Effects of antifungal interventions on the outcome of experimental infections with phenotypic switch variants of Cryptococcus neoformans.
In cryptococcal infection, phenotypic switching from a smooth to a mucoid variant can occur in vivo, producing variants with enhanced virulence that are subsequently selected and affect the outcome of infection. Here, we demonstrate that antifungal treatment of the chronically infected host can promote this phenomenon. Amphotericin B treatment reduces fungal burden less effectively in mucoid variant-infected than in smooth variant-infected mice. Consequently, amphotericin B treatment resulted in a more pronounced prolongation of survival in smooth variant-infected than in mucoid variant-infected mice (20 versus 42 days; P < 0.05). Administration of anticapsular monoclonal antibody mediated better protection in smooth variant-infected than in mucoid variant-infected mice, although a protective effect was not consistently observed at all doses. Most interestingly, both antifungal drug therapy and administration of anticapsular monoclonal antibody promoted the selection of mucoid variants in smooth variant-infected mice, a phenomenon manifested by a statistically higher percentage of mucoid colonies in smooth variant-infected mice than in nontreated control mice. This finding suggests that both chemotherapeutic and immunological antifungal interventions may promote the selection of the more virulent mucoid variant, which could affect the outcome of infection in chronically infected hosts.
Fries
Bettina C
BC
Department of Medicine, Albert Einstein College of Medicine, Golding 702, 1300 Morris Park Ave., Bronx, New York 10461, USA. fries@aecom.yu.edu
Cook
Emily
E
Wang
Xiabo
X
Casadevall
Arturo
A
D000666:Amphotericin B / Q000008:administration & dosage / Q000627:therapeutic use*; D000818:Animals; D000908:Antibodies, Fungal / Q000008:administration & dosage / Q000627:therapeutic use; D000935:Antifungal Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D002908:Chronic Disease; D003453:Cryptococcosis / Q000188:drug therapy* / Q000276:immunology / Q000382:microbiology; D003455:Cryptococcus neoformans / Q000145:classification* / Q000187:drug effects / Q000276:immunology / Q000472:pathogenicity*; D006801:Humans; D008172:Lung Diseases, Fungal / Q000188:drug therapy* / Q000276:immunology / Q000382:microbiology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008826:Microbial Sensitivity Tests; D010641:Phenotype; D016896:Treatment Outcome; D014774:Virulence
D000908:Antibodies, Fungal; D000935:Antifungal Agents; D000666:Amphotericin B