This article is missing information about list of teleomorph genera e.g. Kluyveromyces ; consider PMID 26526658 & PMID 33028600.(February 2022) |
Candida | |
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Candida albicans at 200× magnification | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Fungi |
Division: | Ascomycota |
Class: | Saccharomycetes |
Order: | Saccharomycetales |
Family: | Saccharomycetaceae |
Genus: | Candida Berkh. (1923) |
Type species | |
Candida vulgaris Berkh. (1923) |
Candida is a genus of yeasts. It is the most common cause of fungal infections worldwide and the largest genus of medically important yeasts. [1] [2]
The genus Candida encompasses about 200 species. [2] Many species are harmless commensals or endosymbionts of hosts including humans. When mucosal barriers are disrupted or the immune system is compromised, however, they can invade and cause disease, known as an opportunistic infection. [3] Candida is located on most mucosal surfaces and mainly the gastrointestinal tract, along with the skin. [3] Candida albicans is one of the most commonly isolated species and can cause infections (candidiasis or thrush) in humans and other animals. In winemaking, some species of Candida can potentially spoil wines. [4]
Many species are found in gut flora, including C. albicans in mammalian hosts, whereas others live as endosymbionts in insects. [5] [6] [7] Systemic infections of the bloodstream and major organs (candidemia or invasive candidiasis), particularly in patients with an impaired immune system (immunocompromised), affect over 90,000 people a year in the US. [8]
The genome of several Candida species has been sequenced. [8]
Antibiotics promote yeast (fungal) infections, including gastrointestinal (GI) Candida overgrowth and penetration of the GI mucosa. [9] While women are more susceptible to genital yeast infections, men can also be infected. Certain factors, such as prolonged antibiotic use, increase the risk for both men and women. People with diabetes or the immunocompromised, such as those infected with HIV, are more susceptible to yeast infections. [10] [11]
Candida antarctica and Candida rugosa are a source of industrially important lipases, while Candida krusei is prominently used to ferment cacao during chocolate production. Lipases from Candida rugosa are also used to digest fats in laboratory assays because of their broad range of activity. [12]
When grown in a laboratory, Candida appears as large, round, white or cream (albicans means "whitish" in Latin) colonies, which emit a yeasty odor on agar plates at room temperature. [13] C. albicans ferments glucose and maltose to acid and gas, sucrose to acid, and does not ferment lactose, which helps to distinguish it from other Candida species. [14]
Recent molecular phylogenetic studies show that the genus Candida, as currently defined, is extremely polyphyletic (encompassing distantly-related species that do not form a natural group). [15] Before the advent of inexpensive molecular methods, yeasts that were isolated from infected patients were often called Candida without clear evidence of relationship to other Candida species. For example, Candida glabrata , Candida guilliermondii , and Candida lusitaniae are clearly misclassified [15] and will be placed in other genera once phylogenetic reorganization is complete (for example, see Khunnamwong et al. 2015). [16]
Some species of Candida use a non-standard genetic code in the translation of their nuclear genes into the amino acid sequences of polypeptides. [17] The difference in the genetic code between species possessing this alternative code is that the codon CUG (normally encoding the amino acid leucine) is translated by the yeast as a different amino acid, serine. The alternative translation of the CUG codon in these species is due to a novel nucleic acid sequence in the serine-tRNA (ser-tRNACAG), which has a guanosine located at position 33, 5' to the anticodon. In all other tRNAs, this position is normally occupied by a pyrimidine (often uridine). This genetic code change is the only such known alteration in cytoplasmic mRNA, in both the prokaryotes, and the eukaryotes, involving the reassignment of a sense codon. [18] This novel genetic code may be a mechanism for more rapid adaptation to the organism's environment, as well as playing an important role in the evolution of the genus Candida by creating genetic barriers that encouraged speciation. [18]
Candida are almost universal in low numbers on healthy adult skin [14] and C. albicans is part of the normal flora of the mucous membranes of the respiratory, gastrointestinal and female genital tracts. The dryness of skin compared to other tissues prevents the growth of the fungus, but damaged skin or skin in intertriginous regions is more amenable to rapid growth. [19]
Overgrowth of several species, including C. albicans, can cause infections ranging from superficial, such as oropharyngeal candidiasis (thrush) or vulvovaginal candidiasis (vaginal candidiasis) and subpreputial candidiasis, which may cause balanitis, to systemic, such as fungemia and invasive candidiasis. Oral candidiasis is common in elderly denture-wearers. [20] In otherwise healthy individuals, these superficial infections can be cured with topical or systemic antifungal medications [21] (commonly over-the-counter antifungal treatments like miconazole or clotrimazole). In debilitated or immunocompromised patients, or if introduced intravenously (into the bloodstream), candidiasis may become a systemic disease producing abscesses, thrombophlebitis, endocarditis, or infections of the eyes or other organs. [8] [14] Typically, relatively severe neutropenia (low neutrophils) is a prerequisite for Candida to pass through the defenses of the skin and cause disease in deeper tissues; in such cases, mechanical disruption of the infected skin sites is typically a factor in the fungal invasion of the deeper tissues. [19] The most common way to treat invasive candida infections is with the use of amphotericin or fluconazole; other methods would include surgery. [22]
C. albicans has been used in combination with carbon nanotubes (CNT) to produce stable electrically conductive bio-nano-composite tissue materials that have been used as temperature-sensing elements. [23]
Among Candida species, C. albicans, which is a normal constituent of the human flora, a commensal of the skin and the gastrointestinal and genitourinary tracts, is responsible for the majority of Candida bloodstream infections (candidemia). [24] Yet, there is an increasing incidence of infections caused by C. glabrata and C. rugosa , which could be because they are frequently less susceptible to the currently used azole-group of antifungals. [25] Other medically important species include C. parapsilosis , C. tropicalis , C. dubliniensis . [8] and the more recently emerging pathogen C. auris . [26]
Other Candida species, such as C. oleophila , have been used as biological control agents in fruit. [27]
Candidiasis is a fungal infection due to any species of the genus Candida. When it affects the mouth, in some countries it is commonly called thrush. Signs and symptoms include white patches on the tongue or other areas of the mouth and throat. Other symptoms may include soreness and problems swallowing. When it affects the vagina, it may be referred to as a yeast infection or thrush. Signs and symptoms include genital itching, burning, and sometimes a white "cottage cheese-like" discharge from the vagina. Yeast infections of the penis are less common and typically present with an itchy rash. Very rarely, yeast infections may become invasive, spreading to other parts of the body. This may result in fevers, among other symptoms.
Candida albicans is an opportunistic pathogenic yeast that is a common member of the human gut flora. It can also survive outside the human body. It is detected in the gastrointestinal tract and mouth in 40–60% of healthy adults. It is usually a commensal organism, but it can become pathogenic in immunocompromised individuals under a variety of conditions. It is one of the few species of the genus Candida that cause the human infection candidiasis, which results from an overgrowth of the fungus. Candidiasis is, for example, often observed in HIV-infected patients. C. albicans is the most common fungal species isolated from biofilms either formed on (permanent) implanted medical devices or on human tissue. C. albicans, C. tropicalis, C. parapsilosis, and C. glabrata are together responsible for 50–90% of all cases of candidiasis in humans. A mortality rate of 40% has been reported for patients with systemic candidiasis due to C. albicans. By one estimate, invasive candidiasis contracted in a hospital causes 2,800 to 11,200 deaths yearly in the US. Nevertheless, these numbers may not truly reflect the true extent of damage this organism causes, given new studies indicating that C. albicans can cross the blood–brain barrier in mice.
Fluconazole is an antifungal medication used for a number of fungal infections. This includes candidiasis, blastomycosis, coccidioidomycosis, cryptococcosis, histoplasmosis, dermatophytosis, and tinea versicolor. It is also used to prevent candidiasis in those who are at high risk such as following organ transplantation, low birth weight babies, and those with low blood neutrophil counts. It is given either by mouth or by injection into a vein.
Oral candidiasis (Acute pseudomembranous candidiasis),which is also known as oral thrush, among other names, is candidiasis that occurs in the mouth. That is, oral candidiasis is a mycosis (yeast/fungal infection) of Candida species on the mucous membranes of the mouth.
Fungal infection, also known as mycosis, is a disease caused by fungi. Different types are traditionally divided according to the part of the body affected; superficial, subcutaneous, and systemic. Superficial fungal infections include common tinea of the skin, such as tinea of the body, groin, hands, feet and beard, and yeast infections such as pityriasis versicolor. Subcutaneous types include eumycetoma and chromoblastomycosis, which generally affect tissues in and beneath the skin. Systemic fungal infections are more serious and include cryptococcosis, histoplasmosis, pneumocystis pneumonia, aspergillosis and mucormycosis. Signs and symptoms range widely. There is usually a rash with superficial infection. Fungal infection within the skin or under the skin may present with a lump and skin changes. Pneumonia-like symptoms or meningitis may occur with a deeper or systemic infection.
Terconazole is an antifungal drug used to treat vaginal yeast infection. It comes as a lotion or a suppository and disrupts the biosynthesis of fats in a yeast cell. It has a relatively broad spectrum compared to azole compounds but not triazole compounds. Testing shows that it is a suitable compound for prophylaxis for those that suffer from chronic vulvovaginal candidiasis.
Fungemia is the presence of fungi or yeast in the blood. The most common type, also known as candidemia, candedemia, or systemic candidiasis, is caused by Candida species. Candidemia is also among the most common bloodstream infections of any kind. Infections by other fungi, including Saccharomyces, Aspergillus and Cryptococcus, are also called fungemia. It is most commonly seen in immunosuppressed or immunocompromised patients with severe neutropenia, cancer patients, or in patients with intravenous catheters. It has been suggested that otherwise immunocompetent patients taking infliximab may also be at a higher risk.
Candida parapsilosis is a fungal species of yeast that has become a significant cause of sepsis and of wound and tissue infections in immunocompromised people. Unlike Candida albicans and Candida tropicalis, C. parapsilosis is not an obligate human pathogen, having been isolated from nonhuman sources such as domestic animals, insects and soil. C. parapsilosis is also a normal human commensal and it is one of the fungi most frequently isolated from human hands. There are several risk factors that can contribute to C. parapsilosis colonization. Immunocompromised individuals and surgical patients, particularly those undergoing surgery of the gastrointestinal tract, are at high risk for infection with C. parapsilosis. There is currently no consensus on the treatment of invasive candidiasis caused by C. parapsilosis, although the therapeutic approach typically includes the removal of foreign bodies such as implanted prostheses and the administration of systemic antifungal therapy. amphotericin B and fluconazole are often used in the treatment of C. parapsilosis infection.
Pichia kudriavzevii is a budding yeast involved in chocolate production. P. kudriavzevii is an emerging fungal nosocomial pathogen primarily found in the immunocompromised and those with hematological malignancies. It has natural resistance to fluconazole, a standard antifungal agent. It is most often found in patients who have had prior fluconazole exposure, sparking debate and conflicting evidence as to whether fluconazole should be used prophylactically. Mortality due to P. kudriavzevii fungemia is much higher than the more common C. albicans. Other Candida species that also fit this profile are C. parapsilosis, C. glabrata, C. tropicalis, C. guillermondii and C. rugosa.
Nakaseomyces glabratus is a species of haploid yeast of the genus Nakaseomyces, previously known as Candida glabrata. Despite the fact that no sexual life cycle has been documented for this species, N. glabratus strains of both mating types are commonly found. N. glabrata is generally a commensal of human mucosal tissues, but in today's era of wider human immunodeficiency from various causes, N. glabratus is often the second or third most common cause of candidiasis as an opportunistic pathogen. Infections caused by N. glabratus can affect the urogenital tract or even cause systemic infections by entrance of the fungal cells in the bloodstream (Candidemia), especially prevalent in immunocompromised patients.
Echinocandins are a class of antifungal drugs that inhibit the synthesis of β-glucan in the fungal cell wall via noncompetitive inhibition of the enzyme 1,3-β glucan synthase. The class has been dubbed the "penicillin of antifungals," along with the related papulacandins, as their mechanism of action resembles that of penicillin in bacteria. β-glucans are carbohydrate polymers that are cross-linked with other fungal cell wall components, the fungal equivalent to bacterial peptidoglycan. Caspofungin, micafungin, and anidulafungin are semisynthetic echinocandin derivatives with limited clinical use due to their solubility, antifungal spectrum, and pharmacokinetic properties.
Pathogenic fungi are fungi that cause disease in humans or other organisms. Although fungi are eukaryotic, many pathogenic fungi are microorganisms. Approximately 300 fungi are known to be pathogenic to humans; their study is called "medical mycology". Fungal infections are estimated to kill more people than either tuberculosis or malaria—about two million people per year.
Vaginal yeast infection, also known as candidal vulvovaginitis and vaginal thrush, is excessive growth of yeast in the vagina that results in irritation. The most common symptom is vaginal itching, which may be severe. Other symptoms include burning with urination, a thick, white vaginal discharge that typically does not smell bad, pain during sex, and redness around the vagina. Symptoms often worsen just before a woman's period.
Mycobiota are a group of all the fungi present in a particular geographic region or habitat type. An analogous term for Mycobiota is funga.
Candida auris is a species of fungus that grows as yeast. It is one of the few species of the genus Candida which cause candidiasis in humans. Often, candidiasis is acquired in hospitals by patients with weakened immune systems. C. auris can cause invasive candidiasis (fungemia) in which the bloodstream, the central nervous system, and internal organs are infected. It has attracted widespread attention because of its multiple drug resistance. Treatment is also complicated because it is easily misidentified as other Candida species.
Invasive candidiasis is an infection (candidiasis) that can be caused by various species of Candida yeast. Unlike Candida infections of the mouth and throat or vagina, invasive candidiasis is a serious, progressive, and potentially fatal infection that can affect the blood (fungemia), heart, brain, eyes, bones, and other parts of the body.
Candida tropicalis is a species of yeast in the genus Candida. It is a common pathogen in neutropenic hosts, in whom it may spread through the bloodstream to peripheral organs. For invasive disease, treatments include amphotericin B, echinocandins, or extended-spectrum triazole antifungals.
Carol Kumamoto is an American microbiologist who is Professor of Molecular Biology & Microbiology at Tufts University. She investigates the filamentous growth of Candida albicans, a fungal pathogen that causes several diseases. She is also interested in how C. albicans interacts with its host during colonisation and invasive diseases. She is a Fellow of the American Association for the Advancement of Science and the American Academy of Microbiology.
Topical antifungaldrugs are used to treat fungal infections on the skin, scalp, nails, vagina or inside the mouth. These medications come as creams, gels, lotions, ointments, powders, shampoos, tinctures and sprays. Most antifungal drugs induce fungal cell death by destroying the cell wall of the fungus. These drugs inhibit the production of ergosterol, which is a fundamental component of the fungal cell membrane and wall.
Candida catenulata is a yeast-form fungus in the phylum Ascomycota. It is distributed globally and commonly found on the skin of humans and animals, in soil, and in dairy products.