[Fungal and bacterial nail infections].

Fungal and bacterial infections are very common causes of nail deformity. The majority of fungal nail infections are caused by dermatophytes. Dermatophytosis result from a human contamination. A dermatophyte is always a pathogenic agent. Very effective drugs are available to treat dermatophyte nail infections. Yeasts of the genus Candida, notably C. albicans are the second most common cause of nail infection. The infections of nails due to Candida and bacteria are related with Candida sp and bacteria which are common commensals of the gastrointestinal tract, vagina or skin. Except C. albicans which is always a pathogen of skin, the other species of Candida and the bacteria could be a commensal of the skin, a colonizer of a dermatological disease or a true pathogen of nail. It is important to consider these different situations. More rarely, environmental moulds, most often known as saprophytic agents, can affect nails. They do not respond to conventional antifungal drugs. So, their diagnosis do not suffer any error. In order to evaluate properly the patient with possible fungal or bacterial infection of nails and also to choice an accurate therapy, the laboratory confirmation is essential. Clinical diagnosis is not sufficient to distinguish an infection of nails from a dermatological disease (psoriasis, traumatism) and to identify the responsible agent.