SummaryCryptococcus neoformans is a facultative intracellular pathogen. The most distinctive feature of C. neoformans is a polysaccharide capsule that enlarges depending on environmental stimuli. The mechanism by which C. neoformans avoids killing during phagocytosis is unknown. We hypothesized that capsule growth conferred resistance to microbicidal molecules produced by the host during infection, particularly during phagocytosis. We observed that capsule enlargement conferred resistance to reactive oxygen species produced by H 2O2 that was not associated with a higher catalase activity, suggesting a new function for the capsule as a scavenger of reactive oxidative intermediates. Soluble capsular polysaccharide protected C. neoformans and Saccharomyces cerevisiae from killing by H2O2. Acapsular mutants had higher susceptibility to free radicals. Capsular polysaccharide acted as an antioxidant in the nitroblue tetrazolium (NBT) reduction coupled to b-nicotinamide adenine dinucleotide (NADH)/phenazine methosulfate (PMS) assay. Capsule enlargement conferred resistance to antimicrobial peptides and the antifungal drug Amphotericin B. Interestingly, the capsule had no effect on susceptibility to azoles and increased susceptibility to fluconazole. Capsule enlargement reduced phagocytosis by environmental predators, although we also noticed that in this system, starvation of C. neoformans cells produced resistance to phagocytosis. Our results suggest that capsular enlargement is a mechanism that enhances C. neoformans survival when ingested by phagocytic cells.

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The antifungal susceptibility profiles of 77 clinical strains of Mucorales species, identified by internal transcribed spacer sequencing, were analyzed. MICs obtained at 24 and 48 h were compared. Amphotericin B was the most active agent against all isolates, except for Cunninghamella and Apophysomyces isolates. Posaconazole also showed good activity for all species but Cunninghamella bertholletiae. Voriconazole had no activity against any of the fungi tested. Terbinafine showed good activity, except for Rhizopus oryzae, Mucor circinelloides, and Rhizomucor variabilis isolates.

In vitro susceptibility profiles of 58 Paecilomyces clinical isolates are reported. Amphotericin B, itraconazole, and echinocandins showed poor activity against Paecilomyces lilacinus, while the new triazoles were active against it. Paecilomyces variotii exhibited a different susceptibility pattern, being susceptible to most antifungal agents apart from voriconazole and ravuconazole.Paecilomyces species are saprophytic filamentous fungi that are found worldwide in soil and as air and water contaminants (9, 13). Among species in this genus, Paecilomyces lilacinus and Paecilomyces variotii are of clinical importance, as they are an increasing cause for opportunistic and usually severe human infections (2, 4, 5, 15) generally associated with the use of immunosuppression therapy, implants, or ocular surgery.The differentiation between these two species is clinically important, since P. lilacinus and P. variotii seem to present marked differences in their in vitro susceptibilities to the antifungal agents. We report here the in vitro susceptibility profile of a collection of P. variotii and P. lilacinus clinical isolates.Strains. This study included 58 clinical isolates of Paecilomyces spp. obtained from a variety of clinical sources.Morphological identification. The strains were subcultured at 30°C in malt extract agar (2% malt extract) (Oxoid S.A., Madrid, Spain) and potato dextrose agar (Oxoid) to ascertain their macroscopic and microscopic morphologies.Molecular identification by sequencing of internal transcribed spacer (ITS) region. Molds were cultured in GYEP medium (0.3% yeast extract, 1% peptone) (Difco, Soria Melguizo S.A., Madrid, Spain) with 2% glucose (Sigma-Aldrich Quimica, Madrid, Spain) for 24 to 48 h at 30°C. Genomic DNA was isolated using an extraction procedure previously described (10).DNA segments comprising the ITS1 and ITS2 regions were amplified with primers ITS1 (5Ј-TCCGTAGGTGAACCTGC GG-3Ј) and ITS4 (5Ј-TCCTCCGCTTATTGATATGC-