Nakaseomyces glabratus | |
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Nakaseomyces glabratus 1600x | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Fungi |
Division: | Ascomycota |
Class: | Saccharomycetes |
Order: | Saccharomycetales |
Family: | Saccharomycetaceae |
Genus: | Nakaseomyces |
Species: | N. glabratus |
Binomial name | |
Nakaseomyces glabratus (H. W. Anderson) Sugita & Takashima (2022) | |
Synonyms | |
Cryptococcus glabratusH.W.Anderson (1917) Contents |
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. [1] N. glabrata is generally a commensal of human mucosal tissues, but in today's era of wider human immunodeficiency from various causes (for example, therapeutic immunomodulation, longer survival with various comorbidities such as diabetes, and HIV infection), N. glabratus is often the second or third most common cause of candidiasis as an opportunistic pathogen. [2] 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. [2]
N. glabratus is of special relevance in nosocomial infections due to its innately high resistance to antifungal agents, specifically the azoles. [2] Besides its innate tolerance to antifungal drugs, other potential virulence factors contribute to N. glabratus pathogenicity. One of them is the expression of a series of adhesins genes. [3] These genes, which in N. glabratus are mostly encoded in the subtelomeric region of the chromosome, have their expression highly activated by environmental cues, so that the organism can adhere to biotic and abiotic surfaces in microbial mats. Adhesin expression is the suspected first mechanism by which N. glabratus forms fungal biofilms, proved to be more resistant to antifungals than the planktonic cells. [4]
N. glabratus genome frequently undergoes rearrangements that are hypothesized to contribute to the improvement of this yeast's fitness towards exposure to stressful conditions, and some authors consider that this property is connected to the virulence potential of this yeast. [5]
Cultures are an effective method for identifying non-albicans vaginal infections. Urinalyses are less accurate in this process. The culture may take several days to grow, but the identification of the yeast species is quick once the yeast is isolated. Skin disease diagnosis is difficult, as cultures collected from swabs and biopsies will test negative for fungus and a special assessment is required. Listed under the 'Rare Diseases' database on the NIH web site[ verification needed ], Torulopsis glabrata, or N. glabratus can also be found on the CDC's web site. [6] Although listed as the second most virulent yeast after Candida albicans , the fungus is becoming more and more resistant to common treatments like fluconazole. N. glabratus resistance to Echinocandin is also increasing, leaving expensive and toxic antifungal treatments available for those infected. [6] Although high mortality rates are listed, assessment of the critical nature of a glabrata infection is a gray area.
N. glabratus ferments and assimilates only glucose and trehalose, opposing to Candida species and this repertoire of sugar utilization is used by several commercially available kits for identification. [7]
A major phenotype and potential virulence factor that N. glabratus possesses is low-level intrinsic resistance to the azole medications, which are the most commonly prescribed antifungal (antimycotic) medications. These medications, including fluconazole and ketoconazole, are "not effective in 15–20% of cases" [2] against N. glabratus. It is still highly vulnerable to polyene medications such as amphotericin B and nystatin, along with variable vulnerability to flucytosine and caspofungin. However, intravenous amphotericin B is a medication of last resort, causing among other side effects, chronic kidney failure. Amphotericin B vaginal suppositories are used as an effective form of treatment in combination with boric acid capsules as they are not absorbed into the bloodstream.
A first-line treatment for vaginal infections may be the use of terconazole 7-day cream. Several courses may be needed. The cure-rate for this treatment is approximately 40%. Recurrences are common, causing chronic infections and spread to other areas such as skin and scalp. Blood infections might be best assessed per symptoms if other areas are involved.
An experimental, but effective second-line treatment for chronic infections, is the use of boric acid. Compounding pharmacies can create boric acid vaginal suppositories. Use of Vitamin E oil may be used in conjunction to combat irritation. Amphotericin B vaginal suppositories have also been used in case studies to treat chronic infections, both symptomatic and asymptomatic. Borax and boric acid may be used for persistent scalp and skin infections.
N. glabratus is more closely related to Saccharomyces cerevisiae than to Candida species. In fact, N. glabratus belongs to the group of Nakaseomyces inside the whole genome duplication clade within Saccharomycetaceae. [8] The whole genome duplication event occurred about 90 million years ago, whereas phylogenetic studies indicate that the common ancestor between N. glabratus and C. albicans is dated between 200 and 300 million years ago. The largest phylogenetic study to date about Saccharomycotina, also known as budding yeasts, indicated in 2018 that the (currently construed) genus Candida is found in Pichiaceae, CUG-Ser1 clade, Phaffomycetaceae and Saccharomycetaceae. Consequently, despite that the name Candida evokes a unitary notion of candidiasis, the pathogenic power of some budding yeasts is a paraphyletic trait shared by several subphyla with different kinds of metabolism. [9]
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.
Cryptococcus neoformans is an encapsulated yeast belonging to the class Tremellomycetes and an obligate aerobe that can live in both plants and animals. Its teleomorph is a filamentous fungus, formerly referred to Filobasidiella neoformans. In its yeast state, it is often found in bird excrement. Cryptococcus neoformans can cause disease in apparently immunocompetent, as well as immunocompromised, hosts.
An antifungal medication, also known as an antimycotic medication, is a pharmaceutical fungicide or fungistatic used to treat and prevent mycosis such as athlete's foot, ringworm, candidiasis (thrush), serious systemic infections such as cryptococcal meningitis, and others. Such drugs are usually obtained by a doctor's prescription, but a few are available over the counter (OTC). The evolution of antifungal resistance is a growing threat to health globally.
Candida is a genus of yeasts. It is the most common cause of fungal infections worldwide and the largest genus of medically important yeasts.
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), 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.
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.
Clavispora lusitaniae, formerly also known by the anamorph name Candida lusitaniae, is a species of yeast in the genus Candida or Clavispora. The species name is a teleomorph name.
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 termed 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.
Clotrimazole, sold under the brand name Lotrimin, among others, is an antifungal medication. It is used to treat vaginal yeast infections, oral thrush, diaper rash, tinea versicolor, and types of ringworm including athlete's foot and jock itch. It can be taken by mouth or applied as a cream to the skin or in the vagina.
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.
A blastoconidium is an asexual holoblastic conidia formed through the blowing out or budding process of a yeast cell, which is a type of asexual reproduction that results in a bud arising from a parent cell. The production of a blastoconidium can occur along a true hyphae, pseudohyphae, or a singular yeast cell. The word "conidia" comes from the Greek word konis and eidos, konis meaning dust and eidos meaning like. The term "bud" comes from the Greek word blastos, which means bud. Yeasts such as Candida albicans and Cryptococcus neoformans produce these budded cells known as blastoconidia.
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.
In biology, a pathogen, in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ.
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.
Candida haemulonii is a yeast fungal pathogen that is known to cause infections in humans. C. haemulonii is an emerging opportunistic pathogen that is found in hospitals and healthcare settings. Infections are difficult to treat because the fungus has resistance to antifungal agents. Since its emergence, little research has been conducted on this fungus. However, in recent years, research has been conducted to help identify the various properties of C. haemulonii.
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