Candida is a type of yeast, comprising over 150 species. The Candida species are the most common causes of opportunistic fungal infections in the world, says the Doctor Fungus website. Candida species are part of normal human flora and fauna, although with compromised immunity, antibiotic use or poor nutrition, Candida can cause infection in human skin and mucous membranes. Of all the Candida species, only six are frequently encountered with human infections.
Candida albicans is the most abundant and significant species that causes yeast infections, called candidiasis, in people. According to the journal “Clinical Infectious Diseases,” it is estimated that C. albicans accounts for about 50 percent of all invasive candidiasis episodes. C. albicans, which is sometimes referred to as monilia, is the most common agent behind vaginal candidiasis, oral thrush, intestinal candidiasis, Candida esophagitis and life-threatening systemic candidiasis.
Candida tropicalis is the second most frequently encountered medical pathogen after C. albicans, and it is estimated that is involved in about 15 to 30 percent of blood infections from yeast. According to Mycology Online, C. tropicalis is a main cause of septicemia and disseminated candidiasis, especially in people with lymphoma, leukemia and diabetes. This species is becoming more resistant to common antifungals, such as flucytosine. C. tropicalis is not as aggressive as the albicans species, and is usually found in the gastrointestinal tract and on the surface of the skin. The tropicalis species has a use in industry, as it can be used to produce biodiesel from the olive tree.
According to Doctor Fungus, infections from Candida species such as glabrata have been on the rise, and are now estimated to be involved in about 15 to 30 percent of yeast infections. C. glabrata is a common cause of oral thrush, which is very common in AIDS patients, and involves white, cheese-like lesions on the inside of the cheeks, the gums and the tongue. C. glabrata infections have a higher mortality rate than most other yeast species.
Candida parapsilosis is a species also on the rise, now estimated to be involved in 15 to 30 percent of Candida infections. The increase in C. parapsilosis is causing concern in hospitals, especially in Europe, because it has been involved in a growing number of fungemia and tissue infections in immune-weakened people and it displays a high natural resistance to antimicrobial drugs. C. parapsilosis may cause fungal infections of the nail beds and systemic disease, especially endocarditis, as noted by Mycology Online.
Candida krusei is a fairly rare species, only accounting for about 1 percent of candidiasis. C. krusei is most often associated with infant diarrhea and occasionally with systemic candidiasis. It is also found in the gastrointestinal, respiratory and urinary tracts of patients with granulocytopenia. Patients receiving fluconazole preventively are at risk of developing infections due to fluconazole-resistant C. krusei strains.
Candida lusitaniae is another rare species, accounting for about 1 percent of Candida infections, but it has been involved in several cases of disseminated candidiasis, including septicemia and pyelonephritis, according to Mycology Online. Many strains of C. lusitaniae are now resistant to Amphotericin-B, a mainline drug to fight against fungal infections. C. lusitaniae is very similar in structure to C. tropicalis.