Fungal pneumonia refers to an infectious process in the lung which is caused by one or a combination of opportunistic or endemic fungi. Endemic fungal pathogens eg Histoplasma capsulatum, Paracoccidioides brasiliensis, Blastomyces dermatitidis, Coccidioides immitis bring on infection in healthy individuals and in persons with compromised immunity in certain specific geographic locations of the Americas and some other places around the world. In patients with congenital or acquired defects in their immune system defenses, opportunistic fungal organisms (eg Aspergillus species, Mucor species, Cryptococcus neoformans and Candida species are likely to cause pneumonia.
Fungal infection means an infection of lungs by fungi and can be caused by endemic or opportunistic fungi or both.
Certain specific instances of fungal infections that are discernible with pulmonary involvement include:
Although fungal pneumonias are rare, they are quite serious and need prompt diagnosis and treatment. Many a times the clinical symptoms and presentation is identical to atypical or the more common bacterial pneumonias. In such instances, the diagnosis is either accidentally made from samples obtained to identify the suspected bacterial pathogen or not made at all. Other cases symptomatically seem to indicate bacterial or atypical pneumonia but naturally, do not show improvement when treated with antibacterial agents. If such is the case then it is advisable to avoid giving a series of treatment courses with varying antibacterial antibiotics covering the same range of pathogens. Instead, the diagnostic efforts must be stepped up to more aggressive methods (fine needle aspiration, fiberoptic bronchoscopy and at times even thoracoscopic or traditional open lung biopsy) until a conclusive diagnosis is made. In certain cases there are some clinical symptoms or clues that indicate a fungal cause. Minute attention to these indications can result in prompt and fast diagnosis and immediate commencement of required therapy.
Fungi enter the lung when their spores are inhaled but they can also reach the lung through the bloodstream if other body parts are infected. Even the reactivation of a latent infection can cause fungal pneumonia. Once they reach inside the alveoli, fungi penetrate into spaces between cells and also through connecting spores between adjacent alveoli. This invasion sets off a chain reaction and triggers the immune system to send white blood cells to attack the microorganisms (neutrophils) to the lungs. The neutrophils surround and attack the offending organisms but along with this, they release cytokines which result in the immune system getting generally activated. This in turn results in chills, fever and fatigue which are the common symptoms of fungal and bacterial pneumonia. The leaked fluid from the surrounding blood vessels fill the alveoli and lead to impaired and weakened oxygen transportation.
Three types of fungi commonly cause pneumonia are Histoplasma capsulatum, (causes histoplasmosis), Coccidioides immitis, (causes coccidioidomycosis), and Blastomyces dermatitidis, (causes blastomycosis). Most infected people may show only minor symptoms and might not even know that they are infected. Some people may become gravely ill. Fungal infections occur primarily in people with an acute weakened immune system.
Histoplasmosis: Though histoplasmosis occurs worldwide, it is prevalent in river valleys of temperate and tropical climates. In the United States, the fungus is predominant Mississippi and Ohio river valleys and in the river valleys of the East. Studies have revealed that more than 80% of people living in the Mississippi and Ohio river valleys have been exposed to the fungus.
Once the fungus is inhaled, it may cause no symptoms in many people. Most of the people realize that a fungus has infected them only when they carry out a skin test or a chest x-ray that shows a nodule or enlarged lymph nodes. Calcium deposits may be present in these areas. The symptoms like cough, fever, muscle aches, and chest pain may develop. The infection can lead to acute pneumonia, or may cause chronic pneumonia with symptoms that persist for months. The infection rarely spreads to other areas of the body, especially the spleen, bone marrow, liver, and digestive tract. This disseminated form of the disease usually affects the people who have AIDS or other immune system disorders.
In the diagnosis, the fungus is identified in a sputum sample, by performing a blood test, that identifies certain antibodies, or by performing a blood or urine test, that detects the organism. Antifungal drugs are used in the treatment of the disease. They are itraconazole Some Trade Names SPORANOX or amphotericin B.
Coccidioidomycosis: Coccidioidomycosis occurs primarily in semiarid climates, especially the southwestern United States and certain parts of South America and Central America. It is often referred to as valley fever. After inhalation, the fungus may cause no symptoms. In some cases, it may cause either acute or chronic pneumonia. The infection may spread beyond the respiratory system and infect the skin, bones, joints, and tissues covering the brain (meninges). This complication mostly occurs in men, especially Filipinos and blacks. People with AIDS or other immune system disorders are susceptible to this fungal infection.
The diagnosis is carried out by identifying the fungus in a sputum sample or a sample taken from another infected area or by performing a blood test that identifies certain antibodies. Antifungal drug such as fluconazole or aramphotericin B is used in the treatment of the disease.
Blastomycosis: Blastomycosis is prevalent in the southeastern, south central, and midwestern United States and in areas around the Great Lakes. Once the fungus is inhaled, it causes infection primarily in the lungs with no symptoms. Some people have flu-like illness. Symptoms of a chronic lung infection may last for months. There are chances that the disease may spread to other parts of the body, especially the bones, skin, joints, and prostate gland.
Usually, the fungus is identified through proper diagnosis. Samples of the sputum are used to identify the fungus. There is no blood test for this fungus. It is usually treated with antifungal drug, such as itraconazole or amphotericin B, however, many people do not require treatment.
Other Fungal Infections: Includes Infections like cryptococcosis, (caused by Cryptococcus neoformans); aspergillosis, (caused by Aspergillus); and mucormycosis, (caused by fungi of the order Mucorales). The most common fungal infection is Cryptococcosis that may occur in a healthy person, but is usually severe in people with underlying immune system disorders, such as AIDS. Cryptococcosis may spread to the meninges, where it results in a disease called cryptococcal meningitis. Another common and important diseases id Aspergillosis, which causes pulmonary infections in people who have acute leukemia or AIDS, have undergone organ transplantation, or are receiving long-term treatment with corticosteroids. Mucormycosis is a rare fungal infection and occurs mostly in people with severe diabetes or leukemia. These three infections can be treated with antifungal drugs, such as itraconazole, fluconazole, and amphotericin B. However, people who are diagnosed with AIDS or other immune system disorders may develop resistance to the medications and may not recover from these infections.
Natural recovery without any treatment usually occurs, especially in patients with mild infection and is immunocompetent without dissemination. This only happens in endemic mycoses. In acute cases, fungal pneumonia treatment has to be administered.
If in a person with weakened immune system, aspergillosis, mucormycosis, and candidiasis occur, then the factors affecting the patient’s immune status could be reversed. This will assure successful recovery of the patient from the infection. The following ancillary events can be followed to promote recovery from the opportunistic infection:
Antifungal therapy can be initiated in patients if they show the following indications:
It is necessary to conduct surgical debridement or resection of infective tissue in addition to antifungal treatment. Anti-inflammatory agents are recommended for rheumatologic syndromes. Antifungal agents like Amphotericin B, fluconazole or itraconazole are used.
Following indications suggest antifungal therapy:
Amphotericin B, Fluconazole are used to treat cryptococcosis.
The indications are:
Surgical care and other treatments include recurrent pneumonia; repair of bronchopleural fistula; significant hemoptysis; corticosteroids in severe hypoxia and anti-inflammatory agents to treat rheumatologic syndromes. Antifungal drug used is Amphoterin B.
Indications of the disease are as follows:
Aggressive surgical debridement of necrotic tissue is important in mucormycosis, especially if confined to lungs. Swift tapering of immunosuppressive agents and corticosteroids and reversal of neutropenia is recommended.
The indications for antifungal therapy are as follows:
Amphotericin B, Itraconazole, Ketoconazole, Fluconazole are the antifungal drugs recommended.
Indications are as follows:
Amphotericin B, Flucytosine, Fluconazole and Echinocandins are some of the antifungal used to treat this disease.