51
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Chung D, Thammahong A, Shepardson KM, Blosser SJ, Cramer RA. Endoplasmic reticulum localized PerA is required for cell wall integrity, azole drug resistance, and virulence in Aspergillus fumigatus. Mol Microbiol 2014; 92:1279-98. [PMID: 24779420 DOI: 10.1111/mmi.12626] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/24/2014] [Indexed: 11/29/2022]
Abstract
GPI-anchoring is a universal and critical post-translational protein modification in eukaryotes. In fungi, many cell wall proteins are GPI-anchored, and disruption of GPI-anchored proteins impairs cell wall integrity. After being synthesized and attached to target proteins, GPI anchors undergo modification on lipid moieties. In spite of its importance for GPI-anchored protein functions, our current knowledge of GPI lipid remodelling in pathogenic fungi is limited. In this study, we characterized the role of a putative GPI lipid remodelling protein, designated PerA, in the human pathogenic fungus Aspergillus fumigatus. PerA localizes to the endoplasmic reticulum and loss of PerA leads to striking defects in cell wall integrity. A perA null mutant has decreased conidia production, increased susceptibility to triazole antifungal drugs, and is avirulent in a murine model of invasive pulmonary aspergillosis. Interestingly, loss of PerA increases exposure of β-glucan and chitin content on the hyphal cell surface, but diminished TNF production by bone marrow-derived macrophages relative to wild type. Given the structural specificity of fungal GPI-anchors, which is different from humans, understanding GPI lipid remodelling and PerA function in A. fumigatus is a promising research direction to uncover a new fungal specific antifungal drug target.
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Affiliation(s)
- Dawoon Chung
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
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Scaria PV, Liu Y, Leng Q, Chou ST, Mixson AJ, Woodle MC. Enhancement of antifungal activity by integrin-targeting of branched histidine rich peptides. J Drug Target 2014; 22:536-42. [PMID: 24731059 DOI: 10.3109/1061186x.2014.905948] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The treatment of invasive candidiasis associated with growing numbers of immunocompromised patients remains a major challenge complicated by increasing drug resistance. A novel class of branched histidine-lysine (bHK) peptides has promising antifungal activity, and exhibits a mechanism similar to natural histatins, and thus may avoid drug resistance. The present studies evaluate ligand targeting of bHK peptides to fungal surface integrins by determining whether a cyclic RGD (cRGD) peptide with a large PEG linker could enhance bHK peptide antifungal activity. Whereas conjugates containing only the PEG linker reduced bHK peptide activity, conjugates with the cRGD-PEG ligand resulted in marked enhancement of activity against Candida albicans. This study provides the first demonstration of benefit from ligand targeting of antifungal agents to fungal surface receptors.
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González de Molina F, Martínez-Alberici MDLÁ, Ferrer R. Treatment with echinocandins during continuous renal replacement therapy. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2014; 18:218. [PMID: 25029596 PMCID: PMC4056439 DOI: 10.1186/cc13803] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Echinocandins are indicated as first-line treatment for invasive candidiasis in moderate to severe illness. As sepsis is the main cause of acute kidney injury, the combination of echinocandin treatment and continuous renal replacement therapy (CRRT) is common. Optimizing antibiotic dosage in critically ill patients receiving CRRT is challenging. The pharmacokinetics of echinocandins have been studied under various clinical conditions; however, data for CRRT patients are scarce. Classically, drugs like echinocandins with high protein binding and predominantly non-renal elimination are not removed by CRRT, indicating that no dosage adjustment is required. However, recent studies report different proportions of echinocandins lost by filter adsorption. Nevertheless, the clinical significance of these findings remains unclear.
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Early state research on antifungal natural products. Molecules 2014; 19:2925-56. [PMID: 24609016 PMCID: PMC6271505 DOI: 10.3390/molecules19032925] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Revised: 01/01/2014] [Accepted: 01/09/2014] [Indexed: 01/20/2023] Open
Abstract
Nosocomial infections caused by fungi have increased greatly in recent years, mainly due to the rising number of immunocompromised patients. However, the available antifungal therapeutic arsenal is limited, and the development of new drugs has been slow. Therefore, the search for alternative drugs with low resistance rates and fewer side effects remains a major challenge. Plants produce a variety of medicinal components that can inhibit pathogen growth. Studies of plant species have been conducted to evaluate the characteristics of natural drug products, including their sustainability, affordability, and antimicrobial activity. A considerable number of studies of medicinal plants and alternative compounds, such as secondary metabolites, phenolic compounds, essential oils and extracts, have been performed. Thus, this review discusses the history of the antifungal arsenal, surveys natural products with potential antifungal activity, discusses strategies to develop derivatives of natural products, and presents perspectives on the development of novel antifungal drug candidates.
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55
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Thomas L, Baggen L, Chisholm J, Sharland M. Diagnosis and treatment of aspergillosis in children. Expert Rev Anti Infect Ther 2014; 7:461-72. [DOI: 10.1586/eri.09.19] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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56
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Dalrymple SA, Ko J, Sheoran I, Kaminskyj SGW, Sanders DAR. Elucidation of substrate specificity in Aspergillus nidulans UDP-galactose-4-epimerase. PLoS One 2013; 8:e76803. [PMID: 24116166 PMCID: PMC3792076 DOI: 10.1371/journal.pone.0076803] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Accepted: 08/27/2013] [Indexed: 11/18/2022] Open
Abstract
The frequency of invasive fungal infections has rapidly increased in recent years. Current clinical treatments are experiencing decreased potency due to severe host toxicity and the emergence of fungal drug resistance. As such, new targets and their corresponding synthetic pathways need to be explored for drug development purposes. In this context, galactofuranose residues, which are employed in fungal cell wall construction, but are notably absent in animals, represent an appealing target. Herein we present the structural and biochemical characterization of UDP-galactose-4-epimerase from Aspergillus nidulans which produces the precursor UDP-galactopyranose required for galactofuranose synthesis. Examination of the structural model revealed both NAD+ and UDP-glucopyranose were bound within the active site cleft in a near identical fashion to that found in the Human epimerase. Mutational studies on the conserved catalytic motif support a similar mechanism to that established for the Human counterpart is likely operational within the A. nidulans epimerase. While the Km and kcat for the enzyme were determined to be 0.11 mM and 12.8 s-1, respectively, a single point mutation, namely L320C, activated the enzyme towards larger N-acetylated substrates. Docking studies designed to probe active site affinity corroborate the experimentally determined activity profiles and support the kinetic inhibition results.
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Affiliation(s)
- Sean A. Dalrymple
- Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - John Ko
- Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Inder Sheoran
- Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | | | - David A. R. Sanders
- Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
- * E-mail:
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Balhara M, Ruhil S, kumar M, Dhankhar S, Chhillar AK. An anti-Aspergillusprotein fromEscherichia coliDH5α: Putative inhibitor of siderophore biosynthesis inAspergillus fumigatus. Mycoses 2013; 57:153-62. [DOI: 10.1111/myc.12119] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 07/18/2013] [Accepted: 07/18/2013] [Indexed: 12/01/2022]
Affiliation(s)
- Meenakshi Balhara
- Centre for Biotechnology; Maharshi Dayanand University; Rohtak Haryana India
| | - Sonam Ruhil
- Centre for Biotechnology; Maharshi Dayanand University; Rohtak Haryana India
| | - Manish kumar
- Centre for Biotechnology; Maharshi Dayanand University; Rohtak Haryana India
| | - Sandeep Dhankhar
- Centre for Biotechnology; Maharshi Dayanand University; Rohtak Haryana India
| | - A. K. Chhillar
- Centre for Biotechnology; Maharshi Dayanand University; Rohtak Haryana India
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Spampinato C, Leonardi D. Candida infections, causes, targets, and resistance mechanisms: traditional and alternative antifungal agents. BIOMED RESEARCH INTERNATIONAL 2013; 2013:204237. [PMID: 23878798 PMCID: PMC3708393 DOI: 10.1155/2013/204237] [Citation(s) in RCA: 200] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 06/06/2013] [Accepted: 06/06/2013] [Indexed: 11/25/2022]
Abstract
The genus Candida includes about 200 different species, but only a few species are human opportunistic pathogens and cause infections when the host becomes debilitated or immunocompromised. Candida infections can be superficial or invasive. Superficial infections often affect the skin or mucous membranes and can be treated successfully with topical antifungal drugs. However, invasive fungal infections are often life-threatening, probably due to inefficient diagnostic methods and inappropriate initial antifungal therapies. Here, we briefly review our current knowledge of pathogenic species of the genus Candida and yeast infection causes and then focus on current antifungal drugs and resistance mechanisms. An overview of new therapeutic alternatives for the treatment of Candida infections is also provided.
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Affiliation(s)
- Claudia Spampinato
- Departamento de Química Biológica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), Suipacha 531, 2000 Rosario, Argentina
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI, UNR-CONICET), Suipacha 531, 2000 Rosario, Argentina
| | - Darío Leonardi
- Departamento de Tecnología Farmacéutica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), Suipacha 531, 2000 Rosario, Argentina
- Instituto de Química Rosario (IQUIR, UNR-CONICET), Suipacha 531, 2000 Rosario, Argentina
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Fink M, Zerlauth U, Kaulfersch C, Rab A, Alberer D, Preiss P, Sternad-Klobschauer K, Habernig E, Wandschneider W, Grimm G. A severe case of haemodynamic instability during anidulafungin administration. J Clin Pharm Ther 2013; 38:241-2. [DOI: 10.1111/jcpt.12046] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Accepted: 12/03/2012] [Indexed: 01/22/2023]
Affiliation(s)
- M. Fink
- Department of Cardiothoracic and Vascular Surgery; Klinikum Klagenfurt am Wörthersee; Klagenfurt Austria
- Department of Hospital Epidemiology and Infection Control; Klinikum Klagenfurt am Wörthersee; Klagenfurt Austria
| | - U. Zerlauth
- Department of Hospital Epidemiology and Infection Control; Klinikum Klagenfurt am Wörthersee; Klagenfurt Austria
| | - C. Kaulfersch
- Department of Internal Medicine; Klinikum Klagenfurt am Wörthersee; Klagenfurt Austria
| | - A. Rab
- Department of Internal Medicine; Klinikum Klagenfurt am Wörthersee; Klagenfurt Austria
| | - D. Alberer
- Department of Internal Medicine; Klinikum Klagenfurt am Wörthersee; Klagenfurt Austria
| | - P. Preiss
- Department of Cardiothoracic and Vascular Surgery; Klinikum Klagenfurt am Wörthersee; Klagenfurt Austria
| | | | - E. Habernig
- Department of Hospital Pharmacy; Klinikum Klagenfurt am Wörthersee; Klagenfurt Austria
| | - W. Wandschneider
- Department of Cardiothoracic and Vascular Surgery; Klinikum Klagenfurt am Wörthersee; Klagenfurt Austria
| | - G. Grimm
- Department of Internal Medicine; Klinikum Klagenfurt am Wörthersee; Klagenfurt Austria
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Singh SB, Ondeyka J, Harris G, Herath K, Zink D, Vicente F, Bills G, Collado J, Platas G, González del Val A, Martin J, Reyes F, Wang H, Kahn JN, Galuska S, Giacobbe R, Abruzzo G, Roemer T, Xu D. Isolation, structure, and biological activity of Phaeofungin, a cyclic lipodepsipeptide from a Phaeosphaeria sp. Using the Genome-Wide Candida albicans Fitness Test. JOURNAL OF NATURAL PRODUCTS 2013; 76:334-345. [PMID: 23259972 DOI: 10.1021/np300704s] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Phaeofungin (1), a new cyclic depsipeptide isolated from Phaeosphaeria sp., was discovered by application of reverse genetics technology, using the Candida albicans fitness test (CaFT). Phaeofungin is comprised of seven amino acids and a β,γ-dihydroxy-γ-methylhexadecanoic acid arranged in a 25-membered cyclic depsipeptide. Five of the amino acids were assigned with d-configurations. The structure was elucidated by 2D-NMR and HRMS-MS analysis of the natural product and its hydrolyzed linear peptide. The absolute configuration of the amino acids was determined by Marfey's method by complete and partial hydrolysis of 1. The CaFT profile of the phaeofungin-containing extract overlapped with that of phomafungin (3), another structurally different cyclic lipodepsipeptide isolated from a Phoma sp. using the same approach. Comparative biological characterization further demonstrated that these two fungal lipodepsipeptides are functionally distinct. While phomafungin was potentiated by cyclosporin A (an inhibitor of the calcineurin pathway), phaeofungin was synergized with aureobasidin A (2) (an inhibitor of the sphingolipid biosynthesis) and to some extent caspofungin (an inhibitor of glucan synthase). Furthermore, phaeofungin caused ATP release in wild-type C. albicans strains but phomafungin did not. It showed modest antifungal activity against C. albicans (MIC 16-32 μg/mL) and better activity against Aspergillus fumigatus (MIC 8-16 μg/mL) and Trichophyton mentagrophytes (MIC 4 μg/mL). The linear peptide was inactive, suggesting that the macrocyclic depsipeptide ring is essential for target engagement and antifungal activity.
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Affiliation(s)
- Sheo B Singh
- Department of Medicinal Chemistry, Merck Research Laboratories , PO Box 2000, Rahway, New Jersey 07065, USA.
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Moriyama B, Henning SA, Penzak SR, Walsh TJ. The postantifungal and paradoxical effects of echinocandins against Candida spp. Future Microbiol 2012; 7:565-9. [PMID: 22568712 DOI: 10.2217/fmb.12.31] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Echinocandins induce a postantifungal effect and a paradoxical effect. The postantifungal effect is a concentration-dependent process that allows for sustained kill of Candida spp. after relatively brief exposures to a compound. The paradoxical effect is growth that occurs at high echinocandin concentrations above the MIC. Paradoxical growth varies in terms of media, species, strain and type of echinocandin. The study by Shields et al. evaluated the impact of a brief exposure of caspofungin on paradoxical growth and postantifungal effects in Candida albicans isolates. In the postantifungal effect experiments, prolonged concentration-dependent killing occurred. Maximum postantifungal effects occurred with caspofungin exposures of 5 or 15 min. A brief exposure of caspofungin eliminated the paradoxical growth that was observed in the time-kill experiments. The report by Shields et al. illustrates that short exposures to an echinocandin may lead to prolonged postantifungal effects and furthers our understanding of the paradoxical effect in C. albicans.
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Affiliation(s)
- Brad Moriyama
- NIH Clinical Center, Pharmacy Department, Bethesda, MD, USA
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63
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Metzke B, Neubauer WC, Hieke S, Jung M, Wäsch R, Engelhardt M. Use of systemic antifungals in daily clinical practice in the haematology and oncology setting: results of a prospective observational analysis. Pharmacoepidemiol Drug Saf 2012; 21:953-63. [DOI: 10.1002/pds.3278] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Revised: 03/01/2012] [Accepted: 03/13/2012] [Indexed: 11/07/2022]
Affiliation(s)
- Barbara Metzke
- Department of Hematology and Oncology; University Medical Center Freiburg; Hugstetter Str. 55; D-79106; Freiburg; Germany
| | | | - Stefanie Hieke
- Institute of Medical Biometry and Medical Informatics; University Medical Center Freiburg; Hugstetter Str. 55; D-79106; Freiburg; Germany
| | - Manfred Jung
- Institute of Pharmaceutical Sciences; University of Freiburg; Freiburg; Germany
| | - Ralph Wäsch
- Department of Hematology and Oncology; University Medical Center Freiburg; Hugstetter Str. 55; D-79106; Freiburg; Germany
| | - Monika Engelhardt
- Department of Hematology and Oncology; University Medical Center Freiburg; Hugstetter Str. 55; D-79106; Freiburg; Germany
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64
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Martos AI, Martín-Mazuelos E, Romero A, Serrano C, González T, Almeida C, Puche B, Cantón E, Pemán J, Espinel-Ingroff A. Evaluation of disk diffusion method compared to broth microdilution for antifungal susceptibility testing of 3 echinocandins against Aspergillus spp. Diagn Microbiol Infect Dis 2012; 73:53-6. [DOI: 10.1016/j.diagmicrobio.2012.01.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Revised: 01/15/2012] [Accepted: 01/17/2012] [Indexed: 11/27/2022]
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Kale-Pradhan PB, Wilhelm SM, Johnson LB. Clinical Relevance of In Vitro Resistance of Echinocandins: a Focus on Candida parapsilosis. CURRENT FUNGAL INFECTION REPORTS 2012. [DOI: 10.1007/s12281-012-0087-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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66
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Perkhofer S, Hell M, Gustorff B, Von Goedecke A, Illievich U, Kratzer C, Moosbauer W, Wimmer P, Zerlauth U, Nachbaur K, Vogel W, Bellmann R, Schwameis F, Lass-Flörl C. Austrian clinical practice with anidulafungin in 2008: a multicenter survey. J Chemother 2012; 23:285-9. [PMID: 22005061 DOI: 10.1179/joc.2011.23.5.285] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Anidulafungin had demonstrated favorable efficacy versus fluconazole in a randomized trial on invasive Candida infections. Since patient characteristics in the post-approval use of antifungals likely deviate from clinical trials, we surveyed the use of anidulafungin in clinical routine. We performed a retrospective survey of the post-approval use of anidulafungin in 9 Austrian clinical centers. Anidulafungin was used in 129 critically ill patients with severe comorbidities and multiple risk factors. Indications were suspected invasive fungal infections (IFI) (61%), proven candidemia (19%), and at risk for IFI (prophylaxis, 20%). Candida colonization in conjunction with other risk factors prompted treatment in many patients. predominant pathogens were C. albicans, C. glabrata and C. krusei. Anidulafungin was mostly used for pre-emptive (69%) and first-line treatment (17%) of invasive candidiasis. Treatment response, i.e. complete response/stabilization as determined by investigators (89% in the overall population; 87% for documented candidemia) and survival rates (81% and 75%, respectively) were similar to previous trial data. No breakthrough IFI and few adverse events were reported. Overall, favorable clinical experiences were documented with anidulafungin in the clinical routine setting.
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Affiliation(s)
- S Perkhofer
- Division of Hygiene and Medical Microbiology, Innsbruck Medical University, Innsbruck, Austria
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Effects of echinocandins on cytokine/chemokine production by human monocytes activated by infection with Candida glabrata or by lipopolysaccharide. Diagn Microbiol Infect Dis 2012; 72:226-33. [DOI: 10.1016/j.diagmicrobio.2011.11.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Revised: 11/11/2011] [Accepted: 11/13/2011] [Indexed: 11/23/2022]
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Fungal infections: their diagnosis and treatment in transplant recipients. Int J Hepatol 2012; 2012:106923. [PMID: 22966464 PMCID: PMC3433127 DOI: 10.1155/2012/106923] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Accepted: 04/23/2012] [Indexed: 11/18/2022] Open
Abstract
Systemic fungal infections typically occur in individuals who are seriously ill with recognized risk factors such as those frequently found in transplant recipients. Unfortunately, they are often diagnosed late, when the efficacy of the available treatments is low, often less than 50%, and the cost in terms of lives lost, hospital length of stay, and total hospital costs is substantially increased. The application of antifungal therapies associated with reported efficacy rates greater than 50% are those used prophylactically. When used prophylactically, these infections are reduced in greater than 95% of the expected cases. The choice of a prophylactic agent should be based upon its ease of administration, lack of adverse effects, reduced likelihood of potential drug interactions, and its efficacy in patients with established risk factors and comorbid disease processes that include renal, hepatic, and chronic pulmonary disease. The indications for the use of currently available antifungal agents, their adverse effects, drug interactions, ease of dosing, and applicability in patients with preexisting disease states, and especially in liver transplant recipients, are presented in this paper.
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Antifungal resistance and new strategies to control fungal infections. Int J Microbiol 2011; 2012:713687. [PMID: 22187560 PMCID: PMC3236459 DOI: 10.1155/2012/713687] [Citation(s) in RCA: 262] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 09/06/2011] [Indexed: 11/28/2022] Open
Abstract
Despite improvement of antifungal therapies over the last 30 years, the phenomenon of antifungal resistance is still of major concern in clinical practice. In the last 10 years the molecular mechanisms underlying this phenomenon were extensively unraveled. In this paper, after a brief overview of currently available antifungals, molecular mechanisms of antifungal resistance will be detailed. It appears that major mechanisms of resistance are essential due to the deregulation of antifungal resistance effector genes. This deregulation is a consequence of point mutations occurring in transcriptional regulators of these effector genes. Resistance can also follow the emergence of point mutations directly in the genes coding antifungal targets. In addition we further describe new strategies currently undertaken to discover alternative therapy targets and antifungals. Identification of new antifungals is essentially achieved by the screening of natural or synthetic chemical compound collections. Discovery of new putative antifungal targets is performed through genome-wide approaches for a better understanding of the human pathogenic fungi biology.
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71
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Posaconazole: A new agent for the prevention and management of severe, refractory or invasive fungal infections. CANADIAN JOURNAL OF INFECTIOUS DISEASES & MEDICAL MICROBIOLOGY 2011; 19:297-305. [PMID: 19436511 DOI: 10.1155/2008/825901] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2008] [Accepted: 06/02/2008] [Indexed: 11/17/2022]
Abstract
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.
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Allou N, Allyn J, Montravers P. When and how to cover for fungal infections in patients with severe sepsis and septic shock. Curr Infect Dis Rep 2011; 13:426-32. [PMID: 21792550 DOI: 10.1007/s11908-011-0204-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Candida species remain the most frequently isolated fungi in intensive care unit (ICU) patients with severe sepsis or septic shock. Delayed antifungal therapy in these patients is a recognized risk factor for mortality. However, the diagnosis of invasive candidiasis remains difficult and is frequently delayed. Clinical scores have been proposed to assess the risk of development of invasive candidiasis or candidemia. Laboratory tools for early diagnosis are disappointing or still under development. Triazoles, polyenes, and echinocandins are the key drugs used to treat invasive candidiasis in ICU patients with similar efficacy, but very variable tolerability. The increasing incidence of fluconazole-resistant and susceptible-dose dependent strains and the safety profile of antifungal agents must be taken into account when selecting empiric therapy, frequently leading to the initial use of echinocandins in ICU patients with severe sepsis or septic shock.
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Affiliation(s)
- Nicolas Allou
- Department of Anesthesiology and Surgical Intensive Care Unit, CHU Bichat-Claude Bernard, Assistance Publique Hôpitaux de Paris; Université Paris VII Denis Diderot, 46 rue Henri Huchard, 75018, Paris, France,
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Abstract
It has been nearly a decade since caspofungin was approved for clinical use as the first echinocandin class antifungal agent, followed by micafungin and anidulafungin. The echinocandin drugs target the fungal cell wall by inhibiting the synthesis of β-1,3-D-glucan, a critical cell wall component of many pathogenic fungi. They are fungicidal for Candida spp. and fungistatic for moulds, such as Aspergillus fumigatus, where they induce abnormal morphology and growth properties. The echinocandins have a limited antifungal spectrum but are highly active against most Candida spp., including azole-resistant strains and biofilms. As they target glucan synthase, an enzyme absent in mammalian cells, the echinocandins have a favorable safety profile. They show potent MIC and epidemiological cutoff values against susceptible Candida and Aspergillus isolates, and the frequency of resistance is low. When clinical breakthrough occurs, it is associated with high MIC values and mutations in Fks subunits of glucan synthase, which can reduce the sensitivity of the enzyme to the drug by several thousand-fold. Such strains were not adequately captured by an early clinical breakpoint for susceptibility prompting a revised lower value, which addresses the FKS resistance mechanism and new pharmacokinetic/pharmacodynamic studies. Elevated MIC values unlinked to therapeutic failure can occur and result from adaptive cell behavior, which is FKS-independent and involves the molecular chaperone Hsp90 and the calcineurin pathway. Mutations in FKS1 and/or FKS2 alter the kinetic properties of glucan synthase, which reduces the relative fitness of mutant strains causing them to be less pathogenic. The echinocandin drugs also modify the cell wall architecture exposing buried glucans, which in turn induce a variety of important host immune responses. Finally, the future for glucan synthase inhibitors looks bright with the development of new orally active compounds.
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Affiliation(s)
- David S Perlin
- Public Health Research Institute, New Jersey Medical School-UMDNJ, Newark, NJ 07103, USA.
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Mishra BB, Tiwari VK. Natural products: An evolving role in future drug discovery. Eur J Med Chem 2011; 46:4769-807. [DOI: 10.1016/j.ejmech.2011.07.057] [Citation(s) in RCA: 565] [Impact Index Per Article: 43.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Revised: 07/29/2011] [Accepted: 07/30/2011] [Indexed: 11/16/2022]
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Smith RP, Baltch A, Bopp LH, Ritz WJ, Michelsen PP. Post-antifungal effects and time-kill studies of anidulafungin, caspofungin, and micafungin against Candida glabrata and Candida parapsilosis. Diagn Microbiol Infect Dis 2011; 71:131-8. [PMID: 21865002 DOI: 10.1016/j.diagmicrobio.2011.06.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Revised: 06/29/2011] [Accepted: 06/29/2011] [Indexed: 10/17/2022]
Abstract
Candida glabrata (Cgl) and Candida parapsilosis (Cpa) can cause serious infections and can be resistant to some antifungal drugs. In treating infections caused by these organisms, killing rates and post-antifungal effects (PAFE) are important factors in both dose interval choice and outcome. Two strains each of Cgl and Cpa were studied. For PAFE studies, each organism was exposed to micafungin (MCF), anidulafungin (ANF), or caspofungin (CAS) for 1 h at concentrations ranging from 0.25 to 16×MIC. Cell suspensions were then washed 3 times and resuspended in fresh broth. Time 0 was immediately after resuspension of the yeast. Time-kill experiments were done using similar drug concentrations. Samples were removed at each time point (0-120 h) and viable counts determined. PAFE of ANF and CAS were generally very long, were markedly longer than those of MCF, and increased with increased drug concentration. For ANF and CAS, PAFE for Cgl were greater than those for Cpa only at 0.5 to 2 × MIC. Time-kill experiments showed that ANF, CAS, and MCF were fungicidal at 8 to 16 × MIC up to 120 h. CAS had the greatest activity against Cgl, while ANF and MCF were more active than CAS against Cpa. Because of the prolonged PAFE of these echinocandins, especially ANF and CAS, less frequent dosing during therapy of Cpa and Cgl infections could be considered. Further studies are needed to determine the clinical efficacy of longer dosing intervals.
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Affiliation(s)
- Raymond P Smith
- Stratton VA Medical Center, Infectious Disease Research Laboratory, Albany, NY 12208, USA
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Time-kill studies with micafungin and voriconazole against Candida glabrata intracellularly in human monocyte-derived macrophages and extracellularly in broth. Diagn Microbiol Infect Dis 2011; 70:468-74. [DOI: 10.1016/j.diagmicrobio.2011.04.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Revised: 04/13/2011] [Accepted: 04/13/2011] [Indexed: 11/20/2022]
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Pharmacology and metabolism of anidulafungin, caspofungin and micafungin in the treatment of invasive candidosis: review of the literature. Eur J Med Res 2011; 16:159-66. [PMID: 21486730 PMCID: PMC3352072 DOI: 10.1186/2047-783x-16-4-159] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Echinocandins represent the newest class of antifungal agents. Currently, three echinocandins, anidulafungin, caspofungin and micafungin are licensed for clinical use in various indications. They act as inhibitors of β-(1,3)-glucan synthesis in the fungal cell wall and have a favorable pharmacological profile. They have a broad spectrum of activity against all Candida species. Higher MIC's have been observed against C. parapsilosis and C. guilliermondii. Data from clinical trials for invasive Candida infections/candidaemia suggest that the clinical outcome of patients treated with either drug may be very similar. A comparison has been done between caspofungin and micafungin but for anidulafungin a comparative trial with another echinocandin is still lacking. All three drugs are highly effective if not superior to treatment with either fluconazole or Amphotericin B, particularly in well-defined clinical settings such as invasive Candida infections, Candida oesophagitis and candidaemia. Differences between the three echinocandins with regard to the route of metabolism, requirement for a loading dose, dose adjustment in patients with moderate to severe hepatic disease and different dosing schedules for different types of Candida infections have to be considered. Relevant drug-drug interactions of Caspofungin and Micafungin are minimal. Anidulafungin has no significant drug interactions at all. However, echinocandins are available only for intravenous use. All three agents have an excellent safety profile.
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Holt SL, Drew RH. Echinocandins: Addressing outstanding questions surrounding treatment of invasive fungal infections. Am J Health Syst Pharm 2011; 68:1207-20. [DOI: 10.2146/ajhp100456] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Walraven CJ, Mercier RC, Lee SA. Antifungal Pharmacokinetics and Dosing Considerations in Burn Patients. CURRENT FUNGAL INFECTION REPORTS 2011. [DOI: 10.1007/s12281-011-0047-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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81
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Clinical breakpoints for the echinocandins and Candida revisited: Integration of molecular, clinical, and microbiological data to arrive at species-specific interpretive criteria. Drug Resist Updat 2011; 14:164-76. [DOI: 10.1016/j.drup.2011.01.004] [Citation(s) in RCA: 276] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Revised: 01/17/2011] [Accepted: 01/20/2011] [Indexed: 11/24/2022]
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Glöckner A. Treatment and prophylaxis of invasive candidiasis with anidulafungin, caspofungin and micafungin:review of the literature. Eur J Med Res 2011; 16:167-79. [PMID: 21486731 PMCID: PMC3352073 DOI: 10.1186/2047-783x-16-4-167] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Accepted: 02/16/2011] [Indexed: 12/03/2022] Open
Abstract
Working by a distinct cell wall-specific mechanism of action, the echinocandin class of antifungals has substantially expanded the range of available treatments for invasive Candida infections. Anidulafungin, caspofungin and micafungin were investigated versus drugs from earlier antifungal classes in large clinical trials that demonstrated their excellent clinical and microbiological efficacy in the primary treatment of invasive candidiasis. Therefore, and supported by a number of favourable pharmacological characteristics, the echinocandins rapidly became established in guidelines and clinical practice as primary treatment options for moderately to severely ill patients with invasive candidiasis. This article reviews the relevant clinical evidence that forms the basis for the use of echinocandins in the management of invasive candidiasis, and discusses their current role in the context of recent guideline recommendations and treatment optimization strategies.
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Mayr A, Aigner M, Lass-Flörl C. Anidulafungin for the treatment of invasive candidiasis. Clin Microbiol Infect 2011; 17 Suppl 1:1-12. [PMID: 21251147 DOI: 10.1111/j.1469-0691.2010.03448.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
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.
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Affiliation(s)
- A Mayr
- Division of Hygiene and Social Medicine, Medical University Innsbruck, Innsbruck, Austria
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84
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Definitions and Epidemiology of Candida Species not Susceptible to Echinocandins. CURRENT FUNGAL INFECTION REPORTS 2011. [DOI: 10.1007/s12281-011-0053-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Kale-Pradhan PB, Morgan G, Wilhelm SM, Johnson LB. Comparative efficacy of echinocandins and nonechinocandins for the treatment of Candida parapsilosis Infections: a meta-analysis. Pharmacotherapy 2011; 30:1207-13. [PMID: 21114387 DOI: 10.1592/phco.30.12.1207] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
STUDY OBJECTIVE To compare the efficacy of echinocandins and nonechinocandins in the treatment of candidemia or invasive candidiasis due to Candida parapsilosis. DESIGN Meta-analysis of five randomized, blinded, comparative trials. PATIENTS A total of 1169 patients (mean age 55.5 yrs, 57.8% male) with invasive candidiasis or candidemia treated with an echinocandin or other antifungal agents. MEASUREMENTS AND MAIN RESULTS The PubMed, MEDLINE, Toxnet, and Cochrane Central Register of Controlled Trials databases were searched for relevant English-language articles to identify appropriate randomized trials. The quality of studies was assessed with the Jadad scoring system. Data on number of patients, age, and treatment success rate were extracted by two investigators independently into a standardized data collection form. Overall C. parapsilosis treatment success rates with echinocandins were compared with nonechinocandins. Jadad scores of the five studies that met all of the selection criteria ranged from 2-5 (out of 5), with a median of 4. Among the 1169 patients with invasive candidiasis or candidemia, 202 (17.3%) had C. parapsilosis. Among these C. parapsilosis cases, 102 received an echinocandin and 100 received a comparator drug. The success rates of treating C. parapsilosis were similar for the echinocandin group versus other antifungal treatment groups (76.5% [78/102] vs 73% [73/100]). A fixed-effects model was applied secondary to a low level of heterogeneity among the studies (I²=0%). The combined risk ratio demonstrated that echinocandins are not significantly different from other antifungal agents for the treatment of candidemia or invasive candidiasis due to C. parapsilosis (risk ratio 1.03, 95% confidence interval 0.88-1.21). CONCLUSION Echinocandins are as effective as comparator drugs for the treatment of candidemia or invasive candidiasis due to C. parapsilosis.
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Affiliation(s)
- Pramodini B Kale-Pradhan
- Department of Pharmacy Practice, Eugene Applebaum College of Pharmacy and Health Science, Wayne State University, Detroit, Michigan, USA.
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86
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Pound MW, Townsend ML, Dimondi V, Wilson D, Drew RH. Overview of treatment options for invasive fungal infections. Med Mycol 2011; 49:561-80. [PMID: 21366509 DOI: 10.3109/13693786.2011.560197] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The introduction of several new antifungals has significantly expanded both prophylaxis and treatment options for invasive fungal infections (IFIs). Relative to amphotericin B deoxycholate, lipid-based formulations of amphotericin B have significantly reduced the incidence of nephrotoxicity, but at a significant increase in drug acquisition cost. Newer, broad-spectrum triazoles (notably voriconazole and posaconazole) have added significantly to both the prevention and treatment of IFIs, most notably Aspergillus spp. (with voriconazole) and the treatment of some emerging fungal pathogens. Finally, a new class of parenteral antifungals, the echinocandins, is employed most frequently against invasive candidal infections. While the role of these newer agents continues to evolve, this review summarizes the activity, safety and clinical applications of agents most commonly employed in the treatment of IFIs.
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Affiliation(s)
- Melanie W Pound
- Campbell University College of Pharmacy and Health Sciences, Buies Creek, NC 27506, USA.
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87
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des Champs-Bro B, Leroy-Cotteau A, Mazingue F, Pasquier F, François N, Corm S, Lemaitre L, Poulain D, Yakoub-Agha I, Alfandari S, Sendid B. Invasive fungal infections: epidemiology and analysis of antifungal prescriptions in onco-haematology. J Clin Pharm Ther 2011; 36:152-60. [DOI: 10.1111/j.1365-2710.2010.01166.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Foy DS, Trepanier LA. Antifungal treatment of small animal veterinary patients. Vet Clin North Am Small Anim Pract 2011; 40:1171-88. [PMID: 20933143 DOI: 10.1016/j.cvsm.2010.07.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Antifungal therapy has progressed significantly with the development of new drugs directed at various processes in fungal cell metabolism. Within veterinary medicine, treatment options for systemic mycoses remain limited to amphotericin B, ketoconazole, fluconazole, and itraconazole. However, newer triazoles, echinocandins, and lipid-based formulations of amphotericin B are now approved for use in humans. This article provides a comprehensive review of the antifungal medications available for veterinary patients, and includes a brief discussion of the newer, presently cost-prohibitive, antifungal therapies used for systemic mycoses in humans.
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Affiliation(s)
- Daniel S Foy
- Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, 2015 Linden Drive, Madison, WI 53706, USA.
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89
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Abstract
Melanized or dematiaceous fungi are associated with a wide variety of infectious syndromes, including chromoblastomycosis, mycetoma, and phaeohyphomycosis. [corrected]. Many are soil organisms and are generally distributed worldwide, though certain species appear to have restricted geographic ranges. Though they are uncommon causes of disease, melanized fungi have been increasingly recognized as important pathogens, with most reports occurring in the past 20 years. The spectrum of diseases with which they are associated has also broadened and includes allergic disease, superficial and deep local infections, pneumonia, brain abscess, and disseminated infection. For some infections in immunocompetent individuals, such as allergic fungal sinusitis and brain abscess, they are among the most common etiologic fungi. Melanin is a likely virulence factor for these fungi. Diagnosis relies on careful microscopic and pathological examination, as well as clinical assessment of the patient, as these fungi are often considered contaminants. Therapy varies depending upon the clinical syndrome. Local infection may be cured with excision alone, while systemic disease is often refractory to therapy. Triazoles such as voriconazole, posaconazole, and itraconazole have the most consistent in vitro activity. Further studies are needed to better understand the pathogenesis and optimal treatment of these uncommon infections.
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90
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Cornet M, Sendid B, Fradin C, Gaillardin C, Poulain D, Nguyen HV. Molecular identification of closely related Candida species using two ribosomal intergenic spacer fingerprinting methods. J Mol Diagn 2010; 13:12-22. [PMID: 21227390 DOI: 10.1016/j.jmoldx.2010.11.014] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/08/2010] [Indexed: 12/24/2022] Open
Abstract
Recent changes in the epidemiology of candidiasis highlighted an increase in non- Candida albicans species emphasizing the need for reliable identification methods. Molecular diagnostics in fungal infections may improve species characterization, particularly in cases of the closely related species in the Candida complexes. We developed two PCR/restriction fragment length polymorphism assays, targeting either a part of the intergenic spacer 2 or the entire intergenic spacer (IGS) of ribosomal DNA using a panel of 270 isolates. A part of the intergenic spacer was used for discrimination between C. albicans and C. dubliniensis and between species of the C. glabrata complex (C. glabrata/C. bracarensis/C. nivariensis). The whole IGS was applied to C. parapsilosis, C. metapsilosis, and C. orthopsilosis, and to separate C. famata (Debaryomyces hansenii) from C. guilliermondii (Pichia guilliermondii) and from the other species within this complex (ie, C. carpophila, C. fermentati and C. xestobii). Sharing similar biochemical patterns, Pichia norvegensis and C. inconspicua exhibited specific IGS profiles. Our study confirmed that isolates of C. guilliermondii were frequently mis-identified as C. famata. As much as 67% of the clinical isolates phenotypically determined as C. famata were recognized mostly as true P. guilliermondii. Conversely, 44% of the isolates initially identified as C. guilliermondii were corrected by the IGS fingerprints as C. parapsilosis, C. fermentati, or C. zeylanoides. These two PCR/restriction fragment length polymorphism methods may be used as reference tools [either alternatively or adjunctively to the existing ribosomal DNA (26S or ITS) sequence comparisons] for unambiguous determination of the Candida species for which phenotypic characterization remains problematic.
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Affiliation(s)
- Muriel Cornet
- Laboratoire de Microbiologie, Hôtel-Dieu, AP-HP, Université Paris Descartes, Paris, France
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91
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Profiling the Aspergillus fumigatus proteome in response to caspofungin. Antimicrob Agents Chemother 2010; 55:146-54. [PMID: 20974863 DOI: 10.1128/aac.00884-10] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The proteomic response of Aspergillus fumigatus to caspofungin was evaluated by gel-free isobaric tagging for relative and absolute quantitation (iTRAQ) as a means to determine potential biomarkers of drug action. A cell fractionation approach yielding 4 subcellular compartment fractions was used to enhance the resolution of proteins for proteomic analysis. Using iTRAQ, a total of 471 unique proteins were identified in soluble and cell wall/plasma membrane fractions at 24 and 48 h of growth in rich media in a wild-type drug-susceptible strain. A total of 122 proteins showed at least a 2-fold change in relative abundance following exposure to caspofungin (CSF) at just below the minimum effective concentration (0.12 μg/ml). The largest changes were seen in the mitochondrial hypoxia response domain protein (AFUA_1G12250), the level of which decreased >16-fold in the secreted fraction, and ChiA1, the level of which decreased 12.1-fold in the cell wall/plasma membrane fraction. The level of the major allergen and cytotoxin AspF1 was also shown to decrease by 12.1-fold upon the addition of drug. A subsequent iTRAQ analysis of an echinocandin-resistant strain (fks1-S678P) was used to validate proteins specific to drug action. A total of 103 proteins in the 2 fractions tested by iTRAQ were differentially expressed in the wild-type susceptible strain but not significantly changed in the resistant strain. Of these potential biomarkers, 11 had levels that changed at least 12-fold. Microarray analysis of the susceptible strain was performed to evaluate the correlation between proteomics and genomics, with a total of 117 genes found to be changing at least 2-fold. Of these, a total of 22 proteins with significant changes identified by iTRAQ also showed significant gene expression level changes by microarray. Overall, these data have the potential to identify biomarkers that assess the relative efficacy of echinocandin drug therapy.
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Differential Aspergillus lentulus echinocandin susceptibilities are Fksp independent. Antimicrob Agents Chemother 2010; 54:4992-8. [PMID: 20855747 DOI: 10.1128/aac.00774-10] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The recently described species Aspergillus lentulus exhibits differential and reduced susceptibilities to echinocandins and other antifungal drugs in vitro. A. lentulus isolates overall are less susceptible to caspofungin, although they maintain susceptibility to anidulafungin and micafungin. Mutations or polymorphisms in fks, the gene encoding the catalytic subunit of β-1,3-glucan synthase, are known to confer decreased susceptibility to echinocandins in Candida spp. and Aspergillus fumigatus. The analysis of the A. lentulus fks sequence did not reveal a polymorphism at any of the known hot-spot regions of the gene. Caspofungin and micafungin kinetic inhibition profiles of the A. lentulus glucan synthase were comparable to those from susceptible A. fumigatus enzymes. Although the basal cell wall chitin levels in A. lentulus averaged 60% of those in A. fumigatus, echinocandin treatment promoted the increase of cell wall chitin in both organisms, indicating that A. lentulus displays a compensatory chitin response similar to that of A. fumigatus. The data suggest that differential echinocandin susceptibilities in A. lentulus are independent of the echinocandin target, Fksp, and they emphasize the potential that the drugs' capacity to inhibit the target enzyme is unequal at the cellular level.
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93
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FKS mutations and elevated echinocandin MIC values among Candida glabrata isolates from U.S. population-based surveillance. Antimicrob Agents Chemother 2010; 54:5042-7. [PMID: 20837754 DOI: 10.1128/aac.00836-10] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Candida glabrata is the second leading cause of candidemia in the United States. Its high-level resistance to triazole antifungal drugs has led to the increased use of the echinocandin class of antifungal agents for primary therapy of these infections. We monitored C. glabrata bloodstream isolates from a population-based surveillance study for elevated echinocandin MIC values (MICs of ≥0.25 μg/ml). From the 490 C. glabrata isolates that were screened, we identified 16 isolates with an elevated MIC value (2.9% of isolates from Atlanta and 2.0% of isolates from Baltimore) for one or more of the echinocandin drugs caspofungin, anidulafungin, and micafungin. All of the isolates with elevated MIC values had a mutation in the previously identified hot spot 1 of either the glucan synthase FKS1 (n = 2) or FKS2 (n = 14) gene. No mutations were detected in hot spot 2 of either FKS1 or FKS2. The predominant mutation was mutation of FKS2-encoded serine 663 to proline (S663P), found in 10 of the isolates with elevated echinocandin MICs. Two of the mutations, R631G for FKS1 and R665G for FKS2, have not been reported previously for C. glabrata. Multilocus sequence typing indicated that the predominance of the S663P mutation was not due to the clonal spread of a single sequence type. With a rising number of echinocandin therapy failures reported, it is important to continue to monitor rates of elevated echinocandin MIC values and the associated mutations.
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94
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Mojumder DK, Concepcion FA, Patel SK, Barkmeier AJ, Carvounis PE, Wilson JH, Holz ER, Wensel TG. Evaluating retinal toxicity of intravitreal caspofungin in the mouse eye. Invest Ophthalmol Vis Sci 2010; 51:5796-803. [PMID: 20505203 DOI: 10.1167/iovs.10-5541] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
PURPOSE Caspofungin is a synthetic echinocandin antifungal agent that inhibits the synthesis of β(1,3)-D-glucan, an essential component of the cell wall of susceptible Aspergillus and Candida species. In this study, retinal toxicity was determined after intravitreal injection of caspofungin in a mouse model to assess its safety profile for the treatment of fungal endophthalmitis. METHODS Caspofungin acetate was injected intravitreally in the left eyes of male C57BL/6 mice, with final vitreal concentrations corresponding to 0.41, 1.2, 2.5, 4.1, and 41 μM (five mice per cohort). A total of 25 age-matched male C57BL/6 mice injected with balanced salt solution were used as control subjects (five for each of the five different caspofungin acetate concentrations). Electroretinograms (ERGs) were recorded 7 weeks after the injections, and the injected eyes were examined histologically. RESULTS Mice injected with caspofungin at vitreal concentrations from 0.41 to 4.1 μM did not have significant alterations in their ERG waveforms, and their retinas had no detectable morphologic changes or loss of cells. At the vitreal concentration of 41 μM, caspofungin reduced the amplitudes of the a-waves, b-waves, and scotopic threshold responses of the ERG and also produced a decrease in the number of cells in the ganglion cell layer. CONCLUSIONS Caspofungin is a safe antifungal agent at vitreal concentrations of 0.41 to 4.1 μM in mice and consequently shows promise for the treatment of fungal endophthalmitis in humans. Much higher doses produce toxicity and should not be used.
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Affiliation(s)
- Deb K Mojumder
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
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Glöckner A, Karthaus M. Current aspects of invasive candidiasis and aspergillosis in adult intensive care patients. Mycoses 2010; 54:420-33. [PMID: 20492530 DOI: 10.1111/j.1439-0507.2010.01885.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Sepsis is a leading cause of death in the intensive care unit (ICU), with Candida spp. in the forefront among the important pathogens. As recent studies have shown, survival outcome is strongly influenced by adequate antifungal therapy at an early stage that is often delayed by the time lag associated with microbiological diagnosis. Risk factor-based prediction models have a high negative predictive value, but positive prediction of candidaemia in the individual patient remains elusive. New antigen- or DNA-based methods for early diagnosis still await clinical validation. Their routine use is hampered by methodological issues. Species distribution of invasive Candida isolates in the ICU appears to be influenced primarily by age, previous hospitalisation and colonising species. In the context of the importance of adequate first-line treatment, recent guidelines favour the use of echinocandins in critically ill patients with symptoms evoking high suspicion of invasive candidiasis. This is supported by robust clinical trial data, a few interactions and low toxicity. Fluconazole is characterised by reduced activity against some important Candida species, elevated rates of persistent infection seen in comparative trials. Amphotericin B deoxycholate should be considered obsolete in ICU patients because of its high toxicity. Invasive aspergillosis (IA) is a rare devastating infection in the general ICU population, but some centres have reported elevated incidences and underdiagnosis as determined in autopsy-controlled studies. Treatment with mould-active agents such as voriconazole must be initiated early in patients with suspected IA.
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Affiliation(s)
- A Glöckner
- BDH-Klinik Greifswald GmbH, Greifswald, Germany.
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96
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Jose A Vazquez. Management of oropharyngeal and esophageal candidiasis in patients with HIV infection. ACTA ACUST UNITED AC 2010. [DOI: 10.2217/hiv.10.18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mucocutaneous candidiasis is frequently one of the first signs of HIV infection. Over 90% of patients with AIDS will develop oropharyngeal candidiasis at some time during their illness. Although numerous antifungal agents have been developed, azoles, both topical (clotrimazole) and systemic (fluconazole, itraconazole, voriconazole and posaconazole), have replaced older topical antifungals (gentian violet and nystatin) in the management of oropharyngeal candidiasis in these patients. The systemic azoles are generally safe and effective agents in HIV-infected patients with oropharyngeal candidiasis. A constant concern in these patients are relapses, which depend on the degree of immunosuppression and are commonly encountered after topical therapy rather than with systemic azole therapy. In patients with fluconazole-refractory mucosal candidiasis, treatment options now include itraconazole solution, voriconazole, posaconazole and the newer echinocandins (caspofungin, micafungin and anidulafungin). The objective of this article is to review the epidemiology, diagnosis and newer management modalities of oropharyngeal and esophageal candidiasis in HIV-infected individuals.
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97
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Bernardo SM, Lee SA. Candida albicans SUR7 contributes to secretion, biofilm formation, and macrophage killing. BMC Microbiol 2010; 10:133. [PMID: 20433738 PMCID: PMC2887802 DOI: 10.1186/1471-2180-10-133] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2009] [Accepted: 04/30/2010] [Indexed: 12/13/2022] Open
Abstract
Background Candida albicans SUR7 has been shown to be required for plasma membrane organization and cell wall synthesis, but its role in virulence is not known. Using a bioinformatics strategy, we previously identified several novel putative secretion pathway proteins potentially involved in virulence, including the C. albicans homolog of the Saccharomyces cerevisiae endocytosis-related protein Sur7p. We therefore generated a C. albicans sur7Δ null mutant and examined its contribution to key virulence attributes. Results Structurally, the C. albicans sur7Δ mutant was impaired in response to filamentation-inducing conditions, and formed aberrant hyphae with extensive accumulation of plasma membrane-derived structures within the cell. Absence of SUR7 resulted in a temperature-sensitive growth defect at high temperatures (42°C), which was partially rescued by addition of NaCl. We next examined the role of the SUR7 paralog C. albicans FMP45 in this temperature-sensitive phenotype. Analysis of C. albicans Fmp45p-GFP demonstrated co-localization of Fmp45p with Sur7p and increased fluorescence in the plasma membrane in the presence of high salt. We next focused on key virulence-related phenotypes. The C. albicans sur7Δ null mutant exhibited secretory defects: reduced lipase secretion, and increased levels of secreted Sap2p. The null mutant was hyper-susceptible to sub-inhibitory concentrations of caspofungin, but not amphotericin B and 5-fluorocytosine. Functionally, the sur7Δ mutant demonstrated increased adhesion to polystyrene and of note, was markedly defective in biofilm formation. In an in vitro macrophage model of virulence, the sur7Δ mutant was impaired in macrophage killing. Conclusions Plasma membrane and cell wall organization are important for cell morphology, and alterations of these structures contributed to impairment of several key virulence-associated phenotypes in the C. albicans sur7Δ mutant.
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Affiliation(s)
- Stella M Bernardo
- Section of Infectious Diseases, New Mexico Veterans Healthcare System, Albuquerque, NM, USA
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98
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Vazquez JA. Optimal management of oropharyngeal and esophageal candidiasis in patients living with HIV infection. HIV AIDS (Auckl) 2010; 2:89-101. [PMID: 22096388 PMCID: PMC3218701 DOI: 10.2147/hiv.s6660] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Mucocutaneous candidiasis is frequently one of the first signs of human immunodeficiency virus (HIV) infection. Over 90% of patients with AIDS will develop oropharyngeal candidiasis (OPC) at some time during their illness. Although numerous antifungal agents are available, azoles, both topical (clotrimazole) and systemic (fluconazole, itraconazole, voriconazole, posaconazole) have replaced older topical antifungals (gentian violet and nystatin) in the management of oropharyngeal candidiasis in these patients. The systemic azoles, are generally safe and effective agents in HIV-infected patients with oropharyngeal candidiasis. A constant concern in these patients is relapse, which is dependent on the degree of immunosuppression commonly seen after topical therapy, rather than with systemic azole therapy. Candida esophagitis (CE) is also an important concern since it occurs in more than 10% of patients with AIDS and can lead to a decrease in oral intake and associated weight loss. Fluconazole has become the most widely used antifungal in the management of mucosal candidiasis. However, itraconazole and posaconazole have similar clinical response rates as fluconazole and are also effective alternative agents. In patients with fluconazole-refractory mucosal candidiasis, treatment options now include itraconazole solution, voriconazole, posaconazole, and the newer echinocandins (caspofungin, micafungin, and anidulafungin).
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Affiliation(s)
- Jose A Vazquez
- Division of Infectious Diseases, Henry Ford Hospital, Wayne State University School of Medicine, Detroit, MI, USA
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99
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Njoku JC, Gumeel D, Hermsen ED. Antifungal Therapy in Pregnancy and Breastfeeding. CURRENT FUNGAL INFECTION REPORTS 2010. [DOI: 10.1007/s12281-010-0009-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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100
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Pound MW, Townsend ML, Drew RH. Echinocandin pharmacodynamics: review and clinical implications. J Antimicrob Chemother 2010; 65:1108-18. [PMID: 20335190 DOI: 10.1093/jac/dkq081] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Echinocandins have made a significant impact in the treatment of select invasive fungal infections, most notably invasive candidiasis and aspergillosis. However, treatment outcomes for such infections are still less than optimal, prompting an examination of dosing and administration techniques in an attempt to exploit known pharmacodynamic properties and improve outcomes. Echinocandins generally exhibit concentration-dependent, fungicidal activity against Candida spp. and fungistatic activity against Aspergillus spp. However, increasing drug concentrations of echinocandins above the organism's MIC may result in a paradoxical increase in fungal growth as demonstrated in some in vitro and in vivo models (known most commonly as the 'Eagle effect'). Therefore, the potential impact of dose escalations on improving the clinical efficacy of echinocandins based on in vitro and animal models are uncertain and are still being evaluated. In addition, such strategies have to consider the potential for increased treatment-related toxicities and costs. To date, published clinical studies (both superiority and non-inferiority) demonstrating the potential for dose-related improvements in treatment outcomes have been limited to mucocutaneous and oesophageal candidiasis. Further research is needed to determine if a role exists for optimizing echinocandin pharmacodynamics in various clinical settings.
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Affiliation(s)
- Melanie W Pound
- Campbell University School of Pharmacy, Buies Creek, NC, USA.
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