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Roberts D, Salmon J, Cubeta MA, Gilger BC. Phase-Dependent Differential In Vitro and Ex Vivo Susceptibility of Aspergillus flavus and Fusarium keratoplasticum to Azole Antifungals. J Fungi (Basel) 2023; 9:966. [PMID: 37888221 PMCID: PMC10608098 DOI: 10.3390/jof9100966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 09/19/2023] [Accepted: 09/21/2023] [Indexed: 10/28/2023] Open
Abstract
Fungal keratitis (FK) is an invasive infection of the cornea primarily associated with Aspergillus and Fusarium species. FK is treated empirically with a limited selection of topical antifungals with varying levels of success. Though clinical infections are typically characterized by a dense network of mature mycelium, traditional models used to test antifungal susceptibility of FK isolates exclusively evaluate susceptibility in fungal cultures derived from asexual spores known as conidia. The purpose of this study was to characterize differences in fungal response when topical antifungal treatment is initiated at progressive phases of fungal development. We compared the efficacy of voriconazole and luliconazole against in vitro cultures of A. flavus and F. keratoplasticum at 0, 24, and 48 h of fungal development. A porcine cadaver corneal model was used to compare antifungal efficacy of voriconazole and luliconazole in ex vivo tissue cultures of A. flavus and F. keratoplasticum at 0, 24, and 48 h of fungal development. Our results demonstrate phase-dependent susceptibility of both A. flavus and F. keratoplasticum to both azoles in vitro as well as ex vivo. We conclude that traditional antifungal susceptibility testing with conidial suspensions does not correlate with fungal susceptibility in cultures of a more advanced developmental phase. A revised method of antifungal susceptibility testing that evaluates hyphal susceptibility may better predict fungal response in the clinical setting where treatment is often delayed until days after the initial insult.
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Affiliation(s)
- Darby Roberts
- Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606, USA; (D.R.)
| | - Jacklyn Salmon
- Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606, USA; (D.R.)
| | - Marc A. Cubeta
- Department of Entomology and Plant Pathology, Center for Integrated Fungal Research, North Carolina State University, Raleigh, NC 27606, USA;
| | - Brian C. Gilger
- Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606, USA; (D.R.)
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2
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Alam F, Siddiqui B, Hasan N, Arif S, Maheshwari V, Alam K, Hasan M, Khan R, Khan PA, Ahmed A, Gautam S. Rapid Cytological Diagnosis With Evaluation of Pre- and Post-Therapeutic Fungal Morphological Characteristics in Mucormycosis. J Clin Med Res 2023; 15:31-37. [PMID: 36755764 PMCID: PMC9881490 DOI: 10.14740/jocmr4835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 11/23/2022] [Indexed: 01/26/2023] Open
Abstract
Background Mucormycosis necessitates rapid diagnosis and treatment. Microscopy and culture have been considered the gold standard for diagnosis but both take time of 3 - 5 days. KOH mount is another method for fungal identification that takes 1 - 2 h, but it has its own limitations. This study evaluated crush smear as a means of rapid cytological diagnosis. Methods Biopsy tissue (pre-treatment) from clinically suspicious mucormycosis patients (n = 52) was received in normal saline and crush/imprint smears were prepared; the remaining tissue was processed as routine biopsy specimen. After the rapid initial cytological identification, the patients were managed according to the standard clinical protocol. Random post-therapeutic biopsy samples of some of these patients (n = 19) were also obtained and again evaluated cytologically. Results Crush smears showed sensitivity/specificity of 77.7%/75.0% with histopathology and 72.2%/62.5% with culture, respectively, while KOH mount had values of 71.4%/70.5% with histopathology and 79.3%/69.5% with culture, respectively. Degenerative fungal morphological characteristics and cellular inflammatory infiltrate (predominantly neutrophilic) in the vicinity of fungal hyphae were compared in pre- and post-treatment groups, and we found a statistically significant difference (P < 0.05) between them. Conclusion Our preliminary results suggest that crush smear cytology is a simple, rapid, cost-effective and easily available method for diagnosing mucormycosis. Moreover, crush smears also demonstrated morphological alteration in hyphal structure and accompanying immune cell infiltration which may provide valuable insights into mechanism of therapy/host immune response against fungal pathogen.
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Affiliation(s)
- Feroz Alam
- Department of Pathology, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, India,Corresponding Author: Feroz Alam, Department of Pathology, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh 202002, India.
| | - Bushra Siddiqui
- Department of Pathology, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, India
| | - Naba Hasan
- Department of Pathology, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, India
| | - S.H. Arif
- Department of Pathology, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, India
| | - Veena Maheshwari
- Department of Pathology, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, India
| | - Kiran Alam
- Department of Pathology, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, India
| | - Mahboob Hasan
- Department of Pathology, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, India
| | - Roobina Khan
- Department of Pathology, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, India
| | - Parvez Anwer Khan
- Department of Microbiology, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, India
| | - Aftab Ahmed
- Department of Otorhinolaryngology, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, India
| | - Surabhi Gautam
- Department of Pathology, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, India
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Mello TP, Oliveira SSC, Branquinha MH, Santos ALS. Decoding the antifungal resistance mechanisms in biofilms of emerging, ubiquitous and multidrug-resistant species belonging to the Scedosporium/Lomentospora genera. Med Mycol 2022; 60:6596289. [PMID: 35641191 DOI: 10.1093/mmy/myac036] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 05/14/2022] [Accepted: 05/24/2022] [Indexed: 11/13/2022] Open
Abstract
The opportunistic filamentous fungi belonging to the Scedosporium and Lomentospora genera are highly tolerant to all classes of available antifungal drugs. Moreover, the mature biofilm formed by these fungi presents higher antifungal resistance when compared to planktonic cells. Nevertheless, the resistance mechanisms developed by the biofilm lifestyle are not completely elucidated. In the current study, we have investigated the mainly known resistance mechanisms to azoles (voriconazole and fluconazole) and polyenes (amphotericin B - AMB) in S. apiospermum, S. minutisporum, S. aurantiacum, and L. prolificans (formerly S. prolificans) biofilms. Both classes of antifungals can physically bind to the extracellular matrix of mature biofilms, preventing the drugs from reaching their targets on biofilm-forming cells, which precludes their activity and toxicity. In addition, the activity of efflux pumps, measured by Rhodamine 6 G, was increased along the maturation of the biofilm. The efflux pump's inhibition by L-Phe-L-Arg-β-naphthylamide culminated in a 2- to 16-fold increase in azole susceptibility in conidial cells, but not in mature biofilms. Finally, we demonstrated by using specific inhibitors that in conidia, but not in biofilms, AMB induced the production of reactive oxygen species through the activity of the oxidative phosphorylation system (complex I to IV and alternative oxidases). However, the cellular redox imbalance caused by AMB was well coped with the high activity of antioxidative enzymes, such as superoxide dismutase and catalase. Altogether, our results revealed that Scedosporium/Lomentospora biofilm resistance occurs through various mechanisms that operate concomitantly, which could explain the huge challenge in the clinical treatment of scedosporiosis/lomentosporiosis.
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Affiliation(s)
- Thaís P Mello
- Laboratório de Estudos Avançados de Microrganismos Emergentes e Resistentes (LEAMER), Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Góes (IMPG), Centro de Ciências da Saúde (CCS), Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil
| | - Simone S C Oliveira
- Laboratório de Estudos Avançados de Microrganismos Emergentes e Resistentes (LEAMER), Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Góes (IMPG), Centro de Ciências da Saúde (CCS), Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil
| | - Marta H Branquinha
- Laboratório de Estudos Avançados de Microrganismos Emergentes e Resistentes (LEAMER), Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Góes (IMPG), Centro de Ciências da Saúde (CCS), Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil.,Rede Micologia RJ - Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ)
| | - André L S Santos
- Laboratório de Estudos Avançados de Microrganismos Emergentes e Resistentes (LEAMER), Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Góes (IMPG), Centro de Ciências da Saúde (CCS), Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil.,Rede Micologia RJ - Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ).,Programa de Pós-Graduação em Bioquímica, Instituto de Química, Universidade Federal do Rio de Janeiro (UFRJ), Brazil
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4
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van de Sande WWJ. In vitro susceptibility testing for black grain eumycetoma causative agents. Trans R Soc Trop Med Hyg 2021; 115:343-354. [PMID: 33537781 PMCID: PMC8046409 DOI: 10.1093/trstmh/traa184] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 11/30/2020] [Accepted: 12/21/2020] [Indexed: 12/17/2022] Open
Abstract
Eumycetoma is a neglected tropical implantation mycosis characterized by large subcutaneous swellings. Inside the infected tissue, the causative agents are found in grains. The most common causative agents form black grains and are sterile upon isolation. In vitro susceptibility assays were developed for eumycetoma causative agents. They were based on the Clinical and Laboratory Standards Institute M38A protocol and modified to enable the use of hyphae as a starting inoculum. To ease endpoint reading, viability dyes such as resazurin or XTT have been used. So far the in vitro susceptibility assays developed have mainly been used to establish if causative agents are inhibited in growth by various antifungal agents, but not for clinical decision making. For drug discovery, the assay proved useful in determining which compounds were able to prevent hyphal growth. However, a clear correlation between in vitro inhibition in terms of the half maximal inhibitory concentration or 50% minimum inhibitory concentration (MIC50) and therapeutic efficacy assayed in a novel model system in terms of Galleria mellonella larval survival was not found. For clinical decision making, a range of MICs were found for each antifungal agent. However, no clinical breakpoints have been established for any of the causative agents. For itraconazole, the MIC50 of most causative agents was below the attainable serum levels, which might indicate that they are susceptible. However, before in vitro susceptibility can be used in clinical decision making for mycetoma, a correlation between MIC and clinical outcome needs to be made.
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Affiliation(s)
- Wendy W J van de Sande
- Erasmus Medical Center, University Medical Center Rotterdam, Department of Medical Microbiology and Infectious Diseases, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
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Kim JH, Cheng LW, Chan KL, Tam CC, Mahoney N, Friedman M, Shilman MM, Land KM. Antifungal Drug Repurposing. Antibiotics (Basel) 2020; 9:antibiotics9110812. [PMID: 33203147 PMCID: PMC7697925 DOI: 10.3390/antibiotics9110812] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 10/30/2020] [Accepted: 11/13/2020] [Indexed: 12/19/2022] Open
Abstract
Control of fungal pathogens is increasingly problematic due to the limited number of effective drugs available for antifungal therapy. Conventional antifungal drugs could also trigger human cytotoxicity associated with the kidneys and liver, including the generation of reactive oxygen species. Moreover, increased incidences of fungal resistance to the classes of azoles, such as fluconazole, itraconazole, voriconazole, or posaconazole, or echinocandins, including caspofungin, anidulafungin, or micafungin, have been documented. Of note, certain azole fungicides such as propiconazole or tebuconazole that are applied to agricultural fields have the same mechanism of antifungal action as clinical azole drugs. Such long-term application of azole fungicides to crop fields provides environmental selection pressure for the emergence of pan-azole-resistant fungal strains such as Aspergillus fumigatus having TR34/L98H mutations, specifically, a 34 bp insertion into the cytochrome P450 51A (CYP51A) gene promoter region and a leucine-to-histidine substitution at codon 98 of CYP51A. Altogether, the emerging resistance of pathogens to currently available antifungal drugs and insufficiency in the discovery of new therapeutics engender the urgent need for the development of new antifungals and/or alternative therapies for effective control of fungal pathogens. We discuss the current needs for the discovery of new clinical antifungal drugs and the recent drug repurposing endeavors as alternative methods for fungal pathogen control.
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Affiliation(s)
- Jong H. Kim
- Foodborne Toxin Detection and Prevention Research Unit, Western Regional Research Center, Agricultural Research Service, United States Department of Agriculture, Albany, CA 94710, USA; (L.W.C.); (K.L.C.); (C.C.T.); (N.M.)
- Correspondence: ; Tel.: +1-510-559-5841
| | - Luisa W. Cheng
- Foodborne Toxin Detection and Prevention Research Unit, Western Regional Research Center, Agricultural Research Service, United States Department of Agriculture, Albany, CA 94710, USA; (L.W.C.); (K.L.C.); (C.C.T.); (N.M.)
| | - Kathleen L. Chan
- Foodborne Toxin Detection and Prevention Research Unit, Western Regional Research Center, Agricultural Research Service, United States Department of Agriculture, Albany, CA 94710, USA; (L.W.C.); (K.L.C.); (C.C.T.); (N.M.)
| | - Christina C. Tam
- Foodborne Toxin Detection and Prevention Research Unit, Western Regional Research Center, Agricultural Research Service, United States Department of Agriculture, Albany, CA 94710, USA; (L.W.C.); (K.L.C.); (C.C.T.); (N.M.)
| | - Noreen Mahoney
- Foodborne Toxin Detection and Prevention Research Unit, Western Regional Research Center, Agricultural Research Service, United States Department of Agriculture, Albany, CA 94710, USA; (L.W.C.); (K.L.C.); (C.C.T.); (N.M.)
| | - Mendel Friedman
- Healthy Processed Foods Research Unit, Western Regional Research Center, Agricultural Research Service, United States Department of Agriculture, Albany, CA 94710, USA;
| | | | - Kirkwood M. Land
- Department of Biological Sciences, University of the Pacific, Stockton, CA 95211, USA;
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6
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Rodriguez-de la Noval C, Ruiz Mendoza S, de Souza Gonçalves D, da Silva Ferreira M, Honorato L, Peralta JM, Nimrichter L, Guimarães AJ. Protective Efficacy of Lectin-Fc(IgG) Fusion Proteins In Vitro and in a Pulmonary Aspergillosis In Vivo Model. J Fungi (Basel) 2020; 6:jof6040250. [PMID: 33120893 PMCID: PMC7712007 DOI: 10.3390/jof6040250] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 10/21/2020] [Accepted: 10/23/2020] [Indexed: 12/14/2022] Open
Abstract
Aspergillosis cases by Aspergillus fumigatus have increased, along with fungal resistance to antifungals, urging the development of new therapies. Passive immunization targeting common fungal antigens, such as chitin and β-glucans, are promising and would eliminate the need of species-level diagnosis, thereby expediting the therapeutic intervention. However, these polysaccharides are poorly immunogenic. To overcome this drawback, we developed the lectin-Fc(IgG) fusion proteins, Dectin1-Fc(IgG2a), Dectin1-Fc(IgG2b) and wheat germ agglutinin (WGA)-Fc(IgG2a), based on their affinity to β-1,3-glucan and chitooligomers, respectively. The WGA-Fc(IgG2a) previously demonstrated antifungal activity against Histoplasma capsulatum, Cryptococcus neoformans and Candida albicans. In the present work, we evaluated the antifungal properties of these lectin-Fc(s) against A. fumigatus. Lectin-Fc(IgG)(s) bound in a dose-dependent manner to germinating conidia and this binding increased upon conidia germination. Both lectin-Fc(IgG)(s) displayed in vitro antifungal effects, such as inhibition of conidia germination, a reduced length of germ tubes and a diminished biofilm formation. Lectin-Fc(IgG)(s) also enhanced complement deposition on conidia and macrophage effector functions, such as increased phagocytosis and killing of fungi. Finally, administration of the Dectin-1-Fc(IgG2b) and WGA-Fc(IgG2a) protected mice infected with A. fumigatus, with a 20% survival and a doubled life-span of the infected mice, which was correlated to a fungal burden reduction in lungs and brains of treated animals. These results confirm the potential of lectin-Fc(IgGs)(s) as a broad-spectrum antifungal therapeutic.
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Affiliation(s)
- Claudia Rodriguez-de la Noval
- Laboratório de Bioquímica e Imunologia das Micoses, Departamento de Microbiologia e Parasitologia, Instituto Biomédico, Universidade Federal Fluminense, Niterói 24020-141, RJ, Brazil; (C.R.-d.l.N.); (S.R.M.); (D.d.S.G.); (M.d.S.F.)
- Laboratório de Glicobiologia de Eucariotos, Instituto de Microbiologia Professor Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, RJ, Brazil; (L.H.); (L.N.)
| | - Susana Ruiz Mendoza
- Laboratório de Bioquímica e Imunologia das Micoses, Departamento de Microbiologia e Parasitologia, Instituto Biomédico, Universidade Federal Fluminense, Niterói 24020-141, RJ, Brazil; (C.R.-d.l.N.); (S.R.M.); (D.d.S.G.); (M.d.S.F.)
- Departamento de Imunologia, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, RJ, Brazil;
| | - Diego de Souza Gonçalves
- Laboratório de Bioquímica e Imunologia das Micoses, Departamento de Microbiologia e Parasitologia, Instituto Biomédico, Universidade Federal Fluminense, Niterói 24020-141, RJ, Brazil; (C.R.-d.l.N.); (S.R.M.); (D.d.S.G.); (M.d.S.F.)
- Pós-Graduação em Doenças Infecciosas e Parasitárias, Faculdade de Medicina, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-913, RJ, Brazil
| | - Marina da Silva Ferreira
- Laboratório de Bioquímica e Imunologia das Micoses, Departamento de Microbiologia e Parasitologia, Instituto Biomédico, Universidade Federal Fluminense, Niterói 24020-141, RJ, Brazil; (C.R.-d.l.N.); (S.R.M.); (D.d.S.G.); (M.d.S.F.)
- Departamento de Imunologia, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, RJ, Brazil;
| | - Leandro Honorato
- Laboratório de Glicobiologia de Eucariotos, Instituto de Microbiologia Professor Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, RJ, Brazil; (L.H.); (L.N.)
| | - José Mauro Peralta
- Departamento de Imunologia, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, RJ, Brazil;
- Pós-Graduação em Doenças Infecciosas e Parasitárias, Faculdade de Medicina, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-913, RJ, Brazil
| | - Leonardo Nimrichter
- Laboratório de Glicobiologia de Eucariotos, Instituto de Microbiologia Professor Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, RJ, Brazil; (L.H.); (L.N.)
| | - Allan J. Guimarães
- Laboratório de Bioquímica e Imunologia das Micoses, Departamento de Microbiologia e Parasitologia, Instituto Biomédico, Universidade Federal Fluminense, Niterói 24020-141, RJ, Brazil; (C.R.-d.l.N.); (S.R.M.); (D.d.S.G.); (M.d.S.F.)
- Programa de Pós-Graduação em Microbiologia e Parasitologia Aplicadas (PPGMPA), Instituto Biomédico, Universidade Federal Fluminense, Rua Professor Hernani Pires de Melo 101, São Domingos, Niterói 24210-130, RJ, Brazil
- Correspondence: ; Tel.: +55-21-2629-2410
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Khamkhenshorngphanuch T, Kulkraisri K, Janjamratsaeng A, Plabutong N, Thammahong A, Manadee K, Na Pombejra S, Khotavivattana T. Synthesis and Antimicrobial Activity of Novel 4-Hydroxy-2-quinolone Analogs. Molecules 2020; 25:molecules25133059. [PMID: 32635479 PMCID: PMC7412474 DOI: 10.3390/molecules25133059] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 06/30/2020] [Accepted: 07/03/2020] [Indexed: 11/16/2022] Open
Abstract
Alkyl quinolone has been proven to be a privileged scaffold in the antimicrobial drug discovery pipeline. In this study, a series of new 4-hydroxy-2-quinolinone analogs containing a long alkyl side chain at C-3 and a broad range of substituents on the C-6 and C-7 positions were synthesized. The antibacterial and antifungal activities of these analogs against Staphylococcus aureus, Escherichia coli, and Aspergillus flavus were investigated. The structure-activity relationship study revealed that the length of the alkyl chain, as well as the type of substituent, has a dramatic impact on the antimicrobial activities. Particularly, the brominated analogs 3j with a nonyl side chain exhibited exceptional antifungal activities against A. flavus (half maximal inhibitory concentration (IC50) = 1.05 µg/mL), which surpassed that of the amphotericin B used as a positive control. The antibacterial activity against S. aureus, although not as potent, showed a similar trend to the antifungal activity. The data suggest that the 4-hydroxy-2-quinolone is a promising framework for the further development of new antimicrobial agents, especially for antifungal treatment.
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Affiliation(s)
- Thitiphong Khamkhenshorngphanuch
- Department of General Education, Faculty of Science and Health Technology, Navamindradhiraj University, Bangkok 10300, Thailand;
| | - Kittipat Kulkraisri
- Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand; (K.K.); (A.J.)
| | - Alongkorn Janjamratsaeng
- Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand; (K.K.); (A.J.)
| | - Napasawan Plabutong
- Antimicrobial Resistance and Stewardship Research Unit, Department of Microbiology, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand; (N.P.); (A.T.)
| | - Arsa Thammahong
- Antimicrobial Resistance and Stewardship Research Unit, Department of Microbiology, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand; (N.P.); (A.T.)
| | - Kanitta Manadee
- Department of Microbiology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand; (K.M.); (S.N.P.)
| | - Sarisa Na Pombejra
- Department of Microbiology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand; (K.M.); (S.N.P.)
| | - Tanatorn Khotavivattana
- Center of Excellence in Natural Products Chemistry, Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
- Correspondence: ; Tel.: +66-2-218-7621
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The Inhibitory Effect of Validamycin A on Aspergillus flavus. Int J Microbiol 2020; 2020:3972415. [PMID: 32676114 PMCID: PMC7336217 DOI: 10.1155/2020/3972415] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 05/08/2020] [Accepted: 06/03/2020] [Indexed: 12/13/2022] Open
Abstract
Aspergillus flavus is one of the most common isolates from patients with fungal infections. Aspergillus infection is usually treated with antifungal agents, but side effects of these agents are common. Trehalase is an essential enzyme involved in fungal metabolism, and the trehalase inhibitor, validamycin A, has been used to prevent fungal infections in agricultural products. In this study, we observed that validamycin A significantly increased trehalose levels in A. flavus conidia and delayed germination, including decreased fungal adherence. In addition, validamycin A and amphotericin B showed a combinatorial effect on A. flavus ATCC204304 and clinical isolates with high minimum inhibitory concentrations (MICs) of amphotericin B using checkerboard assays. We observed that validamycin A and amphotericin B had a synergistic effect on A. flavus strains resistant to amphotericin B. The MICs in the combination of validamycin A and amphotericin B were at 0.125 μg/mL and 2 μg/mL, respectively. The FICI of validamycin A and amphotericin B of these clinical isolates was about 0.25-0.28 with synergistic effects. No drug cytotoxicity was observed in human bronchial epithelial cells treated with validamycin A using LDH-cytotoxicity assays. In conclusion, this study demonstrated that validamycin A inhibited the growth of A. flavus and delayed conidial germination. Furthermore, the combined effect of validamycin A with amphotericin B increased A. flavus killing, without significant cytotoxicity to human bronchial epithelial cells. We propose that validamycin A could potentially be used in vivo as an alternative treatment for A. flavus infections.
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In Vitro Evaluation of Radiolabeled Amphotericin B for Molecular Imaging of Mold Infections. Antimicrob Agents Chemother 2020; 64:AAC.02377-19. [PMID: 32393491 DOI: 10.1128/aac.02377-19] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 05/02/2020] [Indexed: 12/17/2022] Open
Abstract
Invasive pulmonary aspergillosis and mucormycosis are life-threatening complications in immunocompromised patients. A rapid diagnosis followed by early antifungal treatment is essential for patient survival. Given the limited spectrum of biomarkers for invasive mold infections, recent studies have proposed the use of radiolabeled siderophores or antibodies as molecular probes to increase the specificity of radiological findings by nuclear imaging modalities. While holding enormous diagnostic potential, most of the currently available molecular probes are tailored to the detection of Aspergillus species, and their cost-intensive and sophisticated implementation restricts their accessibility at less specialized centers. In order to develop cost-efficient and broadly applicable tracers for pulmonary mold infections, this study established streamlined and high-yielding protocols to radiolabel amphotericin B (AMB) with the gamma emitter technetium-99m (99mTc-AMB) and the positron emitter gallium-68 (68Ga-AMB). The radiochemical purity of the resulting tracers consistently exceeded 99%, and both probes displayed excellent stability in human serum (>98% after 60 to 240 min at 37°C). The uptake kinetics by representative mold pathogens were assessed in an in vitro Transwell assay using infected endothelial cell layers. Both tracers accumulated intensively and specifically in Transwell inserts infected with Aspergillus fumigatus, Rhizopus arrhizus, and other clinically relevant mold pathogens compared with their accumulation in uninfected inserts and inserts infected with bacterial controls. Inoculum-dependent enrichment was confirmed by gamma counting and autoradiographic imaging. Taken together, this pilot in vitro study proposes 99mTc-AMB and 68Ga-AMB to be facile, stable, and specific probes, meriting further preclinical in vivo evaluation of radiolabeled amphotericin B for molecular imaging in invasive mycoses.
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Peptide-Like Nylon-3 Polymers with Activity against Phylogenetically Diverse, Intrinsically Drug-Resistant Pathogenic Fungi. mSphere 2018; 3:3/3/e00223-18. [PMID: 29794056 PMCID: PMC5967195 DOI: 10.1128/msphere.00223-18] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 05/01/2018] [Indexed: 11/20/2022] Open
Abstract
Understanding the dimensions of fungal diversity has major implications for the control of diseases in humans, plants, and animals and in the overall health of ecosystems on the planet. One ancient evolutionary strategy organisms use to manage interactions with microbes, including fungi, is to produce host defense peptides (HDPs). HDPs and their synthetic analogs have been subjects of interest as potential therapeutic agents. Due to increases in fungal disease worldwide, there is great interest in developing novel antifungal agents. Here we describe activity of polymeric HDP analogs against fungi from 18 pathogenic genera composed of 41 species and 72 isolates. The synthetic polymers are members of the nylon-3 family (poly-β-amino acid materials). Three different nylon-3 polymers show high efficacy against surprisingly diverse fungi. Across the phylogenetic spectrum (with the exception of Aspergillus species), yeasts, dermatophytes, dimorphic fungi, and molds were all sensitive to the effects of these polymers. Even fungi intrinsically resistant to current antifungal drugs, such as the causative agents of mucormycosis (Rhizopus spp.) and those with acquired resistance to azole drugs, showed nylon-3 polymer sensitivity. In addition, the emerging pathogens Pseudogymnoascus destructans (cause of white nose syndrome in bats) and Candida auris (cause of nosocomial infections of humans) were also sensitive. The three nylon-3 polymers exhibited relatively low toxicity toward mammalian cells. These findings raise the possibility that nylon-3 polymers could be useful against fungi for which there are only limited and/or no antifungal agents available at present.IMPORTANCE Fungi reside in all ecosystems on earth and impart both positive and negative effects on human, plant, and animal health. Fungal disease is on the rise worldwide, and there is a critical need for more effective and less toxic antifungal agents. Nylon-3 polymers are short, sequence random, poly-β-amino acid materials that can be designed to manifest antimicrobial properties. Here, we describe three nylon-3 polymers with potent activity against the most phylogenetically diverse set of fungi evaluated thus far in a single study. In contrast to traditional peptides, nylon-3 polymers are highly stable to proteolytic degradation and can be produced efficiently in large quantities at low cost. The ability to modify nylon-3 polymer composition easily creates an opportunity to tailor efficacy and toxicity, which makes these materials attractive as potential broad-spectrum antifungal therapeutics.
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Koziróg A, Brycki B, Pielech-Przybylska K. Impact of Cationic and Neutral Gemini Surfactants on Conidia and Hyphal Forms of Aspergillus brasiliensis. Int J Mol Sci 2018; 19:E873. [PMID: 29543767 PMCID: PMC5877734 DOI: 10.3390/ijms19030873] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 03/09/2018] [Accepted: 03/09/2018] [Indexed: 12/02/2022] Open
Abstract
This study investigates the biological activity of two cationic gemini surfactants, hexamethylene-1,6-bis-(N,N-dimethyl-N-dodecylammonium bromide) C6 and pentamethylene-1,5-bis-(N,N-dimethyl-N-dodecyla,.mmonium bromide) C5, and their two neutral analogs, hexamethylene-1,6-bis-(N-methyl-N-dodecylamine) (A6) and pentamethylene-1,5-bis-(N-methyl-N-dodecylamine) (A5). Experiments were performed with Aspergillus brasiliensis, which is used in the standard tests for biocides. The minimal inhibitory concentration (MIC) values for conidia and mycelium were determined using the dilution method. The viability of the conidia was evaluated using the plate count method. The dry mass of the mycelium was determined using the thermogravimetric method. Ergosterol was extracted from the mycelium and evaluated by gas chromatography. The effect of gemini surfactants on fungal morphology was observed using scanning electron microscopy. Cationic gemini surfactants were found to be active at lower concentrations compared to their non-ionic analogues, rapidly reducing the total number of conidia that were able to grow. They also decreased both the ergosterol content in the mycelium and its dry weight. These results suggest that cationic gemini surfactants C6 and C5 could have a wide range of practical applications as active compounds. However, it should be remembered that usage at too low concentrations, below the MIC, will only lead to short-term disturbances in the development of conidia and mycelium.
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Affiliation(s)
- Anna Koziróg
- Institute of Fermentation Technology and Microbiology, Faculty of Biotechnology and Food Science, Lodz University of Technology, Wólczańska 171/173, 90-924 Lodz, Poland.
| | - Bogumił Brycki
- Laboratory of Microbiocides Chemistry, Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89b, 61-614 Poznan, Poland.
| | - Katarzyna Pielech-Przybylska
- Institute of Fermentation Technology and Microbiology, Faculty of Biotechnology and Food Science, Lodz University of Technology, Wólczańska 171/173, 90-924 Lodz, Poland.
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12
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Mello TPD, Aor AC, Oliveira SSCD, Branquinha MH, Santos ALSD. Conidial germination in Scedosporium apiospermum, S. aurantiacum, S. minutisporum and Lomentospora prolificans: influence of growth conditions and antifungal susceptibility profiles. Mem Inst Oswaldo Cruz 2017; 0:0. [PMID: 27355215 PMCID: PMC4957502 DOI: 10.1590/0074-02760160200] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 06/02/2016] [Indexed: 12/05/2022] Open
Abstract
In the present study, we have investigated some growth conditions capable of inducing the conidial germination in Scedosporium apiospermum, S. aurantiacum, S. minutisporum and Lomentospora prolificans. Germination in Sabouraud medium (pH 7.0, 37ºC, 5% CO2) showed to be a typically time-dependent event, reaching ~75% in S. minutisporum and > 90% in S. apiospermum, S. aurantiacum and L. prolificans after 4 h. Similar germination rate was observed when conidia were incubated under different media and pHs. Contrarily, temperature and CO2 tension modulated the germination. The isotropic conidial growth (swelling) and germ tube-like projection were evidenced by microscopy and cytometry. Morphometric parameters augmented in a time-dependent fashion, evidencing changes in size and granularity of fungal cells compared with dormant 0 h conidia. In parallel, a clear increase in the mitochondrial activity was measured during the transformation of conidia-into-germinated conidia. Susceptibility profiles to itraconazole, fluconazole, voriconazole, amphotericin B and caspofungin varied regarding each morphotype and each fungal species. Overall, the minimal inhibitory concentrations for hyphae were higher than conidia and germinated conidia, except for caspofungin. Collectively, our study add new data about the conidia-into-hyphae transformation in Scedosporium and Lomentospora species, which is a relevant biological process of these molds directly connected to their antifungal resistance and pathogenicity mechanisms.
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Affiliation(s)
- Thaís Pereira de Mello
- Universidade Federal do Rio de Janeiro, Instituto de Microbiologia Paulo de Góes, Departamento de Microbiologia Geral, Laboratório de Investigação de Peptidases, Rio de Janeiro, RJ, Brasil
| | - Ana Carolina Aor
- Universidade Federal do Rio de Janeiro, Instituto de Microbiologia Paulo de Góes, Departamento de Microbiologia Geral, Laboratório de Investigação de Peptidases, Rio de Janeiro, RJ, Brasil
| | - Simone Santiago Carvalho de Oliveira
- Universidade Federal do Rio de Janeiro, Instituto de Microbiologia Paulo de Góes, Departamento de Microbiologia Geral, Laboratório de Investigação de Peptidases, Rio de Janeiro, RJ, Brasil
| | - Marta Helena Branquinha
- Universidade Federal do Rio de Janeiro, Instituto de Microbiologia Paulo de Góes, Departamento de Microbiologia Geral, Laboratório de Investigação de Peptidases, Rio de Janeiro, RJ, Brasil
| | - André Luis Souza Dos Santos
- Universidade Federal do Rio de Janeiro, Instituto de Microbiologia Paulo de Góes, Departamento de Microbiologia Geral, Laboratório de Investigação de Peptidases, Rio de Janeiro, RJ, Brasil
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Addition of 17-(allylamino)-17-demethoxygeldanamycin to a suboptimal caspofungin treatment regimen in neutropenic rats with invasive pulmonary aspergillosis delays the time to death but does not enhance the overall therapeutic efficacy. PLoS One 2017; 12:e0180961. [PMID: 28742113 PMCID: PMC5524388 DOI: 10.1371/journal.pone.0180961] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 06/23/2017] [Indexed: 12/31/2022] Open
Abstract
Caspofungin (CAS) which is used as salvage therapy in patients with invasive pulmonary aspergillosis (IPA) inhibits the 1,3-β-D-glucan synthesis in Aspergillus fumigatus. Inhibiting 1,3-β-D-glucan synthesis induces a stress response and in an invertebrate model it was demonstrated that inhibiting this response with geldamycin enhanced the therapeutic efficacy of CAS. Since geldamycin itself is toxic to mammalians, the therapeutic efficacy of combining geldamycin with CAS was not studied in rodent models. Therefore in this study we investigated if the geldamycin derivate 17-(allylamino)-17-demethoxygeldanamycin (17-AAG) was able to enhance the therapeutic efficacy of CAS in vitro and in our IPA model in transiently neutropenic rats. In vitro we confirmed the earlier demonstrated synergy between 17-AAG and CAS in ten A. fumigatus isolates. In vivo we treated A. fumigatus infected neutropenic rats with a sub-optimal dose of 0.75 mg/kg/day CAS and 1 mg/kg/day 17-AAG for ten days. Survival was monitored for 21 days after fungal inoculation. It appeared that the addition 17-AAG delayed death but did not improve overall survival of rats with IPA. Increasing the doses of 17-AAG was not possible due to hepatic toxicity. This study underlines the need to develop less toxic and more fungal specific geldamycin derivatives and the need to test such drugs not only in invertebrate models but also in mammalian models.
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Perdoni F, Signorelli P, Cirasola D, Caretti A, Galimberti V, Biggiogera M, Gasco P, Musicanti C, Morace G, Borghi E. Antifungal activity of Myriocin on clinically relevant Aspergillus fumigatus strains producing biofilm. BMC Microbiol 2015; 15:248. [PMID: 26519193 PMCID: PMC4628231 DOI: 10.1186/s12866-015-0588-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Accepted: 10/23/2015] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND The human pathogenic mold Aspergillus fumigatus is able to form a complex biofilm embedded in extracellular matrix. Biofilms confer antimicrobial resistance and it is well known that aspergillosis is often refractory to the conventional antifungal therapy. The treatment of biofilm-related infections poses a significant clinical challenge on a daily basis, promoting the search for new therapeutic agents. Our aim was to exploit the modulation of sphingolipid mediators as new therapeutic target to overcome antifungal resistance in biofilm-related infections. RESULTS Antifungal susceptibility testing was performed on 20 clinical isolates of Aspergillus fumigatus and one reference strain (A. fumigatus Af293) according the EUCAST protocol. Sessile MICs were assessed on 24-h preformed-biofilm by means of XTT-reduction assay. Myriocin (0.25-64 mg/L), a commercial sphingolipid synthesis inhibitor, was used. The MEC50 value (mg/L) of Myriocin was 8 (range 4-16) for both planktonic and sessile cells. Drug-induced morphological alterations were analyzed by optical and electron microscopy (TEM) on 24h preformed A. fumigatus Af293 biofilms. An evident hyphal damage, resulting in short, stubby, and highly branched hyphae was observed by optical microscopy. At 24h, TEM studies showed important morphological alterations, such as invaginations of the cell membrane, modification in the vacuolar system and presence of multilamellar bodies, in some cases within vacuoles. CONCLUSIONS The direct antifungal activity, observed on both planktonic and sessile fungi, suggests that inhibition of sphingolipid synthesis could represent a new target to fight biofilm-related A. fumigatus resistance.
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Affiliation(s)
- Federica Perdoni
- Department of Health Sciences, Università degli Studi di Milano, Polo Universitario San Paolo, Blocco C, ottavo piano, via di Rudinì 8, 20142, Milan, Italy.
| | - Paola Signorelli
- Department of Health Sciences, Università degli Studi di Milano, Polo Universitario San Paolo, Blocco C, ottavo piano, via di Rudinì 8, 20142, Milan, Italy.
| | - Daniela Cirasola
- Department of Health Sciences, Università degli Studi di Milano, Polo Universitario San Paolo, Blocco C, ottavo piano, via di Rudinì 8, 20142, Milan, Italy.
| | - Anna Caretti
- Department of Health Sciences, Università degli Studi di Milano, Polo Universitario San Paolo, Blocco C, ottavo piano, via di Rudinì 8, 20142, Milan, Italy.
| | - Valentina Galimberti
- Department of Biology and Biotechnology, Università degli Studi di Pavia, Pavia, Italy.
| | - Marco Biggiogera
- Department of Biology and Biotechnology, Università degli Studi di Pavia, Pavia, Italy.
| | | | | | - Giulia Morace
- Department of Health Sciences, Università degli Studi di Milano, Polo Universitario San Paolo, Blocco C, ottavo piano, via di Rudinì 8, 20142, Milan, Italy.
| | - Elisa Borghi
- Department of Health Sciences, Università degli Studi di Milano, Polo Universitario San Paolo, Blocco C, ottavo piano, via di Rudinì 8, 20142, Milan, Italy.
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15
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Chadha S, Kale S. Simple fluorescence-based high throughput cell viability assay for filamentous fungi. Lett Appl Microbiol 2015; 61:238-44. [DOI: 10.1111/lam.12460] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Revised: 06/09/2015] [Accepted: 06/18/2015] [Indexed: 01/28/2023]
Affiliation(s)
- S. Chadha
- Nuclear Agriculture and Biotechnology Division; Bhabha Atomic Research Centre; Mumbai India
| | - S.P. Kale
- Nuclear Agriculture and Biotechnology Division; Bhabha Atomic Research Centre; Mumbai India
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16
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Ahmed SA, de Hoog GS, Stevens DA, Fahal AH, van de Sande WWJ. In vitro antifungal susceptibility of coelomycete agents of black grain eumycetoma to eight antifungals. Med Mycol 2015; 53:295-301. [PMID: 25631481 DOI: 10.1093/mmy/myu098] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Fungal mycetoma (eumycetoma) represents one of the most difficult infections to appropriately manage. The current recommended treatment is based on extensive surgical debridement combined with prolonged antifungal therapy with ketoconazole or itraconazole. Despite the different phylogenetic positions of black-grain eumycetoma species, they are all treated with the same antifungal agents. The in vitro antifungal susceptibility of coelomycetous eumycetoma agents in the order of Pleosporales presently is largely unknown. Here we determined the in vitro activity of eight antifungal agents against seven species causing human eumycetoma using the Sensititre YeastOne method. High minimum inhibitory concentrations (MICs) were found with fluconazole, caspofungin, flucytosine, and amphotericin B. Voriconazole and posaconazole were found to be active against all species tested. Of the species included in the investigation, MICs of Medicopsis romeroi differed from the rest of the mycetoma causative agents belonging to the order of the Pleosporales. We found significantly lower MICs for amphotericin B and significantly higher MICs for fluconazole, ketoconazole, and itraconazole against this species. Our results emphasised that identification of black grain mycetoma agent is important as well as performing susceptibility testing before starting of antifungal treatment.
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Affiliation(s)
- Sarah Abdalla Ahmed
- Faculty of Medical Laboratory Sciences, University of Khartoum, Khartoum, Sudan Centraalbureau voor Schimmelcultures KNAW Fungal Biodiversity Centre, Utrecht, The Netherlands Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, The Netherlands
| | - G Sybren de Hoog
- Centraalbureau voor Schimmelcultures KNAW Fungal Biodiversity Centre, Utrecht, The Netherlands Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, The Netherlands Peking University Health Science Center, Research Center for Medical Mycology, Beijing, China, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China, Shanghai Institute of Medical Mycology, Changzheng Hospital, Second Military Medical University, Shanghai, China, Basic Pathology Department, Federal University of Paraná State, Curitiba, Paraná, Brazil, King Abdulaziz University, Jeddah, Saudi Arabia
| | - David A Stevens
- California Institute for Medical Research, and Division of Infectious Diseases, Department of Medicine, Stanford University Medical School, San Jose and Stanford, California
| | - Ahmed H Fahal
- Mycetoma Research Centre, University of Khartoum, Khartoum, Sudan
| | - Wendy W J van de Sande
- ErasmusMC, Department of Medical Microbiology and Infectious Diseases, Rotterdam, The Netherlands
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17
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Abstract
Medical treatment of mycetoma depends on its fungal or bacterial etiology. Clinically, these entities share similar features that can confuse diagnosis, causing a lack of therapeutic response due to inappropriate treatment. This review evaluates the response to available antimicrobial agents in actinomycetoma and the current status of antifungal drugs for treatment of eumycetoma.
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Affiliation(s)
- Oliverio Welsh
- Department of Dermatology, Dr. Jose E. Gonzalez University Hospital, Universidad Autónoma de Nuevo León, Monterrey, Nuevo León, Mexico
- * E-mail:
| | - Hail Mater Al-Abdely
- Section of Infectious Diseases, Department of Medicine, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Mario Cesar Salinas-Carmona
- Department of Immunology, Faculty of Medicine, Universidad Autónoma de Nuevo León, Monterrey, Nuevo León, Mexico
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18
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Fonseca AOS, Pereira DIB, Maia Filho FS, Osorio LG, Maroneze BP, Valente JSS, Potter L, Meireles MCA. In vitro susceptibility of zoospores and hyphae of Pythium insidiosum to antifungals. J Antimicrob Chemother 2014; 69:1564-7. [DOI: 10.1093/jac/dku021] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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19
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In vitro interaction between alginate lyase and amphotericin B against Aspergillus fumigatus biofilm determined by different methods. Antimicrob Agents Chemother 2012; 57:1275-82. [PMID: 23263007 DOI: 10.1128/aac.01875-12] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Aspergillus fumigatus biofilms represent a problematic clinical entity, especially because of their recalcitrance to antifungal drugs, which poses a number of therapeutic implications for invasive aspergillosis, the most difficult-to-treat Aspergillus-related disease. While the antibiofilm activities of amphotericin B (AMB) deoxycholate and its lipid formulations (e.g., liposomal AMB [LAMB]) are well documented, the effectiveness of these drugs in combination with nonantifungal agents is poorly understood. In the present study, in vitro interactions between polyene antifungals (AMB and LAMB) and alginate lyase (AlgL), an enzyme degrading the polysaccharides produced as extracellular polymeric substances (EPSs) within the biofilm matrix, against A. fumigatus biofilms were evaluated by using the checkerboard microdilution and the time-kill assays. Furthermore, atomic force microscopy (AFM) was used to image and quantify the effects of AlgL-antifungal combinations on biofilm-growing hyphal cells. On the basis of fractional inhibitory concentration index values, synergy was found between both AMB formulations and AlgL, and this finding was also confirmed by the time-kill test. Finally, AFM analysis showed that when A. fumigatus biofilms were treated with AlgL or polyene alone, as well as with their combination, both a reduction of hyphal thicknesses and an increase of adhesive forces were observed compared to the findings for untreated controls, probably owing to the different action by the enzyme or the antifungal compounds. Interestingly, marked physical changes were noticed in A. fumigatus biofilms exposed to the AlgL-antifungal combinations compared with the physical characteristics detected after exposure to the antifungals alone, indicating that AlgL may enhance the antibiofilm activity of both AMB and LAMB, perhaps by disrupting the hypha-embedding EPSs and thus facilitating the drugs to reach biofilm cells. Taken together, our results suggest that a combination of AlgL and a polyene antifungal may prove to be a new therapeutic strategy for invasive aspergillosis, while reinforcing the EPS as a valuable antibiofilm drug target.
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20
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Egerer G. Ambulante Therapie von Aspergillosen bei hämatologischen und onkologischen Patienten. Mycoses 2012; 55 Suppl 2:30-4. [DOI: 10.1111/j.1439-0507.2012.02181.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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21
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Biancalana FSC, Lyra L, Moretti ML, Schreiber AZ. Susceptibility testing of terbinafine alone and in combination with amphotericin B, itraconazole, or voriconazole against conidia and hyphae of dematiaceous molds. Diagn Microbiol Infect Dis 2011; 71:378-85. [DOI: 10.1016/j.diagmicrobio.2011.08.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Revised: 07/31/2011] [Accepted: 08/04/2011] [Indexed: 10/17/2022]
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22
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Shapiro RS, Robbins N, Cowen LE. Regulatory circuitry governing fungal development, drug resistance, and disease. Microbiol Mol Biol Rev 2011; 75:213-67. [PMID: 21646428 PMCID: PMC3122626 DOI: 10.1128/mmbr.00045-10] [Citation(s) in RCA: 384] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Pathogenic fungi have become a leading cause of human mortality due to the increasing frequency of fungal infections in immunocompromised populations and the limited armamentarium of clinically useful antifungal drugs. Candida albicans, Cryptococcus neoformans, and Aspergillus fumigatus are the leading causes of opportunistic fungal infections. In these diverse pathogenic fungi, complex signal transduction cascades are critical for sensing environmental changes and mediating appropriate cellular responses. For C. albicans, several environmental cues regulate a morphogenetic switch from yeast to filamentous growth, a reversible transition important for virulence. Many of the signaling cascades regulating morphogenesis are also required for cells to adapt and survive the cellular stresses imposed by antifungal drugs. Many of these signaling networks are conserved in C. neoformans and A. fumigatus, which undergo distinct morphogenetic programs during specific phases of their life cycles. Furthermore, the key mechanisms of fungal drug resistance, including alterations of the drug target, overexpression of drug efflux transporters, and alteration of cellular stress responses, are conserved between these species. This review focuses on the circuitry regulating fungal morphogenesis and drug resistance and the impact of these pathways on virulence. Although the three human-pathogenic fungi highlighted in this review are those most frequently encountered in the clinic, they represent a minute fraction of fungal diversity. Exploration of the conservation and divergence of core signal transduction pathways across C. albicans, C. neoformans, and A. fumigatus provides a foundation for the study of a broader diversity of pathogenic fungi and a platform for the development of new therapeutic strategies for fungal disease.
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Affiliation(s)
| | | | - Leah E. Cowen
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
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23
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BELEWA V, BAIJNATH H, SOMAI B. AQUEOUS EXTRACTS FROM THE BULBS OF TULBAGHIA VIOLACEA ARE ANTIFUNGAL AGAINST ASPERGILLUS FLAVUS. J Food Saf 2011. [DOI: 10.1111/j.1745-4565.2010.00282.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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24
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Azole resistance of Aspergillus fumigatus biofilms is partly associated with efflux pump activity. Antimicrob Agents Chemother 2011; 55:2092-7. [PMID: 21321135 DOI: 10.1128/aac.01189-10] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
This study investigated the phase-dependent expression and activity of efflux pumps in Aspergillus fumigatus treated with voriconazole. Fourteen strains were shown to become increasingly resistant in the 12-h (16- to 128-fold) and 24-h (>512-fold) phases compared to 8-h germlings. An Ala-Nap uptake assay demonstrated a significant increase in efflux pump activity in the 12-h and 24-h phases (P<0.0001). The efflux pump activity of the 8-h germling cells was also significantly induced by voriconazole (P<0.001) after 24 h of treatment. Inhibition of efflux pump activity with the competitive substrate MC-207,110 reduced the voriconazole MIC values for the A. fumigatus germling cells by 2- to 8-fold. Quantitative expression analysis of AfuMDR4 mRNA transcripts showed a phase-dependent increase as the mycelial complexity increased, which was coincidental with a strain-dependent increase in azole resistance. Voriconazole also significantly induced this in a time-dependent manner (P<0.001). Finally, an in vivo mouse biofilm model was used to evaluate efflux pump expression, and it was shown that AfuMDR4 was constitutively expressed and significantly induced by treatment with voriconazole after 24 h (P<0.01). Our results demonstrate that efflux pumps are expressed in complex A. fumigatus biofilm populations and that this contributes to azole resistance. Moreover, voriconazole treatment induces efflux pump expression. Collectively, these data may provide evidence for azole treatment failures in clinical cases of aspergillosis.
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Madurella mycetomatis is not susceptible to the echinocandin class of antifungal agents. Antimicrob Agents Chemother 2010; 54:2738-40. [PMID: 20350944 DOI: 10.1128/aac.01546-09] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Eumycetoma caused by Madurella mycetomatis is treated surgically and with high doses of ketoconazole. Therapeutic responses are poor, and recurrent infections are common. In search of therapeutic alternatives in the treatment of mycetoma, we determined the in vitro susceptibilities of M. mycetomatis isolates against caspofungin, anidulafungin, and micafungin. As a comparator fungus, Aspergillus fumigatus was used. Minimal effective concentrations (MECs) and MICs were assessed and compared to those of ketoconazole. M. mycetomatis isolates were not susceptible to the echinocandins.
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26
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Deak E, Wilson SD, White E, Carr JH, Balajee SA. Aspergillus terreus accessory conidia are unique in surface architecture, cell wall composition and germination kinetics. PLoS One 2009; 4:e7673. [PMID: 19888344 PMCID: PMC2766032 DOI: 10.1371/journal.pone.0007673] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2009] [Accepted: 10/08/2009] [Indexed: 11/19/2022] Open
Abstract
Infection with Aspergillus terreus is more likely to result in invasive, disseminated disease when compared to other Aspergillus species; importantly this species appears to be less susceptible to the antifungal drug amphotericin B. Unique to this species is the ability to produce specialized structures denoted as accessory conidia (AC) directly on hyphae both in vitro and in vivo. With the hypothesis that production of AC by A. terreus may enhance virulence of this organism, we analyzed the phenotype, structure and metabolic potential of these conidia. Comparison of A. terreus phialidic conidia (conidia that arise from conidiophores, PC) and AC architecture by electron microscopy revealed distinct morphological differences between the two conidial forms; AC have a smoother, thicker outer cell surface with no apparent pigment-like layer. Further, AC germinated rapidly, had enhanced adherence to microspheres, and were metabolically more active compared to PC. Additionally, AC contained less cell membrane ergosterol, which correlated with decreased susceptibility to AMB as determined using a flow cytometry based analysis. Furthermore, AC exhibited surface patches of β1-3 glucan, suggestive of attachment scarring. Collectively, the findings of this study suggest a possible role for AC in A. terreus pathogenesis.
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Affiliation(s)
- Eszter Deak
- Mycotic Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Selwyn D. Wilson
- Mycotic Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Elizabeth White
- Infectious Diseases Pathology Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Janice H. Carr
- Clinical and Environmental Microbiology Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - S. Arunmozhi Balajee
- Mycotic Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
- * E-mail:
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