Detection of circulating galactomannan by Pastorex Aspergillus in experimental invasive aspergillosis

The performance of Pastorex Aspergillus, a new latex agglutination test for the detection of circulating galactomannan in the serum of patients with invasive aspergillosis, was evaluated in a blind trial in standardized guinea-pig models of invasive aspergillosis and other invasive mycoses. In these animal models, the invasive nature of the fungal infection was confirmed by re-isolation of the etiologic agent from the organs of every animal. Ninety-two plasma samples from 42 animals with invasive aspergillosis were submitted to the test. In 41 of these animals, at least one plasma sample was positive with the latex test (sensitivity 97.6%), titers ranging from 1/1 to 1/512. In general, antigen titers increased as a function of time, reaching the highest values shortly before death. Guinea-pigs infected with Penicillium marneffei also yielded positive agglutination reactions but antigen titers were lower (maximal titer 1/8). Plasma samples from animals with invasive candidosis (23), disseminated trichophytosis (11) and cryptococcosis (23) were all negative with the latex test. In 80 guinea-pigs without fungal infection, 3 false positive results (titers 1/1) were observed, which means a specificity of 96.2% in this control group.