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:
- Histoplasmosis which has hematogenous dissemination and primary pulmonary lesions
- Coccidioidomycosis which starts as a self limited respiratory infection (also known as "San Joaquin fever" or "Valley fever")
- Pulmonary blastomycosis
- Sporotrichosis – basically a lymphocutanaeous disease which can affect the lungs as well
- Cryptococcosis – it is contracted by the inhalation of soil contaminated with yeast and can show up as a pulmonary or dessiminated infection.
- Aspergillosis, which results in invasive pulmonary aspergillosis
- In rare cases, candidiasis shows pulmonary manifestations in patients with compromised immunity and resistance.
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.
Fungal Pneumonia Causes
Fungal Pneumonia Symptoms
Fungal Pneumonia Diagnosis and Treatment