Pseudallescheriasis - Causes, Clinical Features, and Treatment

Introduction

Pseudallescheria is a prevalent filamentous fungus that causes human infection. It is isolated from soil, sewage, contaminated water, and animal dung. It is a new opportunistic pathogen (usually present in the normal flora of the human body but causes infection in weak immune patients) that can infect humans with several different illnesses. Scedosporium apiospermum and Graphium eumorphum are the parents of Pseudallescheria boydii.

The Scedosporium species complex includes Scedosporium apiospermum, Scedosporium boydii (previously pseudallescheria boydii), and Scedosporium aurantiacum, which can cause the disease scedosporiosis also known as pseudallescheriasis in humans. Scedosporiosis refers to all illnesses caused by Scedosporium species. Lungs, bones, joints, and the central nervous system (CNS) are the most prevalent sites of infection. It can also cause endocarditis (inflammation of the heart wall), prostatitis (inflammation of the prostate), keratitis (eye infection), endophthalmitis, skin and soft tissue infections, and sinusitis.

What Is the Cause of Pseudallescheriasis?

1. The disease occurs through traumatic skin injection or inhalation of these fungal organisms into the lungs or paranasal sinuses. Even though this organism is more likely to cause colonization than infection, immunocompromised patients are more often affected than immunocompetent patients. In immunocompromised patients, it causes an invasive pulmonary disease that resembles invasive pulmonary aspergillosis.

2. Local trauma is the most frequent cause of ocular, soft tissue, and osteoarticular infections in previously healthy individuals. In addition, both immunocompromised and healthy people can develop CNS infections. However, immunocompetent (strong immunity) people typically experience subacute to chronic infections, whereas immunocompromised patients frequently experience acute and severe infections.

3. Scedosporium can invade the paranasal sinuses or lungs in patients with cystic fibrosis. In infection, lung cavities contain large numbers of hyphae (fungus balls). It can also cause sinusitis, allergic bronchopulmonary illness (a condition comparable to allergic bronchopulmonary aspergillosis), lung abscess, pleural space infection, and pneumonia, including aspiration pneumonia. Similar to invasive pulmonary aspergillosis, chronic neutropenia, prolonged high-dose corticosteroid medication, or allogeneic bone marrow transplantation are the three risk factors for developing invasive pulmonary scedosporiosis.

4. Patients with acquired immunodeficiency syndrome (AIDS) and those with solid-organ transplants usually experience invasive lung illnesses. In individuals with severe immunosuppression, the pulmonary illness typically presents as fever, cough, pleuritic discomfort (chest discomfort), and frequent hemoptysis (blood in sputum). Nodule formation, cellular infiltrates in the lungs and alveoli, consolidation (hardness), or cavitation may be visible on chest radiography. A patient with an apparent immunocompromised state has been characterized as having an invasive lung illness that can extend to the vertebrae.

What Are the Clinical Features of Pseudallescheriasis?

1. Pseudallescheria boydii can affect various organs and systems in the body. It can cause skin infections, sinusitis, keratitis, lymphadenitis, endophthalmitis, meningoencephalitis (inflammation in the brain and meninges of the brain), brain abscess, endocarditis, pneumonia, lung abscess, pulmonary fungus ball, allergic bronchopulmonary fungal illness, bursitis, and disseminated infections. If left untreated, widespread infections frequently result in death. In addition, near-drowning patients frequently experience cerebral infections as a consequence.

2. Mycetoma and pseudallescheriasis can develop in humans after infection with Pseudallescheria boydii. Scedosporiosis and pseudallescheriasis describe all other diseases brought on by Pseudoallescheria boydii. Both immune impairment and localized disease can occur. The fungus is typically implanted traumatically in soil or water.

3. Immunocompromised patients, including those with AIDS, may develop brain abscesses due to a known or undetected lung lesion. In contrast to many other mycoses, patients with pseudallescheriasis appear to have a disproportionately high prevalence of CNS infection. It can also cause neutrophilic meningitis (a type of brain infection), generally in patients with intravenous drug misuse or HIV infection.

4. The diagnosis was made at autopsy (dead body examination). Meningitis, which was most likely caused by an anesthetic injection following a lumbar puncture, was the first known instance of pseudallescheriasis in a human. Blood vascular invasion and thrombosis are frequent in patients.

What Are the Macroscopic Features of Pseudallescheriasis?

At 25 degrees Celsius, Pseudallescheria boydii colonies expand quickly. It has a wooly to cottony texture. The color appears white from the front before changing to dark gray or smoky brown. It is whitish on the back with zones of brownish-black color.

How to Diagnose Pseudallescheriasis?

Numerous locations are used to diagnose Pseudallescheria boydii, including the respiratory tract, soft tissue, bone, gastric aspirate, maxillary sinus, wound, urine, brain abscess, ear, and tonsils. In cultures, pulmonary colonization is the most prevalent type of pseudallescheriasis of lung patients with pulmonary infections who had either undergone immunosuppressive therapy or had an underlying disorder. P. boydii is rarely cultivated from blood.

The growth of the organism from sputum, bronchoalveolar lavage, draining wounds, or paranasal sinus aspirates is less convincing. The fungus thrives in standard mycological media. After a few days, the mold colony becomes tan and develops sporulating structures dissimilar to Aspergillus. However, sequencing and MALDI-TOF (matrix-assisted laser desorption/ionization time-of-flight) mass spectrometry are widely utilized for mold identification. There are currently no clinically relevant serologic or other fast identification tests.

What Is the Treatment for Pseudallescheriasis?

Developing an effective treatment plan still needs to be solved. The condition will not cure by itself, and surgical débridement is a crucial adjunct in treating pseudallescheriasis of soft tissue, bone, joint, pleural, and paranasal sinuses. Intra-articular injections of Amphotericin B are helpful. The most successful treatments for CNS infections are surgery and intravenous Miconazole.

The use of Itraconazole and Ketoconazole in most patients with localized infections and debridement is helpful with combined treatment using liposomal Amphotericin B medication.

The echinocandins (Anidulafungin, Caspofungin, and Micafungin) and the more recent broad-spectrum azole antifungals (including Voriconazole, Posaconazole, Isavuconazole, Ravuconazole, and Albaconazole) used in vitro. A growing number of patients give a good clinical response to Voriconazole therapy. Therefore, most medical professionals use voriconazole as the first-line treatment for pseudallescheriasis.

Conclusion

Pseudallescheria boydii is a fungus easily isolated from soil and water and can cause pseudallescheriasis. This fungus can also produce a wide variety of clinical symptoms. The symptoms closely resemble those of aspergillosis and other opportunistic fungal diseases. Due to this, the clinician may face challenges in managing pseudallescheriasis. The treatment modality still needs to be clarified. But surgical debridement and antifungal agents provide some sort of treatment to combat the condition.