Pathogenic fungi
Encyclopedia
Pathogenic fungi are fungi that cause disease in humans or other organism
s. The study of pathogenic fungi is referred to as medical mycology. Although fungi are eukaryotic organisms many pathogenic fungi are also microorganism
s.
species are important human pathogens that are best known for causing opportunist infections in immunocompromised hosts (e.g. transplant patients, AIDS sufferers, cancer patients). Infections are difficult to treat and can be very serious: 30-40% of systemic infections result in death. The sequencing of the genome of C. albicans and those of several other medically-relevant Candida species has provided a major impetus for Candida comparative and functional genomic analyses. These studies are aiding the development of sensitive diagnostic strategies and novel antifungal therapies.
The most common pathogenic species are Aspergillus fumigatus
and Aspergillus flavus
. Aspergillus flavus produces aflatoxin
which is both a toxin and a carcinogen and which can potentially contaminate foods such as nuts. Aspergillus fumigatus and Aspergillus clavatus
can cause allergic disease. Some Aspergillus species cause disease on grain crops, especially maize
, and synthesize mycotoxin
s including aflatoxin
. Aspergillosis
is the group of diseases caused by Aspergillus. The symptoms include fever, cough, chest pain or breathlessness. Usually, only patients with weakened immune system
s or with other lung
conditions are susceptible.:)
can cause a severe form of meningitis
and meningo-encephalitis in patients with HIV
infection and AIDS
. The majority of Cryptococcus species live in the soil and do not cause disease in humans. Cryptococcus neoformans
is the major human and animal pathogen. Cryptococcus laurentii and Cryptococcus albidus have been known to occasionally cause moderate-to-severe disease in human patients with compromised immunity. Cryptococcus gattii
is endemic to tropical parts of the continent of Africa and Australia and can cause disease in non-immunocompromised people.
in humans, dogs and cats. The fungus is most prevalent in the Americas, India and southeastern Asia. It is endemic in certain areas of the United States
. Infection is usually due to inhaling contaminated air.
(or Pneumocystis carinii) can cause a form of pneumonia
in people with weakened immune system
s, such as premature children, the elderly, and AIDS
patients.
or "black mold" can cause respiratory damage and severe headaches. It frequently occurs in houses in regions that are chronically damp.
s are being used to study the expression profiling of pathogenic fungi and proteomics
is aiding research in the development of resistance to various antifungal drugs.
Organism
In biology, an organism is any contiguous living system . In at least some form, all organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homoeostasis as a stable whole.An organism may either be unicellular or, as in the case of humans, comprise...
s. The study of pathogenic fungi is referred to as medical mycology. Although fungi are eukaryotic organisms many pathogenic fungi are also microorganism
Microorganism
A microorganism or microbe is a microscopic organism that comprises either a single cell , cell clusters, or no cell at all...
s.
Candida
CandidaCandida (genus)
Candida is a genus of yeasts. Many species are harmless commensals or endosymbionts of animal hosts including humans, but other species, or harmless species in the wrong location, can cause disease. Candida albicans can cause infections in humans and other animals, especially in immunocompromised...
species are important human pathogens that are best known for causing opportunist infections in immunocompromised hosts (e.g. transplant patients, AIDS sufferers, cancer patients). Infections are difficult to treat and can be very serious: 30-40% of systemic infections result in death. The sequencing of the genome of C. albicans and those of several other medically-relevant Candida species has provided a major impetus for Candida comparative and functional genomic analyses. These studies are aiding the development of sensitive diagnostic strategies and novel antifungal therapies.
Aspergillus
Aerosolized Aspergillus spores are found nearly everywhere so we are routinely and almost constantly exposed to them. Such exposure is a normal part of the human condition and generally poses no adverse health effects. Nevertheless, Aspergillus can and does cause disease in three major ways: through the production of mycotoxins; through induction of allergenic responses; and through localized or systemic infections. With the latter two categories, the immune status of the host is pivotal. Allergies and asthma are thought to be caused by an active host immune response against the presence of fungal spores or hyphae. In contrast, with invasive aspergillosis, the immune system has collapsed and little or no defence can be mounted.The most common pathogenic species are Aspergillus fumigatus
Aspergillus fumigatus
Aspergillus fumigatus is a fungus of the genus Aspergillus, and is one of the most common Aspergillus species to cause disease in individuals with an immunodeficiency....
and Aspergillus flavus
Aspergillus flavus
Aspergillus flavus is a fungus. It is a common mold in the environment, and can cause storage problems in stored grains. It can also be a human pathogen, associated with aspergillosis of the lungs and sometimes causing corneal, otomycotic, and nasoorbital infections. Many strains produce...
. Aspergillus flavus produces aflatoxin
Aflatoxin
Aflatoxins are naturally occurring mycotoxins that are produced by many species of Aspergillus, a fungus, the most notable ones being Aspergillus flavus and Aspergillus parasiticus. Aflatoxins are toxic and among the most carcinogenic substances known...
which is both a toxin and a carcinogen and which can potentially contaminate foods such as nuts. Aspergillus fumigatus and Aspergillus clavatus
Aspergillus clavatus
Aspergillus clavatus is a species of Aspergillus with conidia dimensions 3-4.5 x 2.5-4.5 micrometres. It is found in soil and animal manure...
can cause allergic disease. Some Aspergillus species cause disease on grain crops, especially maize
Maize
Maize known in many English-speaking countries as corn or mielie/mealie, is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times. The leafy stalk produces ears which contain seeds called kernels. Though technically a grain, maize kernels are used in cooking as a vegetable...
, and synthesize mycotoxin
Mycotoxin
A mycotoxin is a toxic secondary metabolite produced by organisms of the fungus kingdom, commonly known as molds. The term ‘mycotoxin’ is usually reserved for the toxic chemical products produced by fungi that readily colonize crops...
s including aflatoxin
Aflatoxin
Aflatoxins are naturally occurring mycotoxins that are produced by many species of Aspergillus, a fungus, the most notable ones being Aspergillus flavus and Aspergillus parasiticus. Aflatoxins are toxic and among the most carcinogenic substances known...
. Aspergillosis
Aspergillosis
Aspergillosis 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...
is the group of diseases caused by Aspergillus. The symptoms include fever, cough, chest pain or breathlessness. Usually, only patients with weakened 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...
s or with other 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...
conditions are susceptible.:)
Cryptococcus
Cryptococcus neoformansCryptococcus neoformans
Cryptococcus neoformans is an encapsulated yeast that can live in both plants and animals. Its teleomorph is Filobasidiella neoformans, a filamentous fungus belonging to the class Tremellomycetes. It is often found in pigeon excrement....
can cause a severe form of meningitis
Meningitis
Meningitis is inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. The inflammation may be caused by infection with viruses, bacteria, or other microorganisms, and less commonly by certain drugs...
and meningo-encephalitis in patients with HIV
HIV
Human immunodeficiency virus is a lentivirus that causes acquired immunodeficiency syndrome , a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive...
infection and AIDS
AIDS
Acquired immune deficiency syndrome or acquired immunodeficiency syndrome is a disease of the human immune system caused by the human immunodeficiency virus...
. The majority of Cryptococcus species live in the soil and do not cause disease in humans. Cryptococcus neoformans
Cryptococcus neoformans
Cryptococcus neoformans is an encapsulated yeast that can live in both plants and animals. Its teleomorph is Filobasidiella neoformans, a filamentous fungus belonging to the class Tremellomycetes. It is often found in pigeon excrement....
is the major human and animal pathogen. Cryptococcus laurentii and Cryptococcus albidus have been known to occasionally cause moderate-to-severe disease in human patients with compromised immunity. Cryptococcus gattii
Cryptococcus gattii
Cryptococcus gattii, formerly known as Cryptococcus neoformans var gattii, is an encapsulated yeast found primarily in tropical and subtropical climates...
is endemic to tropical parts of the continent of Africa and Australia and can cause disease in non-immunocompromised people.
Histoplasma
Histoplasma capsulatum can cause histoplasmosisHistoplasmosis
Histoplasmosis is a disease caused by the fungus Histoplasma capsulatum. Symptoms of this infection vary greatly, but the disease primarily affects the lungs...
in humans, dogs and cats. The fungus is most prevalent in the Americas, India and southeastern Asia. It is endemic in certain areas of the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
. Infection is usually due to inhaling contaminated air.
Pneumocystis
Pneumocystis jiroveciiPneumocystis jirovecii
Pneumocystis jirovecii is a yeast-like fungus of the genus Pneumocystis. The causative organism of Pneumocystis pneumonia, it is an important human pathogen, particularly among immunocompromised hosts. Prior to its discovery as a human-specific pathogen, P. jirovecii was known as P...
(or Pneumocystis carinii) can cause a form of pneumonia
Pneumonia
Pneumonia is an inflammatory condition of the lung—especially affecting the microscopic air sacs —associated with fever, chest symptoms, and a lack of air space on a chest X-ray. Pneumonia is typically caused by an infection but there are a number of other causes...
in people with weakened 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...
s, such as premature children, the elderly, and AIDS
AIDS
Acquired immune deficiency syndrome or acquired immunodeficiency syndrome is a disease of the human immune system caused by the human immunodeficiency virus...
patients.
Stachybotrys
Stachybotrys chartarumStachybotrys chartarum
Stachybotrys chartarum, also called Stachybotrys atra, Stachybotrys alternans or Stilbospora chartarum, is a black mold that produces its conidia in slime heads. It is sometimes found in soil and grain, but mostly isolated from cellulose-rich building materials in damp or water-damaged buildings. S...
or "black mold" can cause respiratory damage and severe headaches. It frequently occurs in houses in regions that are chronically damp.
Drug resistance
Treatment with antifungal drugs often results in the appearance of resistant strains of fungi. Various mechanisms leading to resistance have been described. For example, a number of resistant clinical isolates overexpress genes encoding drug efflux pumps. Recent advances in molecular biology have allowed the study of the phenomenon of multi-drug resistance on a genome-wide scale. DNA microarrayDNA microarray
A DNA microarray is a collection of microscopic DNA spots attached to a solid surface. Scientists use DNA microarrays to measure the expression levels of large numbers of genes simultaneously or to genotype multiple regions of a genome...
s are being used to study the expression profiling of pathogenic fungi and proteomics
Proteomics
Proteomics is the large-scale study of proteins, particularly their structures and functions. Proteins are vital parts of living organisms, as they are the main components of the physiological metabolic pathways of cells. The term "proteomics" was first coined in 1997 to make an analogy with...
is aiding research in the development of resistance to various antifungal drugs.