Disseminated trichosporonosis: meeting the challenge

The fungal resistome: a risk and an opportunity for the development of novel antifungal therapies

The risks for toxicity of novel antifungal compounds, together with the emergence of resistance, makes the use of inhibitors of resistance, in combination with antifungal compounds, a suitable strategy for developing novel antifungal formulations. Among them, inhibitors of efflux pumps are suitable candidates. Increasing drug influx or interfering with the stress response may also improve the efficacy of antifungals. Therapies as induction of fungal apoptosis or immunostimulation are also good strategies for reducing the risks for resistance and to improve antifungals' efficacy. Understanding the effect of the acquisition of resistance on the fungal physiology and determining the collateral sensitivity networks are useful for the development of novel strategies based on combination of antifungals for improving the efficacy of the therapy.

Newer antifungal therapy for emerging fungal pathogens

As the number of immunocompromised patients increases, there is a concomitant increase in the number and diversity of fungal infections. Fungi that were once considered harmless or contaminants are now pathogenic in the immunocompromised host. Often these emerging pathogens are indistinguishable from the more familiar fungal infections; however, they are generally more recalcitrant to conventional antifungal therapies. With the antifungal armamentarium now expanding, the clinician now has many more options for these difficult-to-treat mycoses. We review many of the newer antifungal agents (second-generation triazoles, echinocandins, etc.) as therapeutic options for the recently emerging fungal pathogens.

In vitro antifungal susceptibilities of Trichosporon species

The in vitro activities of amphotericin B, itraconazole, fluconazole, voriconazole, posaconazole, and ravuconazole against 39 isolates of Trichosporon spp. were determined by the NCCLS M27-A microdilution method. The azoles tested appeared to be more potent than amphotericin B. Low minimal fungicidal concentration/MIC ratios were observed for voriconazole, posaconazole, and ravuconazole, suggesting fungicidal activity.

Prospective study of fungaemia in a single cancer institution over a 10-y period: aetiology, risk factors, consumption of antifungals and outcome in 140 patients

Over a 10-y period (1989-99) we prospectively evaluated all patients with fungaemia among 16,555 admissions (21,004 blood cultures) at a national cancer referral institution in the Slovak Republic. A prospective protocol was completed on 140 patients with fungaemia, which was then analysed in terms of aetiology, clinical characteristics, potential risk factors and outcome. The most frequently isolated organism was C. albicans, in 75 patients (52.9%), followed by non-albicans Candida spp. in 45 patients (32.1%). Non-Candida spp. yeasts represented 16 episodes in 16 patients (11.4%). Moulds caused 4 episodes in 4 patients (3.6% of all fungaemias) and all were caused by Fusarium spp. Mucositis (p = 0.025), > or = 3 positive blood cultures (p = 0.02), acute leukaemia (p = 0.00001), neutropenia (p = 0.0015), quinolone prophylaxis (p < 0.000005) and breakthrough fungaemia (p = 0.004) during prophylaxis with fluconazole (p = 0.03) and itraconazole (p = 0.005) were significantly more associated with non-Candida than C. albicans spp. Furthermore, attributable mortality was higher in the subgroup of non-Candida than C. albicans spp. (50.0 vs. 18.7%, p < 0.02). The only independent risk factor for inferior outcome was antifungal therapy of < 10 d duration (odds ratio 2.1, 95% confidence interval, p < 0.001). Aetiology, neutropenia and mucositis were not independent risk factors for higher mortality in multivariate analysis; however, they were risk factors for inferior outcome in univariate analysis (p < 0.05-0.005).

Antifungal susceptibility testing. New technology and clinical applications

The state of the art for susceptibility testing of yeasts is comparable with that of bacteria. Standardized methods for performing antifungal susceptibility testing are reproducible, accurate, and available in clinical laboratories. The development of quality control limits and interpretive criteria for a limited number of antifungal agents provides a basis for the application of this testing in the clinical laboratory. A proficiency testing program is available as a quality assurance measure for laboratories and has documented steady improvement among laboratories using the NCCLS method. As with antibacterial agents, surveillance programs are now in place using reference quality testing methods to monitor antifungal resistance trends on a global scale. It is clear that antifungal susceptibility testing can predict outcome in several clinical situations. Susceptibility testing is most helpful in dealing with infection caused by non-albicans species of Candida, and susceptibility testing of azoles is increasingly important in the management of candidiasis in critically ill patients. Susceptibility testing also has been standardized for filamentous fungi that cause invasive infections. Studies are ongoing to further refine this approach and evaluate the in vivo correlation with the in vitro data for molds. Future efforts must be directed toward establishing and validating interpretive break-points for licensed antifungals such as amphotericin B, and for new antifungals that are not yet licensed. Finally, procedures must be optimized for testing non-Candida yeasts (e.g., C. neoformans) and molds.

Longitudinal 10-year prospective survey of fungaemia in Slovak Republic: trends in etiology in 310 episodes. Slovak Fungaemia study group

A 10-year prospective survey of fungaemia in the Slovak Republic, involving 31 microbiology laboratories and 71 hospitals, was conducted from 1989-1998 (10 years): 310 fungaemias were analyzed for etiology, clinical characteristics, therapy, and outcome. C. albicans was responsible for 191 (61.6%) fungaemias, non-albicans Candida spp. (NAC) for 97 (31.3%), non-Candida yeasts for 18 (5.8%) and moulds (Fulsarium spp.) for four fungaemias. The most frequent NAC isolated from blood cultures were C. parapsilosis--30 (9.7%), C. krusei--18 (5.8%), C. tropicalis--14 (4.5%), and C. glabrata--10 (3.2%). Secular trends in etiology showed a sustaining decrease of C. albicans (from 100% in 1989 to 50.7% in 1998) and increase of NAC (from 0% in 1989-1990 to 46.3% in 1998). Non-Candida yeasts and moulds showed a stable proportion during the investigated period. There were statistically significant differences in etiology of fungaemia various subgroups of patients: non-albicans Candida spp. was significantly more frequent observed among subgroups of patients with pancreatitis and coma (53.3% vs. 31.3%, p < or = 0.02) and less frequently in the subgroup of neonates (15.0% vs. 31.3%, p < or = 0.006). Vice versa, C. albicans appeared more frequently in neonates (85%).

Invasive yeast infections other than Candida spp. in acute leukaemia

During the last two decades, the treatment of leukaemia has changed significantly; increasing intensity of chemotherapy and bone marrow transplantation have lead to profound immunosuppression, prolonged stays in hospital, vascular catheterization, administration of broad spectrum antimicrobial agents and extensive use of prophylactic antifungal drugs. All but the last of these risk factors have increased the incidence of fungal infections in leukaemic patients and have significantly changed the spectrum of pathogens in favour of non-Candida species. In major haematological centres in Europe and the US, the proportion of non-Candida yeast isolated from patients increased from 1 to 5% in 1980 to 10 to 25% after 1990. However, there are not enough data to assess whether mortality due to these species is higher than that due to Candida spp. (30-40%) or filamentous fungi (50-70%). In this article, specific risk factors and therapeutic outcome of yeast infections other than Candida spp. in leukaemia such as Malassezia furfur, Trichosporon spp., Blastoschizomyces capitatus, Rhodotorula rubra, Saccharomyces cerevisiae, Clavispora lusitaniae, Cryptococcus laurentii and Hansenula anomala are reviewed. An analysis of risk factors from the National Cancer Institute, Bratislava has shown that non-Candida yeast infections (N = 15) in cancer patients are associated with leukaemia and neutropenia (P = < 0.002, 0.005), more often fatal than those caused by C. albicans (N = 51) (P < 0.006) but not non-albicans Candida (N = 34) and are associated with quinolone (P < 0.0001) and itraconazole prophylaxis (P < or = 0.05, 0.015) compared to both C. albicans or non-albicans Candida respectively.

Treatment of chronic disseminated Geotrichum capitatum infection with high cumulative dose of colloidal amphotericin B and itraconazole in a leukaemia patient

A case of disseminated granulomatous Geotrichum capitatum infection is reported. A young patient with blastic crisis of chronic myelogenous leukaemia developed septicaemia caused by G. capitatum in the post-chemotherapy aplastic phase. Subsequently, disseminated infection of the liver, spleen, pancreas and kidneys was observed. Treatment with high cumulative doses of a lipid formulation of amphotericin B (Amphocil, 20.2 g in 11 weeks) and maintenance with itraconazole resolved clinical manifestations of G. capitatum granulomatous disseminated disease and controlled reactivation of the infection during the two subsequent courses of cytotoxic chemotherapy.

Trichosporon beigelii fungemia and metastatic pneumonia in a trauma patient

Trichosporon beigelii is a fungus which usually produces cutaneous involvement in immunocompetent hosts, being rarely reported to cause systemic infection. A case of fungemia and metastatic pneumonia caused by Trichosporon beigelii in a trauma patient is reported.

Laboratory aids in the diagnosis of invasive candidiasis

The laboratory diagnosis of candidiasis continues to be problematic; however, there have been several advances in the past decade which promise to enhance our ability to identify patients at high risk for infection and/or to document invasive candidiasis in critically ill and immunocompromised patients. The introduction of commercially available biphasic blood culture medium and subsequently the lysis-centrifugation procedure has markedly improved the ability of laboratories to detect fungemia. Although serologic methods have not been very successful in diagnosing candidiasis in immunocompromised patients, several antigen detection methods are now under investigation. In addition, detection of fungal metabolites such as D-arabinitol remains promising. Finally, application of the techniques of molecular biology for typing and detection of fungal pathogens has expanded our understanding of candidal infections and may offer the most sensitive and specific means of diagnosing invasive candidiasis.

Impact of the changing epidemiology of fungal infections in the 1990s

The increase in fungal infections over the past decade is striking. This is particularly true for hospitalized patients where the rate of candidal bloodstream infection has increased by as much as 487% over the decade of the 1980s. This increase in fungal infections is accompanied by a significant excess mortality and excess length of stay in hospital. The emergence of "new" fungal pathogens such as Candida krusei, Torulopsis glabrata, Fusarium and Trichosporon beigelii is now recognized as a significant problem in many patient populations. The documentation of nosocomial transmission of fungal pathogens and the recognition of resistance to both new and established anti-fungal agents poses a significant problem entering the 1990s. Continued effort is needed to develop new and better therapeutic agents and more effective strategies for prophylaxis of endogenous infections and prevention of transmission within the hospital setting.