Susceptibility of Candida albicans isolates from the oral cavities of HIV-positive patients to histatin-5

Statement of problem. Oral surfaces, including the denture-fitting surface, may serve as a reservoir for disseminated candidal infections, particularly in immunocompromised hosts such as patients with AIDS. Histatins are a group of small, cationic antifungal peptides present in human saliva. There is limited information on the antifungal activity of peptides against Candida albicans isolates from HIV-positive patients. Purpose. This study investigated the fungicidal effects of histatin-5 against oral isolates of C. albicans from HIV-positive and HIV-negative patients. Material and methods. An isolate of C. albicans from each of 2 HIV-positive patients (both male) and 3 HIV-negative patients (2 male and 1 female) was obtained. American Type Culture Collection 90028 served as a reference strain. All isolates were identified with sugar assimilation tests and the germ tube test. Fungicidal assays were performed on exponential C. albicans cells in the presence or absence of 0.315 to 50 μm of histatin-5. Numerical data were subjected to 1-way analysis of variance and Tukey's multiple range test (P<.05). Results. Histatin-5 (50 μm) killed more than 95% of C. albicans isolates from HIV-negative patients and more than 90% of isolates from the reference strain. The same treatment induced 75.3% and 66.1% loss of viability in C. albicans isolates taken from HIV-positive patients (A1 and A2 cells, respectively). The difference between the fungicidal effects in the HIV-positive and HIV-negative groups was significant. (P<.05). Conclusion. Within the limited population of this study, C. albicans isolates from the oral cavities of HIV-positive patients were less sensitive to histatin-5 than oral isolates from HIV-negative patients.