either did not have a low white blood cell count at the time of diagnosis or who quickly recovered their white blood cell count. Death rates of 40% to 60% have been stated in patients with serious, invasive disease.
Patients with a contained infection, like wound infections and skin infections due to T. asahii, have been successfully treated with surgical cleaning and extended antifungal treatments.
Possible Complications When Diagnosed with Trichosporonosis
Some people who have had a transplant have experienced repeated infections of Trichoporonosis, a condition that affects the central nervous system. This may imply that they need long-term treatment. Additionally, there have been cases where T. beigelii, the organism causing this infection, has shown resistance to the common medication Amphotericin B. This could potentially lead to serious and even fatal consequences.
- Repeated Trichoporonosis infections in transplant recipients
- Potential need for long-term treatment
- Resistance to Amphotericin B treatment in some T. beigelii infections
- Potential for serious or fatal outcomes due to drug resistance
