Susceptibility of fluconazole-resistant clinical isolates of Candida spp. to echinocandin LY303366, itraconazole and amphotericin B

Early Empirical Anidulafungin Reduces the Prevalence of Invasive Candidiasis in Critically Ill Patients: A Case-control Study

Introduction

Invasive candidiasis (IC) in critically ill patients is a serious infection with high rate of mortality. As an empirical therapy, like antibiotics, the use of antifungals is not common in intensive care units (ICUs) worldwide. The empirical use of echinocandins including anidulafungin is a recent trend.

Aim of the study

The objective of this study was to assess the impact of empirical anidulafungin in the development of invasive candidiasis in critically ill patients in ICU.

Methods

This retrospective case-control study was conducted on 149 patients with sepsis with/without septic shock and bacterial pneumonia. All the patients were divided into two groups. The ‘control group’ termed as ‘NEAT group’ received no empirical anidulafungin therapy and the ‘treated group’ termed as ‘EAT group’ received empirical anidulafungin therapy in early hospitalization hours.

Results

Seventy-two and 77 patients were divided into the control and the treated group, respectively. Patients in EAT group showed less incidences of IC (5.19%) than that of the NEAT group (29.17%) (p = 0.001). Here, the relative risk (RR) was 0.175 (95% CI, 0.064-0.493) and the risk difference (RD) rate was 24% (95% CI, 12.36%-35.58%). The 30-day all-cause mortality rate in NEAT group was higher (19.44%) than that of in EAT group (10.39%) (p = 0.04). Within the first 10-ICU-day, patients in the EAT group left ICU in higher rate (62.34%) than that in the NEAT group (54.17%).

Conclusion

Early empirical anidulafungin within 6 h of ICU admission reduced the risk of invasive candidiasis, 30-day all-cause mortality rate and increased ICU leaving rate within 10-day of ICU admission in critically ill patients.

Natural Products as Fungicide and Their Role in Crop Protection

Seeking solutions from nature for solving one and all problems is the age-old practice for mankind, and natural products are proved to be the most effective one for keeping up the balance of development as well as the “healthy, wealthy, and well” condition of mother nature. Fungal pathogens are proved to be a common and popular contaminant of agroecosystem that approximately causes 70–80% of total microbial crop loss. To meet the proper global increasing need of food products as a result of population explosion, managing agricultural system in an eco-friendly and profitable manner is the prime target; thus the word “sustainable agriculture” plays it part, and this package is highly effective when coupled with nature-derived fungicidal products that can minimize the event of fungal infections in agrarian ecosystem. Present study enlists the most common and effective natural products that might be of plant or microbial origin, their mode of action, day-by-day development of phytopathogenic resistance against the prevailing fungicides, and also their role in maintenance of sustainability of agricultural practices with special emphasis on their acceptance over the synthetic or chemical one. A large number of bioactive compounds ranging from direct plant (both cryptogams algae and moss and phanerogams)-derived natural extracts, essential oil of aromatic plants, and low-molecular-weight antimicrobial compounds known as phytoalexins to secondary metabolites that are both volatile and nonvolatile organic compounds of microbes (fungal and actinobacterial members) residing inside the host tissue, called endophyte, are widely used as agricultural bioweapons. The rhizospheric partners of plant, mycorrhizae, are also a prime agent of this chemical warfare and protect their green partners from fungal invaders and emphasize the concept of “sustainable agriculture.”

A review of the use of pteridophytes for treating human ailments

The aim of this review was to explore the pharmacological activity of early tracheophytes (pteridophytes) as an alternative medicine for treating human ailments. As the first vascular plants, pteridophytes (aka, ferns and fern allies) are an ancient lineage, and human beings have been exploring and using taxa from this lineage for over 2000 years because of their beneficial properties. We have documented the medicinal uses of pteridophytes belonging to thirty different families. The lycophyte Selaginella sp. was shown in earlier studies to have multiple pharmacological activity, such as antioxidant, anti-inflammatory, anti-cancer, antidiabetic, antiviral, antimicrobial, and anti-Alzheimer properties. Among all the pteridophytes examined, taxa from the Pteridaceae, Polypodiaceae, and Adiantaceae exhibited significant medicinal activity. Based on our review, many pteridophytes have properties that could be used in alternative medicine for treatment of various human illnesses. Biotechnological tools can be used to preserve and even improve their bioactive molecules for the preparation of medicines against illness. Even though several studies have reported medicinal uses of ferns, the possible bioactive compounds of several pteridophytes have not been identified. Furthermore, their optimal dosage level and treatment strategies still need to be determined. Finally, the future direction of pteridophyte research is discussed.

Molecular Mechanism of Drug Resistance

The treatment of microbial infections has suffered greatly in this present century of pathogen dominance. Inspite of extensive research efforts and scientific advancements, the worldwide emergence of microbial tolerance continues to plague survivability. The innate property of microbe to resist any antibiotic due to evolution is the virtue of intrinsic resistance. However, the classical genetic mutations and extrachromosomal segments causing gene exchange attribute to acquired tolerance development. Rampant use of antimicrobials causes certain selection pressure which increases the resistance frequency. Genomic duplication, enzymatic site modification, target alteration, modulation in membrane permeability, and the efflux pump mechanism are the major contributors of multidrug resistance (MDR), specifically antibiotic tolerance development. MDRs will lead to clinical failures for treatment and pose health crisis. The molecular mechanisms of antimicrobial resistance are diverse as well as complex and still are exploited for new discoveries in order to prevent the surfacing of “superbugs.” Antimicrobial chemotherapy has diminished the threat of infectious diseases to some extent. To avoid the indiscriminate use of antibiotics, the new ones licensed for use have decreased with time. Additionally, in vitro assays and genomics for anti-infectives are novel approaches used in resolving the issues of microbial resistance. Proper use of drugs can keep it under check and minimize the risk of MDR spread.

Anidulafungin compared with fluconazole for treatment of candidemia and other forms of invasive candidiasis caused by Candida albicans: a multivariate analysis of factors associated with improved outcome

BACKGROUND

Candida albicans is the most common cause of candidemia and other forms of invasive candidiasis. Systemic infections due to C. albicans exhibit good susceptibility to fluconazole and echinocandins. However, the echinocandin anidulafungin was recently demonstrated to be more effective than fluconazole for systemic Candida infections in a randomized, double-blind trial among 245 patients. In that trial, most infections were caused by C. albicans, and all respective isolates were susceptible to randomized study drug. We sought to better understand the factors associated with the enhanced efficacy of anidulafungin and hypothesized that intrinsic properties of the antifungal agents contributed to the treatment differences.

METHODS

Global responses at end of intravenous study treatment in patients with C. albicans infection were compared post-hoc. Multivariate logistic regression analyses were performed to predict response and to adjust for differences in independent baseline characteristics. Analyses focused on time to negative blood cultures, persistent infection at end of intravenous study treatment, and 6-week survival.

RESULTS

In total, 135 patients with C. albicans infections were identified. Among these, baseline APACHE II scores were similar between treatment arms. In these patients, global response was significantly better for anidulafungin than fluconazole (81.1% vs 62.3%; 95% confidence interval [CI] for difference, 3.7-33.9). After adjusting for baseline characteristics, the odds ratio for global response was 2.36 (95% CI, 1.06-5.25). Study treatment and APACHE II score were significant predictors of outcome. The most predictive logistic regression model found that the odds ratio for study treatment was 2.60 (95% CI, 1.14-5.91) in favor of anidulafungin, and the odds ratio for APACHE II score was 0.935 (95% CI, 0.885-0.987), with poorer responses associated with higher baseline APACHE II scores. Anidulafungin was associated with significantly faster clearance of blood cultures (log-rank p < 0.05) and significantly fewer persistent infections (2.7% vs 13.1%; p < 0.05). Survival through 6 weeks did not differ between treatment groups.

CONCLUSIONS

In patients with C. albicans infection, anidulafungin was more effective than fluconazole, with more rapid clearance of positive blood cultures. This suggests that the fungicidal activity of echinocandins may have important clinical implications.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00058682.

Anidulafungin for the treatment of invasive candidiasis

Candidaemia/invasive candidiasis (C/IC) is the most frequently occurring invasive fungal infection worldwide, with a particularly strong impact and high incidence in the intensive-care unit, where there is a need for new treatment options and strategies. The echinocandin anidulafungin has broad in vitro activity against a wide range of Candida species, along with favourable pharmacokinetics that allow administration in hepatic and renal impairment and with any comedication without the need for dose adjustments. The efficacy and safety of anidulafungin for the treatment of C/IC were demonstrated in a number of clinical studies and by some limited data from clinical practice. In a randomized comparative trial for the treatment of C/IC in adults, 76% of patients receiving anidulafungin and 60% of those given fluconazole were treated successfully (95% CI for difference: 4-27; p 0.01). Post hoc analyses suggest that anidulafungin is significantly more effective than standard-dose fluconazole for the treatment of candidaemia in critically ill patients. Anidulafungin is generally well tolerated, with commonly reported side effects including headache, hypokalaemia, gastrointestinal symptoms, abnormal liver function test results, and rash. In pharmaco-economic analyses, anidulafungin compared favourably with fluconazole (in terms of overall costs and hospital resource use) as well as with other echinocandins. Echinocandins, including anidulafungin, are now generally recommended as first-line therapy in moderately to severely ill patients, those with prior azole exposure, and patients with C/IC caused by Candida glabrata or Candida krusei.

New triazoles and echinocandins: mode of action, in vitro activity and mechanisms of resistance

Different types of mycoses, especially invasive mycoses caused by yeasts and molds, are a growing problem in healthcare. The most notable explanation for this increase is a rise in the number of immunocompromised patients owing to advances in transplantation, the emergence of AIDS and a rise in the number of invasive surgical procedures. Despite advances in medical practice, some therapeutic problems remain. In addition, intrinsic or acquired antifungal resistance may pose a serious problem to antifungal therapy. A new generation of triazole agents (voriconazole, posaconazole, isavuconazole, ravuconazole and albaconazole) and the recent class of the echinocandins (caspofungin, micafungin and anidulafungin) have become available, and represent an alternative to conventional antifungals for serious fungal infection management. Currently, only two of the recent triazole generation (voriconazole and posaconazole) and all three echinocandins are available for clinical use. More precisely, voriconazole and posaconazole are indicated for the treatment of invasive fungal infections and the echinocandins for the treatment of specific candidiasis. Voriconazole and posaconazole have a very broad spectrum of antifungal activity that includes Candida species, and filamentous and dimorphic fungi. Their activity extends to both fluconazole- and itraconazole-resistant strains of Candida. A major difference between posaconazole and voriconazole is that posaconazole has activity against Zygomycetes including Mucor spp., Rhizopus spp. and Cunninghamella spp., and voriconazole has no activity against this class of fungi. Ravuconazole, isavuconazole and albaconazole have shown very potent in vitro activity against species of Candida, Cryptococcus and Aspergillus, and they are currently in various stages of development. All three echinocandin agents, caspofungin, micafungin and anidulafungin, are similar in their spectrum of activity. Echinocandins do not possess in vitro activity against important basidiomycetes, including Cryptococcus, Rhodotorula and Trichosporon. This review attempts to deliver the most up-to-date knowledge on the mode of action and mechanisms of resistance to triazoles and echinocandins in fungal pathogens. In addition, the in vitro activity data available on triazoles and echinocandins are reported.

[In vitro activity of anidulafungin. Comparison with the activity of other echinocandins]

Anidulafungin is a new echinocandin that acts by inhibiting (1,3)-beta-D-glucan synthesis in the fungal cell wall. This agent is a semisynthetic lipopeptide synthesized from a fermentation product of Aspergillus nidulans. The spectrum of activity of anidulafungin includes Candida and Aspergillus, the two main etiological agents causing invasive fungal infections. This drug is also active against strains of these genera resistant to azoles or amphotericin B. However, anidulafungin is not active against Cryptococcus spp., Trichosporon spp., Fusarium spp. or Mucorales spp. Data on the activity of this drug against other species are limited and do not allow conclusions to be drawn or recommendations to be made. Echinocandin resistance is uncommon and has little clinical relevance.

Developments in the treatment of candidiasis: more choices and new challenges

The incidence of oesophageal candidiasis, candidaemia and disseminated candidiasis has increased dramatically. In addition to the amphotericin B formulations and fluconazole, the echinocandins anidulafungin, caspofungin and micafungin and the newer triazoles posaconazole and voriconazole are in the last stages of development and are becoming available for the management of candidiasis. This review presents these new agents and addresses their role in the treatment of candidiasis. All new antifungal agents exhibit potent activity against Candida spp. and echinocandins are fungicidal against most Candida spp. but appear to be less potent against certain species, such as Candida parapsilosis and C. guilliermondii. Systemic antifungal therapy can now be individualised based on the severity of the infection, comorbid conditions and the Candida spp. causing the infection. Studies are needed to investigate the possible development of resistance and the efficacy of these antifungal agents against the more resistant Candida spp.

Anidulafungin: a novel echinocandin

Until recently, the treatment available for serious fungal infections was composed of amphotericin B and azoles, and each class demonstrated significant limitations. Echinocandins are a new class of drugs that have shown promising results in treating a variety of fungal infections. Of these, anidulafungin is a novel echinocandin that appears to have several advantages over existing antifungals. It is unique because it slowly degrades in humans, undergoing a process of biotransformation rather than being metabolized. It has potent in vitro activity against Aspergillus and Candida species, including those resistant to fluconazole or amphotericin B. Results of several clinical trials indicate that anidulafungin is effective in treating esophageal candidiasis, including azole-refractory disease. The results of a recent study comparing fluconazole versus anidulafungin demonstrated the superiority of anidulafungin in the treatment of candidemia and invasive candidiasis (IC). Studies evaluating the concomitant use of anidulafungin and either amphotericin B, voriconazole, or cyclosporine did not demonstrate significant drug-drug interactions or adverse events. To date, anidulafungin appears to have an excellent safety profile. On the basis of early clinical experience, it appears that anidulafungin will be a valuable asset in the management of serious and difficult-to-treat fungal infections.

Species Distribution and Antifungal Susceptibility Profile of Oral Candida Isolates from HIV-infected Patients in the Antiretroviral Therapy Era

In this study, we investigated the yeasts colonization of genus Candida, including C. dubliniensis, isolated of HIV-infected patients oral cavities and we accessed in vitro susceptibility pattern of the Candida isolates to four antifungal agents. Out of 99 patients investigated, 62 (62.6%) were colonized with yeasts. C. albicans was the prevailing species (50%). C. dubliniensis isolates were not recovered in our study. We verified that 8.1% of the yeasts isolated were resistant to fluconazole, 8.1% to itraconazole and 3.2% to voriconazole. The isolates demonstrated very low voriconazole MICs, in which 79% (49/62) presented values of 0.015 mug/ml. All Candida isolates were susceptible to amphotericin B. The results reported here showed that although C. albicans continues to be present in one-half of oral Candida carriage of HIV-infected patients, Candida non-albicans species are increasing among these patients. Besides, the findings of resistant isolates endorse the role of antifungal susceptibility testing whenever antifungal treatment with azoles is planned.

Anidulafungin: a new echinocandin with a novel profile

BACKGROUND

Until recently, available treatment for serious fungal infections comprised amphotericin B and azoles, which have limitations. Renal toxicity is a major concern with amphotericin B, while drug-drug interactions, hepatotoxicity, and skin rashes are the primary concerns with the azole medications. The development of the echinocandins, including caspofungin, has helped to fill the need for more efficacious antifungals that are useful across different patient populations and have a good safety profile. Anidulafungin is an echinocandin being developed to treat mucosal and invasive fungal infections.

OBJECTIVE

The aim of this report was to describe the pharmacodynamic and pharmacokinetic (PK) properties of anidulafungin.

METHODS

Data were identified using MEDLINE and National Library of Medicine Gateway searches for English-language literature (key words: anidulafungin, esophageal candidiasis, echinocandin, caspofungin, ravuconazole, voriconazole, posaconazole, micafungin, and fluconazole; years: 1996-2004), and from meeting abstracts of the American Society for Blood and Marrow Transplantation (Arlington Heights, Illinois), European Congress of Clinical Microbiology and Infectious Diseases (Basel, Switzerland), International Conference on Antimicrobial Agents and Chemotherapy (Washington, DC), and Infectious Diseases Society of America (Arlington, Virginia).

RESULTS

Anidulafungin has potent in vitro activity against Aspergillus and Candida spp, including those resistant to either fluconazole or amphotericin B. Results of several clinical trials imply that anidulafungin is effective in treating esophageal candidiasis (EC), candidemia, and invasive candidiasis (IC). In a Phase III, randomized, blinded clinical trial evaluating anidulafungin (50 mg/d) versus fluconazole (100 mg/d) for the treatment of EC, 97.2% and 98.9% of patients who received anidulafungin and fluconazole, respectively, showed evidence of cure or improvement (treatment difference, -1.6%; 95% CI, -4.1 to 0.8). In a Phase II study of candidasis and candidemia, anidulafungin showed success rates of 72%, 85%, and 83% in patients receiving the drug at dosages of 50, 75, or 100 mg/d, respectively. Studies evaluating the concomitant use of anidulafungin and either amphotericin, voriconazole, or cyclosporine did not show clinically significant drug-drug interactions or altered adverse-event (AE) profiles (P < 0.05). A population PK analysis showed no significant effect of age, race, concomitant medications, or renal or hepatic insufficiency on the PK properties of anidulafungin (P < 0.05).

CONCLUSIONS

Anidulafungin may offer a new option to treat serious fungal infections, such as EC, azole-refractory EC, candidemia, and IC. In addition, anidulafungin has been associated with no clinically significant drug-drug interactions and few treatment-related AEs. Anidulafungin may offer a new option in the management of serious and difficult-to-treat invasive fungal infections.

Safety and pharmacokinetics of intravenous anidulafungin in children with neutropenia at high risk for invasive fungal infections

Anidulafungin is an echinocandin with activity against Candida species and Aspergillus species. Adult dosages under study are 50 mg/day for esophageal candidiasis and 100 mg/day for invasive candidiasis and aspergillosis. Little is known, however, about the safety and pharmacokinetics of anidulafungin in children. A multicenter, ascending-dosage study of neutropenic pediatric patients was therefore conducted. Patients were divided into two age cohorts (2 to 11 years and 12 to 17 years) and were enrolled into sequential groups to receive 0.75 or 1.5 mg/kg of body weight/day. Blood samples were obtained following the first and fifth doses. Anidulafungin was assayed in plasma, and pharmacokinetic parameters were determined. Safety was assessed using National Cancer Institute (NCI) common toxicity criteria. Pharmacokinetic parameters were determined for 12 patients at each dosage (0.75 mg/kg/day or 1.5 mg/kg/day). Concentrations and drug exposures were similar for patients between age cohorts, and weight-adjusted clearance was consistent across age. No drug-related serious adverse events were observed. One patient had fever (NCI toxicity grade of 3), and one patient had facial erythema, which resolved with slowing the infusion rate. Anidulafungin in pediatric patients was well tolerated and can be dosed based on body weight. Pediatric patients receiving 0.75 mg/kg/day or 1.5 mg/kg/day have anidulafungin concentration profiles similar to those of adult patients receiving 50 or 100 mg/day, respectively.

Microwave-assisted synthesis of antimicrobial dihydropyridines and tetrahydropyrimidin-2-ones: Novel compounds against aspergillosis

Ten 4-aryl-1,4-dihydropyridine and three 4-aryl-1,2,3,4-tetrahydropyrimidin-2-one derivatives have been synthesized and examined for their activity against pathogenic strains of Aspergillus fumigatus and Candida albicans. Although none of the three compounds belonging to pyrimidin-2-one series showed any activity against two pathogens, two of the compounds of the dihydropyridine series, that is, diethyl 4-(4-methoxyphenyl)-2,6-dimethyl-1,4-dihydropyridin-3,5-dicarboxylate and dimethyl 4-(4-methoxyphenyl)-2,6-dimethyl-1,4-dihydropyridin-3,5-dicarboxylate, exhibited significant activity against A. fumigatus in disc diffusion, microbroth dilution and percent spore germination inhibition assays. The most active diethyl dihydropyridine derivative exhibited a MIC value of 2.92 microg/disc in disc diffusion and 15.62 microg/ml in microbroth dilution assays. The MIC(90) value of the most active compound by percent germination inhibition assay was found to be 15.62 microg/ml. The diethyl dicarboxylate derivative of dihydropyridine also exhibited appreciable activity against C. albicans. The in vitro toxicity of the most active diethyl dihydropyridine derivative was evaluated using haemolytic assay, in which the compound was found to be non-toxic to human erythrocytes even at a concentration of 625 microg/ml. The standard drug amphotericin B exhibited 100% lysis of erythrocytes at a concentration almost 16 times less than the safer concentration of the most active dihydropyridine derivative.

Effectiveness of anidulafungin in eradicating Candida species in invasive candidiasis

In a phase 2 open-label, dose-ranging study in patients with candidemia, anidulafungin was effective in eradicating Candida albicans and other species of Candida. The anidulafungin MIC distribution showed that Candida albicans and C. glabrata were the most susceptible species and C. parapsilosis was the least susceptible species.

In vitro interactions of anidulafungin with azole antifungals, amphotericin B and 5-fluorocytosine against Candida species

Anidulafungin, an echinocandin, is in late stage development for the treatment of fungal infections. We investigated the activity of anidulafungin in combination with other antifungal agents (fluconazole, itraconazole, ketoconazole, amphotericin B and 5-fluorocytosine) against four isolates each of Candida albicans, Candida glabrata, Candida parapsilosis and Candida tropicalis, and two isolates of Candida krusei using a macrobroth chequerboard method with interactions evaluated by fractional inhibitory concentration indices (FICIs). Additive activity (FICI > 0.5 to 1) or indifference (FICI > 1 to < 4) was observed in 85 of 90 interactions of anidulafungin with another antifungal agent. Synergy with itraconazole (FICI<or=0.5) was observed for one strain of C. glabrata, and antagonism with ketoconazole (FICI>or=4), a drug rarely used systemically, was noted for four strains of C. tropicalis. The combination of anidulafungin and amphotericin B demonstrated additive activity for each of the 18 isolates of Candida tested. These results suggest additional studies are warranted, for example in animal models, to evaluate further the potential of combination antifungal therapy with anidulafungin for Candida infections.

Anidulafungin: a novel echinocandin

We evaluated the safety and efficacy of primary systemic chemotherapy (PSC) with docetaxel (DOC), epirubicin (EPI) and capecitabine (Xeloda:XLD) in 10 patients with advanced breast cancer. Their mean age was 54.7 years,and preoperative stages were IIB, seven cases; IIIA, two; and IV, one,respectively. The regimen consisted of XLD (2,400 or 3,000 mg/day) orally for 14 consecutive days, and DOC (60 or 70 mg/m2) and EPI (50 or 60 mg/m2) intravenously on day 8. This was repeated 4 times every 3 weeks. One patient discontinued this regimen after one course at her own request. Although the results revealed leucopenia and neutropenia of more than grade 3 in 8 and 10 patients,they could be treated on an outpatient basis with the use of G-CSF to maintain this regimen. Alopecia of grade 2 was found in all patients,neutropenic fever of more than 38.5 degrees C in 5,and hand-foot syndrome in 3. Downstaging after PSC was demonstrated in 7 cases (Stage IIB to I, three cases; IIB to IIA, three; and III A to I, one), with a response rate of 77.8%. Breast conserving therapy was performed in 8/10 patients. Pathological findings on cytological degeneration showed grade 0, one; grade 1a,seven; grade 2, one; and grade 3, one, respectively. Axillary lymph node metastasis was revealed in 7 cases. This regimen would be an alternative to PSC on an outpatient basis while taking great care of myelosuppression and hand-foot syndrome.

In vitro activities of anidulafungin against more than 2,500 clinical isolates of Candida spp., including 315 isolates resistant to fluconazole

Anidulafungin is an echinocandin antifungal agent with potent activity against Candida spp. We assessed the in vitro activity of anidulafungin against 2,235 clinical isolates of Candida spp. using the CLSI broth microdilution method. Anidulafungin was very active against Candida spp. (the MIC at which 90% of strains are inhibited [MIC(90)] was 2 microg/ml when MIC endpoint criteria of partial inhibition [MIC-2] were used). Candida albicans, C. glabrata, C. tropicalis, C. krusei, and C. kefyr were the most susceptible species of Candida (MIC(90), 0.06 to 0.12 microg/ml), and C. parapsilosis, C. lusitaniae, and C. guilliermondii were the least susceptible (MIC(90), 0.5 to 2 microg/ml). In addition, 315 fluconazole-resistant isolates were tested, and 99% were inhibited by < or =1 microg/ml of anidulafungin. These results provide further evidence for the spectrum and potency of anidulafungin activity against a large and geographically diverse collection of clinically important isolates of Candida spp.

Colonization of Candida species in denture wearers with emphasis on HIV infection: a literature review

Candida colonization in denture wearers, especially immunocompromised patients, can be disruptive to dental treatment and may be a barrier to patient health. The surface irregularities of acrylic resin are a factor in the entrapment of microorganisms. Consequently, controlling the spread of fungal infection in HIV-infected patients who wear removable prostheses and who are more susceptible to fungal infections because of their immunosuppression is of critical importance. This article reviews the literature on the colonization of Candida species in HIV-infected denture wearers using keywords such as complete dentures, candidiasis, and HIV-infection . The source for this review was representative English-language, peer-reviewed articles between the period of 1885 to 2003 obtained using Medline, as well as a hand search.

A Randomized, Double-Blind Trial of Anidulafungin versus Fluconazole for the Treatment of Esophageal Candidiasis

Anidulafungin is a novel antifungal agent of the echinocandin class. This randomized, double-blind, double-dummy study compared the efficacy and safety of intravenous anidulafungin to that of oral fluconazole in 601 patients with endoscopically and microbiologically documented esophageal candidiasis. Patients received intravenous anidulafungin (100 mg on day 1, followed by 50 mg per day) or oral fluconazole (200 mg on day 1, followed by 100 mg per day) for 7 days beyond resolution of symptoms (range, 14-21 days). At the end of therapy, the rate of endoscopic success for anidulafungin (242 [97.2%] of 249 treated patients) was found to be statistically noninferior to that for fluconazole (252 [98.8%] of 255 treated patients; treatment difference, -1.6%; 95% confidence interval, -4.1 to 0.8). The safety profile of anidulafungin was similar to that of fluconazole; treatment-related adverse events occurred in 9.3% and 12.0% of patients, respectively. Laboratory parameters were similar between treatment arms. Anidulafungin is as safe and effective as oral fluconazole for the treatment of esophageal candidiasis, when assessed at the completion of therapy.

Phase 2, randomized, dose-ranging study evaluating the safety and efficacy of anidulafungin in invasive candidiasis and candidemia

This study evaluated the safety and efficacy of anidulafungin, a novel echinocandin, in patients with invasive candidiasis, including candidemia. A total of 123 eligible patients were randomized to one of three intravenous regimens, 50, 75, or 100 mg once daily. Treatment continued for 2 weeks beyond resolution or improvement of signs and symptoms. The primary efficacy criterion was a successful global response rate (i.e., clinical and microbiological success) in the evaluable population at the follow-up (FU) visit, 2 weeks after end of therapy (EOT). One hundred twenty (120) patients received at least one dose of anidulafungin; 68 were evaluable. Review of adverse events and laboratory data indicated no dose response for safety parameters. Non-albicans Candida species accounted for approximately one-half of all isolates. Success rates at EOT were 84, 90, and 89% in the 50-, 75-, and 100-mg groups, respectively. At FU, the success rates were 72, 85, and 83%. Phase 3 studies of anidulafungin for the treatment of invasive candidiasis and candidemia are warranted.

Fungal biofilms and drug resistance

Candida species, including the novel opportunistic pathogen Candida dubliniensis, are now emerging as major agents of nosocomial infections. Many such manifestations of infections associated with the formation of Candida biofilms include those occurring on devices such as indwelling intravascular catheters. Fungal biofilm-associated infections are frequently refractory to conventional therapy because of resistance to antimicrobial agents. This resistance could be in part due to the surface-induced upregulation of drug efflux pumps. Biofilm-associated Candida show uniform resistance to a wide spectrum of the currently available conventional antifungal agents, which implies that antimicrobial drugs that specifically target biofilm-associated infections are needed. The novel classes of antifungal agents, the lipid formulation of amphotericins, and the echinocandins have demonstrated unique antifungal activity against the resistant Candida biofilms, providing a breakthrough in the treatment of life-threatening invasive systemic mycoses. The use of drugs effective in combating biofilm-associated infections could lead to major developments in the treatment of fungal implant infections.

Anidulafungin: ECB, LY 303366, V-echinocandin, VEC, VER 002, VER-02

Vicuron Pharmaceuticals (formerly Versicor Inc.) is developing anidulafungin [LY 303366, ECB, V-echinocandin, VEC, VER-02, VER 002], a lipopeptide echinocandin B derivative, for IV treatment of mycoses. Anidulafungin acts against fungal infection by inhibiting beta-1,3-glucan synthase, an enzyme essential for cell wall formation. Anidulafungin was originally developed for oral use by Eli Lilly and was undergoing phase II clinical trials in the UK and the US for the treatment of Candida, Aspergillus and Pneumocystis carinii infections. However, Eli Lilly discontinued development of the oral formulation due to poor oral bioavailability. In May 1999, Versicor obtained exclusive worldwide commercialisation rights to anidulafungin with responsibility for its development and clinical registration. Under the terms of the agreement, Eli Lilly received a signing fee, and will receive milestone payments upon future development of anidulafungin and royalties on future sales. Eli Lilly also retains an option for the development of an oral formulation of the compound. On 3 March 2003, Versicor Inc. of Fremont (California, USA) and Biosearch Italia SpA of Milan (Italy) announced the completion of a merger agreement, whereby Biosearch was merged with and into Versicor in a stock-for-stock exchange valued at US dollars 260.7 million. The combined company temporarily kept the name Versicor until the new name, Vicuron Pharmaceuticals, was announced on 26 March 2003. In January 2003, Versicor announced that positive results from a phase II trial for anidulafungin IV treatment involving 120 patients in the US with invasive candidiasis/candidaemia, have led to another double-blind, randomised phase III trial being conducted in the US, Canada and Europe for this indication. This additional phase III trial will enrol approximately 300 patients to investigate the efficacy of IV anidulafungin (200 mg loading dose followed by 100 mg maintenance dose) versus IV fluconazole for 10 to 42 days. Vicuron Pharmaceuticals also plans to seek approval for invasive candidiasis/candidaemia in Europe and Canada in the second half of 2003.

Anidulafungin

Anidulafungin is a novel antifungal agent which, like other echinocandins, inhibits beta-(1,3)-D-glucan synthase and disrupts fungal cell-wall synthesis. It has marked antifungal activity against a broad spectrum of Candida spp. and Aspergillus spp., including amphotericin B- and triazole-resistant strains. In clinical trials, anidulafungin has primarily been evaluated in patients with oesophageal and invasive candidiasis. Preliminary data are emerging for other indications such as invasive aspergillosis. In a large, multicentre, double-blind, double-dummy, randomised trial in patients with oesophageal candidiasis, intravenous anidulafungin 50 mg/day was as effective as oral fluconazole 100 mg/day regarding end-of-treatment rates of endoscopic cure and clinical and microbiological success. Duration of treatment was approximately 2-3 weeks, and patients in both groups received a loading dose of study drug (twice the daily maintenance dose) on day 1. Anidulafungin is generally well tolerated. Across the dosage range 50-100 mg/day, adverse events appear not to be dose- or infusion-related. In the largest clinical trial to date, the most common treatment-related adverse events were phlebitis/thrombophlebitis, headache, nausea, vomiting and pyrexia.

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.

Echinocandin antifungal drugs

The echinocandins are large lipopeptide molecules that are inhibitors of beta-(1,3)-glucan synthesis, an action that damages fungal cell walls. In vitro and in vivo, the echinocandins are rapidly fungicidal against most Candida spp and fungistatic against Aspergillus spp. They are not active at clinically relevant concentrations against Zygomycetes, Cryptococcus neoformans, or Fusarium spp. No drug target is present in mammalian cells. The first of the class to be licensed was caspofungin, for refractory invasive aspergillosis (about 40% response rate) and the second was micafungin. Adverse events are generally mild, including (for caspofungin) local phlebitis, fever, abnormal liver function tests, and mild haemolysis. Poor absorption after oral administration limits use to the intravenous route. Dosing is once daily and drug interactions are few. The echinocandins are widely distributed in the body, and are metabolised by the liver. Results of studies of caspofungin in candidaemia and invasive candidiasis suggest equivalent efficacy to amphotericin B, with substantially fewer toxic effects. Absence of antagonism in combination with other antifungal drugs suggests that combination antifungal therapy could become a general feature of the echinocandins, particularly for invasive aspergillosis.

Systemic mycoses in the immunocompromised host: an update in antifungal therapy

Despite significant advances in the management of immunosuppressed patients, invasive fungal infections remain an important life-threatening complication. In the last decade several new antifungal agents, including compounds in pre-existing classes (new generation of triazoles, polyenes in lipid formulations) and novel classes of antifungals with a unique mechanism of action (echinocandins), have been introduced in clinical practice. Ongoing and future studies will determine their exact role in the management of different mycoses. The acceleration of antifungal drug discovery offers promise for the management of these difficult to treat opportunistic infections.

In vitro activity of voriconazole, itraconazole, caspofungin, anidulafungin (VER002, LY303366) and amphotericin B against aspergillus spp

Voriconazole, anidulafungin (VER002, LY303366) and caspofungin are promising antifungal agents which provide a good protection against a variety of fungi, including yeasts and filamentous fungi. In this study, we tested the in vitro efficacy of voriconazole, itraconazole, caspofungin, anidulafungin (VER002, LY303366) and amphotericin B, against different species of Aspergillus spp. isolated from clinical specimens, using a microdilution broth method and following the NCCLS guidelines (document M38-P). We also evaluated the effect that time readings have on MIC results. For caspofungin, we determined the minimun effective concentration (MEC), defined like the lowest concentration of caspofungin causing abnormal hyphal growth. Anidulafungin (VER002, LY303366) was the most active antifungal agent tested with MIC(90) of < or =0,03 mg/L. The activity of voriconazole, and itraconazole very similar with MIC(90) of 0,12 mg/L, 0,12 mg/L respectively. For caspofungin the MEC(90) was of 0,25 mg/L. Amphotericin B was the lest active antifungal agent studied with MIC(90) of 1 mg/L. There were no differences between MIC values at 48 and 72 h. These data demonstrate promising activity of voriconazole, anidulafungin (VER002, LY303366) and caspofungin against Apergillus spp.

Antifungal drug resistance

The increasing incidence of invasive fungal infections is the result of many factors, including an increasing number of patients with severe immunosuppression. Although new drugs have been introduced to combat this problem, the development of resistance to antifungal drugs has become increasingly apparent, especially in patients who require long-term treatment or who are receiving antifungal prophylaxis, and there is growing awareness of shifts of flora to more-resistant species. The frequency, interpretation, and, in particular, mechanism of resistance to current classes of antifungal agents, particularly the azoles (where resistance has climbed most prominently) are discussed in this review.

Evaluation of the in vitro activity of caspofungin against bloodstream isolates of Candida species from cancer patients: comparison of Etest and NCCLS reference methods

The in vitro activity of caspofungin (CAS) was compared with the activity of fluconazole, itraconazole and amphotericin B against 178 bloodstream Candida spp. from cancer patients. The activities were assessed using the reference NCCLS M-27A microdilution method and the Etest method. With both the NCCLS microdilution reference method and the Etest method, CAS was the most active agent (MIC90s 0.19-0.5 mg/l) against Candida albicans, C. glabrata and C. tropicalis. CAS showed substantial activity against azole-resistant Candida. The percentages of agreement within +/-2 dilutions between the NCCLS reference microdilution method and Etest MICs ranged from 81 to 97%. CAS showed good in vitro activity against invasive azole-susceptible and azole-resistant Candida isolates. The CAS Etest MICs correlated well with the NCCLS reference MICs and may provide more choice for laboratories in assessing the activity of antifungal agents. The clinical correlation of these in vitro observations needs to be established.

Comparative evaluation of disk diffusion with microdilution assay in susceptibility testing of caspofungin against Aspergillus and Fusarium isolates

We compared the disk diffusion and broth microdilution methods for susceptibility testing of caspofungin against Aspergillus (n = 78) and Fusarium (n = 22) isolates. Microdilution testing followed the NCCLS M-38P guidelines but was performed in antibiotic medium 3 supplemented to 2% glucose (AM3). Disk diffusion assays were performed on AM3 agar plates with a 2- micro g caspofungin disk. By both methods, caspofungin showed favorable activity against Aspergillus isolates and no activity against Fusarium isolates. In the disk-based format, intrazonal growth that was not influenced by the drug concentration gradient was consistently observed for all of the Aspergillus isolates tested.

Antifungal susceptibility of Candida biofilms: unique efficacy of amphotericin B lipid formulations and echinocandins

Biofilms, likely the predominant mode of device-related microbial infection, exhibit resistance to antimicrobial agents. Evidence suggests that Candida biofilms have dramatically reduced susceptibility to antifungal drugs. We examined antifungal susceptibilities of Candida albicans and Candida parapsilosis biofilms grown on a bioprosthetic model. In addition to conventional agents, we determined if new antifungal agents (triazoles, amphotericin B lipid formulations, and echinocandins) have activities against Candida biofilms. We also explored effects of preincubation of C. albicans cells with subinhibitory concentrations (sub-MICs) of drugs to see if they could modify subsequent biofilm formation. Finally, we used confocal scanning laser microscopy (CSLM) to image planktonic- and biofilm-exposed blastospores to examine drug effects on cell structure. Candida biofilms were formed on silicone elastomer and quantified by tetrazolium and dry weight (DW) assays. Susceptibility testing of fluconazole, nystatin, chlorhexidine, terbenafine, amphotericin B (AMB), and the triazoles voriconazole (VRC) and ravuconazole revealed resistance in all Candida isolates examined when grown as biofilms, compared to planktonic forms. In contrast, lipid formulations of AMB (liposomal AMB and AMB lipid complex [ABLC]) and echinocandins (caspofungin [Casp] and micafungin) showed activity against Candida biofilms. Preincubation of C. albicans cells with sub-MIC levels of antifungals decreased the ability of cells to subsequently form biofilm (measured by DW; P < 0.0005). CSLM analysis of planktonic and biofilm-associated blastospores showed treatment with VRC, Casp, and ABLC resulted in morphological alterations, which differed with each agent. In conclusion, our data show that Candida biofilms show unique susceptibilities to echinocandins and AMB lipid formulations.

Studies on antimycotic properties of Datura metel

The hexane, chloroform, acetone and methanolic fractions of Datura metel L. were investigated for antifungal properties using pathogenic species of Aspergillus. The chloroform fraction was found to be endowed with antifungal activity. The minimum inhibitory concentration (MIC) of chloroform fraction of D. metel L. was 625.0 microg ml(-1) against all the three species of Aspergillus, i.e. A. fumigatus, A. flavus and A. niger, by microbroth dilution and percent spore germination inhibition assays. The MIC by disc diffusion assay was observed to be 12.5 microg disc(-1). The chloroform fraction of D. metel, when investigated for potency, turned to be 9.2 times less active than amphotericin B. However, it was important to note that the cytotoxicity of chloroform fraction in vitro was 117.8 times less than amphotericin B.

Recent advances in the epidemiology, prevention, diagnosis, and treatment of fungal pneumonia

Although pneumonia caused by fungi is not a common occurrence in the general population, disease in an enlarging immunocompromised population is encountered with increasing frequency. Fungal pneumonias are most frequently caused by Aspergillus spp., dimorphic fungi and Cryptococcus neoformans. Recent studies have identified risk factors of thrombocytopenia, environmental events (such as construction or renovation) and immunosuppressive drug therapies as being specific risk factors for invasive fungal disease in select patient populations. Diagnostic strategies to detect circulating antigens and polymerase chain reaction based detection systems have been explored to improve identification prior to the progressive advanced disease. Advances in prophylactic strategies include increased use of aerosolized formulations of amphotericin B, usually in conjunction with new and old systemic antifungal agents. Despite recent published guidelines for treatment of fungal pneumonia based on etiology, mortality remains high in some infections with advanced disease. Caspofungin, a new echinocandin antifungal, has recently been approved by the US Food and Drug Administration for the treatment of invasive Aspergillus infections in patients unresponsive to or unable to receive amphotericin B. A triazole antifungal, voriconazole, has shown promise in phase III clinical trials in patients with refractory fungal infections and is expected to be available in early 2002. Other echinocandin and triazole antifungals are under development in attempts to provide improved effective therapy for fungal pneumonia.