Fungal pneumonia

Fungal pneumonia is an infection of the lungs by fungi. It can be caused by either endemic or opportunistic fungi or a combination of both. Case mortality in fungal pneumonias can be as high as 90% in immunocompromised patients, Meersseman W, Lagrou K, Maertens J, Van Wijngaerden E. Invasive aspergillosis in the intensive care unit. "Clin Infect Dis". 2007 Jul 15;45(2):205-16.] , Bulpa P, Dive A, Sibille Y. Invasive pulmonary aspergillosis in patients with chronic obstructive pulmonary disease. "Eur Respir J". 2007 Oct;30(4):782-800.] , though immunocompetent patients generally respond well to anti-fungal therapy.

Pathogens

Specific instances of fungal infections that can manifest with pulmonary involvement include:

*histoplasmosis, which has primary pulmonary lesions and hematogenous dissemination
*coccidioidomycosis, which begins with an often self-limited respiratory infection (also called "Valley fever" or "San Joaquin fever")
*pulmonary blastomycosis
*pneumocystis pneumonia, which typically occurs in immunocompromised people, especially AIDS
*sporotrichosis - primarily a lymphocutaneous disease, but can involve the lungs as well
*cryptococcosis - contracted through inhalation of soil contaminated with the yeast, it can manifest as a pulmonary infection and as a disseminated one
*aspergillosis, resulting in invasive pulmonary aspergillosis
*rarely, candidiasis has pulmonary manifestations in immunocompromised patients.

Pathophysiology

Fungi typically enter the lung with inhalation of their spores, though they can reach the lung through the bloodstream if other parts of the body are infected. Also, fungal pneumonia can be caused by reactivation of a latent infection. Once inside the alveoli, fungi travel into the spaces between the cells and also between adjacent alveoli through connecting pores. This invasion triggers the immune system to respond by sending white blood cells responsible for attacking microorganisms (neutrophils) to the lungs. The neutrophils engulf and kill the offending organisms but also release cytokines which result in a general activation of the immune system. This results in the fever, chills, and fatigue common in bacterial and fungal pneumonia. The neutrophils and fluid leaked from surrounding blood vessels fill the alveoli and result in impaired oxygen transportation.

Diagnosis

Fungal pneumonia can be diagnosed in a number of ways. The simplest and cheapest method is to culture the fungus from a patient's respiratory fluids; such tests are insensitive and are also slow, time being a critical factor in preventing mortality. Studies have shown that slow diagniosis of fungal pneumonia is linked to high mortality(e.g., Morrell M, Fraser VJ, Kollef MH. Delaying the empiric treatment of "candida" bloodstream infection until positive blood culture results are obtained: a potential risk factor for hospital mortality. "Antimicrob Agents Chemother" 2005;49:3640-5.] ). Microscopy is also a slow and impresice method. Supplementing classical methods is the detection of antigens, notably, galactomannan and ß-1-3 D glucan in Aspergillus. , Hope WW, Walsh TJ, Denning DW. Laboratory diagnosis of invasive aspergillosis. "Lancet Infectious Diseases" 2005:9:609-22.] Such methods are faster, but are currently confined to Aspergillus, and can be les sensitive and specific than classical methods. [http://www.myconostica.co.uk/files/myconostica_webinar_presentation_18_sep_2008.pdf Webinar on fungal diagnostics] , D Denning, September 2008.]

A molecular test based on real-time PCR is also available, from Myconostica. this test relies on DNA detection, and as such is the fastest, most sensitive and most specific test available for fungal pneumonia , Philippe Hauser, Lagrou K, Cui X, PerlinD S, Park S, Harrison E, Meerssman W, Hughes M J, Bowyer P, Denning DW, Bille J, Lass-Flor C, Maertens J. Clinical performance of FXG™ : RESP (Asp +) assay for "Aspergillus" spp. and "Pneumocystis jirovecii" on respiratory specimens. Unpublished Data.] This method requires more expertise than methods such as culturing, and is more expensive.

Treatment

Fungal pneumonia can be treated with antifungal drugs and sometimes by surgical debridement.

References

External links

* [http://www.valley-fever.org/ Coccidioidomycosis]

ee also

*Pneumonia