Mohammad Ashraf Hossain

Efficacy of FK463, a (1,3)-β-d-Glucan Synthase Inhibitor, in Disseminated Azole-Resistant Candida albicans Infection in Mice

ABSTRACT The efficacy of FK463, a new (1,3)-β-d-glucan synthase inhibitor, against azole-resistant Candida albicans strains has been studied. The MIC of FK463 was lower than those of azoles and amphotericin B againstCDR1-expressing C26 and CaMDR-expressing C40 strains. All mice treated with FK463 (1 mg/kg) survived disseminated murine candidiasis. The fungal burden in the kidney after 6 days was markedly reduced after therapy with FK463 and amphotericin B sodium deoxycholate, and plasma (1,3)-β-d-glucan concentration was found to be lower in FK463-treated mice. In our study, FK463 was found to be a potent antifungal agent against disseminated infection with azole-resistant C. albicans.

Comparison between Wako‐WB003 and Fungitec G tests for detection of (1→3)‐β‐D‐glucan in systemic mycosis

The limulus factor G reacts with (1→3)‐β‐D‐glucan, a major structural component of fungal cell walls. The Fungitec G test is a colorimetric assay that measures the concentration of (1→3)‐β‐D‐glucan and is used as a serodiagnostic test for deep mycosis. Wako‐WB003 is another assay for (1→3)‐β‐D‐glucan that determines the change in turbidity of the gelatin reaction of limulus factor G with (1→3)‐β‐D‐glucan. In five rabbits inoculated intravenously with 1 × 107 CFU of Candida albicans, the concentration of (1→3)‐β‐D‐glucan measured by the fungitec G test increased gradually reaching a peak of 660.9 ± 427.9 pg/ml (mean ± SD) 4 days after inoculation, but to 42.225 ± 41.275 ng/ml on day 6 in the Wako‐WB003 test. In one rabbit challenged intravenously with 5 × 106 CFU of C. albicans, (1→3)‐β‐D‐glucan increased to 101.5 pg/ml on day 4 on the fungitec G test, whereas the level remained below the detection limit of the Wako‐WB003 test throughout the course of the disease. We also detected high concentrations of (1→3)‐β‐D‐glucan in 11 patients with candidemia, 4 with suspected candidemia, 1 with invasive pulmonary aspergillosis, and 12 patients with aspergilloma. The concentration of (1→3)‐β‐D‐glucan measured by the Fungitec G test was > 150, > 1006.8, 312.1, and 55.6 ± 37.4 pg/ml (range, 20.1–138.0 pg/ml), and by the Wako‐WB003 test > 153.000, > 17.70, 153.000 and 2.645 ± 7.248 ng/ml (range, < 25.20 ng/ml) in these patients, respectively. In contrast, the concentration of (1→3)‐β‐D‐glucan in 9 patients with pulmonary cryptococcosis and 6 with superficial candida colonization ranged from < 13.2 and < 15.3 pg/ml in the Fungitec G test and < 0.53 and < 0.12 ng/ml in Wako‐WB003 test. There was a weak relationship between the concentration of (1→3)‐β‐D‐glucan measured by the Fungitec G test and Wako‐WB003 test (r = 0.521). Our results indicate that the sensitivity of the Wako‐WB003 test is lower than that of the Fungitec G test. J. Clin. Lab. Anal. 11:73–77.

Heat shock protein 70 (hsp70) as a major target of the antibody response in patients with pulmonary cryptococcosis

Cryptococcus neoformans causes infection in individuals with defective T cell function, such as AIDS, as well as without underlying disease. It has been suggested that humoral as well as cellular immunity might play an important role in the immune response to C. neoformans infection. We have recently shown, using immunoblotting, that the 70‐kD hsp family of C. neoformans was the major target molecule of the humoral response in murine pulmonary cryptococcosis. In this study we also used immunoblotting to define the antibody responses in the sera of 24 patients with pulmonary cryptococcosis: 21 proven and three suspected diagnoses. Anti‐C. neoformans hsp70 antibody was detected in 16 of 24 (66.7%) patients with pulmonary cryptococcosis. Fourteen of 17 (82.3%) patients with high antigen titres (≥ 1:8) and two of seven (28.6%) patients with low titres (≤ 1:4) had detectable levels of anti‐hsp70 antibody. Sera from patients positive for anti‐hsp70 antibody showed high titres in the Eiken latex agglutination test for the detection of serum cryptococcal antigen. Our results indicate that the 70‐kD hsp family from C. neoformans appears to be a major target molecule of the humoral response, not only in murine pulmonary cryptococcosis, but also in human patients with pulmonary cryptococcosis.