Improved outcomes associated with advances in therapy for invasive fungal infections in immunocompromised hosts

Identifying genetic susceptibility to Aspergillus fumigatus infection using collaborative cross mice and RNA-Seq approach

BACKGROUND

Aspergillus fumigatus (Af) is one of the most ubiquitous fungi and its infection potency is suggested to be strongly controlled by the host genetic background. The aim of this study was to search for candidate genes associated with host susceptibility to Aspergillus fumigatus (Af) using an RNAseq approach in CC lines and hepatic gene expression.

METHODS

We studied 31 male mice from 25 CC lines at 8 weeks old; the mice were infected with Af. Liver tissues were extracted from these mice 5 days post-infection, and next-generation RNA-sequencing (RNAseq) was performed. The GENE-E analysis platform was used to generate a clustered heat map matrix.

RESULTS

Significant variation in body weight changes between CC lines was observed. Hepatic gene expression revealed 12 top prioritized candidate genes differentially expressed in resistant versus susceptible mice based on body weight changes. Interestingly, three candidate genes are located within genomic intervals of the previously mapped quantitative trait loci (QTL), including Gm16270 and Stox1 on chromosome 10 and Gm11033 on chromosome 8.

CONCLUSIONS

Our findings emphasize the CC mouse model's power in fine mapping the genetic components underlying susceptibility towards Af. As a next step, eQTL analysis will be performed for our RNA-Seq data. Suggested candidate genes from our study will be further assessed with a human cohort with aspergillosis.

Polyene Antibiotics Physical Chemistry and Their Effect on Lipid Membranes; Impacting Biological Processes and Medical Applications

This review examined a collection of studies regarding the molecular properties of some polyene antibiotic molecules as well as their properties in solution and in particular environmental conditions. We also looked into the proposed mechanism of action of polyenes, where membrane properties play a crucial role. Given the interest in polyene antibiotics as therapeutic agents, we looked into alternative ways of reducing their collateral toxicity, including semi-synthesis of derivatives and new formulations. We follow with studies on the role of membrane structure and, finally, recent developments regarding the most important clinical applications of these compounds.

The antifungal activity of caspofungin in combination with antifungals or non-antifungals against Candida species in vitro and in clinical therapy

Introduction: Candida species have been regarded as global health threats due to their ability to cause invasive infections. It is challenging to treat Candida bloodstream infections, which are associated with high mortality levels. Monotherapy with antifungals is sometimes not effective against severe Candida infections, and combination therapy is needed in clinical practice.Areas covered: This review was undertaken based on data from a PubMed search for English language reports published before March 2021 by using the terms 'caspofungin,' 'Candida species,' 'combination therapy,' 'antifungal effect,' and 'novel antifungal agent.'Expert opinion: Combination therapy is an empirical strategy for treating refractory Candida infections. Caspofungin has been recommended to treat candidaemia. Caspofungin in combination therapy has some applications, while the efficacy of combination therapy in the treatment of refractory Candida infections needs more study, such as randomized controlled trials. In addition, novel compounds or drugs with potential antifungal activities have been examined, and some of them exhibit synergistic interactions with caspofungin. Thus, the antifungal activity of caspofungin in combination with antifungals or non-antifungals against Candida species in vitro and in clinical therapy is summarized.

Selection and characterization of toxic Aspergillus spore-specific DNA aptamer using spore-SELEX

As airborne spores of toxic Aspergillus species cause mild symptoms to invasive fungal infections, their indoor concentration should be controlled through real-time management. Aptamer-based biosensors could provide economical and simple solutions for point-of-care. In this study, we isolated aptamers binding to the spores of three representative toxic Aspergillus species (A. fumigatus, A. flavus, and A. niger) for the first time, using cell-SELEX (systematic evolution of ligands through exponential enrichment). Among the aptamer candidates, Asp-3 showed a broad and high binding affinity for the Aspergillus spores. Considering the low binding affinity with proteinase-treated spores, we speculated that the Asp-3 binding sites could be possibly associated with cell surface proteins. The high Asp-3 specificity was confirmed by comparing the binding affinity between the Aspergillus target species and other common indoor fungal species. Moreover, we also established quantitative linear relationships between Asp-3 and the spore concentration of each Aspergillus species. Therefore, the selected Asp-3 aptamer, conjugated with detection sensors, could be an effective biorecognition element for the spores of three toxic Aspergillus species.

Novel Sulfones with Antifungal Properties: Antifungal Activities and Interactions with Candida spp. Virulence Factors

Since candidiasis is so difficult to eradicate with an antifungal treatment and the existing antimycotics display many limitations, hopefully new sulfone derivatives may overcome these deficiencies. It is pertinent to study new strategies such as sulfone derivatives targeting the virulence attributes of C. albicans that differentiate them from the host. During infections, the pathogenic potential of C. albicans relies on the virulence factors as follows: hydrolytic enzymes, transcriptional factors, adhesion, and development of biofilms. In the article we explored how the above-presented C. albicans fitness and virulence attributes provided a robust response to the environmental stress exerted by sulfones upon C. albicans; C. albicans fitness and virulence attributes are fungal properties whose inactivation attenuates virulence. Our understanding of how these mechanisms and factors are inhibited by sulfones has increased over the last years. As lack of toxicity is a prerequisite for medical approaches, sulfones (non-toxic as assessed in vitro and in vivo) may prove to be useful for reducing C. albicans pathogenesis in humans. The antifungal activity of sulfones dealing with these multiple virulence factors and fitness attributes is discussed.

Microfluidic System for Rapid Detection of Airborne Pathogenic Fungal Spores

Airborne fungi, including Aspergillus species, are the major causes of human asthma. Direct capture and analysis of pathogenic fungi in indoor air is important for disease prevention and control. In this paper, we demonstrated an integrated microfluidic system capable of enrichment and high-throughput detection for airborne fungal spores of Aspergillus niger, a well-known allergenic harmful species. The microfluidic system allowed semiquantitative detection of Aspergillus niger spores based on immunofluorescence analysis. To assess its contaminated level, the whole analysis time could be completed in 2-3 h including ∼1 h of enrichment and ∼1 h of target detection. The detection limit was ∼20 spores, equivalent to ∼300 spores·m^-3 of the concerned targets in air. In addition, the microfluidic system has integrated sampling and sample analysis to avoid additional sample concentration step, showing the potential for point-of-care detection for other pathogenic fungal spores.

Long QT Syndrome Leading to Multiple Cardiac Arrests After Posaconazole Administration in an Immune-Compromised Patient with Sepsis: An Unusual Case Report

BACKGROUND

We present the case of a septic patient with severe immunodeficiency, who developed QT interval prolongation followed by episodes of lethal cardiac arrhythmia. Cardiac events occurred after posaconazole administration, incriminating posaconazole use, alone or in combination with voriconazole, as the culpable agent.

CASE REPORT

A 26-year-old female patient underwent orthopedic surgery to remove ectopic calcifications in her left hip joint. On the first post-operative day she became septic due to a surgical wound infection. Despite being treated according to the therapeutic protocols for sepsis, no clinical improvement was noticed and further assessment revealed an underlying immunodeficiency. Considering the underlying immunodeficiency and to that point poor clinical response, an antifungal agent was added to the antibiotic regiment. Following discontinuation of multiple antifungal agents due to adverse effects, posaconazole was administered. Posaconazole oral intake was followed by episodes of bradycardia and QT interval prolongation. The patient suffered continuous incidents of cardiac arrest due to polymorphic ventricular tachycardia (torsades des pointes) that degenerated to lethal ventricular fibrillation. Posaconazole was immediately discontinued and a temporary pacemaker was installed. The patient finally recovered without any neurological deficit, and was discharged in a good clinical status.

CONCLUSIONS

Close cardiac monitoring is recommended in cases where posaconazole administration is combined with coexisting risk factors, as they may lead to severe ECG abnormalities and cardiac arrhythmias such as long QT interval syndrome and torsades de pointes. Posaconazole interactions with medications metabolized via the CYP3A4 pathway should be considered an additional risk factor for lethal cardiac incidents.

Assessment of efficacy of antifungals against Aspergillus fumigatus: value of real-time bioluminescence imaging

Aspergillus fumigatus causes life-threatening infections, especially in immunocompromised patients. Common drugs for therapy of aspergillosis are polyenes, azoles, and echinocandins. However, despite in vitro efficacy of these antifungals, treatment failure is frequently observed. In this study, we established bioluminescence imaging to monitor drug efficacy under in vitro and in vivo conditions. In vitro assays confirmed the effectiveness of liposomal amphotericin B, voriconazole, and anidulafungin. Liposomal amphotericin B and voriconazole were fungicidal, whereas anidulafungin allowed initial germination of conidia that stopped elongation but allowed the conidia to remain viable. In vivo studies were performed with a leukopenic murine model. Mice were challenged by intranasal instillation with a bioluminescent reporter strain (5 × 10(5) and 2.5 × 10(5) conidia), and therapy efficacies of liposomal amphotericin B, voriconazole, and anidulafungin were monitored. For monotherapy, the highest treatment efficacy was observed with liposomal amphotericin B, whereas the efficacies of voriconazole and anidulafungin were strongly dependent on the infectious dose. When therapy efficacy was studied with different drug combinations, all combinations improved the rate of treatment success compared to that with monotherapy. One hundred percent survival was obtained for treatment with a combination of liposomal amphotericin B and anidulafungin, which prevented not only pulmonary infections but also infections of the sinus. In conclusion, combination therapy increases treatment success, at least in the murine infection model. In addition, our novel approach based on real-time imaging enables in vivo monitoring of drug efficacy in different organs during therapy of invasive aspergillosis.

Overview of invasive fungal infections

The incidence of invasive fungal infections (IFIs) has seen a marked increase in the last two decades. This is especially evident among transplant recipients, patients suffering from AIDS, in addition to those in receipt of immunosuppressive therapy. Worryingly, this increased incidence includes infections caused by opportunistic fungi and emerging fungal infections which are resistant to or certainly less susceptible than others to standard antifungal agents. As a direct response to this phenomenon, there has been a resolute effort over the past several decades to improve early and accurate diagnosis and provide reliable screening protocols thereby promoting the administration of appropriate antifungal therapy for fungal infections. Early diagnosis and treatment with antifungal therapy are vital if a patient is to survive an IFI. Substantial advancements have been made with regard to both the diagnosis and subsequent treatment of an IFI. In parallel, stark changes in the epidemiological profile of these IFIs have similarly occurred, often in direct response the type of antifungal agent being administered. The effects of an IFI can be far reaching, ranging from increased morbidity and mortality to increased length hospital stays and economic burden.

Resistant Fusarium keratitis progressing to endophthalmitis

OBJECTIVE

To report a case of multidrug-resistant Fusarium sp keratitis that progressed to endophthalmitis and that eventually required enucleation.

METHODS

Case report and literature review. Isolate identification and susceptibility testing were performed by the Fungus Testing Laboratory at San Antonio, TX.

RESULTS

A 52-year-old soft contact lens wearer had a corneal abrasion and developed a corneal infiltrate. Examination of corneal scrapings revealed filamentous hyphae with septation and conidia. Despite aggressive antifungal therapy with topical natamycin, amphotericin B, and systemic fluconazole, the keratitis progressed, and a penetrating keratoplasty was performed. Histopathologic analysis of the corneal button showed disruption of Descemet's membrane with periodic acid-Schiff-positive fungal hyphae on both sides. Recurrent infection of the graft and progression to endophthalmitis was treated with repeated intravitreal amphotericin B injections, repeat penetrating keratoplasties, and pars plana vitrectomies. Even after systemic use of itraconazole, voriconazole, and posaconazole and topical use of voriconazole, the infection progressed and an enucleation was required. Isolate identification and susceptibility testing found a multidrug-resistant Fusarium solani species complex, partially sensitive to natamycin only.

CONCLUSIONS

Multidrug-resistant Fusarium sp is rare and may have devastating consequences in patients with advanced keratitis progressing to endophthalmitis. Such an extensive multidrug resistance is surprising in that resistance to antifungal treatment is supposedly rare. Empirical antifungal therapy is usually instituted using one or more antifungal agents, without checking antifungal sensitivities. In light of the growing concern for increased emergence of resistant strains, we propose a lower threshold to check for sensitivities in the face of unresponsive fungal infections.

It only takes one to do many jobs: Amphotericin B as antifungal and immunomodulatory drug

“Amphotericin B acts through pore formation at the cell membrane after binding to ergosterol” is an accepted dogma about the action mechanism of this antifungal, and this sentence is widely found in the literature. But after 60 years of investigation, the action mechanism of Amphotericin B is not fully elucidated. Amphotericin B is a polyene substance that is one of the most effective drugs for the treatment of fungal and parasite infections. As stated above, the first mechanism of action described was pore formation after binding to the ergosterol present in the membrane. But it has also been demonstrated that AmB induces oxidative damage in the cells. Moreover, amphotericin B modulates the immune system, and this activity has been related to the protective effect of the molecule, but also to its toxicity in the host. This review tries to provide a general overview of the main aspects of this molecule, and highlight the multiple effects that this molecule has on both the fungal and host cells.

Multidisciplinary approach to the treatment of invasive fungal infections in adult patients. Prophylaxis, empirical, preemptive or targeted therapy, which is the best in the different hosts?

The high morbidity, mortality, and health care costs associated with invasive fungal infections, especially in the critical care setting and immunocompromised host, have made it an excellent target for prophylactic, empiric, and preemptive therapy interventions principally based on early identification of risk factors. Early diagnosis and treatment are associated with a better prognosis. In the last years there have been important developments in antifungal pharmacotherapy. An approach to the new diagnosis tools in the clinical mycology laboratory and an analysis of the use new antifungal agents and its application in different clinical situations has been made. Furthermore, an attempt of developing a state of the art in each clinical scenario (critically ill, hematological, and solid organ transplant patients) has been performed, trying to choose the best strategy for each clinical situation (prophylaxis, pre-emptive, empirical, or targeted therapy). The high mortality rates in these settings make mandatory the application of early de-escalation therapy in critically ill patients with fungal infection. In addition, the possibility of antifungal combination therapy might be considered in solid organ transplant and hematological patients.

Posaconazole: A new agent for the prevention and management of severe, refractory or invasive fungal infections

Posaconazole is the newest antifungal agent to be approved for use in Canada. With excellent in vitro activity against a broad spectrum of yeasts and filamentous fungi, as well as having a well-tolerated oral formulation, posaconazole offers many potential advantages. Of particular interest are its seemingly lower potential for cross-resistance with other azoles and its activity (unique among oral antifungal agents) against the zygomycetes. As the incidence of both common and uncommon fungal infections increases commensurate with the growing population of immunocompromised individuals, posaconazole may ultimately become an important therapeutic option. The present article reviews the in vitro and in vivo data describing its activity, and focuses on both the proven and the potential clinical applications of this new triazole agent.

Posaconazole in the management of refractory invasive fungal infections

The rising incidence of invasive fungal infections due to the expanding population of immunocompromised hosts and the increasing prevalence of fungal resistance has led to the need for novel antifungal agents. Posaconazole, a new member of the triazole class has demonstrated in vitro activity against a broad spectrum of fungi and clinical activity against various fungal pathogens, including Aspergillus spp., Candida spp., zygomycetes, and Fusarium spp. To date, posaconazole has been approved for prophylaxis of invasive fungal infections in stem cell transplant recipients with acute graft versus host disease (GVHD) and neutropenic patients receiving intensive induction chemotherapy for acute myelogenous leukemia and myelodys-plastic syndrome. In addition, it has been licensed for use in oropharyngeal candidiasis and for salvage therapy in invasive aspergillosis, fusariosis, coccidioidomycosis, chromoblastomycosis, and mycetoma. Posaconazole is the only azole with activity against zygomycetes and other difficult-to-treat fungi, representing a potential treatment option for refractory invasive mycosis. This article reviews available preclinical and clinical data of posaconazole, focusing on its role in the teatment of refractory invasive fungal infections.

Phagocytosis of melanized Aspergillus conidia by macrophages exerts cytoprotective effects by sustained PI3K/Akt signalling

Host cell death is a critical component of innate immunity and often determines the progression and outcome of infections. The opportunistic human pathogen Aspergillus fumigatus can manipulate the immune system either by inducing or by inhibiting host cell apoptosis dependent on its distinct morphological form. Here, we show that conidia of Aspergillus ssp. inhibit apoptosis of macrophages induced via the intrinsic (staurosporine) and extrinsic (Fas ligand) pathway. Hence, mitochondrial cytochrome c release and caspase activation were prevented. We further found that the anti-apoptotic effect depends on both host cell de novo protein synthesis and phagocytosis of conidia by macrophages. Moreover, sustained PI3K/Akt signalling in infected cells is an important determinant to resist apoptosis. We demonstrate that pigmentless pksP mutant conidia of A. fumigatus failed to trigger protection against apoptosis and provide evidence that the sustained survival of infected macrophages depends on the presence of the grey-green conidial pigment consisting of dihydroxynaphthalene-melanin. In conclusion, we revealed a novel potential function of melanin in the pathogenesis of A. fumigatus. For the first time, we show that melanin itself is a crucial component to inhibit macrophage apoptosis which may contribute to dissemination of the fungus within the host.

Antimicrobial therapy for the treatment of opportunistic infections in HIV/AIDS patients: a critical appraisal

The widespread use of antiretroviral therapy (ART) has entirely changed the management of human immunodeficiency virus (HIV) infection and dramatically reduced the rates of opportunistic infections (OI). However, OI continue to cause significant morbidity and mortality in both developed countries, where presentation with advanced HIV infection is common, and also in developing countries where ART is less widely available. Evidence to direct OI guidelines is partly limited by the fact that many large-scale studies date from the pre-ART era and more recent studies are sometimes poorly powered due to the falling rates of OI. Treatment of OI is now known to be as much about antimicrobials as about immune reconstitution with ART, and recent studies help guide the timing of initiation of ART in different infections. OI have also become complicated by the immune reconstitution inflammatory syndrome phenomenon which may occur once successful immune recovery begins. Trimethoprim-sulfamethoxazole has long been one of the most important antibiotics in the treatment and prevention of OI and remains paramount. It has a broad spectrum of activity against Pneumocystis jiroveci, toxoplasmosis, and bacterial infections and has an important role to play in preventing life-threatening OI. New advances in treating OI are coming from a variety of quarters: in cytomegalovirus eye disease, the use of oral rather than intravenous drugs is changing the face of therapy; in cryptococcal meningitis, improved drug formulations and combination therapy is improving clearance rates and reducing drug toxicities; and in gut disease, the possibility of rapid immune restitution with ART is replacing the need for antimicrobials against cryptosporidia and microsporidia.

Evaluation of the Etest method for susceptibility testing of Aspergillus spp. and Fusarium spp. to three echinocandins

We performed Etest and broth microdilution (BMD) susceptibility testing of caspofungin, micafungin and anidulafungin against 67 clinical isolates of Aspergillus spp. and 10 Fusarium spp. Minimal effective concentrations (MECs) by BMD were read after 24 h of incubation at 35 degrees C and Etest MICs were read at 24 and 48 h. MECs < or =0.25 mg/l were obtained with caspofungin for all Aspergillus spp. tested but Etest MICs were < or =1 mg/l at 24 h. The agreement between caspofungin Etest and broth microdilution was good for all Aspergillus species tested (range 82.4-100%) except for A. niger and A. glaucus at 24 h of incubation. Micafungin and anidulafungin MEC and MIC results were lower than those of caspofungin (< or =0.015 mg/l) at 24 and 48 h for all Aspergillus tested. The agreement between the methods was excellent (100%) for micafungin and anidulafungin for all Aspergillus species tested. The three echinocandins were inactive against all isolates of Fusarium spp. showing MECs and MICs >8 mg/l. The Etest method could be a suitable procedure to test the susceptibility of most Aspergillus species to caspofungin, micafungin and anidulafungin; the best agreement was at 24 h.

Overall survival and fungal infection-related mortality in patients with invasive fungal infection and neutropenia after myelosuppressive chemotherapy in a tertiary care centre from 1995 to 2006

Objectives

Invasive fungal infections (IFIs) contribute significantly to mortality and morbidity in patients receiving myelosuppressive chemotherapy for haematological malignancies. The present study investigates the overall survival (OS), infection-related mortality and changes in treatment of IFIs in our department from 1995 until 2006.

Methods

Outcomes of all chemotherapy courses were retrospectively evaluated using a standard questionnaire. Modified EORTC/MSG criteria for IFIs were applied: a positive PCR result for Aspergillus spp. in bronchoalveolar lavage was also defined as probable IFI.

Results

In total, 1693 chemotherapy courses in 592 patients were evaluated. Sixty-three percent of chemotherapy courses were given to treat acute myeloid leukaemia, with the rest for acute lymphoblastic leukaemia or aggressive lymphoma. IFIs were observed in 139/592 patients [23.5%, 95% confidence interval (CI) 20%–27%] and in 149/1693 courses (8.8%, 95% CI 8%–10%). IFI-related mortality was 56.9% in 1995–2001 and 28.6% in 2002–06, P < 0.001. Accordingly, median OS in patients with IFI increased: 54 days (95% CI 26–82 days) in 1995–2001 versus 229 days (95% CI 35–423 days) in 2002–06, P = 0.001. By multivariate analysis, factors predictive for better OS were controlled disease after chemotherapy [hazard ratio (HR) 0.228, P < 0.001], possible IFI (in contrast to proven/probable IFI, HR 0.537, P = 0.005), age <60 years (HR 0.583, P = 0.008), time period 2002–06 (HR 0.612, P = 0.021) and use of novel antifungals (HR 0.589, P = 0.033).

Conclusions

Compared with 1995–2001, IFI-related mortality decreased and OS in patients with IFI increased significantly in recent years. Improved OS was associated with controlled haematological disease, certainty of IFI diagnosis (possible), younger age, time period 2002–06 and the use of novel antifungals.

Activity of MGCD290, a Hos2 histone deacetylase inhibitor, in combination with azole antifungals against opportunistic fungal pathogens

We report on the in vitro activity of the Hos2 fungal histone deacetylase (HDAC) inhibitor MGCD290 (MethylGene, Inc.) in combination with azoles against azole-resistant yeasts and molds. Susceptibility testing was performed by the CLSI M27-A3 and M38-A2 broth microdilution methods. Testing of the combinations (MGCD290 in combination with fluconazole, posaconazole, or voriconazole) was performed by the checkerboard method. The fractional inhibitory concentrations were determined and were defined as <0.5 for synergy, >or=0.5 but <4 for indifference, and >or=4 for antagonism. Ninety-one isolates were tested, as follows: 30 Candida isolates, 10 Aspergillus isolates, 15 isolates of the Zygomycetes order, 10 Cryptococcus neoformans isolates, 8 Rhodotorula isolates, 8 Fusarium isolates, 5 Trichosporon isolates, and 5 Scedosporium isolates. MGCD290 showed modest activity when it was used alone (MICs, 1 to 8 microg/ml) and was mostly active against azole-resistant yeasts, but the MICs against molds were high (16 to >32 microg/ml). MGCD290 was synergistic with fluconazole against 55 (60%) of the 91 isolates, with posaconazole against 46 (51%) of the 91 isolates, and with voriconazole against 48 (53%) of the 91 isolates. Synergy between fluconazole and MGCD290 was observed against 26/30 (87%) Candida isolates. All 23 of the 91 Candida isolates that were not fluconazole susceptible demonstrated a reduced fluconazole MIC that crossed an interpretive breakpoint (e.g., resistant [MIC, >or=64 microg/ml] to susceptible [MIC, <or=8 microg/ml]) when fluconazole was combined with MGCD290 at 0.12 to 4 microg/ml. The activity of fluconazole plus MGCD290 was also synergistic against 6/10 Aspergillus isolates. Posaconazole plus MGCD290 demonstrated synergy against 14/15 Zygomycetes (9 Rhizopus isolates and 5 Mucor isolates). Voriconazole plus MGCD290 demonstrated synergy against six of eight Fusarium isolates. Thus, MGCD290 demonstrated in vitro synergy with azoles against the majority of clinical isolates tested, including many azole-resistant isolates and genera inherently resistant to azoles (e.g., Mucor and Fusarium). Further evaluation of fungal HDAC inhibitor-azole combinations is indicated.

Studies on peptidyl nucleoside antibiotics: synthesis and antifungal evaluation of pyranosyl nucleoside analogs of nikkomycin

Background: The Streptomyces-derived nikkomycins are a unique class of peptidyl nucleoside natural products, with potent antifungal activity against a variety of pathogenic fungi. Results: In continuation of our structure–activity relationship studies on the nikkomycins, this paper describes the strategic design, synthesis and biological evaluation of a ‘doubly modified’ generation of nikkomycin analogs. The structural modifications included a ring-expanded carbohydrate core and a simplified peptidyl side chain. Biological screening of these novel analogs against clinical isolates of various human pathogenic fungi indicated that the described modifications of the structural features of nikkomycin could be a potentially beneficial strategy towards optimizing the antifungal potency of this class of peptidyl nucleoside antibiotics. Conclusion: Continued investigation of the pyranosyl nikkomycin analogs is warranted to fully explore and optimize the structural features of this novel lead for the desired development of a new class of therapeutically useful antifungal drugs.

Primary aspergilloma and subacute invasive aspergillosis in two AIDS patients

Although uncommon, invasive aspergillosis in the setting of AIDS is important because of its peculiar clinical presentation and high lethality. This report examines two AIDS patients with a history of severe cellular immunosuppression and previous neutropenia, who developed subacute invasive aspergillosis. One female patient developed primary lung aspergilloma, with dissemination to the mediastinum, vertebrae, and spine, which was fatal despite antifungal treatment. The second patient, who had multiple cavitary brain lesions, and eye and lung involvement, recovered following voriconazole and itraconazole, and drugs for increasing neutrophil and CD4+ lymphocyte levels. These cases demonstrate the importance of Aspergillus infections following neutropenia in AIDS patients, and emphasize the need for early and effective antifungal therapy.

Significant alterations in the epidemiology and treatment outcome of invasive fungal infections in patients with hematological malignancies

Invasive fungal infections (IFI) remain a leading cause of morbidity and mortality in immunocompromised patients. This retrospective single-center study analyzed incidence, treatment and outcome of invasive fungal infections in 1,095 patients with hematological malignancies receiving either cytoreductive chemotherapy or autologous or allogeneic hematopoietic stem cell transplantation at our institution between 1995 and 2004. IFI occurred in 167/1,095 (15%) patients with a significant increase over time (12.7% between 1995 and 2000 vs. 18.1% in the later IFI cohort, P = 0.0134). Fifty-four (32%) patients had proven, 70 (42%) patients had probable, and 43 (26%) patients suffered from possible IFI according to EORTC/MSG criteria. In 108/124 (87%) cases with proven or probable IFI, moulds were the causative pathogens. Both, Aspergillus fumigatus (n = 46) and Aspergillus terreus (n = 41) were predominant. Yeast infections (Candida spp.) were documented in 16/124 (10%) cases with proven or probable IFI. Median overall survival of the entire IFI cohort was 7 (3-17) months. Overall survival was significantly better in patients with probable or possible IFI (37 and 38%, respectively) compared with patients with proven IFI (28%, P = 0.019). In 35% of patients, IFI was the principal cause of death with a significant decrease over time (44% in time cohort 1995-2000 vs. 28% in the later IFI cohort, P = 0.018) accompanied by an increased use of novel antifungals. By multivariate analysis, only proven IFI was significantly predictive for death (HR 1.7, P = 0.018). A significant decrease in fungus-related deaths was observed despite a significant increase of IFI over time, probably due to improved diagnostic and therapeutic approaches.

The characteristics of Aspergillus fumigatus mycetoma development: is this a biofilm?

Aspergillus fumigatus is an increasingly prevalent opportunistic fungal pathogen of various immuno-compromised individuals. It has the ability to filament within the lungs forming dense intertwined mycelial balls. These morphological characteristics resemble those of microbial biofilms, which are matrix enclosed microbial populations, adherent to each other and/or to surfaces or interfaces. The purpose of this paper is to review some recent experiments that indicate the potential biofilm forming capacity of A. fumigatus in vitro. Initially it was established that conidial seeding density is important for stable biofilm development. In the optimized model conidial germination and filamentous growth characteristics were not observed until 8 h, after which a multi-cellular population expanded exponentially forming a thick structure (approx. 250 microm). Calcofluor white staining of this revealed the presence of extracellular polymeric matrix material, which increased as the biofilm matured. Subsequent antifungal sensitivity testing of this structure showed that azoles, polyenes and echinocandins were ineffective in reducing the cellular viability at therapeutically attainable concentrations. Microarray and real-time PCR analysis demonstrated the up-regulation of AfuMDR4 during multicellular growth and development, which may account the recalcitrance observed. Overall, A. fumigatus appears to possess the classical elements of biofilm growth, namely multicellularity, matrix production and sessile resistance. This controversial approach to understanding the biology of A. fumigatus infection may provide crucial information on how to treat this pathogenic fungus more effectively.