One of the most frequent forms of infection caused by fungi is a disease called candidiasis, also known as thrush or yeast infection. It is caused by a fungus of Candida species, in most of the cases Candida albicans. The genus has over 81 species, from which 7 are implicated in human pathology.

Candidiasis is an infection that has various and different kind of manifestations, with various localizations and degrees of severity, from mild to possibly life threatening. In most of the cases, candidiasis appears simply as a result of disequilibrium of the normal flora and the infection can be easily treated, without leading to any complications and without being a symptom of a more severe disease. The infections can appear and develop in different regions of the body, such as the oral , perioral or esophageal region, coetaneous region, genital region, pulmonary region. Nevertheless, in some few cases the infection can be so severe and the organism so immunosupressed that candidiasis can become generalized.

Normally, fungi of the Candida genus are part of the flora of different region of the body, such as the gastro-intestinal system or the vagina and their presence isn't considerated a pathological condition. In this situation, they don't produce an infection or have any manifestations. The symptoms appear when, in certain conditions, the fungi overgrowth, producing pseudomycelliums both in cultures and pathological products and at tissue's level.

The conditions that lead to development of candida's filaments are caused by a wide range of factors:

1. Internal factors, dependent on the organism: extreme ages (children or elderly) have a lower immunity level and sometimes aren't able to control the growth of the fungi. Pregnancy (starting with the 4th month) and endocrine disorders can lead to disturbances in the level of hormones, especially sexual hormones, creating a favorable environment for fungal growth. Malignant tumors located especially at the level of the digestive system (e.g. colon cancer) but also in other regions of the body can have candidiasis as their first symptom, because they also lower the immunity. HIV infection and AIDS cause recurrent generalized infections, usually hard to treat and possibly life threatening.
2. External factors: lesions of various causes located at the level of the tegument favor the entrance of the fungi inside the body. Incorrect antibiotic treatment is maybe one of the most important causes of candidiasis, because antibiotics are created to kill “bad” bacteria that cause different diseases, but during their action they can also kill “good” bacteria, which can be normally found in different regions of the body and have an important role in keeping under control the development of the local flora. This is why an antibiotic treatment should be administrated only if the doctor recommends it and in certain cases should be accompanied by antifungal medication. Candidiasis also appears in patients undergoing chimiotherapy or immunosupresive treatment after transplants, in patients with diabetes mellitus or in women using contraceptive drugs (especially those with a high concentration of estrogenic hormones). During various surgical interventions, if the asepsis conditions are not rigorous, Candida can enter the blood stream, leading to the development of the disease.

Pathogenic Candida species (such as Candida albicans) adhere to epithelial and mucous layers of the tissues because they have affinity for the components of the cellular wall, colonize the area and then multiply, appearing as psudofilaments. In some cases they can later pass through the cellular wall, invade the capillaries , causing fungal septicemia.

Locally, the fungus determines the appearance of white patches, associated with symptoms like itching, burning or soreness. When the infection is localized at genital level, the patient can present irritation of the vagina and/or vulva, redness and a white or white-grey discharge, in great amount. Although candidiasis is not a sexually transmitted disease, it can become manifest in men after intercourse with an infected woman. The symptoms of the infection are red patchy sores near the head of the penis and a white discharge, often in the morning.

The first step in the diagnosis is the microscopic examination of the pathological assay. Hyphae and yeast cells are observed during examination, indicating the presence of a fungus, but the identification of the species can be made only after the second step, the culturing method. For identification is used a special medium, called the Sabourd medium, in most of the cases associated with antibiotics. The medium is incubated 24-96 hours, at 28 degrees Celsius, to allow growth of the fungal colonies. Thus, the species implicated in the infection can be identified using the characteristics of the colonies appeared on the medium.

Finally, after identification of the species, the sensibility to different antibiotics is tested.

Another method of diagnosis is the immunological diagnosis, using the candidine intradermoreaction. Although the reaction is positive in most of the adults, it brings important information about the immune response of the organism.

As said before, Candida is a normal component of the oral, intestinal or vaginal flora. Its simple presence shouldn't be considered a disease and treated. When infections with Candida appear and develop, they are treated with antimycotic or antifungal medication, such as clotrimazol, nystatin, fluconazole or ketocanazole. Causes that determine Candida infections, most commonly wrong use of antibiotics, should be avoided and great attention should be given to alimentation.