[Genetic diagnosis of aspergillosis]

Abstract

Aspergillosis is an opportunistic infection caused by pathogenic Aspergillus species (spp.) and is a major hazard for immunocompromised patients and even for non-immunocompromised individuals. Clinical diagnosis of aspergillosis, especially invasive pulmonary aspergillosis (IPA) is difficult and is largely presumptive, typically based on spiking fevers not responding to antibiotics in a patient with the risk factors. It is well known that Aspergillus spp. can be only infrequently cultured from clinical specimens, and that the cultural examination is laborious and time-consuming. Moreover, positive culture from bronchoalveolar lavage or sputa is indicative, but not proof of infection. The criterion for diagnosis of pulmonary infection by aspergilli requires repeated isolation of the same species of Aspergillus from respiratory specimens. There have been some successful attempts using serological assays to detect circulating antibodies to Aspergillus spp. in the noninvasive form of the disease, but these are generally negative in an acute phase IPA patient. A currently available serodiagnostic kit, Pastrex Aspergillus is limited in clinical usefulness because of low sensitivity and specificity in spite of being simple and rapid. Contamination of clinical specimens with various saprophytic filamentous fungi other than aspergilli also often give false positive. Diagnostic methods using such molecular biological techniques, as polymerase chain reaction (PCR) have recently been employed to identify DNA from a number of pathogens when diagnostic means are limited. PCR is known as the most sensitive and specific technique by which to detect a specific DNA sequence. In this paper we have reviewed new genetic methods of diagnosing aspergillosis including PCR and in situ hybridization.