Effects of lipid formulations of amphotericin B on activity of human monocytes against Aspergillus fumigatus

Daptomycin exerts differential immunomodulatory effects on host responses against methicillin-resistant Staphylococcus aureus biofilms

BACKGROUND

Daptomycin (DAP) is indicated for difficult-to-treat Gram-positive infections, especially those caused by methicillin-resistant S. aureus (MRSA). Exposure of S. aureus to sub-inhibitory concentrations (sub-MICs) of antibiotics have been shown to alter cell morphology or biofilm formation.

OBJECTIVES

To investigate the influence of DAP biofilm sub-MICs on the damage caused by human polymorphonuclear neutrophils (PMNs) against MRSA biofilms and the potential immunomodulatory activity of DAP on human monocytes (MNCs) exposed to MRSA biofilms.

METHODS

DAP activity against biofilms and the impact of DAP on the PMNs-induced biofilm damage were evaluated by the XTT reduction assay, whereas pathogen recognition, signal transduction and cytokine modulation of DAP on MNCs in response to MRSA biofilms were assessed by RT-PCR and ELISA methodology.

RESULTS

The MIC50 of DAP to MRSA biofilms was 16 to 32 mg/L. Pre-treatment of MRSA to 1, 2 or 4 mg/L DAP caused a synergistic effect on PMN-mediated biofilm damage, being dependent on the effector-to-target ratio. MNCs responded to MRSA biofilms and DAP through Toll like receptor 2 (TLR2) upregulation and increased NLRP3 inflammasome production. DAP caused 2.5-fold greater TLR2 mRNA levels than those caused by MRSA biofilms. A predominantly inflammatory response was induced by either component, causing the release of significantly increased IFN-γ, TNF-α, IL-8 and IL-6 levels by MNCs exposed to the combination treatment. MRSA biofilms alone or combined with DAP caused low amounts of IL-10 production, but increased IL-1β levels.

CONCLUSIONS

DAP may condition MNCs towards an inflammatory response through TLR2 engagement and NLRP3 inflammasome activation, possibly controlling biofilm-associated pathogenicity.

Immunomodulatory effects of colistin on host responses against carbapenem-resistant Klebsiella pneumoniae biofilms

Colistin (CST) is a last-resort therapeutic option for carbapenem-resistant Klebsiella pneumoniae (CR-Kp) infections in critically ill patients. The effect of subinhibitory CST concentrations (sub-MICs) on biofilm formation is organism-dependent. We investigated the interactions between CST and innate immune cells against CR-Kp biofilms (CR-KpBF) by studying the effect of biofilm sub-MICs of CST on (i) damage induced by human polymorphonuclear neutrophils (PMNs) on CR-KpBF and (ii) the immunomodulatory potential on human mononuclear cells (MNCs) exposed to CR-KpBF. The impact of CST on PMN-induced biofilm damage was assessed by XTT reduction assay. Signal transduction and gene expression profiles in response to CST sub-MICs of MNCs exposed to CR-KpBF were studied by RT-PCR and multiplex ELISA. Pre-exposure of CR-Kp to 0.06 mg/L CST led to subsequent increased PMN-mediated biofilm damage against CR-KpBF in the presence of CST biofilm sub-MICs: there was an additive effect at 2, 4, 8 and 16 mg/L. However, the overall biofilm damage was not >52%. MNCs responded to CR-KpBF through Toll-like receptor 2 (TLR2) by 2.5-fold upregulation and NLRP3 inflammasome activation. CR-KpBF stimulated increased production of interleukin 1-beta (IL-1β), tumour necrosis factor-alpha (TNFα), IL-8 and IL-6. In the combination treatment, 0.5 mg/L CST reduced IL-1β, TNFα and IL-8 levels, whereas at 2 mg/L and 8 mg/L it increased the anti-inflammatory cytokine IL-10 (P < 0.05). Biofilm sub-MICs of CST enhance PMN killing capacity and attenuate production of inflammatory cytokines by MNCs exposed to CR-KpBF, playing a potentially important immunotherapeutic role especially for patients with cytokine deregulation.

Role of Echinocandins in Fungal Biofilm-Related Disease: Vascular Catheter-Related Infections, Immunomodulation, and Mucosal Surfaces

Biofilm-related infections have become an increasingly important clinical problem. Many of these infections occur in patients with multiple comorbidities or with impaired immunity. Echinocandins (caspofungin, micafungin, and anidulafungin) exert their fungicidal activity by inhibition of the synthesis of the (1→3)-β-d-glucan. They are active among in vitro and in vivo model systems against a number of Candida species and filamentous fungi in their planktonic and biofilm phenotype. Their superior activity against biofilms poses them in an advantageous position among the antifungal armamentarium. However, additional studies are warranted to expand our knowledge on the role of echinocandins against biofilm-related infections.

Interaction of platelets and anidulafungin against Aspergillus fumigatus

The combination of platelets and anidulafungin at 0.03 μg/ml significantly (P < 0.05) reduced the germination rate and hyphal elongation in Aspergillus fumigatus compared to those with either anidulafungin only or an untreated control. Platelets decreased the expression of the fks gene, which plays an important role in cell wall synthesis. Our results suggest that human platelets plus anidulafungin might contribute to defense against A. fumigatus.

Interactions of liposome carriers with infectious fungal hyphae reveals the role of β-glucans

Relatively little is known about how liposomal formulations modulate drug delivery to fungal pathogens. We compared patterns of hyphal cell wall binding for empty rhodmine-labeled liposomes and the clinically available amphotericin B-containing liposomal formulation (AmBisome) in Aspergillus fumigatus and Candida albicans. Following 0.5 h of coincubation with A. fumigatus , empty liposomes concentrated primarily in fungal septae along at the surface of the cell wall, suggesting that liposome uptake is concentrated in areas of the cell wall where linear glucan is exposed on the cell surface, which was confirmed by aniline blue staining. Consistent with this hypothesis, pretreatment of liposomes with soluble linear glucan (laminarin) decreased liposome binding in both Aspergillus and Candida fungal hyphae, while growth of Aspergillus hyphae in the presence of an agent that increases fungal cell wall surface exposure of linear β-glucans without cell death (caspofungin) increased liposome uptake throughout the Aspergillus fungal cell wall. Increasing the polyethylene glycol (PEG) concentration in liposomes from 0 to 30% significantly increased fungal uptake of liposomes that was only modestly attenuated when fungal cells were incubated in serum concentrations ranging from 10 to 100%. The presence of β-glucans on the fungal hyphae cell walls of Aspergillus fumigatus is one of the factors responsible for mediating the binding of liposome carriers to the hyphae and could explain possible synergy reported between liposomal amphotericin B and echinocanins.

Immunomodulatory properties of antifungal agents on phagocytic cells

Phagocytic cells, particularly neutrophils and monocytes/macrophages, are the first line and the most effective form of innate host defence against pathogenic fungi. During antifungal therapy these phagocytic cells are also exposed to antifungal agents. In the phagocyte-fungus-antifungal agent interplay, drugs may directly interact with phagocytes through specific pattern recognition receptors, leading to altered antifungal activities. Antifungal agents, through modulation of fungal virulence, may initiate different immune response programs in the phagocytes, leading to antifungal synergism/antagonism or up-regulation of gene expression for a pro-inflammatory response. Additionally, indirect modulation of phagocyte behavior by pretreatment of neutrophils, monocytes, and macrophages with cytokines and exposure to antifungal agents have shown promising findings for combined drug-cytokine therapy that may improve treatment of life-threatening fungal diseases. In this review, we discuss the main in vitro and in vivo immunomodulatory effects of antifungal agents on phagocytes in response to pathogenic fungi, as well as we address underlying immunopharmacologic mechanisms and their potential impact on clinical outcome.

Synergistic interaction of the triple combination of amphotericin B, ciprofloxacin, and polymorphonuclear neutrophils against Aspergillus fumigatus

Aspergillus is damaged by polymorphonuclear neutrophils (PMNs) by means of nonoxidative and oxidative mechanisms, which may be affected by antifungal and antibacterial agents that patients with invasive pulmonary aspergillosis often receive. The pharmacodynamic interactions among deoxycholate amphotericin B (AMB), ciprofloxacin (CIP), and human PMNs against Aspergillus fumigatus growth are unknown. We therefore studied the interactions between 0.032 to 2.0 μg/ml of AMB, 0.1 to 50 μg/ml of CIP at a fixed AMB/CIP ratio of 1:3.125, and PMNs from six donors at an effector-to-target (E:T) ratio of 400:1 against a clinical A. fumigatus isolate using an XTT metabolic assay and the Bliss independence pharmacodynamic-interaction model. CIP exhibited no antifungal activity alone or in combination with PMNs. Synergy was found between AMB and PMNs, with interaction indices (II) of 0.06 to 0.21; the highest interaction of 21% ± 3.6% was observed at 0.22 ± 0.09 μg/ml of AMB. The AMB and CIP (AMB+CIP) combination was synergistic (II = 0.39) at low AMB concentrations and antagonistic (II = 1.39) at high AMB concentrations, with a maximal synergistic interaction of 16% ± 3.7% observed at 0.16 ± 0.08 μg/ml of AMB. The triple combination AMB+CIP+PMNs was synergistic, with interaction indices of 0.05 to 0.20, and a maximal synergistic interaction of 24% ± 4% was observed at 0.20 ± 0.07 μg/ml of AMB. The increased percentage of Bliss synergy of the triple combination AMB+CIP+PMNs (24% ± 4%) was the product of those of the constituent double combinations AMB+PMNs (21% ± 3.6%) and AMB+CIP (16% ± 3.7%). Thus, the antifungal activity of AMB, at clinically relevant concentrations, was enhanced in combination with PMNs and CIP against A. fumigatus growth in a concentration-dependent manner.

Dose-response relationships of three amphotericin B formulations in a non-neutropenic murine model of invasive aspergillosis

New lipid-associated formulations of amphotericin B (AmB) have been developed in order to reduce toxicity and enhance the efficacy of AmB by allowing administration of higher doses of the drug. We determined the in vivo dose-response relationships of 1 day and 7 day treatment of AmB, Ambisome (AmBi) and Abelcet (ABLC) in a non-neutropenic murine model of invasive aspergillosis by using survival as an endpoint. Female CD-1 mice were infected intravenously 48 h prior to start therapy with Aspergillus fumigatus (1 x 10(7) conidia/mouse). Groups of 10 mice were treated iv for 1 day or 7 days with increasing 2-fold doses of AmB, ABLC and AmBi up to a maximum of 20 mg/kg/day. Mortality was determined twice daily until day 15. Results were analyzed using product-moment survival analysis and by determining the dose response relationships on day 15. Survival at day 15 of mice with 7 day AmBi or ABLC treatment was significantly better than that of controls or AmB. The ED50s of AmBi and ABLC were 0.06 (95% CI: 0.03-0.127) mg/kg and 0.21 (0.06-0.66) mg/kg respectively. In addition, the maximum effect was higher for AmBi than ABLC, 90% survival versus 68%, respectively. Most of the effects of treatment with AmBi were reached after 1 day of treatment, indicating that the first dose given is most important in predicting survival. This study shows that AmBi and ABLC were significantly more efficacious than AmB in a non-neutropenic murine model of invasive aspergillosis, and that the effect observed was primarily dependent on the first dose administered.

Differential transcriptional profiles induced by amphotericin B formulations on human monocytes during response to hyphae of Aspergillus fumigatus

Amphotericin B formulations possess diverse immunomodulatory properties that may contribute to the activity of phagocytes against invasive aspergillosis. In this work we provide a novel set of data on different gene transcriptional profiles of monocytes exposed to the combination of Aspergillus fumigatus and amphotericin B formulations. We used pathway-specific microarray analysis, RT-PCR analysis and enzyme-linked immunosorbent assays to compare the effects of amphotericin B deoxycholate (DAMB) at 1 μg/ml and amphotericin B lipid complex (ABLC) at 5 μg/ml to assess gene expression of immune molecules of THP-1 cells exposed to A. fumigatus hyphae (AF) for 4 h. A. fumigatus hyphae at effector/target ratio 10/1 induced mostly chemotactic factors for monocyte recruitment. DAMB at 1 μg/ml in the presence or absence of AF induced the most pronounced changes in pro-inflammatory and chemokine gene expression, while ABLC under the same conditions caused less dramatic effect. There was a reciprocal response of increased expression of the genes encoding IL-1β and IL-20 and decreased expression of IL-10, IL-2 and IL-3 in response of monocytes to both the hyphae and antifungal agents. These results demonstrate that amphotericin B formulations exert differential effects on genes encoding pro-inflammatory molecules, immunoregulatory molecules and chemokines by human monocytes during response to A. fumigatus and that these molecules may affect antifungal activity.

Platelets enhance activity of antimycotic substances against non-Aspergillus fumigatus Aspergillus species in vitro

Platelets are known to be part of haemostasis but they are also players in innate host defense. Recently, we observed that platelets attenuate the virulence of Aspergillus spp. in vitro. However, little is known about the antifungal effects of platelets in the presence of antimycotics against non-A. fumigatus Aspergillus species. We therefore investigated whether platelets increase the in vitro activity of amphotericin B, voriconazole, posaconazole and caspofungin against two clinical isolates each of Aspergillus flavus, Aspergillus terreus and Aspergillus niger. The antifungal activity was evaluated by assessing germination percentages, hyphal elongation and hyphal damage by use of XTT. The combination of platelets plus amphotericin B significantly (P < 0.05) enhanced the reduction of germination percentage compared to either substance alone. Among triazoles, voriconazole exhibited significant effects with platelets for all tested aspergilli. Overall, these findings suggest that among the tested antimycotic substances, amphotericin B in combination with platelets has enhancing effects in reducing germination and hyphal elongation in the tested non-A. fumigatus Aspergillus species. These data indicate that platelets act beneficially with antimycotics in an early stage of fungal growth by blocking and/or delaying fungal germination and hyphal elongation; both crucial mechanisms in the development of invasive fungal disease.

Interactions between human phagocytes and Candida albicans biofilms alone and in combination with antifungal agents

BACKGROUND

Biofilm formation is an important component of vascular catheter infections caused by Candida albicans. Little is known about the interactions between human phagocytes, antifungal agents, and Candida biofilms.

METHODS

The interactions between C. albicans biofilms and human phagocytes alone and in combination with anidulafungin or voriconazole were investigated and compared with their corresponding planktonic counterparts by means of an in vitro biofilm model with clinical intravascular and green fluorescent protein (GFP)-expressing strains. Phagocyte-mediated and antifungal agent-mediated damages were determined by 2,3-bis[ 2- methoxy-4-nitro-5-sulfophenyl]2H-tetrazolium-5-carboxanilide assay, and structural effects were visualized by confocal microscopy. Oxidative burst was evaluated by flow cytometric measurement of dihydrorhodamine 123 oxidation, and cytokine release was measured by enzyme-linked immunosorbent assay.

RESULTS

Phagocytes alone and in combination with antifungal agents induced less damage against biofilms compared with planktonic cells. However, additive effects occurred between phagocytes and anidulafungin against Candida biofilms. Confocal microscopy demonstrated the absence of phagocytosis within biofilms but marked destruction caused by anidulafungin and phagocytes. Anidulafungin but not voriconazole elicited tumor necrosis factor alpha release from phagocytes compared with that from untreated biofilms.

CONCLUSIONS

C. albicans within biofilms are more resistant to phagocytic host defenses but are susceptible to additive effects between phagocytes and an echinocandin.

Innate immunity to Aspergillus species

All humans are continuously exposed to inhaled Aspergillus conidia, yet healthy hosts clear the organism without developing disease and without the development of antibody- or cell-mediated acquired immunity to this organism. This suggests that for most healthy humans, innate immunity is sufficient to clear the organism. A failure of these defenses results in a uniquely diverse set of illnesses caused by Aspergillus species, which includes diseases caused by the colonization of the respiratory tract, invasive infection, and hypersensitivity. A key concept in immune responses to Aspergillus species is that the susceptibilities of the host determine the morphological form, antigenic structure, and physical location of the fungus. In this review, we summarize the current literature on the multiple layers of innate defenses against Aspergillus species that dictate the outcome of this host-microbe interaction.

Invasive fungal infections in the ICU

Invasive fungal infections are major causes of morbidity and mortality in critically ill patients. Foremost among these is invasive candidiasis. In recent years, invasive aspergillosis (IA) and zygomycosis have emerged as major problems in susceptible, critically ill patients. Risk factors for invasive fungal infections, including disrupted anatomic barriers, suppressed antifungal host responses, and exposure to potentially opportunistic fungi are common in critically ill patients. The expanded antifungal armamentarium and advent of rapid diagnostic techniques are altering the approach to invasive fungal infections in the intensive care unit (ICU). Herein, we review recent developments in the field of antifungal host defenses, the changing epidemiology of fungal infections in the ICU, the pharmacology of antifungal agents of importance to critically ill patients, and the evolving approaches to therapy in this setting.

Liposomal amphotericin B: a review of its use as empirical therapy in febrile neutropenia and in the treatment of invasive fungal infections

Liposomal amphotericin B (AmBisome) is a lipid-associated formulation of the broad-spectrum polyene antifungal agent amphotericin B. It is active against clinically relevant yeasts and moulds, including Candida spp., Aspergillus spp. and filamentous moulds such as Zygomycetes, and is approved for the treatment of invasive fungal infections in many countries worldwide. It was developed to improve the tolerability profile of amphotericin B deoxycholate, which was for many decades considered the gold standard of antifungal treatment, despite being associated with infusion-related events and nephrotoxicity. In well controlled trials, liposomal amphotericin B had similar efficacy to amphotericin B deoxycholate and amphotericin B lipid complex as empirical therapy in adult and paediatric patients with febrile neutropenia. In addition, caspofungin was noninferior to liposomal amphotericin B as empirical therapy in adult patients with febrile neutropenia. For the treatment of confirmed invasive fungal infections, liposomal amphotericin B was more effective than amphotericin B deoxycholate treatment in patients with disseminated histoplasmosis and AIDS, and was noninferior to amphotericin B deoxycholate in patients with acute cryptococcal meningitis and AIDS. In adults, micafungin was shown to be noninferior to liposomal amphotericin B for the treatment of candidaemia and invasive candidiasis. Data from animal studies suggested that higher dosages of liposomal amphotericin B might improve efficacy; however, in the AmBiLoad trial in patients with invasive mould infection, there was no statistical difference in efficacy between the standard dosage of liposomal amphotericin B 3 mg/kg/day and a higher 10 mg/kg/day dosage, although the standard dosage was better tolerated. Despite being associated with fewer infusion-related adverse events and less nephrotoxicity than amphotericin B deoxycholate and amphotericin B lipid complex, liposomal amphotericin B use is still limited to some extent by these adverse events. Both echinocandins were better tolerated than liposomal amphotericin B. The cost of liposomal amphotericin B therapy may also restrict its use, but further pharmacoeconomic studies are required to fully define its cost effectiveness compared with other antifungal agents. Based on comparative data from well controlled trials, extensive clinical experience and its broad spectrum of activity, liposomal amphotericin B remains a first-line option for empirical therapy in patients with febrile neutropenia and in those with disseminated histoplasmosis, and is an option for the treatment of AIDS-associated cryptococcal meningitis, and for invasive Candida spp. or Aspergillus spp. infections. Amphotericin B, a macrocyclic, polyene antifungal agent, is thought to act by binding to ergosterol, the principal sterol in fungal cell membranes and Leishmania cells. This results in a change in membrane permeability, causing metabolic disturbance, leakage of small molecules and, as a consequence, cell death. In vitro and in vivo studies have shown that liposomal amphotericin B remains closely associated with the liposomes in the circulation, thereby reducing the potential for nephrotoxicity and infusion-related toxicity associated with conventional amphotericin B. Amphotericin B shows very good in vitro activity against a broad spectrum of clinically relevant fungal isolates, including most strains of Candida spp. and Aspergillus spp., and other filamentous fungi such as Zygomycetes. Liposomal amphotericin B has proven effective in various animal models of fungal infections, including those for candidiasis, aspergillosis, fusariosis and zygomycosis. Liposomal amphotericin B also shows immunomodulatory effects, although the mechanisms involved are not fully understood, and differ from those of amphotericin B deoxycholate and amphotericin B colloidal dispersion. In adult patients with febrile neutropenia, intravenous liposomal amphotericin B has nonlinear pharmacokinetics, with higher than dose-proportional increases in exposure being consistent with reticuloendothelial saturation and redistribution of amphotericin B in the plasma compartment. Liposomal amphotericin B is rapidly and extensively distributed after single and multiple doses, with steady-state concentrations of amphotericin B attained within 4 days and no clinically relevant accumulation of the drug following multiple doses of 1-7.5 mg/kg/day. In autopsy tissue, the highest concentrations of the drug were found in the liver and spleen, followed by the kidney, lung, myocardium and brain tissue. Elimination of liposomal amphotericin B, like that of amphotericin B deoxycholate, is poorly understood; its route of metabolism is not known and its excretion has not been studied. The terminal elimination half-life is about 7 hours. No dosage adjustment is required based on age or renal impairment. In several randomized, double-blind trials (n = 73-1095) in adult and/or paediatric patients, liposomal amphotericin B was effective as empirical therapy or as treatment for confirmed invasive fungal infections, including invasive candidiasis, candidaemia, invasive mould infection (mainly aspergillosis), histoplasmosis and cryptococcal meningitis. All agents were administered as an intravenous infusion; the typical dosage for liposomal amphotericin B was 3 mg/kg/day. Treatment was generally given for 1-2 weeks. Participants in trials evaluating empirical therapy had neutropenia and a persistent fever despite antibacterial treatment and had received chemotherapy or undergone haematopoietic stem cell transplantation. As empirical therapy in adult and paediatric patients, liposomal amphotericin B appeared to be as effective as amphotericin B deoxycholate (approximately 50% of patients in each group achieved treatment success) or amphotericin B lipid complex (approximately 40% of liposomal amphotericin B recipients experienced treatment success). Of note, in the first trial, results of the statistical test to determine equivalence between treatments were not reported. In the second trial, efficacy was assessed as an 'other' endpoint. In another trial, caspofungin was shown to be noninferior to liposomal amphotericin B, with approximately one-third of patients in each group experiencing treatment success. Liposomal amphotericin B was significantly more effective than amphotericin B deoxycholate for the treatment of moderate to severe disseminated histoplasmosis in patients with AIDS, with 88% and 64% of patients, respectively, having a successful response. Liposomal amphotericin B was noninferior to amphotericin B deoxycholate for the treatment of cryptococcal meningitis in terms of mycological success. Micafungin therapy was shown to be noninferior to liposomal amphotericin B for the treatment of adult patients with candidaemia or invasive candidiasis. In a substudy in paediatric patients, which was not powered to determine noninferiority, liposomal amphotericin B was as effective as micafungin for the treatment of candidaemia or invasive candidiasis. In this patient population, within each trial, 90% of adult patients and approximately three-quarters of paediatric patients in both treatment groups experienced a successful response. In patients with invasive mould infection (mainly aspergillosis), there was no difference in efficacy between a higher dosage of liposomal amphotericin B (10 mg/kg/day) and the standard dosage (3 mg/kg/day), with 46% and 50% of patients experiencing a favourable overall response. In well designed clinical trials, liposomal amphotericin B was generally at least as well tolerated as other lipid-associated formulations of amphotericin B and better tolerated than amphotericin B deoxycholate in adult and paediatric patients. Compared with other amphotericin B formulations, liposomal amphotericin B treatment was associated with a lower incidence of infusion-related adverse events and nephrotoxicity. A higher than recommended dosage of liposomal amphotericin B (10 mg/kg/day) was associated with an increased incidence of nephrotoxicity compared with the standard dosage (3 mg/kg/day), although the incidence of infusion-related reactions did not differ between treatment groups. In general, liposomal amphotericin B treatment was not as well tolerated as echinocandin therapy in well designed clinical trials. As empirical therapy or for the treatment of confirmed invasive fungal infections in adult patients, liposomal amphotericin B recipients experienced more infusion-related events and nephrotoxicity than caspofungin or micafungin recipients. There was no difference in the incidence of these adverse events between the liposomal amphotericin B and micafungin groups in a study in paediatric patients.

Posaconazole enhances the activity of amphotericin B against hyphae of zygomycetes in vitro

The in vitro activity of posaconazole plus amphotericin B against conidia and hyphae of 30 clinical zygomycetes was investigated. The combination of posaconazole with amphotericin B was found to be significantly more synergistic (40%) against hyphae (P < 0.05) than against conidia (10%). Antagonism was not observed.

Susceptibility testing of anidulafungin and voriconazole alone and in combination against conidia and hyphae of Aspergillus spp. under hypoxic conditions

MICs and fractional inhibitory concentrations were evaluated for anidulafungin and voriconazole alone and in combination against conidia and hyphae under hypoxic (1% oxygen-5% CO(2)-94% nitrogen) conditions against 31 Aspergillus isolates. Anidulafungin exhibited excellent activity against conidia and hyphae of Aspergillus spp. The visual reading of the MIC for anidulafungin was optimal under hypoxic conditions.

Differential activities of newer antifungal agents against Candida albicans and Candida parapsilosis biofilms

The activities of voriconazole, posaconazole, caspofungin, and anidulafungin against Candida albicans and Candida parapsilosis biofilms were evaluated. In contrast to planktonic cells, the MICs for voriconazole and posaconazole for the biofilms of the two species were high (>or=256 and >64 mg/liter, respectively) but relatively low for the echinocandins caspofungin and anidulafungin (<or=1 and <or=2 mg/liter, respectively).