Cryptococcosis in Australasia and the treatment of cryptococcal and other fungal infections with liposomal amphotericin B

Abstract

Abstract Cryptococcus neoformans is an important fungal pathogen in both immunocompromised and immunocompetent hosts. The mean annual incidence during 1994–1997 was 6.6 cases per million people per year in Australia, and 2.2 cases per million people per year in New Zealand. C. neoformans var. neoformans caused 85% of 312 episodes (98% of episodes in immunocompromised hosts) and C. neoformans var. gattii caused 15% (44% in immunocompetent hosts). The AIDS-specific incidence declined significantly over the 3 years. Mortality from cryptococcosis remains substantial. In trials involving small numbers of AIDS patients, liposomal amphotericin B (AmBisome) was found to be active against C. neoformans, with mycological response rates of 67–85%; however, maintenance therapy with an oral antifungal agent is required indefinitely. In a randomized study of patients with cryptococcal meningitis, AmBisome (4 mg/kg/day) produced mycological eradication in 73% of patients compared with 38% with conventional amphotericin. AmBisome resulted in significantly earlier sterilization of cerebrospinal fluid than conventional amphotericin (7–14 days versus 21 days) and was less nephrotoxic. The benefit of this reduced toxicity is denied to many patients because of an enormous cost barrier. In a survey of the practices of clinical mycologists in Australia, 11 experts responded to a questionnaire survey regarding the use of available lipid preparations. Their indications for use as initial therapy were mucormycosis (7/10), renal failure (7/10), Fusarium infection (2/10) and aspergillosis (2/10). Cryptococcosis, candidosis and febrile neutropenia were rarely regarded as an indication; failed therapy with conventional amphotericin was an indication to use AmBisome for 8/11 respondents. The majority believed that AmBisome was equivalent to conventional amphotericin, with amphotericin B lipid complex and AmBisome equivalent to each other in terms of efficacy. The main barrier to replacement of conventional amphotericin with lipid preparations was seen as an issue of cost.