A genus of destructive root-parasitic OOMYCETES in the family Pythiaceae, order Peronosporales, commonly found in cultivated soils all over the world. Differentiation of zoospores takes place in a vesicle.
Life cycle of the pathogen Pythium insidiosum. The upper panel represent its life cycle in nature. The lower panel shows the possible mechanism of infection
This is a generalized life cycle proposed by John J. Ruffolo, Ph.D. (Cushion, MT, 1988) for the various species of Pneumocystis. These fungi are found in the lungs of mammals where they reside without causing overt infection until the host's immune system becomes debilitated. Then, an oftentimes lethal pneumonia can result. Asexual phase: trophic forms replicate by mitosis to . Sexual phase: haploid trophic forms conjugate and produce a zygote or sporocyte (early cyst) . The zygote undergoes meiosis and subsequent mitosis to produce eight haploid nuclei (late phase cyst) . Spores exhibit different shapes (such as, spherical and elongated forms). It is postulated that elongation of the spores precedes release from the spore case. It is believed that the release occurs through a rent in the cell wall. After release, the empty spore case usually collapses, but retains some residual cytoplasm . A trophic stage, where the organisms probably multiply by binary fission is also recognized to exist. The organism causes disease in immunosuppressed individuals.
Paracoccidioides brasiliensis is a dimorphic fungus and the causative agent of the disease paracoccidioidomycosis. The fungus has been affiliated with the family Ajellomycetaceae (division Ascomycota) although a sexual state or teleomorph has not yet been found.
Black piedra is a superficial fungal infection of the hair shaft caused by Piedra hortae, an ascomycetous fungus forming hard black nodules on the shafts of the scalp, beard, moustache and pubic hair.
It is common in Central and South America and South-East Asia.
The Epsilometer test (usually abbreviated Etest) is a laboratory test used by microbiologists to determine whether or not a specific strain of bacterium or fungus is susceptible to the action of a specific antibiotic.
This is most commonly used in the setting of medicine, where a particular organism has been found to infect a patient, and the doctor treating the patient is seeking guidance on what concentration of antibiotic is suitable.
C. albicans is naturally present in the respiratory tract and mouth of most people, and the vagina of most women. The yeast causes no problem in healthy individuals, as its numbers are controlled by naturally occurring microorganisms. If the natural balance between these microorganisms and Candida is perturbed, the virus may multiply, producing a candidiasis such as thrush.
Symptoms of the disease: small white plaques, usually observed on the tongue and in the mouth.
Incubation period: two to five days.
Contagious period: as long as lesions are present.
Transmission: direct contact with oral, dermal or vaginal secretions or excretions from infected individuals. Transmission may also occur from mother to infant during birth.
Treatment of the disease: nystatin and azole, both taken orally.
Geographical distribution of the microorganism: worldwide.
Prevention: disinfection of beds in nurseries, in order to avoid transmission of thrush from one infant to another.
Yeast cell. Computer artwork showing the structure of a yeast cell.
Computer artwork of Penicillum chrysogenum, which has been used industrially to produce penicillin
Malassezia skin fungus. Coloured scanning electron micrograph (SEM) of spore clusters from the fungus Malassezia lipophilis. Malassezia fungi are naturally found on the skin surfaces of many animals, including humans. Some species can cause hypopigmentation on the trunk and other locations in humans.
The new ascosporogenous yeast species Sporopachydermia quercuum has been found to react positively with the diazonium blue B reagent, a feature normally associated exclusively with yeasts of basidiomycetous affinity.
Synnemata form from the aggregation of hyphae resulting in an erect spore bearing complex structures. This shows a simple type.
Caspofungin acetate (Cancidas) is used to treat aspergillosis, a life threatenting fungal infection
Some representative methods of conidium production
in mitosporic fungi
- Neurospora crassa is a filamentous fungus, a bread mold, which in its natural environments can be found growing on dead plant matters predominantly in tropical and subtropical regions.
- Neurospora crassa is one of most important model organisms of our times. Most of its life stages are haploid which significantly simplifies genetic analysis. Research programs dedicated to Neurospora crassa focus on circadian rhythms, genetiss, gene silencing, ecology, evolution, and many other areas.
Pythium is a genus of parasitic oomycete. Most species are plant parasites, but Pythium insidiosum is an important pathogen of animals. Because this group of organisms were once classified as fungi, they are sometimes still treated as such.
Human pythiosis associated with thalassemia hemoglobinopathy syndrome
Microsporum canis (Arthroderma otae)
Microsporum canis var. distortum
Nonseptate hyphae of Mucor pusillus which have occluded a vessel.
H & E stain
Microconidia on long phialides, macroconidia and chlamydospores of
Favus, also termed tinea favosa, is a chronic inflammatory dermatophytic infection usually caused by Trichophyton schoenleinii.Rarely, favus is caused by Trichophyton violaceum,
Trichophyton mentagrophytes var quinckeanum, or Microsporum gypseum.
Favus typically affects scalp hair but also may infect glabrous skin and nails.
2014/5/20">Life cycle of coccidioides
2013/8/6">Aspergillus clavatus images
2012/9/26">Reaction of an ascomycetous yeast with diazonium blue B