The clinical presentation and diagnosis of invasive fungal infections.

The frequency of invasive fungal infections is increasing owing to the increasing numbers and improved survival of immuno-compromised patients. The fungi responsible for these infections are predominantly opportunistic pathogens. The clinical features and diagnosis of the four commonest infections (invasive candidosis and aspergillosis, cryptococcosis and mucormycosis) are discussed. Particular emphasis is given to the identification of risk factors for these infections, which are different for each disease. As these organisms are common contaminants or commensals, definitive diagnosis requires culture from sites that are normally sterile or histological demonstration of tissue invasion. Definitive diagnosis is not always possible, in part owing to the severe nature of patients' underlying illnesses. A high proportion of cases are diagnosed post mortem because of difficulties in establishing a diagnosis. Clinical diagnoses thus need to be made early in the course of these infections, but a high index of suspicion and knowledge of the clinical manifestations are required.