Candida is a genus of yeasts and is currently the most common cause of fungal infections worldwide. Many species are harmless commensals or endosymbionts of hosts including humans; however, when mucosal barriers are disrupted or the immune system is compromised they can invade and cause disease. Candida albicans is currently the most commonly isolated species, and can cause infections (candidiasis or thrush) in humans and other animals. In winemaking, some species of Candida can create potential faults in wines.
The DNA of several Candida species have been sequenced.
Antibiotics promote yeast infections, including gastrointestinal Candida overgrowth, and penetration of the GI mucosa. While women are more susceptible to genital yeast infections, men can in fact get them as well. Certain factors, like prolonged antibiotic use, increase the risk for both men and women. Also, individuals with diabetes or impaired immune systems, such as those with HIV, are more susceptible to yeast infections.
Some practitioners of alternative medicine say that Candida overgrowth can cause many health problems, including fatigue, headache, poor memory and weight gain, but most medical doctors state that there is little evidence to support this and that a yeast problem should not be diagnosed without definite clinical signs of an infection.
Candida antarctica is a source of industrially important lipases.
Grown in the laboratory, Candida appears as large, round, white or cream (albicans is from Latin meaning 'whitish') colonies with a yeasty odor on agar plates at room temperature. C. albicans ferments glucose and maltose to acid and gas, sucrose to acid, and does not ferment lactose, which help to distinguish it from other Candida species.
Candida are almost universal in low numbers on healthy adult skin and albicans is part of the normal flora of the mucous membranes of the respiratory, gastrointestinal, and female genital tracts. In the case of skin, 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 of fungi.
But overgrowth of several species including albicans can cause superficial infections such as oropharyngeal candidiasis (thrush) and vulvovaginal candidiasis (vaginal candidiasis). Oral candidiasis is common in elderly denture wearers. In otherwise healthy individuals, these infections can be cured with topical or systemic antifungal medications  (commonly over-the-counter antifungal treatments like miconazole or clotrimazole). In debilitated or immunocompromised patients, or if introduced intravenously, candidiasis may become a systemic disease producing abscess, thrombophlebitis, endocarditis, or infections of the eyes or other organs. Typically, relatively severe neutropenia is a prerequisite for the 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.
Application in engineering
Candida 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
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). 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 antifungals. Other medically important Candida species include C. parapsilosis, C. tropicalis, and C. dubliniensis.
Many practitioners of alternative medicine use the term Candida to refer to a complex with broad spectrum of symptoms, the majority of which center around gastrointestinal distress, rashes, sore gums and other miscellaneous symptoms. Candida is accorded responsibility for symptoms as specific as hay fever, as vague as "brain fog" and as common as weight gain or flatulence. These symptoms are attributed by some alternative medicine practitioners to the "overgrowth" of intestinal Candida albicans, which they claim leads to the spread of the yeast to other parts of the body via the digestive tract and bloodstream.
Use of the term Candida in alternative medicine to describe this complex is unassociated with its use in clinical medicine to refer to the fungus that causes vaginal yeast infections and thrush. This can be confusing for patients. No studies have proven that having intestinal candidiasis causes any symptoms of illness.
To treat what they refer to as Candida, some alternative medicine practitioners have recommended avoiding antibiotics, birth control pills, and foods that are high in sugar or yeast, ostensibly to "eliminate excess yeast" in the body. However, there is little clinically valid evidence that these "Candida cleanse" treatments treat intestinal candidiasis effectively, or cure any of the symptoms claimed by the proponents of the hypothesis. But, many people apparently suffering from candidiasis claim relief from these methods.
The probiotic Saccharomyces boulardii has been shown to diminish levels of intestinal Candida in mice. This is therefore one of the specific probiotic strains often recommended by alternative medicine practitioners alongside a more general probiotic, for anyone on a "Candida cleanse" or "Candida diet". However, the efficacy of such a diet has not been proved scientifically.
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