Systemic fungal infections, caused by a wide variety of fungi, contribute to high mortality in humans with immunocompromised conditions. However, there are few classes of antifungal drugs available, limiting therapeutic options. Azoles are the most commonly used class of antifungals to treat many fungal infections, but resistance to azoles can be induced or, for some fungi, is an inherent property. One of major mechanisms of azole resistance is overexpression of drug efflux pumps in fungal cell membranes, such as the energy-dependent ATP-binding cassette (ABC) transporters. We have developed a protein hyperexpression system to facilitate functional analysis of efflux pumps using a Saccharomyces cerevisiae strain as the host for heterologous expression. The system is well suited for the hyperexpression of individual fungal ABC transporters for structural and functional studies. Furthermore, the recombinant yeast strains expressing heterologous membrane proteins can be used to screen for compounds that overcome fungal drug resistance. Also in this review, the mechanisms of azole resistance in Candida glabrata and C. krusei will be considered in relation to the recent increase in the incidence of Candida infections caused by non-albicans Candida. The development of possible novel antifungal agents will also be discussed.

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Molecular biological approaches have recently begun to be applied to molecular genetics studies of dermatophytes. High-throughput gene analysis methodologies, such as EST sequencing, differential cDNA screening, and cDNA-based microarray analysis have been used to obtain information on many dermatophyte genes and their expression profiles under different experimental conditions. In addition, whole genome sequencing projects are underway for several important dermatophytes, such as Trichophyton rubrum and Microsporum canis. These studies will provide large amounts of valuable information for elucidating the molecular basis of host invasion by dermatophytes and their virulence. Targeted gene disruption by homologous recombination is one of the most common approaches for determining the functions and roles of numerous genes isolated from pathogenic fungi. However, the difficulty of genetic manipulation due to low transformation frequency of dermatophytes may limit the successful production of null mutants by targeted gene disruption via homologous recombination. To overcome these problems, our group has developed useful genetic manipulation systems for dermatophytes using the clinically important dermatophyte, T. mentagrophytes.

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We report a case of subcutaneous abscess caused by Nocardia farcinica in a 44-year-old man, who had been treated with systemic prednisolone and cyclosporin for aplastic anemia. He had been affected by aplastic anemia for 8 years, and was previously treated with antithymocyte globulin. The effect was insufficient, and platelet and erythrocyte transfusion was required. Bone marrow transplantation was not adopted due to a psychological problem. He had also been treated with prednisolone and cyclosporin for 3 years. Without apparent cause, swelling and pain of left upper extremity developed in April, 2008. There was no abnormality in cutaneous macroscopic findings, such as a wound or a sting. He was administered antibiotics, but they were ineffective and effusion were excreted into the skin. After hospitalization, he was treated by incision and drainage and antibiotics were started. The pathogen was identified as Nocardia farcinica by its biochemical characters. There was no dissemination to other organs like lung or brain and he recovered completely with a treatment of antibiotics for 1 year. We studied the epidemiological and clinical characteristics of Nocardia infections reported in Japan from 2000 to 2008 and identified 92 cases using the medical article search engine Ichushi-Web (Japan Medical Abstract Society). The results indicate that the most important risk factor in systemic nocardiosis ia an immunosuppressive agent such as prednisolone, cyclosporine, or azathioprine. We believe that we should take the possibility of Nocardia infection into consideration in a compromised host.

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β-Glucan is a major component of the cell walls and pathogen-associated microbial patterns of fungi. We previously reported the presence of an antibody which reacts to β-glucan, anti-β-glucan (BG) antibody, in human sera. In livestock and domestic pets, the antibody's response to fungal cell wall β-glucan is little understood. In this study, we examined the existence and reactivity of anti-BG antibody in various animal species.
We demonstrated the presence of the anti-BG antibody in each animal's serum. Individual differences in the titer existed. The antibody was highly reactive to Candida solubilized cell wall β-glucan (CSBG) while reacting little to grifolan (GRN) from Grifola frondosa. This suggested that the anti-BG antibody interacted with fungal cell wall β-glucan and participated in the immune-response to pathogenic fungi.

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Aspergillosis is an important mycosis caused primarily by Aspergillus fumigatus and its relatives. The genus Emericella is a teleomorph related to the Aspergillus section Nidulantes. The typical anamorphic stage species in this genus is Aspergillus nidulans, which is sometimes a significant agent in chronic granulomatous disease (CGD) patients. The mortality rate of osteomyelitis in CGD patients due to A. nidulans ( E. nidulans ) is very high compared to that due to A. fumigatus. Moreover, two Emericella species ( E. nidulans and E. quadrilineata ) from clinical specimens exhibit different sensitivities against several antifungal drugs. In aspergillosis, correct species identification is important for antifungal therapy.
We attempted to develop rapid and specific molecular discrimination by polymerase chain reaction (PCR) and loop-mediated isothermal amplification (LAMP) methods in the principal pathogenic Emericella species, and succeeded in establishing species-specific primers corresponding to the hydrophobin gene. These primers discriminate E. nidulans and E. quadrilineata rapidly and specifically. These methods and primers make it possible to diagnose etiological agents in aspergillosis quickly and easily.

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