Fungal pneumonia
Encyclopedia
Fungal pneumonia is an infection
of the lung
s 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, though immunocompetent patients generally respond well to anti-fungal therapy.
s, 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.
s. This technique is significantly faster but can be less sensitive and specific than the classical methods.
A molecular test based on real-time PCR
is also available from Myconostica. Relying on DNA
detection, this is the most sensitive and specific test available for fungi but it is presently limited to detecting only pneumocystis jirovecii and aspergillus. fungi pneumonia also could be spread to one person to another in places such as dorms and can not be detected through a chest x-ray and may need hospital treatment if nessary.
s and sometimes by surgical debridement
.
Infection
An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...
of the lung
Lung
The lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart...
s by fungi
Fungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...
. It can be caused by either endemic
Endemic (epidemiology)
In epidemiology, an infection is said to be endemic in a population when that infection is maintained in the population without the need for external inputs. For example, chickenpox is endemic in the UK, but malaria is not...
or opportunistic
Opportunistic infection
An opportunistic infection is an infection caused by pathogens, particularly opportunistic pathogens—those that take advantage of certain situations—such as bacterial, viral, fungal or protozoan infections that usually do not cause disease in a healthy host, one with a healthy immune system...
fungi or a combination of both. Case mortality in fungal pneumonias can be as high as 90% in immunocompromised
Immunodeficiency
Immunodeficiency is a state in which the immune system's ability to fight infectious disease is compromised or entirely absent. Immunodeficiency may also decrease cancer immunosurveillance. Most cases of immunodeficiency are acquired but some people are born with defects in their immune system,...
patients, though immunocompetent patients generally respond well to anti-fungal therapy.
Cause
Specific instances of fungal infections that can manifest with pulmonary involvement include:- histoplasmosisHistoplasmosisHistoplasmosis is a disease caused by the fungus Histoplasma capsulatum. Symptoms of this infection vary greatly, but the disease primarily affects the lungs...
, which has primary pulmonary lesions and hematogenous dissemination - coccidioidomycosisCoccidioidomycosisCoccidioidomycosis is a fungal disease caused by Coccidioides immitis or C. posadasii. It is endemic in certain parts of Arizona, California, Nevada, New Mexico, Texas, Utah and northwestern Mexico.C...
, which begins with an often self-limited respiratory infection (also called "Valley fever" or "San Joaquin fever") - pulmonary blastomycosisBlastomycosisBlastomycosis is a fungal infection caused by the organism Blastomyces dermatitidis...
- pneumocystis pneumoniaPneumocystis pneumoniaPneumocystis pneumonia or pneumocystosis is a form of pneumonia, caused by the yeast-like fungus Pneumocystis jirovecii...
, which typically occurs in immunocompromised people, especially AIDSAIDSAcquired immune deficiency syndrome or acquired immunodeficiency syndrome is a disease of the human immune system caused by the human immunodeficiency virus... - sporotrichosisSporotrichosisSporotrichosis is a disease caused by the infection of the fungus Sporothrix schenckii. This fungal disease usually affects the skin, although other rare forms can affect the lungs, joints, bones, and even the brain...
- primarily a lymphocutaneous disease, but can involve the lungs as well - cryptococcosisCryptococcosisCryptococcosis, or cryptococcal disease, is a potentially fatal fungal disease. It is caused by one of two species; Cryptococcus neoformans and Cryptococcus gattii. These were all previously thought to be subspecies of C...
- contracted through inhalation of soil contaminated with the yeast, it can manifest as a pulmonary infection and as a disseminated one - aspergillosisAspergillosisAspergillosis is the name given to a wide variety of diseases caused by fungi of the genus Aspergillus. The most common forms are allergic bronchopulmonary aspergillosis, pulmonary aspergilloma and invasive aspergillosis. Most humans inhale Aspergillus spores every day...
, resulting in invasive pulmonary aspergillosis - rarely, candidiasisCandidiasisThrush redirects here. For the hoof infection see Thrush .Candidiasis or thrush is a fungal infection of any of the Candida species , of which Candida albicans is the most common...
has pulmonary manifestations in immunocompromised patients.
Pathophysiology
Fungi typically enter the lung with inhalation of their sporeSpore
In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoa. According to scientist Dr...
s, 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
Fungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...
travel into the spaces between the cells and also between adjacent alveoli through connecting pores. This invasion triggers the immune system
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
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. However, such tests are not only insensitive but take time to develop which is a major drawback because studies have shown that slow diagnosis of fungal pneumonia is linked to high mortality ). Microscopy is another method but is also slow and imprecise. Supplementing these classical methods is the detection of antigenAntigen
An antigen is a foreign molecule that, when introduced into the body, triggers the production of an antibody by the immune system. The immune system will then kill or neutralize the antigen that is recognized as a foreign and potentially harmful invader. These invaders can be molecules such as...
s. This technique is significantly faster but can be less sensitive and specific than the classical methods.
A molecular test based on real-time PCR
Real-time polymerase chain reaction
In molecular biology, real-time polymerase chain reaction, also called quantitative real time polymerase chain reaction or kinetic polymerase chain reaction , is a laboratory technique based on the PCR, which is used to amplify and simultaneously quantify a targeted DNA molecule...
is also available from Myconostica. Relying on DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
detection, this is the most sensitive and specific test available for fungi but it is presently limited to detecting only pneumocystis jirovecii and aspergillus. fungi pneumonia also could be spread to one person to another in places such as dorms and can not be detected through a chest x-ray and may need hospital treatment if nessary.
Treatment
Fungal pneumonia can be treated with antifungal drugAntifungal drug
An antifungal medication is a medication used to treat fungal infections such as athlete's foot, ringworm, candidiasis , serious systemic infections such as cryptococcal meningitis, and others...
s and sometimes by surgical debridement
Debridement
Debridement is the medical removal of a patient's dead, damaged, or infected tissue to improve the healing potential of the remaining healthy tissue...
.