Candida causes a wide spectrum of clinical illnesses as follows:
Cutaneous candidiasis: Candidaspecies in immunocompe-tent host can cause infection of any warm and moist part of the body exposed to environment. It causes infection of the nail, rectum, and other skin folds.
Mucocutaneous candidiasis: Mucocutaneous candidiasis(thrush, perianal disease, etc.) is the most common manifesta-tion of candidiasis, but usually does not cause any mortality. In patients with advanced immunodeficiency due to HIV infection, Candida species can cause severe oropharyngeal and esophageal candidiasis that result in poor intake of food, lead-ing to malnutrition, wasting, and early death. These patients are also usually resistant to treatment with antifungal therapy.
Chronic mucocutaneous candidiasis: This is a heteroge-neous group of clinical syndromes. This syndrome is charac-terized by chronic, treatment-resistant, superficial Candida infection of the skin, nails, and oropharynx. However, these patients do not show any evidence of disseminated candidiasis.
Systemic candidiasis: These include endocarditis, gastro-intestinal tract candidiasis, respiratory tract candidiasis, genitourinary candidiasis, and hepatosplenic candidiasis. Systemic candidiasis may be candidemia and disseminated candidiasis. In patients with AIDS, oral thrush and Candidaesophagitis are more common but not candidemia and dis-seminated candidiasis. Candida endophthalmitis and central nervous infection (CNS) infection due to Candida species are other complications of Candida infection.
Disseminated candidiasis: This is increasingly becominga problem in patients with serious hematologic malignan-cies that are treated with immunosuppressive drugs for over a long period of time. Severe neutropenia in these patients is the most important predisposing condition for life-threatening infection caused by Candida. In this condition, Candida usu-ally spreads through the circulation and involves many organs, such as lungs, spleen, kidney, liver, heart, and brain.
However, disseminated candidiasis is not a major prob-lem in patients with AIDS. In such patients, serious infection of the oropharynx and the upper gastrointestinal tract is the major problem. The development of these conditions in pre- viously healthy individuals not receiving broad-spectrum anti- biotic therapy should be strongly suspected for possibility of infection with HIV.
Candida species is distributed worldwide. In recent times, Candida species have replaced Cryptococcus species as the most common fungi affecting the CNS of immunocompromised patients worldwide. C. albicans and Candida glabrata are responsible for causing infection in 70–80% of patients with invasive candidiasis. Candida tropicalis is an important cause of candidemia in patientswith leukemia and in those who have undergone bone marrow transplantation. Candida parapsilosis is an important pathogen associated with the use of vascular catheters.
Since Candida is present as a part of normal flora already in the skin and mucous membrane of the host, it causes infection in the infected host; it is therefore not transmitted.