Recent progress and current problems in treatment of invasive fungal infections in neutropenic patients

Synthesis and characterization of NH2-(AEEA)n-amphotericin B derivatives

To find novel amphotericin B (AmB) derivatives with high therapeutic potential, low toxicity, and water solubility, a series of nine N-substituted AmB derivatives were evaluated for their antifungal activity using the broth dilution method and for their hemolytic toxicity with sterile defibrinated sheep blood. Qualitative screening of the effect of the derivatives on two reference Candida albicans strains and of their solubility was performed based on the value of n (n is a positive integer), resulting in the identification of an optimal compound, NH₂-(AEEA)₅-AmB (DMR005; AEEA is 8-amino-3,6- dioxaoctanoic acid). Preliminary safety assessments of DMR005 were carried out via the MTT cell viability assay in vitro and acute toxicity assay in vivo. In general, DMR005 not only has higher water solubility and less toxicity than the parent polyene but also retains antifungal potency.

Recent Advances in the Treatment of Scedosporiosis and Fusariosis

Species of Scedosporium and Fusarium are considered emerging opportunistic pathogens, causing invasive fungal diseases in humans that are known as scedosporiosis and fusariosis, respectively. These mold infections typically affect patients with immune impairment; however, cases have been reported in otherwise healthy individuals. Clinical manifestations vary considerably, ranging from isolated superficial infection to deep-seated invasive infection—affecting multiple organs—which is often lethal. While there have been a number of advances in the detection of these infections, including the use of polymerase chain reaction (PCR) and matrix-assisted laser desorption ionization/time-of-flight mass spectrometry (MALDI-TOF MS), diagnosis is often delayed, leading to substantial morbidity and mortality. Although the optimal therapy is controversial, there have also been notable advances in the treatment of these diseases, which often depend on a combination of antifungal therapy, reversal of immunosuppression, and in some cases, surgical resection. In this paper, we review these advances and examine how the management of scedosporiosis and fusariosis may change in the near future.

Combination therapy for the treatment of pulmonary mold infections

INTRODUCTION

Pulmonary mold infections are caused by ubiquitous organisms found in soil, water, and decaying vegetation, including Aspergillus spp., the Mucormycetes, hyaline molds, and dematiaceous (black) molds. Areas covered: These infections are often a challenge to diagnose and even more difficult to treat. Recently, antifungal combination therapy has emerged as a promising strategy to treat some forms of invasive mycoses, including pulmonary mold infections. Historically, this approach has been limited due to non-uniform interpretation criteria, variations in pharmacodynamic/pharmacokinetic properties of antifungals used in combination, and an inability to predict clinical success based on in vitro data and animal models. However, recent advances have helped mitigate some of these challenges. Expert commentary: In this paper, we explore what is known about the antifungal combination therapy in the treatment of pulmonary mold infections and explore how it may impact clinical practice. We pay particular attention to novel combinations and the challenges associated with the development of new antifungal agents.

Interdigital intertrigo due to Fusarium oxysporum

Background and Purpose:

Fusariosis is a fungal infection often involving the skin. Various species can cause local, focally invasive, or disseminated infections. The routes of entry for Fusarium species include the respiratory tract, gastrointestinal tract, toe nails, trauma to the skin, and indwelling central venous catheter.

Case Report:

Herein, we present the case of a 35-year-old woman presenting with interdigital intertrigo. The patient had no predisposing factors and she did not take any antifungal agents. Fusiform macroconidia were observed on the slide culture of the fungus. The etiological agent of the infection was identified as Fusarium oxysporum through sequencing of the translation elongation factor-1 alpha (TEF-1α) gene using the primers EF1 and EF2.

Conclusion:

Fusariosis commonly presents as a severe fungal infection in immunocompromised patients. However, this infection may also occur in immunocompetent patients. Although treatment with amphotericin B is a routine antifungal therapy for fusariosis, many azoles such as cloterimazole can be used topically with fewer side-effects

Murine model for Fusarium oxysporum invasive fusariosis reveals organ-specific structures for dissemination and long-term persistence

The soil-borne plant pathogen Fusarium oxysporum causes life-threatening invasive fusariosis in immunocompromised individuals. The mechanism of infection in mammalian hosts is largely unknown. In the present study we show that the symptoms of disseminated fusariosis caused by F. oxysporum in immunosuppressed mice are remarkably similar to those reported in humans. Distinct fungal structures were observed inside the host, depending on the infected organ. Invasive hyphae developed in the heart and kidney, causing massive colonization of the organs. By contrast, chlamydospore-like survival structures were found in lung, spleen and liver. Systemically infected mice also developed skin and eye infections, as well as thrombosis and necrosis in the tail. We further show that F. oxysporum can disseminate and persist in the organs of immunocompetent animals, and that these latent infections can lead to lethal systemic fusariosis if the host is later subjected to immunosuppressive treatment.

Diagnosis and therapy of Candida infections: joint recommendations of the German Speaking Mycological Society and the Paul-Ehrlich-Society for Chemotherapy

Invasive Candida infections are important causes of morbidity and mortality in immunocompromised and hospitalised patients. This article provides the joint recommendations of the German-speaking Mycological Society (Deutschsprachige Mykologische Gesellschaft, DMyKG) and the Paul-Ehrlich-Society for Chemotherapy (PEG) for diagnosis and treatment of invasive and superficial Candida infections. The recommendations are based on published results of clinical trials, case-series and expert opinion using the evidence criteria set forth by the Infectious Diseases Society of America (IDSA). Key recommendations are summarised here: The cornerstone of diagnosis remains the detection of the organism by culture with identification of the isolate at the species level; in vitro susceptibility testing is mandatory for invasive isolates. Options for initial therapy of candidaemia and other invasive Candida infections in non-granulocytopenic patients include fluconazole or one of the three approved echinocandin compounds; liposomal amphotericin B and voriconazole are secondary alternatives because of their less favourable pharmacological properties. In granulocytopenic patients, an echinocandin or liposomal amphotericin B is recommended as initial therapy based on the fungicidal mode of action. Indwelling central venous catheters serve as a main source of infection independent of the pathogenesis of candidaemia in the individual patients and should be removed whenever feasible. Pre-existing immunosuppressive treatment, particularly by glucocorticosteroids, ought to be discontinued, if feasible, or reduced. The duration of treatment for uncomplicated candidaemia is 14 days following the first negative blood culture and resolution of all associated symptoms and findings. Ophthalmoscopy is recommended prior to the discontinuation of antifungal chemotherapy to rule out endophthalmitis or chorioretinitis. Beyond these key recommendations, this article provides detailed recommendations for specific disease entities, for antifungal treatment in paediatric patients as well as a comprehensive discussion of epidemiology, clinical presentation and emerging diagnostic options of invasive and superficial Candida infections.

In vitro activity of isavuconazole against 140 reference fungal strains and 165 clinically isolated yeasts from Japan

The in vitro susceptibilities of 140 laboratory reference strains of fungi, including type strains, and 165 clinical yeast isolates from Japan towards isavuconazole compared with fluconazole (FLC), itraconazole (ITC), voriconazole and amphotericin B were measured. Broth microdilution methods based on Clinical and Laboratory Standards Institute (CLSI) methods were used for yeasts, and RPMI-MOPS medium semi-solidified with 0.2% low-melting-point agarose based on CLSI guidelines was used for moulds. The range of isavuconazole minimum inhibitory concentrations (MICs) was 0.0004-0.21 mg/L for Candida albicans, 0.0036-0.4 mg/L for Candida glabrata, 0.023-0.058 mg/L for Candida krusei, 0.0026-0.032 mg/L for Cryptococcus neoformans, 0.1-0.39mg/L for Aspergillus fumigatus and 0.2-0.39 mg/L for Aspergillus terreus. Isavuconazole was as active as ITC against the dimorphic true pathogenic fungi, with a range of MICs from <0.0004 mg/L to 0.0063 mg/L for Blastomyces dermatitidis and Histoplasma capsulatum. It was also active against uncommon dematiaceous fungi such as Exophiala spp. and Phialophora spp. as well as against dermatophytic species. Isavuconazole showed very good in vitro antifungal activity with a broad spectrum, including against FLC-resistant Candida spp., Aspergillus spp. and uncommon opportunistic fungal species. This is the first report of the in vitro susceptibility of Japanese clinical yeast isolates to isavuconazole. No cross-resistance was found to isavuconazole amongst FLC-resistant strains.

Oxidative burst and phagocytosis of neonatal neutrophils confronting Candida albicans and Candida parapsilosis

BACKGROUND

Candida albicans and Candida parapsilosis are important causes of sepsis among premature neonates. The neutrophil is a key element in the control of Candida infections, yet specific neutrophil mechanisms that may contribute to the susceptibility of the premature neonate to candidiasis are not well understood.

AIMS

The hypothesis for this study is that neonatal neutrophils have a developmental deficiency in their capacity to generate an oxidative burst in response to Candida species.

STUDY DESIGN

Neutrophils were isolated from cord blood of term and preterm infants and from peripheral blood of adult volunteers. Neutrophils were exposed to Candida species, and assays of oxidative burst and phagocytosis were conducted.

RESULTS

Oxidative burst of neutrophils from term and preterm (22-29 weeks) neonates exposed to C. albicans hyphae was similar to adult neutrophils. No detectable burst was induced in either group by exposure to C. parapsilosis yeast, and was attenuated by exposure to C. albicans yeast. Because no deficiency in oxidative burst was seen, phagocytosis was also studied. Phagocytosis of unopsonized C. albicans yeast was low in both adult and neonatal neutrophils (10-12%), but was more efficient with C. parapsilosis as target (76-88%). Neutrophils from both term and preterm infants were capable of phagocytosis equivalent to adults.

CONCLUSION

A deficiency in generation of an oxidative burst or phagocytosis may not contribute to the increased susceptibility of preterm neonates to infections with Candida.

Effect of amphotericin B lipid complex (ABLC) in very low birth weight infants

The aim of this retrospective, case-control study was to determine the effect of the amphotericin B lipid complex (ABLC) on serum creatinine (SCr), blood urea nitrogen (BUN), sodium (Na), and potassium (K) in very low birth weight (VLBW) infants. Medical records of all VLBW infants who were admitted to our Neonatal Intensive Care Unit between May 1998 and May 2006 and had received ABLC for at least 2 weeks were reviewed for patient demographics, use of medications (ABLC, diuretics, xanthines, indomethacin, vancomycin, gentamicin, pressors, and inotropes), fluid intake, urinary output, and serum electrolytes. Thirty-five patients who received ABLC were identified and matched by gestational age (GA) to 35 patients who served as controls. Infants who received ABLC had an average GA of 25.7 +/- 2.1 weeks and a birth weight of 764 +/- 196 g. Between day 1 and 14 of ABLC treatment, the BUN decreased from 17.5 +/- 11.5 to 10.5 +/- 6.8 mg/dl (p = 0.01), the SCr varied between 0.78 +/- 0.32 and 0.69 +/- 0.32 mg/dl, Na varied between 136.6 +/- 5.8 and 137.8 +/- 3.6 mEq/l, and K varied between 4.8 +/- 0.9 and 4.9 +/- 0.6 mEq/l, respectively. Based on these results, we conclude that treatment with ABLC for 2 weeks did not increase BUN or SCr, nor decrease Na or K in VLBW infants.

Cytotoxicity of amphotericin B-incorporated polymeric micelles composed of poly(DL-lactide-co-glycolide)/dextran graft copolymer

In this study, we prepared amphotericin B (AmpB)-encapsulated polymeric micelle of poly(DL-lactideco-glycolide) (PLGA) grafted-dextran (DexLG) copolymer for the cytotoxicity test. The average particle size of AmpB-encapsulated DexLG polymeric micelles was around 30 approximately 70 nm and their morphology showed spherical shapes. Since aggregation states of AmpB are related to intrinsic cytotoxicity, prevention of AmpB aggregation in aqueous solution will provide low cytotoxicity and increased antimicrobial activity for the infectious disease. At UV/VIS spectrum measurement, polymeric micelle prepared from methanol/water mixture (method B) showed a monomeric state of AmpB while polymeric micelle prepared from DMSO (method A) showed an aggregated state. During the hemolysis activity test, polymeric micelle from method B showed reduced hemolysis activity compared to AmpB itself and polymeric micelle from method A. These results indicated that AmpB-incorporated polymeric micelle prepared from methanol/water mixture has low cytotoxicity and favorable antimicrobial activity.

Efficient clearance of Aspergillus fumigatus in murine lungs by an ultrashort antimicrobial lipopeptide, palmitoyl-lys-ala-DAla-lys

Aspergillus fumigatus is an opportunistic fungal pathogen responsible for invasive aspergillosis in immunocompromised individuals. The inefficiency of antifungal agents and high mortality rate resulting from invasive aspergillosis remain major clinical concerns. Recently, we reported on a new family of ultrashort cationic lipopeptides active in vitro against fungi. Mode of action studies supported a membranolytic or a detergent-like effect. Here, we screened several lipopeptides in vitro for their anti-A. fumigatus activity. To investigate the therapeutic properties of the selected peptides in vivo, we challenged immunosuppressed C57BL/6 wild-type mice intranasally with DsRed-labeled A. fumigatus conidia and subsequently treated the animals locally with the lipopeptides. Confocal microscopic analysis revealed the degradation of DsRed-labeled hyphal forms and residual conidia in the lungs of the mice. The most efficient peptide was tested further using a survival assay and was found to significantly prolong the life of the treated animals, whereas no mice survived with the current standard antifungal treatment with amphotericin B. Moreover, as opposed to the drug-treated lungs, the peptide-treated lungs did not display any toxicity of the peptide. Our results highlight the potential of this family of lipopeptides for the treatment of pulmonary invasive aspergillosis.

Lethal double infection with Acremonium strictum and Aspergillus fumigatus during induction chemotherapy in a child with ALL

Fungal infections are a major cause of morbidity and mortality in patients during chemotherapeutic treatments and malignant hematologic disease. We present a case of a double fungal infection with disseminated Acremonium strictum (A. strictum) and pulmonary Aspergillus fumigatus (A. fumigatus) and its rapid clinical course. A 17-year-old boy with prolonged neutropenia developed a disseminated fungal infection during induction chemotherapy of his acute lymphoblastic leukemia. The infection was rapidly lethal despite neutrophil recovery and early antifungal combination therapy with amphotericin B and caspofungin. Since there are only a few reports about invasive Acremonium infections, we present this case with regard to differences in the clinic pathologic features of Aspergillosis and other opportunistic fungal infections due to Fusarium or Acremonium species.

Amphotericin B-Gum Arabic Conjugates: Synthesis, Toxicity, Bioavailability, and Activities Against Leishmania and Fungi

PURPOSE

Gum arabic, a branched polysaccharide consisting of more than 90% arabinogalactan having a molecular weight around 250,000 Da is the oldest and best known of all natural gums. The objective of the present investigation was to examine whether amphotericin B (AmB), the polyene antibiotic when conjugated to periodate oxidized gum arabic still retained its anti-fungal and anti-leishmanial activity and to evaluate its toxicity and bioavailability.

METHODS

AmB conjugated to the oxidized polysaccharide through Schiff's linkages in the unreduced (imine) and reduced (amine) forms were characterized for the drug content, hemolytic potential, molecular mass, in vitro release and were examined for anti-fungal activity against Candida albicans and Cryptococcus neoformans and for anti-leishmanial activity against promastigotes of Leishmania donovani in culture. Toxicity and bioavailability were evaluated by intravenous (i.v) injections of the conjugates in mice and rabbits respectively.

RESULTS

The conjugates were found to be non-hemolytic and mice withstood a dosage of 20 mg (AmB)/kg body weight of both conjugates. Histological examination of the internal organs of mice showed no lesions in kidney, brain, heart or liver. Estimation of the residual drug in the internal organs 7 days post injection showed that the spleen still retained 8.4 +/- 0.53 microg/g of tissue. AmB was found to be released from both conjugates in vitro although the release from the imine conjugate was much faster than from the amine conjugate. The concentrations inhibiting parasite growth by 50% (IC(50)) values for the imine conjugate against promastigotes of L. donovani LV9 and DD8 strains were 0.37 +/- 0.04 and 1.44 +/- 0.18 microM respectively. The IC(50) values for the amine conjugates were much higher. The minimum inhibitory concentration (MIC) against C. albicans and C. neoformans was in the range of 0.5-0.9 microg/mL for both imino and amino conjugates. The bioavailability of the conjugate in rabbits showed that the imine conjugate maintained a plasma concentration in the range of 20 to 5 microg/mL while for the amine conjugate it was in the range of 17 to 3 microg/mL over 24 h.

CONCLUSIONS

The drug conjugates were stable, non-hemolytic and non-toxic to the internal organs of the animal and showed good anti-fungal and anti-leishmanial activity in vitro. In spite of the large molecular weight of the polysaccharide, AmB from the conjugates showed bioavailability after i.v injection. Since the highest concentration of AmB was found in the spleen after a single injection, these conjugates may have potential in anti-leishmanial therapy.

Comparative efficacies, toxicities, and tissue concentrations of amphotericin B lipid formulations in a murine pulmonary aspergillosis model

Invasive aspergillosis, an important cause of morbidity and mortality in immunosuppressed (IS) patients, is often treated with amphotericin B lipid formulations. In the present study, liposomal amphotericin B (L-AMB) and amphotericin B lipid complex (ABLC) were compared in treatment of murine pulmonary aspergillosis. Uninfected, IS mice were treated for 4 days with 1, 4, 8, or 12 mg L-AMB or ABLC/kg of body weight, and their lungs were analyzed by high-performance liquid chromatography for drug concentrations. IS mice intranasally challenged with Aspergillus fumigatus were treated with 12, 15, or 20 mg/kg L-AMB or ABLC and monitored for survival, fungal burden (CFU), and tissue drug concentration. Blood urea nitrogen (BUN) levels and kidney histopathology were determined for uninfected and infected mice given 15 or 20 mg/kg L-AMB or ABLC. The results showed that both drugs had therapeutic levels of drug (>3.0 microg/g) in the lungs of uninfected or infected mice, and 24 h after the last dose, ABLC levels were significantly higher than L-AMB levels (P < 0.02). L-AMB and ABLC at 12 mg/kg both produced 57% survival, but only L-AMB at 15 or 20 mg/kg further increased survival to 80 to 90%, with BUN levels and kidney morphology similar to those of controls. Survival at 15 or 20 mg/kg ABLC was not significantly different than that of controls, and BUN levels were significantly elevated, with tubular alterations in uninfected animals and acute necrosis in kidney tubules of infected animals. In conclusion, although both drugs were effective in prolonging survival at 12 mg/kg, the reduced nephrotoxicity of L-AMB increased its therapeutic index, allowing for its safe and effective use at 15 or 20 mg/kg.

Animal models testing monotherapy versus combination antifungal therapy: lessons learned and future directions

PURPOSE OF REVIEW

The continued rise in serious fungal infections and rises in therapy failure dictate that more efficacious therapies be developed. Combination therapy using available drugs is an attractive choice, yet primarily only anecdotal clinical data are available. We review here data from animal models as an indicator of future potential.

RECENT FINDINGS

The primary data are from murine studies and we will briefly review chemotherapeutic combination studies, some showing benefit over monotherapy and some showing no benefit over monotherapy. In addition, we will address the potential of immunotherapy in combination with conventional therapy.

SUMMARY

The data derived from animal model studies of antifungal drug efficacy have proven to be predictive of clinical utility. Studies on combination therapy will prove useful to the clinician in evaluating courses of treatment, especially where clinical-trial data are not available or probable in the future.

Economic Evaluation of Intravenous Itraconazole for Presumed Systemic Fungal Infections in Neutropenic Patients in Korea

Systemic fungal infections remain a major clinical problem in immunocompromised patients. Presumed systemic fungal infections (PSFI) are treated empirically with an intravenous antifungal agent to reduce the occurrence of documented infections and associated mortality. The objective of this study was to compare the cost-effectiveness of intravenous itraconazole (IVitra) treatment with the current first-line empirical treatment of PSFI with conventional amphotericin B (CAB) in cases of neutropenic cancer and bone marrow transplantation (BMT). Cost-effectiveness was expressed as cost per additional "responder" (defined as a patient without fever or major toxicity). We developed a medical decision analytical tree that included probabilities of toxicity, response and pathogen documentation, and second-line treatments. Clinical data were obtained from randomized clinical trials, and resource use data were obtained from a panel of clinical experts. The total cost of treating PSFI per neutropenic cancer patient was lower for IVitra than for CAB, and this lower cost resulted from a reduced need for second-line antifungals. In a cost-effectiveness analysis, IVitra treatment was superior to CAB treatment. Compared with current treatment with CAB, IVitra therapy was shown to be a cost-effective and cost-saving empirical treatment for PSFI in neutropenic cancer patients and BMT patients.

A fraction from Escherichia coli with anti-Aspergillus properties

The products of various strains of Escherichia coli (BL21, DH5alpha, HB101 and XL Blue) were investigated for antimycotic properties using pathogenic isolates of Aspergillus. Co-culture experiments revealed that E. coli strains exhibited variable activity against Aspergillus fumigatus. The lysates prepared from DH5alpha, HB101 and XL Blue strains of E. coli showed inhibitory activity against A. fumigatus in the protein concentration range of 62.50 to 250.00 microg ml(-1). The highest activity was seen in the lysate of BL21, which inhibited the growth of A. fumigatus and Aspergillus flavus completely at a concentration of 31.25 microg protein ml(-1). The MIC of BL21 lysate against Aspergillus niger was found to be 62.50 microg ml(-1). The in vitro toxicity of BL21 lysate was evaluated using a haemolytic assay. A BL21 lysate protein concentration of 1250.00 microg ml(-1) was found to be nontoxic to human erythrocytes. The standard drug amphotericin B lysed 100 % of erythrocytes at a concentration of 37.50 microg ml(-1). SDS-PAGE showed the presence of at least 15 major proteins in the lysate of BL21. Ion-exchange chromatography resolved the BL21 lysate into five fractions and fraction III was found to be endowed with anti-Aspergillus properties. The MIC of this fraction was found to be 3.90 microg ml(-1). Further work on the purification of the active molecule and its characterization is in progress.

Treatment of Non-Aspergillus Moulds in Immunocompromised Patients, with Amphotericin B Lipid Complex

An assessment was made of the efficacy and renal safety of amphotericin B lipid complex (ABLC) in the treatment of patients with invasive fungal infections caused by moulds other than Aspergillus species, on the basis of a retrospective analysis of data from the Collaborative Exchange of Antifungal Research (CLEAR) database. Data from CLEAR for 64 patients with zygomycosis were published previously. The database was further queried and yielded results for 28 patients with fusariosis and 84 patients infected with other non-Aspergillus moulds. Of 26 patients with fusariosis whose results could be evaluated, 46% (n = 12) were cured or improved, and an additional 12% (n = 3) were stable. Of 79 patients infected with other non-Aspergillus moulds whose results could be evaluated, 61% (n = 48) were cured or improved, and an additional 15% (n = 12) were stable. In an area with little guidance for therapy, the CLEAR data indicate that ABLC can be an effective broad-spectrum treatment choice for several invasive and refractory non-Aspergillus mould infections.

Overview of transplant mycology

PURPOSE

The epidemiology, clinical manifestation, diagnosis, and management of invasive mycoses in transplant patients are described.

SUMMARY

The incidence of and mortality from invasive mycoses have increased in transplant patients. Candida and Aspergillus are the two most common fungal pathogens in this patient population. The use of immunosuppressive and myeloablative therapies and other factors increases the risk of invasive mycoses. A high index of suspicion and clinical clues are needed for the diagnosis of Candida and Aspergillus infections because reliable diagnostic techniques are not available and the patient presentation is nonspecific. Targeted prophylaxis for patients at high risk for morbidity and mortality and early, aggressive treatment using broad-spectrum antifungal agents are recommended. Prophylaxis using itraconazole reduces the risk of treatment failure due to resistant pathogens compared with fluconazole. Voriconazole might prove advantageous compared with fluconazole and itraconazole for prophylaxis because of its extended spectrum and predictable blood levels. Caspofungin seems as effective as and less toxic than amphotericin B for this use. Voriconazole is more effective than amphotericin B for the treatment of aspergillosis. Caspofungin is comparable to voriconazole in efficacy as salvage treatment after failure to respond to other antifungal agents.

CONCLUSION

Caspofungin plus voriconazole and other combination therapies often are used for the treatment of aspergillosis yet data to support such use are yet to be produced. The investigational agents posaconazole, micafungin, and anidulafungin appear promising as salvage treatment of various invasive mycoses.

Candida krusei fungaemia: antifungal susceptibility and clinical presentation of an uncommon entity during 15 years in a single general hospital

BACKGROUND

Candida krusei fungaemia is an uncommon entity described in immunocompromised patients previously exposed to azole agents.

METHODS

From 1988 to 2003, 13 episodes of C. krusei fungaemia (2.3% of all fungaemias) were detected in our institution and compared with 39 Candida albicans controls. Susceptibility testing was carried out with the modified microdilution method according to NCCLS recommendations.

RESULTS

Underlying conditions were: HIV infection (4), haematological malignancies (4), organ transplantation (2), abdominal surgery (2) and lactose intolerance (1). Nine patients (69%) were not neutropenic. In comparison with C. albicans, patients with C. krusei infection had more commonly received antifungal agents (54% versus 15%, P = 0.006), had a haematological disease (31% versus 3%, P = 0.03), or a transplant (15% versus 3%, P = 0.08), were on corticosteroids (47% versus 13%, P = 0.01) and were neutropenic (31% versus 0%, P < 0.001). Patients with C. albicans had more surgical interventions (41% versus 15%, P = 0.09) and bladder catheters (61% versus 31%, P = 0.05). The most common origin for C. albicans was a catheter (41% versus 0%; P = 0.006) whereas for C. krusei the most common origin was unknown (69% versus 20%; P = 0.001). C. krusei presented more commonly with skin lesions in neutropenic patients (23% versus 5%; P = 0.05). Multivariate analysis of these differential characteristics showed that the only factor that independently predicted the presence of C. krusei fungaemia was the administration of antifungal agents before the fungaemia (RR: 6.4; P=0.009; 95%CI 1.6-25.99). Overall mortality of C. krusei fungaemia was 38% (C. albicans 49%). Except for voriconazole (MIC90 0.125 mg/L), azoles and 5-flucytosine had poor activity against C. krusei, whereas amphotericin (MIC90 1 mg/L) and LY-303366 (MIC90 0.06 mg/L) showed good activity.

CONCLUSION

C. krusei fungaemia incidence remains low despite widespread use of azoles. It may occur outside the setting of cancer patients with previous antifungal use. The presence of skin lesions should be a warning sign.

Glycosphingolipid structural analysis and glycosphingolipidomics

Sphingosines, or sphingoids, are a family of naturally occurring long-chain hydrocarbon derivatives sharing a common 1,3-dihydroxy-2-amino-backbone motif. The majority of sphingolipids, as their derivatives are collectively known, can be found in cell membranes in the form of amphiphilic conjugates, each composed of a polar head group attached to an N-acylated sphingoid, or ceramide. Glycosphingolipids (GSLs), which are the glycosides of either ceramide or myo-inositol-(1-O)-phosphoryl-(O-1)-ceramide, are a structurally and functionally diverse sphingolipid subclass; GSLs are ubiquitously distributed among all eukaryotic species and are found in some bacteria. Since GSLs are secondary metabolites, direct and comprehensive analysis (metabolomics) must be considered an essential complement to genomic and proteomic approaches for establishing the structural repertoire within an organism and deducing its possible functional roles. The glycosphingolipidome clearly comprises an important and extensive subset of both the glycome and the lipidome, but the complexities of GSL structure, biosynthesis, and function form the outlines of a considerable analytical problem, especially since their structural diversity confers by extension an enormous variability with respect to physicochemical properties. This chapter covers selected developments and applications of techniques in mass spectrometric (MS) that have contributed to GSL structural analysis and glycosphingolipidomics since 1990. Sections are included on basic characteristics of ionization and fragmentation of permethylated GSLs and of lithium-adducted nonderivatized GSLs under positive-ion electrospray ionization mass spectrometry (ESI-MS) and collision-induced mass spectrometry (CID-MS) conditions; on the analysis of sulfatides, mainly using negative-ion techniques; and on selected applications of ESI-MS and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) to emerging GSL structural, functional, and analytical issues. The latter section includes a particular focus on evolving techniques for analysis of gangliosides, GSLs containing sialic acid, as well as on characterizations of GSLs from selected nonmammalian eukaryotes, such as dipterans, nematodes, cestodes, and fungi. Additional sections focus on the issue of whether it is better to leave GSLs intact or remove the ceramide; on development and uses of thin-layer chromatography (TLC) blotting and TLC-MS techniques; and on emerging issues of high-throughput analysis, including the use of flow injection, liquid chromatography mass spectrometry (LC-MS), and capillary electrophoresis mass spectrometry (CE-MS).

Polymorphonuclear leukocytes (PMNs) induce protective Th1-type cytokine epithelial responses in an in vitro model of oral candidosis

The immune response and the anticandidal activity of keratinocytes and polymorphonuclear leukocytes (PMNs) play a key role in host defence against localized Candida albicans infection. An established model of oral candidosis based on reconstituted human oral epithelium (RHE) was supplemented with PMNs to study the effect of these immune cells during experimental oral candidosis. Infection of RHE with C. albicans induced a strong expression of the chemokine interleukin-8 (IL-8) and the cytokine granulocyte-macrophages colony-stimulating factor (GM-CSF), and a moderate stimulation of interleukin-1α (IL-1α), interleukin-1β (IL-1β), interleukin-6 (IL-6), interferon γ (IFN-γ) and tumour necrosis factor α (TNF-α) by keratinocytes. This immune response was associated with chemoattraction of PMNs to the site of infection, whereas uninfected RHE failed to induce cytokine expression or to attract PMNs. Growth of the pathogen and tissue damage of C. albicans-infected RHE were significantly reduced when PMNs were applied to the apical epithelial surface or when PMNs migrated through a perforated basal polycarbonate filter of the model. Notably, protection against epithelial tissue damage was also observed when PMNs were placed on the basal side of non-perforated filters, which prevented PMN migration into the RHE. Addition of PMNs enhanced a Th1-type immune response (IFN-γ, TNF-α), down-regulated the expression of the Th2-type cytokine interleukin-10 (IL-10), and was associated with protection against Candida-induced tissue damage. This PMN-supplemented model of oral candidosis mimics the in vivo situation, and provides a promising tool for studying the immunological interactions between keratinocytes and C. albicans, as well as the influence of PMNs on C. albicans pathogenesis.

Oral Fluconazole for Empiric Treatment of Prolonged Fever in Neutropenic Patients

Neutropenic patients who continue to be febrile despite adequate broad-spectrum antibacterial treatment require empirical antifungal therapy. The aim of the present study was to evaluate the safety and efficacy of oral fluconazole for empirical antifungal therapy in neutropenic patients with persistent fever. A prospective cohort design was used. The study sample included 250 consecutive patients with high-risk stage II, III, or responding metastatic breast cancer who received high-dose chemotherapy (HDC) with autologous peripheral blood progenitor stem cell transplantation. Those with neutropenic fever lasting more than 72 hours despite broad-spectrum antibacterial coverage were treated with fluconazole. Treatment was continued until fever dropped and/or neutrophil count recovered with blood cultures remaining negative. Antifungal treatment was required in 173 patients (69%). There were no cases of documented deep systemic fungal infection. Two patients (<1%) had positive blood cultures for fungi. None of the patients experienced toxicity related to fluconazole. There was one transplant-related death. Thirty-one patients (18%) were unable to complete the oral fluconazole protocol because of severe mucositis, and they received intravenous fluconazole at the same dose, with similar efficacy. Oral fluconazole is a safe and effective alternative to amphotericin B for empirical early antifungal treatment in persistent neutropenic fever in breast cancer patients undergoing HDC with autologous stem cell support. Further study of oral fluconazole and amphotericin B as empirical agents in other groups of patients with persistent neutropenic fever is warranted.

Synthesis, antimicrobial activity and chemotherapeutic potential of inorganic derivatives of 2-(4′-thiazolyl)benzimidazole{thiabendazole}: X-ray crystal structures of [Cu(TBZH)2Cl]Cl·H2O·EtOH and TBZH2NO3 (TBZH=thiabendazole)

Thiabendazole (TBZH) reacts with iron(III) nitrate causing protonation of the ligand to yield the nitrate salt [TBZH(2)NO(3)] (1). Reaction of TBZH with copper(II) acetate results in the deprotonation of the ligand yielding [Cu(TBZ)2.(H2O)2] (2). Reactions of TBZH with the chloride, nitrate and butanedioate salts of copper(II) yields [Cu(TBZH)2Cl]Cl.H2O.EtOH (3), [Cu(TBZH)(2)(NO(3))(2)] (4) and [Cu(TBZH)(O(2)C-CH(2)CH(2)-CO(2))] (5), respectively. The TBZH acts as a neutral chelating ligand in 3-5. Molecular structures of 1 and 3 were determined crystallographically. In 1, the asymmetric unit contains one TBZH(2)(+) cation and one NO(3)(-) anion. The structure of 3 comprises a five coordinate copper centre with the metal bound to two chelating TBZH ligands and one chloride. The geometry is best described as trigonal bipyramidal. Hydrogen bonding connects the complex cation with the uncoordinated chloride anion and the water and ethanol solvate molecules. Compound 1 and the copper complexes 2-5, the metal free ligands and a number of simple copper(II) salts were each tested for their ability to inhibit the growth of Candida albicans. The metal free TBZH and its nitrate salt (1) exhibited very poor activity. Complex 2, in which the TBZH is present as an anionic ligand (TBZ(-)), exhibits moderate activity towards the pathogen. Chelation of the neutral TBZH to copper centres (complexes 3-5) results in potent anti-candida activity. The dimethyl sulphoxide (DMSO) soluble complexes 3 and 4, along with metal free TBZH were assessed for their cancer chemotherapeutic potential towards two human epithelial-derived cancer model cell lines. Complexes 3 and 4 displayed similar dose-dependent cytotoxicity in both cell lines with IC(50) values of approximately 50 microM, which were found to be significantly lower than that for metal free TBZH.

Efficacy, safety, and plasma pharmacokinetics of escalating dosages of intravenously administered ravuconazole lysine phosphoester for treatment of experimental pulmonary aspergillosis in persistently neutropenic rabbits

Ravuconazole is a new antifungal triazole with broad-spectrum activity and a long half-life in plasma. We studied the antifungal efficacy, safety, and pharmacokinetics of ravuconazole lysine phosphoester in escalating dosages for the treatment of invasive pulmonary aspergillosis due to Aspergillus fumigatus in persistently neutropenic rabbits. Treatment groups consisted of rabbits treated with ravuconazole at 2.5 (RVC2.5), 5 (RVC5), and 10 (RVC10) mg/kg of body weight/day, rabbits treated with amphotericin B (AMB) at 1 mg/kg/day, or untreated controls. There was a dose-dependent reduction of pulmonary residual fungal burden (CFU per gram) in RVC5-, RVC10-, and AMB-treated rabbits in comparison to untreated controls (P < 0.01, P < 0.001, and P < 0.01, respectively). These findings correlated with progressive galactomannan antigenemia in untreated controls and the RVC2.5-treated rabbits, a lower galactomannan index (GMI) in RVC5- and RVC10-treated rabbits, and a similarly low GMI in AMB-treated rabbits (P < 0.01). Rabbits treated with RVC5, RVC10, and AMB also showed a reduction of organism-mediated pulmonary injury, as measured by infarct scores and lung weights, in comparison to untreated controls (P < 0.001). These results were supported by decreased pulmonary infiltrates detected by computed tomography in RVC5- and RVC10-treated rabbits in comparison to untreated controls (P < 0.05). Survival throughout the entire study was achieved in 95% of RVC5-treated rabbits (P < 0.001), 85% of RVC10-treated rabbits (P < 0.001), and 50% of AMB-treated rabbits (P < 0.05) in comparison to none of the untreated controls. Ravuconazole showed linear plasma pharmacokinetics and a large volume of distribution while maintaining concentrations in plasma above the MIC throughout the dosing interval. There was no evidence of hepatotoxicity or nephrotoxicity among ravuconazole-treated animals. Intravenously administered ravuconazole lysine phosphoester showed dose-dependent efficacy and an excellent safety profile for the treatment of invasive pulmonary aspergillosis in persistently neutropenic rabbits.

Aspergillus niger infection in patients with haematological diseases: a report of eight cases. Fallbericht. Aspergillus niger-Infektionen bei Patienten mit hamatologischen Erkrankungen

In this paper we analysed clinical, laboratory characteristics and outcome of patients with haematological diseases who developed an Aspergillus niger infection, in a multicentre study involving 14 Italian Haematological Divisions during a 10-year period. The study recorded 194 consecutive microbiologically documented aspergilloses, eight of which (4%) were due to A. niger, and were observed only in five of the participating centres. The primary localization of infection was lung in seven cases and paranasal sinus in one case. Seven patients died at the end of follow-up. The death was mainly attributable to A. niger progression in six of them. Our study that collected the largest number of cases of A. niger infection in haematological malignancies confirms that this infrequent complication is characterized by a high mortality rate.

Approaches towards the stabilization of hemiaminal function at ornithine unit of mulundocandin

Semisynthetic modifications at position-12 (ornithine-5-position, hemiaminal function) of mulundocandin were carried out to improve its chemical stability. New carbon-carbon (C-C) and carbon-hydrogen (C-H) linkage at hemiaminal function -12 has been achieved. Lewis acid catalyzed introduction of electron rich aryl group at position-12 of mulundocandin is developed. Synthesized mulundocandin analogues were evaluated for their chemical stability and antifungal activity against C. albicans and A. fumigatus.

A new group of antifungal and antibacterial lipopeptides derived from non-membrane active peptides conjugated to palmitic acid

We report on the synthesis, biological function, and a plausible mode of action of a new group of lipopeptides with potent antifungal and antibacterial activities. These lipopeptides are derived from positively charged peptides containing d- and l-amino acids (diastereomers) that are palmitoylated (PA) at their N terminus. The peptides investigated have the sequence K(4)X(7)W, where X designates Gly, Ala, Val, or Leu (designated d-X peptides). The data revealed that PA-d-G and PA-d-A gained potent antibacterial and antifungal activity despite the fact that both parental peptides were completely devoid of any activity toward microorganisms and model phospholipid membranes. In contrast, PA-d-L lost the potent antibacterial activity of the parental peptide but gained and preserved partial antifungal activity. Interestingly, both d-V and its palmitoylated analog were inactive toward bacteria, and only the palmitoylated peptide was highly potent toward yeast. Both PA-d-L and PA-d-V lipopeptides were also endowed with hemolytic activity. Mode of action studies were performed by using tryptophan fluorescence and attenuated total reflectance Fourier transform infrared and circular dichroism spectroscopy as well as transmembrane depolarization assays with bacteria and fungi. The data suggest that the lipopeptides act by increasing the permeability of the cell membrane and that differences in their potency and target specificity are the result of differences in their oligomeric state and ability to dissociate and insert into the cytoplasmic membrane. These results provide insight regarding a new approach of modulating hydrophobicity and the self-assembly of non-membrane interacting peptides in order to endow them with both antibacterial and antifungal activities urgently needed to combat bacterial and fungal infections.

Newer Systemic Antifungal Agents

The past few years have seen the advent of several new antifungal agents, including those of a new class and a new generation of an existing class. Caspofungin, the first available echinocandin, has greatly expanded the antifungal armamentarium by providing a cell wall-active agent with candidacidal activity as well as demonstrated clinical efficacy in the therapy of aspergillosis refractory to available therapy. In addition, in clinical trials, caspofungin had comparable efficacy to amphotericin B for candidaemia and invasive Candida infections. Caspofungin and two more recently introduced echinocandins, micafungin and anidulafungin, are available as intravenous formulations only and characterised by potent anti-candidal activity, as well as few adverse events and drug interactions. Voriconazole, the first available second-generation triazole, available in both intravenous and oral formulations, has added a new and improved therapeutic option for primary therapy of invasive aspergillosis and salvage therapy for yeasts and other moulds. In a randomised trial, voriconazole demonstrated superior efficacy and a survival benefit compared with amphotericin B followed by other licensed antifungal therapy. This and data from a noncomparative study led to voriconazole becoming a new standard of therapy for invasive aspergillosis. Voriconazole has several important safety issues, including visual adverse events, hepatic enzyme elevation and skin reactions, as well as a number of drug interactions. Posaconazole, only available orally and requiring dose administration four times daily, shows encouraging efficacy in difficult to treat infections due to zygomycetes. Ravuconazole, available in both intravenous and oral formulations, has broad-spectrum in vitro potency and in vivo efficacy against a wide range of fungal pathogens. Clinical studies are underway. Despite the advances offered with each of these drugs, the morbidity and mortality associated with invasive fungal infections remains unacceptable, especially for the most at-risk patients. For individuals with severe immunosuppression as a result of chemotherapy, graft-versus-host disease and its therapy, or transplantation, new drugs and strategies are greatly needed.

Glycosphingolipids of the model fungus Aspergillus nidulans: characterization of GIPCs with oligo-alpha-mannose-type glycans

Aspergillus nidulans is a well-established nonpathogenic laboratory model for the opportunistic mycopathogen, A. fumigatus. Some recent studies have focused on possible functional roles of glycosphingolipids (GSLs) in these fungi. It has been demonstrated that biosynthesis of glycosylinositol phosphorylceramides (GIPCs) is required for normal cell cycle progression and polarized growth in A. nidulans (Cheng, J., T.-S. Park, A. S. Fischl, and X. S. Ye. 2001. Mol. Cell Biol. 21: 6198-6209); however, the structures of A. nidulans GIPCs were not addressed in that study, nor were the functional significance of individual structural variants and the downstream steps in their biosynthesis. To initiate such studies, acidic GSL components (designated An-2, -3, and -5) were isolated from A. nidulans and subjected to structural characterization by a combination of one-dimensional (1-D) and 2-D NMR spectroscopy, electrospray ionization-mass spectrometry (ESI-MS), ESI-MS/collision-induced decomposition-MS (MS/CID-MS), ESI-pseudo-[CID-MS]2, and gas chromatography-MS methods. All three were determined to be GIPCs, with mannose as the only monosaccharide present in the headgroup glycans; An-2 and An-3 were identified as di- and trimannosyl inositol phosphorylceramides (IPCs) with the structures Man alpha 1-->3Man alpha 1-->2Ins1-P-1Cer and Man alpha 1-->3(Man alpha 1-->6)Man alpha 1-->2Ins1-P-1Cer, respectively (where Ins = myo-inositol, P = phosphodiester, and Cer = ceramide). An-5 was partially characterized, and is proposed to be a pentamannosyl IPC, based on the trimannosyl core structure of An-3.

Continuous infusion of escalated doses of amphotericin B deoxycholate: an open-label observational study

Amphotericin B deoxycholate (AmB-d) remains a mainstay of antifungal therapy for immunocompromised patients, despite being associated with significant therapy-related toxicity. Because continuous infusion of AmB-d is better tolerated than traditional administration over 2-6 hours, we evaluated escalation of the AmB-d dose in 33 patients (31 of whom were neutropenic), for whom the initial dosage of AmB-d (1 mg/kg/day) was gradually increased to 2.0 mg/kg/day when renal function remained stable and the drug was tolerated. Dose escalation was possible without delay in 28 patients. Median duration of AmB-d therapy was 16 days (range, 7-72 days). Infusion-related reactions accompanied <18% of AmB-d infusions. Twenty-seven patients had a decrease in creatinine clearance while receiving AmB-d therapy. A >2-fold decrease in creatine clearance was observed in 5 patients, and the decrease was dose-limiting in only 1 patient; no dialysis was required. In conclusion, continuous infusion of AmB-d escalated to 2.0 mg/kg/day seems not to cause additional impairment of vital organ functions and to be well tolerated by most patients.

Pathogenic molds (including Aspergillus species) in hospital water distribution systems: a 3-year prospective study and clinical implications for patients with hematologic malignancies

The incidence of mold infections in patients with hematologic malignancies continues to increase despite the widespread use of air filtration systems, suggesting the presence of other hospital sources for these molds. Water sources are known to harbor pathogenic molds. We examined samples from water, water surfaces, air, and other environment sources from a bone marrow transplantation unit with optimal air precautions. Molds (Aspergillus species, others) were recovered in 70% of 398 water samples, in 22% of 1311 swabs from plumbing structures and environmental surfaces, and in 83% of 274 indoor air samples. Microscopic examination of the water plumbing lines revealed hyphal forms compatible with molds. Four findings suggest that indoor airborne molds were aerosolized from the water: (1) higher mean airborne concentrations of molds in bathrooms (16.1 colony-forming units [CFU]/m(3)) than in patient rooms (7 CFU/m(3)) and hallways (8.6 CFU/m(3); P =.00005); (2) a strong type and rank correlation between molds isolated from hospital water and those recovered from indoor hospital; (3) lack of seasonal correlation between the airborne mold concentration in outdoor and indoor air; and (4) molecular relatedness between a clinical strain and a water-related strain (previously reported). Hospital water distribution systems may serve as a potential indoor reservoir of Aspergillus and other molds leading to aerosolization of fungal spores and potential exposure for patients.

Immunomodulation of invasive fungal infections

Genetic and acquired (disease- or therapy- related) host immune factors increase the risk for IFIs. In addition to antifungal drug therapy, modulation of host defenses by the use of HGFs and IFN-gamma has been supported by extensive in vitro and in vivo preclinical data. Clinical studies on the prevention or the adjunctive therapy of IFIs in combination with antifungal agents are limited, however, and do not allow specific recommendations for their cost-effective use in most of the immunodeficient settings. There is an urgent need to push forward with well-structured, randomized clinical trials to determine optimal dose, duration, and timing for different combinations of immunotherapy and antifungal agents in high-risk patients.

Nephrotoxicity of iopamidol in pediatric, adolescent, and young adult patients who have undergone allogeneic bone marrow transplantation

PURPOSE

To assess the effects of the low-osmolar contrast agent iopamidol and antimicrobial drugs on renal function in pediatric, adolescent, and young adult patients who have undergone bone marrow transplantation (BMT).

MATERIALS AND METHODS

A retrospective review of records of 120 consecutive pediatric patients who underwent allogeneic BMT in 1997 or 1998 was performed. Eighty-nine patients (median age, 8.1 years) fulfilled study eligibility criteria. Cumulative doses of nephrotoxic antimicrobial drugs were recorded, as well as serum creatinine and blood urea nitrogen concentrations from 24 hours before to 72 hours after each administration of iopamidol during a computed tomographic examination performed within 100 days after BMT. Random coefficient models were used to estimate nephrotoxic effects.

RESULTS

Mean baseline glomerular filtration rate was 130.2 mL/min/1.73 m(2), and mean baseline creatinine concentration was 0.51 mg/dL (45 micro mol/L). Older age at BMT (P <.001), use of foscarnet (P =.003), and receipt of iopamidol (P =.073) each prompted a rise in serum creatinine concentration. The antiviral drug foscarnet was associated with the largest increase in the creatinine level; the use of iopamidol effected a relatively small rise in creatinine level.

CONCLUSION

Iopamidol nephrotoxicity was negligible in this cohort of pediatric patients who had undergone allogeneic BMT, even in the presence of elevated renal function levels.

Cleaning patient shower facilities: a novel approach to reducing patient exposure to aerosolized Aspergillus species and other opportunistic molds

We previously have demonstrated that the hospital water-distribution system could be a reservoir for airborne molds that leads to secondary aerosolization of these molds in patient shower facilities. In this report, we show that cleaning the floors of patient shower facilities in a bone marrow transplantation unit reduced the mean air concentrations of molds, including Aspergillus species (from 12 cfu/m3 to 4 cfu/m3; P=.0047).

Cutaneous infection by Fusarium species in healthy and immunocompromised hosts: implications for diagnosis and management

Infections by Fusarium species frequently involve the skin, either as the primary or the metastatic site. To better understand the pathophysiology of these infections, 43 new patients with fusariosis were evaluated, and the literature was reviewed. A total of 259 patients (232 immunocompromised and 27 immunocompetent) were identified. Skin involvement was present in 70% of patients, particularly in immunocompromised patients (72% vs. 52%; P=.03). In immunocompetent patients, cutaneous infections were characterized by preceding skin breakdown, localized involvement, slow pace of progression, and good response to therapy. In contrast, skin involvement in immunocompromised patients was only occasionally preceded by skin breakdown and typically was presented as rapidly progressive disseminated lesions at various stages of evolution. Metastatic skin lesions were associated with fungemia, neutropenia, and death. Skin was the single source of diagnosis for the majority of immunocompromised and immunocompetent patients. Recommendations for the prevention of fatal fusariosis originating from skin are presented.

Frequency and clinical significance of bloodstream infections caused by C albicans strains with reduced susceptibility to fluconazole

Reduced susceptibility to fluconazole (RSF) is relatively common in non-albicans Candida isolates and in Candida albicans recovered from HIV-infected patients with relapsing Candida stomatitis or esophagitis. However, little clinical data on bloodstream infections caused by C. albicans with RSF is available. We analyzed 116 episodes of C. albicans fungemia detected over an 11-year period. Four patients (3.4%) had a blood isolate of C. albicans with RSF. Fluconazole MICs were 16 (3 SDD strains) and 128 microg/ml (1 resistant strain), respectively. Three of the patients were HIV (+) and the fourth was a liver transplant recipient. All of them had been previously treated with an azole compound. The liver recipient had breakthrough fungemia while being treated with 400 mg of preemptive fluconazole despite having an MIC of 16 microg/ml. Fluconazole clinical failure was documented in two of the remaining three cases. Only five other patients with C. albicans fungemia caused by fluconazole-resistant strains (>or=64 microg/ml) are described in the literature. Candida albicans fungemia produced by strains with RSF is still uncommon. It should be suspected in patients previously treated with azole agents or with breakthrough fungemia. In our experience, fluconazole remains a safe option for the treatment of most C. albicans fungemias, although surveillance seems advisable.

Comparative antifungal activities and plasma pharmacokinetics of micafungin (FK463) against disseminated candidiasis and invasive pulmonary aspergillosis in persistently neutropenic rabbits

Micafungin (FK463) is an echinocandin that demonstrates potent in vitro antifungal activities against Candida and Aspergillus species. However, little is known about its comparative antifungal activities in persistently neutropenic hosts. We therefore investigated the plasma micafungin pharmacokinetics and antifungal activities of micafungin against experimental disseminated candidiasis and invasive pulmonary aspergillosis in persistently neutropenic rabbits. The groups with disseminated candidiasis studied consisted of untreated controls (UCs); rabbits treated with desoxycholate amphotericin B (DAMB) at 1 mg/kg of body weight/day; or rabbits treated with micafungin at 0.25, 0.5, 1, and 2 mg/kg/day intravenously. Compared with the UCs, rabbits treated with micafungin or DAMB showed significant dosage-dependent clearance of Candida albicans from the liver, spleen, kidney, brain, eye, lung, and vena cava. These in vivo findings correlated with the results of in vitro time-kill assays that demonstrated that micafungin has concentration-dependent fungicidal activity. The groups with invasive pulmonary aspergillosis studied consisted of UCs; rabbits treated with DAMB; rabbits treated with liposomal amphotericin B (LAMB) at 5 mg/kg/day; and rabbits treated with micafungin at 0.5, 1, and 2 mg/kg/day. In comparison to the significant micafungin dosage-dependent reduction of the residual burden (in log CFU per gram) of C. albicans in tissue, micafungin-treated rabbits with invasive pulmonary aspergillosis had no reduction in the concentration of Aspergillus fumigatus in tissue. DAMB and LAMB significantly reduced the burdens of C. albicans and A. fumigatus in tissues (P < 0.01). Persistent galactomannan antigenemia in micafungin-treated rabbits correlated with the presence of an elevated burden of A. fumigatus in pulmonary tissue. By comparison, DAMB- and LAMB-treated animals had significantly reduced circulating galactomannan antigen levels. Despite a lack of clearance of A. fumigatus from the lungs, there was a significant improvement in the rate of survival (P < 0.001) and a reduction in the level of pulmonary infarction (P < 0.05) in micafungin-treated rabbits. In summary, micafungin demonstrated concentration-dependent and dosage-dependent clearance of C. albicans from persistently neutropenic rabbits with disseminated candidiasis but not of A. fumigatus from persistently neutropenic rabbits with invasive pulmonary aspergillosis.

Antifungal activities of posaconazole, ravuconazole, and voriconazole compared to those of itraconazole and amphotericin B against 239 clinical isolates of Aspergillus spp. and other filamentous fungi: report from SENTRY Antimicrobial Surveillance Program, 2000

Posaconazole, ravuconazole, and voriconazole are new triazole derivatives that possess potent, broad-spectrum antifungal activity. We evaluated the in vitro activity of these investigational triazoles compared with that of itraconazole and amphotericin B against 239 clinical isolates of filamentous fungi from the SENTRY Program, including Aspergillus spp. (198 isolates), Fusarium spp. (7 isolates), Penicillium spp. (19 isolates), Rhizopus spp. (4 isolates), Mucor spp. (2 isolates), and miscellaneous species (9 isolates). The isolates were obtained from 16 different medical centers in the United States and Canada between January and December 2000. In vitro susceptibility testing was performed using the microdilution broth method outlined in the National Committee for Clinical Laboratory Standards M38-P document. Overall, posaconazole was the most active compound, inhibiting 94% of isolates at a MIC of < or = 1 microg/ml, followed by voriconazole (91%), amphotericin B (89%), ravuconazole (88%), and itraconazole (70%). All three new triazoles demonstrated excellent activity (MIC, < or = 1 microg/ml) against Aspergillus spp. (114 Aspergillus fumigatus, 22 Aspergillus niger, 13 Aspergillus flavus, 9 Aspergillus versicolor, 8 Aspergillus terreus, and 32 Aspergillus spp.): posaconazole (98%), voriconazole (98%), ravuconazole (92%), amphotericin B (89%), and itraconazole (72%). None of the triazoles were active against Fusarium spp. (MIC at which 50% of the isolates tested were inhibited [MIC(50)], >8 microg/ml) or Mucor spp. (MIC(50), >8 microg/ml). Posaconazole and ravuconazole were more active than voriconazole against Rhizopus spp. (MIC(50), 1 to 2 microg/ml versus >8 microg/ml, respectively). Based on these results, all three new triazoles exhibited promising activity against Aspergillus spp. and other less commonly encountered isolates of filamentous fungi. The clinical value of these in vitro data remains to be seen, and in vitro-in vivo correlation is needed for both new and established antifungal agents. Surveillance efforts should be expanded in order to monitor the spectrum of filamentous fungal pathogens and their in vitro susceptibility as these new antifungal agents are introduced into clinical use.

Insights into the selective inhibition of Candida albicans secreted aspartyl protease: a docking analysis study

Severe fungal infections have taken precedence over other bacterial infections. Of the several fungal species, Candida albicans and others belonging to the genus Candida are responsible for several clinically important fungal infections. Emerging cases of drug resistance to the currently available drugs has limited the spectrum of currently available antifungal agents. Thus, it is imperative that new biochemical targets are identified so that better effective and selective agents can be developed. Many enzymes contribute towards the complex disease process of fungal infections; the secreted aspartyl protease (SAP), expressed both in vitro and during infection, has been implicated as one of the major virulence factors of C. albicans. Three-dimensional crystal structures of C. albicans SAP and closely related clinical isolate designated as SAP2X complexed with the same potent inhibitor A-70450 have been reported. Several analogues of A-70450 with potent C. albicans SAP2X inhibitory activity are also known. However, the structural effects of the binding of these compounds with the enzyme active site are not completely understood. Our efforts in this direction involve the docking analysis of C. albicans SAP2X inhibitors complexed with SAP2X enzyme, which is reported in this work. Docking analysis was performed on a set of molecules with differing selectivities and inhibitory potencies towards C. albicans, renin and cathepsin D. The structural effects of ligand binding were analyzed on the basis of hydrophobic and hydrogen bond interactions, binding energy analysis, interaction energies, rms deviations, etc. in the resulting energy-minimized structures of the receptor-ligand complexes. Structural analysis of the resulting models indicates that hydrophobic and hydrogen bonding interactions together with binding and interaction energies are responsible for selective inhibition of C. albicans SAP2X. Hydrophobic and hydrogen bonding interactions in the various subsites of the enzyme, contributing to both increase as well as decrease in selectivity of the molecules have been detailed. Hydrogen bonding interaction plays an important role for amino acid residues such as Gly-85, Asp-86, Asp-32, Asp-218, Tyr-225, Ala-133, and so on. Significant hydrophobic interactions with the S3, S2 and S2' subsites contribute to selectivity of the compounds. These molecular modeling analyses should, in our view, contribute for further development of selective C. albicans secreted aspartyl protease inhibitors.

Uncommon opportunistic fungi: new nosocomial threats

During the past two decades opportunistic fungal infections have emerged as important causes of morbidity and mortality in patients with severe underlying illnesses and compromised host defenses. While Aspergillus and Candida spp. collectively account for the majority of these infections, recent epidemiological trends indicate a shift towards infections by Aspergillus spp., nonalbicans Candida spp., as well as previously uncommon opportunistic fungi. Apart from an expanding number of different Zygomycetes, previously uncommon hyaline filamentous fungi (such as Fusarium species, Acremonium species, Paecilomyces species, Pseudallescheria boydii, and Scedosporium prolificans), dematiaceous filamentous fungi (such as Bipolaris species, Cladophialophora bantiana, Dactylaria gallopava, Exophiala species, and Alternaria species) and yeast-like pathogens (such as Trichosporon species, Blastoschizomyces capitatus, Malassezia species, Rhodotorula rubra and others) are increasingly encountered as causing life threatening invasive infections that are often refractory to conventional therapies. On the basis of past and current trends, the spectrum of fungal pathogens will continue to evolve in the settings of an expanding population of immunocompromised hosts, selective antifungal pressures, and shifting conditions in hospitals and the environment. An expanded and refined drug arsenal, further elucidation of pathogenesis and resistance mechanisms, establishment of in vitro/in vivo correlations, incorporation of pharmacodynamics, combination- and immunotherapies offer hope for substantial progress in prevention and treatment.

Antifungal efficacy of caspofungin (MK-0991) in experimental pulmonary aspergillosis in persistently neutropenic rabbits: pharmacokinetics, drug disposition, and relationship to galactomannan antigenemia

The antifungal efficacy, pharmacokinetics, and safety of caspofungin (CAS) were investigated in the treatment and prophylaxis of invasive pulmonary aspergillosis due to Aspergillus fumigatus in persistently neutropenic rabbits. Antifungal therapy consisted of 1, 3, or 6 mg of CAS/kg of body weight/day (CAS1, CAS3, and CAS6, respectively) or 1 mg of deoxycholate amphotericin B (AMB)/kg/day intravenously for 12 days starting 24 h after endotracheal inoculation. Prophylaxis (CAS1) was initiated 4 days before endotracheal inoculation. Rabbits treated with CAS had significant improvement in survival and reduction in organism-mediated pulmonary injury (OMPI) measured by pulmonary infarct score and total lung weight (P < 0.01). However, animals treated with CAS demonstrated a paradoxical trend toward increased residual fungal burden (log CFU per gram) and increased serum galactomannan antigen index (GMI) despite improved survival. Rabbits receiving prophylactic CAS1 also showed significant improvement in survival and reduction in OMPI (P < 0.01), but there was no effect on residual fungal burden. In vitro tetrazolium salt hyphal damage assays and histologic studies demonstrated that CAS had concentration- and dose-dependent effects on hyphal structural integrity. In parallel with a decline in GMI, AMB significantly reduced the pulmonary tissue burden of A. fumigatus (P < or = 0.01). The CAS1, CAS3, and CAS6 dose regimens demonstrated dose-proportional exposure and maintained drug levels in plasma above the MIC for the entire 24-h dosing interval at doses that were > or =3 mg/kg/day. As serial galactomannan antigen levels may be used for therapeutic monitoring, one should be aware that profoundly neutropenic patients receiving echinocandins for aspergillosis might have persistent galactomannan antigenemia despite clinical improvement. CAS improved survival, reduced pulmonary injury, and caused dose-dependent hyphal damage but with no reduction in residual fungal burden or galactomannan antigenemia in persistently neutropenic rabbits with invasive pulmonary aspergillosis.