1
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Guo L, Zheng L, Dong Y, Wang C, Deng H, Wang Z, Xu Y. Miconazole induces aneuploidy-mediated tolerance in Candida albicans that is dependent on Hsp90 and calcineurin. Front Cell Infect Microbiol 2024; 14:1392564. [PMID: 38983116 PMCID: PMC11231705 DOI: 10.3389/fcimb.2024.1392564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Accepted: 06/12/2024] [Indexed: 07/11/2024] Open
Abstract
Antifungal resistance and antifungal tolerance are two distinct terms that describe different cellular responses to drugs. Antifungal resistance describes the ability of a fungus to grow above the minimal inhibitory concentration (MIC) of a drug. Antifungal tolerance describes the ability of drug susceptible strains to grow slowly at inhibitory drug concentrations. Recent studies indicate antifungal resistance and tolerance have distinct evolutionary trajectories. Superficial candidiasis bothers millions of people yearly. Miconazole has been used for topical treatment of yeast infections for over 40 years. Yet, fungal resistance to miconazole remains relatively low. Here we found different clinical isolates of Candida albicans had different profile of tolerance to miconazole, and the tolerance was modulated by physiological factors including temperature and medium composition. Exposure of non-tolerant strains with different genetic backgrounds to miconazole mainly induced development of tolerance, not resistance, and the tolerance was mainly due to whole chromosomal or segmental amplification of chromosome R. The efflux gene CDR1 was required for maintenance of tolerance in wild type strains but not required for gain of aneuploidy-mediated tolerance. Heat shock protein Hsp90 and calcineurin were essential for maintenance as well as gain of tolerance. Our study indicates development of aneuploidy-mediated tolerance, not resistance, is the predominant mechanism of rapid adaptation to miconazole in C. albicans, and the clinical relevance of tolerance deserves further investigations.
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Affiliation(s)
- Liangsheng Guo
- Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Lijun Zheng
- Department of Ultrasound Medicine, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Yubo Dong
- Department of Pharmacy, The 960th Hospital of PLA, Jinan, China
| | - Chen Wang
- Department of Pharmacy, The 960th Hospital of PLA, Jinan, China
| | - Huijie Deng
- Department of Pharmacy, The 960th Hospital of PLA, Jinan, China
| | - Zongjie Wang
- Department of Pharmacy, The 960th Hospital of PLA, Jinan, China
| | - Yi Xu
- Department of Pharmacy, The 960th Hospital of PLA, Jinan, China
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2
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Yang F, Berman J. Beyond resistance: antifungal heteroresistance and antifungal tolerance in fungal pathogens. Curr Opin Microbiol 2024; 78:102439. [PMID: 38401284 DOI: 10.1016/j.mib.2024.102439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Revised: 09/18/2023] [Accepted: 02/05/2024] [Indexed: 02/26/2024]
Abstract
Fungal infections are increasing globally, causing alarmingly high mortality and economic burden. In addition to antifungal resistance, other more subtle drug responses appear to increase the likelihood of treatment failures. These responses include heteroresistance and tolerance, terms that are more well-defined for antibacterial drugs, but are also evident in pathogenic fungi. Here, we compare these antifungal responses with similarly named antibacterial responses, and we review recent advances in how we understand the routes by which antifungal heteroresistance and tolerance emerge.
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Affiliation(s)
- Feng Yang
- Department of Pharmacy, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Judith Berman
- Shmunis School of Biomedical and Cancer Research, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.
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3
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Zheng L, Xu Y, Wang C, Yang F, Dong Y, Guo L. Susceptibility to caspofungin is regulated by temperature and is dependent on calcineurin in Candida albicans. Microbiol Spectr 2023; 11:e0179023. [PMID: 37966204 PMCID: PMC10715083 DOI: 10.1128/spectrum.01790-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Accepted: 10/06/2023] [Indexed: 11/16/2023] Open
Abstract
IMPORTANCE Echinocandins are the newest antifungal drugs and are first-line treatment option for life-threatening systemic infections. Due to lack of consensus regarding what temperature should be used when evaluating susceptibility of yeasts to echinocandins, typically either 30°C, 35°C, or 37°C is used. However, the impact of temperature on antifungal efficacy of echinocandins is unexplored. In the current study, we demonstrated that Candida albicans laboratory strain SC5314 was more susceptible to caspofungin at 37°C than at 30°C. We also found that calcineurin was required for temperature-modulated caspofungin susceptibility. Surprisingly, the altered caspofungin susceptibility was not due to differential expression of some canonical genes such as FKS, CHS, or CHT genes. The molecular mechanism of temperature-modulated caspofungin susceptibility is undetermined and deserves further investigations.
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Affiliation(s)
- Lijun Zheng
- Department of Ultrasound Medicine, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Yi Xu
- Department of Pharmacy, The 960 Hospital of PLA, Jinan, China
| | - Chen Wang
- Department of Pharmacy, The 960 Hospital of PLA, Jinan, China
| | - Feng Yang
- Department of Pharmacology, Shanghai Tenth People’s Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yubo Dong
- Department of Pharmacy, The 960 Hospital of PLA, Jinan, China
| | - Liangsheng Guo
- Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Soochow University, Suzhou, China
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4
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Day AW, Kumamoto CA. Selection of Ethanol Tolerant Strains of Candida albicans by Repeated Ethanol Exposure Results in Strains with Reduced Susceptibility to Fluconazole. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.13.557677. [PMID: 37745460 PMCID: PMC10515905 DOI: 10.1101/2023.09.13.557677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
Candida albicans is a commensal yeast that has important impacts on host metabolism and immune function, and can establish life-threatening infections in immunocompromised individuals. Previously, C. albicans colonization has been shown to contribute to the progression and severity of alcoholic liver disease. However, relatively little is known about how C. albicans responds to changing environmental conditions in the GI tract of individuals with alcohol use disorder, namely repeated exposure to ethanol. In this study, we repeatedly exposed C. albicans to high concentrations (10% vol/vol) of ethanol-a concentration that can be observed in the upper GI tract of humans following consumption of alcohol. Following this repeated exposure protocol, ethanol small colony (Esc) variants of C. albicans isolated from these populations exhibited increased ethanol tolerance, altered transcriptional responses to ethanol, and cross-resistance/tolerance to the frontline antifungal fluconazole. These Esc strains exhibited chromosomal copy number variations and carried polymorphisms in genes previously associated with the acquisition of fluconazole resistance during human infection. This study identifies a selective pressure that can result in evolution of fluconazole tolerance and resistance without previous exposure to the drug.
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Affiliation(s)
- Andrew W. Day
- Graduate School of Biomedical Sciences, Tufts University, Boston, Massachusetts, 02111, USA
- Department of Molecular Biology and Microbiology, Tufts University, Boston, Massachusetts, 02111, USA
| | - Carol A. Kumamoto
- Department of Molecular Biology and Microbiology, Tufts University, Boston, Massachusetts, 02111, USA
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5
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Lohse MB, Laurie MT, Levan S, Ziv N, Ennis CL, Nobile CJ, DeRisi J, Johnson AD. Broad susceptibility of Candida auris strains to 8-hydroxyquinolines and mechanisms of resistance. mBio 2023; 14:e0137623. [PMID: 37493629 PMCID: PMC10470496 DOI: 10.1128/mbio.01376-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 06/13/2023] [Indexed: 07/27/2023] Open
Abstract
The fungal pathogen Candida auris represents a severe threat to hospitalized patients. Its resistance to multiple classes of antifungal drugs and ability to spread and resist decontamination in healthcare settings make it especially dangerous. We screened 1,990 clinically approved and late-stage investigational compounds for the potential to be repurposed as antifungal drugs targeting C. auris and narrowed our focus to five Food and Drug Administration (FDA)-approved compounds with inhibitory concentrations under 10 µM for C. auris and significantly lower toxicity to three human cell lines. These compounds, some of which had been previously identified in independent screens, include three dihalogenated 8-hydroxyquinolines: broxyquinoline, chloroxine, and clioquinol. A subsequent structure-activity study of 32 quinoline derivatives found that 8-hydroxyquinolines, especially those dihalogenated at the C5 and C7 positions, were the most effective inhibitors of C. auris. To pursue these compounds further, we exposed C. auris to clioquinol in an extended experimental evolution study and found that C. auris developed only twofold to fivefold resistance to the compound. DNA sequencing of resistant strains and subsequent verification by directed mutation in naive strains revealed that resistance was due to mutations in the transcriptional regulator CAP1 (causing upregulation of the drug transporter MDR1) and in the drug transporter CDR1. These mutations had only modest effects on resistance to traditional antifungal agents, and the CDR1 mutation rendered C. auris more susceptible to posaconazole. This observation raises the possibility that a combination treatment involving an 8-hydroxyquinoline and posaconazole might prevent C. auris from developing resistance to this established antifungal agent. IMPORTANCE The rapidly emerging fungal pathogen Candida auris represents a growing threat to hospitalized patients, in part due to frequent resistance to multiple classes of antifungal drugs. We identify a class of compounds, the dihalogenated 8-hydroxyquinolines, with broad fungistatic ability against a diverse collection of 13 strains of C. auris. Although this compound has been identified in previous screens, we extended the analysis by showing that C. auris developed only modest twofold to fivefold increases in resistance to this class of compounds despite long-term exposure; a noticeable difference from the 30- to 500-fold increases in resistance reported for similar studies with commonly used antifungal drugs. We also identify the mutations underlying the resistance. These results suggest that the dihalogenated 8-hydroxyquinolines are working inside the fungal cell and should be developed further to combat C. auris and other fungal pathogens. Lohse and colleagues characterize a class of compounds that inhibit the fungal pathogen C. auris. Unlike many other antifungal drugs, C. auris does not readily develop resistance to this class of compounds.
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Affiliation(s)
- Matthew B. Lohse
- Department of Microbiology and Immunology, University of California, San Francisco, California, USA
| | - Matthew T. Laurie
- Department of Biochemistry and Biophysics, University of California, San Francisco, California, USA
| | - Sophia Levan
- Department of Medicine, University of California, San Francisco, California, USA
| | - Naomi Ziv
- Department of Microbiology and Immunology, University of California, San Francisco, California, USA
| | - Craig L. Ennis
- Department of Molecular and Cell Biology, School of Natural Sciences, University of California, Merced, California, USA
- Quantitative and Systems Biology Graduate Program, University of California, Merced, California, USA
| | - Clarissa J. Nobile
- Department of Molecular and Cell Biology, School of Natural Sciences, University of California, Merced, California, USA
- Health Sciences Research Institute, University of California, Merced, California, USA
| | - Joseph DeRisi
- Department of Biochemistry and Biophysics, University of California, San Francisco, California, USA
- Chan Zuckerberg Biohub, San Francisco, California, USA
| | - Alexander D. Johnson
- Department of Microbiology and Immunology, University of California, San Francisco, California, USA
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6
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Lu H, Hong T, Jiang Y, Whiteway M, Zhang S. Candidiasis: From cutaneous to systemic, new perspectives of potential targets and therapeutic strategies. Adv Drug Deliv Rev 2023; 199:114960. [PMID: 37307922 DOI: 10.1016/j.addr.2023.114960] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 06/05/2023] [Accepted: 06/07/2023] [Indexed: 06/14/2023]
Abstract
Candidiasis is an infection caused by fungi from a Candida species, most commonly Candida albicans. C. albicans is an opportunistic fungal pathogen typically residing on human skin and mucous membranes of the mouth, intestines or vagina. It can cause a wide variety of mucocutaneous barrier and systemic infections; and becomes a severe health problem in HIV/AIDS patients and in individuals who are immunocompromised following chemotherapy, treatment with immunosuppressive agents or after antibiotic-induced dysbiosis. However, the immune mechanism of host resistance to C. albicans infection is not fully understood, there are a limited number of therapeutic antifungal drugs for candidiasis, and these have disadvantages that limit their clinical application. Therefore, it is urgent to uncover the immune mechanisms of the host protecting against candidiasis and to develop new antifungal strategies. This review synthesizes current knowledge of host immune defense mechanisms from cutaneous candidiasis to invasive C. albicans infection and documents promising insights for treating candidiasis through inhibitors of potential antifungal target proteins.
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Affiliation(s)
- Hui Lu
- Department of Pharmacology, Shanghai Tenth People's Hospital, Tongji University, School of Medicine, Shanghai, China
| | - Ting Hong
- Department of Anesthesiology, Huadong Hospital Affiliated to Fudan University, Shanghai, China
| | - Yuanying Jiang
- Department of Pharmacology, Shanghai Tenth People's Hospital, Tongji University, School of Medicine, Shanghai, China
| | - Malcolm Whiteway
- Department of Biology, Concordia University, Montreal, QC, Canada.
| | - Shiqun Zhang
- Department of Pharmacology, Shanghai Tenth People's Hospital, Tongji University, School of Medicine, Shanghai, China.
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7
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Yang SZ, Peng LT. Significance of the plasma membrane H +-ATPase and V-ATPase for growth and pathogenicity in pathogenic fungi. ADVANCES IN APPLIED MICROBIOLOGY 2023; 124:31-53. [PMID: 37597947 DOI: 10.1016/bs.aambs.2023.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/21/2023]
Abstract
Pathogenic fungi are widespread and cause a variety of diseases in human beings and other organisms. At present, limited classes of antifungal agents are available to treat invasive fungal diseases. With the wide use of the commercial antifungal agents, drug resistance of pathogenic fungi are continuously increasing. Therefore, exploring effective antifungal agents with novel drug targets is urgently needed to cope with the challenges that the antifungal area faces. pH homeostasis is vital for multiple cellular processes, revealing the potential for defining novel drug targets. Fungi have evolved a number of strategies to maintain a stable pH internal environment in response to rapid metabolism and a dramatically changing extracellular environment. Among them, plasma membrane H+-ATPase (PMA) and vacuolar H+-ATPase (V-ATPase) play a central role in the regulation of pH homeostasis system. In this chapter, we will summarize the current knowledge about pH homeostasis and its regulation mechanisms in pathogenic fungi, especially for the recent advances in PMA and V-ATPase, which would help in revealing the regulating mechanism of pH on cell growth and pathogenicity, and further designing effective drugs and identify new targets for combating fungal diseases.
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Affiliation(s)
- S Z Yang
- Key Laboratory of Environment Correlative Dietology, Ministry of Education, College of Food Science and Technology, Huazhong Agricultural University, Wuhan, P.R. China.
| | - L T Peng
- Key Laboratory of Environment Correlative Dietology, Ministry of Education, College of Food Science and Technology, Huazhong Agricultural University, Wuhan, P.R. China
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8
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Druseikis M, Mottola A, Berman J. The Metabolism of Susceptibility: Clearing the FoG Between Tolerance and Resistance in Candida albicans. CURRENT CLINICAL MICROBIOLOGY REPORTS 2023; 10:36-46. [DOI: 10.1007/s40588-023-00189-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
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9
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Antifungal Tolerance and Resistance Emerge at Distinct Drug Concentrations and Rely upon Different Aneuploid Chromosomes. mBio 2023; 14:e0022723. [PMID: 36877011 PMCID: PMC10127634 DOI: 10.1128/mbio.00227-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023] Open
Abstract
Antifungal drug tolerance is a response distinct from resistance, in which cells grow slowly above the MIC. Here, we found that the majority (69.2%) of 133 Candida albicans clinical isolates, including standard lab strain SC5314, exhibited temperature-enhanced tolerance at 37°C and 39°C, and were not tolerant at 30°C. Other isolates were either always tolerant (23.3%) or never tolerant (7.5%) at these three temperatures, suggesting that tolerance requires different physiological processes in different isolates. At supra-MIC fluconazole concentrations (8 to 128 μg/mL), tolerant colonies emerged rapidly at a frequency of ~10-3. In liquid passages over a broader range of fluconazole concentrations (0.25 to 128 μg/mL), tolerance emerged rapidly (within one passage) at supra-MICs. In contrast, resistance appeared at sub-MICs after 5 or more passages. Of 155 adaptors that evolved higher tolerance, all carried one of several recurrent aneuploid chromosomes, often including chromosome R, alone or in combination with other chromosomes. Furthermore, loss of these recurrent aneuploidies was associated with a loss of acquired tolerance, indicating that specific aneuploidies confer fluconazole tolerance. Thus, genetic background and physiology and the degree of drug stress (above or below the MIC) influence the evolutionary trajectories and dynamics with which antifungal drug resistance or tolerance emerges. IMPORTANCE Antifungal drug tolerance differs from drug resistance: tolerant cells grow slowly in drug, while resistant cells usually grow well, due to mutations in a few known genes. More than half of Candida albicans clinical isolates have higher tolerance at body temperature than they do at the lower temperatures used for most lab experiments. This implies that different isolates achieve drug tolerance via several cellular processes. When we evolved different strains at a range of high drug concentrations above inhibitory levels, tolerance emerged rapidly and at high frequency (one in 1,000 cells) while resistance appeared only later at very low drug concentrations. An extra copy of all or part of chromosome R was associated with tolerance, while point mutations or different aneuploidies were seen with resistance. Thus, genetic background and physiology, temperature, and drug concentration all influence how drug tolerance or resistance evolves.
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10
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Sun LL, Li H, Yan TH, Fang T, Wu H, Cao YB, Lu H, Jiang YY, Yang F. Aneuploidy Mediates Rapid Adaptation to a Subinhibitory Amount of Fluconazole in Candida albicans. Microbiol Spectr 2023; 11:e0301622. [PMID: 36853047 PMCID: PMC10101127 DOI: 10.1128/spectrum.03016-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 02/04/2023] [Indexed: 03/01/2023] Open
Abstract
Candida albicans is a prevalent, opportunistic, human fungal pathogen. Antifungal drug resistance and tolerance are two distinct mechanisms of adaptation to drugs. Studies of mechanisms of drug resistance are limited to the applications of high doses of drugs. Few studies have investigated the effects of subinhibitory amounts of drugs on the development of drug resistance or tolerance. In this study, we found that growth in a subinhibitory amount of fluconazole (FLC), a widely used antifungal drug, for just a short time was sufficient to induce aneuploidy in C. albicans. Surprisingly, the aneuploids displayed fitness loss in the presence of subinhibitory FLC, but a subpopulation of cells could tolerate up to 128 μg/mL FLC. Particular aneuploidy (ChrR trisomy) caused tolerance, not resistance, to FLC. In the absence of FLC, the aneuploids were unstable. Depending on the karyotype, aneuploids might become completely euploid or maintain particular aneuploidy, and, accordingly, the tolerance would be lost or maintained. Mechanistically, subinhibitory FLC was sufficient to induce the expression of several ERG genes and as well as the drug efflux gene MDR1. Aneuploids had a constitutive high-level expression of genes on and outside the aneuploid chromosomes, including most of the ERG genes as well as the drug efflux genes MDR1 and CDR2. Therefore, aneuploids were prepared for FLC challenges. In summary, aneuploidy provides a rapid and reversible strategy of adaptation when C. albicans is challenged with subinhibitory concentrations of FLC. IMPORTANCE Genome instability is a hallmark of C. albicans. Aneuploidy usually causes fitness loss in the absence of stress but confers better fitness under particular stress conditions. Therefore, aneuploidy is considered to be a double-edged sword. Here, we extend the understanding of aneuploidy. We found that aneuploidy arose under weak stress conditions but that it did not confer better fitness to the stress. Instead, it was less fit than its euploid counterparts. If the stress was withdrawn, aneuploidy spontaneously reverted to euploidy. If the stress became stronger, aneuploidy enabled subpopulation growth in a dose-independent manner of the stress. Therefore, we posit that aneuploidy enables the rapid and reversible development of drug tolerance in C. albicans. Further studies are required to investigate whether this is a general mechanism in human fungal pathogens.
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Affiliation(s)
- Liu-liu Sun
- Department of Pharmacology, Shanghai Tenth People’s Hospital, Tongji University School of Medicine, Shanghai, China
- Department of Physiology and Pharmacology, School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Hao Li
- Department of Pharmacology, Shanghai Tenth People’s Hospital, Tongji University School of Medicine, Shanghai, China
- Department of Physiology and Pharmacology, School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Tian-hua Yan
- Department of Physiology and Pharmacology, School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Ting Fang
- Department of Pharmacology, Shanghai Tenth People’s Hospital, Tongji University School of Medicine, Shanghai, China
| | - Hao Wu
- Department of Pharmacology, Shanghai Tenth People’s Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yong-bing Cao
- Institute of Vascular Disease, Shanghai TCM-Integrated Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Hui Lu
- Department of Pharmacology, Shanghai Tenth People’s Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yuan-ying Jiang
- Department of Pharmacology, Shanghai Tenth People’s Hospital, Tongji University School of Medicine, Shanghai, China
| | - Feng Yang
- Department of Pharmacology, Shanghai Tenth People’s Hospital, Tongji University School of Medicine, Shanghai, China
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11
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Lohse MB, Laurie MT, Levan S, Ziv N, Ennis CL, Nobile CJ, DeRisi J, Johnson AD. Broad sensitivity of Candida auris strains to quinolones and mechanisms of resistance. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.16.528905. [PMID: 36824717 PMCID: PMC9949084 DOI: 10.1101/2023.02.16.528905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
The fungal pathogen Candida auris represents a severe threat to hospitalized patients. Its resistance to multiple classes of antifungal drugs and ability to spread and resist decontamination in health-care settings make it especially dangerous. We screened 1,990 clinically approved and late-stage investigational compounds for the potential to be repurposed as antifungal drugs targeting C. auris and narrowed our focus to five FDA-approved compounds with inhibitory concentrations under 10 µM for C. auris and significantly lower toxicity to three human cell lines. These compounds, some of which had been previously identified in independent screens, include three dihalogenated 8-hydroxyquinolines: broxyquinoline, chloroxine, and clioquinol. A subsequent structure-activity study of 32 quinoline derivatives found that 8-hydroxyquinolines, especially those dihalogenated at the C5 and C7 positions, were the most effective inhibitors of C. auris . To pursue these compounds further, we exposed C. auris to clioquinol in an extended experimental evolution study and found that C. auris developed only 2- to 5-fold resistance to the compound. DNA sequencing of resistant strains and subsequent verification by directed mutation in naive strains revealed that resistance was due to mutations in the transcriptional regulator CAP1 (causing upregulation of the drug transporter MDR1 ) and in the drug transporter CDR1 . These mutations had only modest effects on resistance to traditional antifungal agents, and the CDR1 mutation rendered C. auris more sensitive to posaconazole. This observation raises the possibility that a combination treatment involving an 8-hydroxyquinoline and posaconazole might prevent C. auris from developing resistance to this established antifungal agent. Abstract Importance The rapidly emerging fungal pathogen Candida auris represents a growing threat to hospitalized patients, in part due to frequent resistance to multiple classes of antifungal drugs. We identify a class of compounds, the dihalogenated hydroxyquinolines, with broad fungistatic ability against a diverse collection of 13 strains of C. auris . Although this compound has been identified in previous screens, we extended the analysis by showing that C. auris developed only modest 2- to 5-fold increases in resistance to this class of compounds despite long-term exposure; a noticeable difference from the 30- to 500- fold increases in resistance reported for similar studies with commonly used antifungal drugs. We also identify the mutations underlying the resistance. These results suggest that the dihalogenated hydroxyquinolines are working inside the fungal cell and should be developed further to combat C. auris and other fungal pathogens. Tweet Lohse and colleagues characterize a class of compounds that inhibit the fungal pathogen C. auris . Unlike many other antifungal drugs, C. auris does not readily develop resistance to this class of compounds.
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12
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Sun LL, Li H, Yan TH, Cao YB, Jiang YY, Yang F. Aneuploidy enables cross-tolerance to unrelated antifungal drugs in Candida parapsilosis. Front Microbiol 2023; 14:1137083. [PMID: 37113223 PMCID: PMC10126355 DOI: 10.3389/fmicb.2023.1137083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 03/17/2023] [Indexed: 04/29/2023] Open
Abstract
Candida parapsilosis is an emerging major human fungal pathogen. Echinocandins are first-line antifungal drugs for the treatment of invasive Candida infections. In clinical isolates, tolerance to echinocandins in Candida species is mostly due to point mutations of FKS genes, which encode the target protein of echinocandins. However, here, we found chromosome 5 trisomy was the major mechanism of adaptation to the echinocandin drug caspofungin, and FKS mutations were rare events. Chromosome 5 trisomy conferred tolerance to echinocandin drugs caspofungin and micafungin and cross-tolerance to 5-flucytosine, another class of antifungal drugs. The inherent instability of aneuploidy caused unstable drug tolerance. Tolerance to echinocandins might be due to increased copy number and expression of CHS7, which encodes chitin synthase. Although copy number of chitinase genes CHT3 and CHT4 was also increased to the trisomic level, the expression was buffered to the disomic level. Tolerance to 5-flucytosine might be due to the decreased expression of FUR1. Therefore, the pleiotropic effect of aneuploidy on antifungal tolerance was due to the simultaneous regulation of genes on the aneuploid chromosome and genes on euploid chromosomes. In summary, aneuploidy provides a rapid and reversible mechanism of drug tolerance and cross-tolerance in C. parapsilosis.
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Affiliation(s)
- Liu-liu Sun
- Department of Pharmacy, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China
- Department of Physiology and Pharmacology, School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Hao Li
- Department of Pharmacy, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China
- Department of Physiology and Pharmacology, School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Tian-hua Yan
- Department of Physiology and Pharmacology, School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Yong-bing Cao
- Department of Vascular Diseases, Shanghai TCM-Integrated Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Yuan-ying Jiang
- Department of Pharmacy, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China
- Yuan-ying Jiang
| | - Feng Yang
- Department of Pharmacy, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China
- *Correspondence: Feng Yang
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13
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Hexyl-Aminolevulinate Ethosomes: a Novel Antibiofilm Agent Targeting Zinc Homeostasis in Candida albicans. Microbiol Spectr 2022; 10:e0243822. [PMID: 36301105 PMCID: PMC9769717 DOI: 10.1128/spectrum.02438-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Substantial drug resistance afforded by Candida albicans biofilms results in ineffective treatment with conventional drugs and persistent infection. Our previous study showed that hexyl-aminolevulinate ethosomes (HAL-ES) act against C. albicans biofilms and weaken their drug resistance and pathogenicity; however, the mechanism involved remains unclear. Here, we systematically evaluated the effects and mechanisms of HAL-ES on biofilm formation and drug resistance. We found that, in addition to mediating antifungal photodynamic therapy, HAL-ES inhibited the early, developmental, and mature stages of biofilm formation compared with fluconazole, HAL, or ES. Notably, adhesion and hyphal formation were significantly inhibited by postdrug effects even after brief exposure (2 h) to HAL-ES. Its therapeutic effect in vivo also has been demonstrated in cutaneous candidiasis. RNA sequencing and quantitative PCR showed that HAL-ES inhibited ribosome biogenesis by disrupting zinc homeostasis in C. albicans, thereby reducing the translation process during protein synthesis. Furthermore, HAL-ES downregulated the expression of multidrug resistance genes and increased fluconazole susceptibility in C. albicans. Our findings provide a novel and efficient method for the treatment of biofilm resistance in C. albicans infection as well as a basis for the application of HAL-ES. We also describe a new strategy for the treatment of biofilm-related infections via zinc restriction. IMPORTANCE Candida albicans is the most prevalent fungal species of the human microbiota. The medical impact of C. albicans on its human host depends on its ability to form biofilms. The intrinsic resistance conferred by biofilms to conventional antifungal drugs makes biofilm-based infections a significant clinical challenge. In this study, we demonstrate the attenuating effect of HAL-ES on C. albicans biofilm formation and drug resistance. Furthermore, we propose that HAL-ES inhibits protein translation by disrupting zinc homeostasis in C. albicans. This study not only provides a novel and effective therapeutic strategy against C. albicans biofilm but also proposes a new strategy to resolve C. albicans biofilm infection by disrupting zinc homeostasis.
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Wang H, Ji Z, Feng Y, Yan T, Cao Y, Lu H, Jiang Y. Myriocin enhances the antifungal activity of fluconazole by blocking the membrane localization of the efflux pump Cdr1. Front Pharmacol 2022; 13:1101553. [PMID: 36618949 PMCID: PMC9815617 DOI: 10.3389/fphar.2022.1101553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 12/12/2022] [Indexed: 12/24/2022] Open
Abstract
Introduction: Extrusion of azoles from the cell, mediated by an efflux pump Cdr1, is one of the most frequently used strategies for developing azole resistance in pathogenic fungi. The efflux pump Cdr1 is predominantly localized in lipid rafts within the plasma membrane, and its localization is sensitive to changes in the composition of lipid rafts. Our previous study found that the calcineurin signal pathway is important in transferring sphingolipids from the inner to the outer membrane. Methods: We investigated multiple factors that enhance the antifungal activity of fluconazole (FLC) using minimum inhibitory concentration (MIC) assays and disk diffusion assays. We studied the mechanism of action of myriocin through qRT-PCR analysis and confocal microscopy analysis. We tested whether myriocin enhanced the antifungal activity of FLC and held therapeutic potential using a mouse infection model. Results: We found that this signal pathway has no function in the activity of Cdr1. We found that inhibiting sphingolipid biosynthesis by myriocin remarkably increased the antifungal activity of FLC with a broad antifungal spectrum and held therapeutic potential. We further found that myriocin potently enhances the antifungal activity of FLC against C. albicans by blocking membrane localization of the Cdr1 rather than repressing the expression of Cdr1. In addition, we found that myriocin enhanced the antifungal activity of FLC and held therapeutic potential. Discussion: Our study demonstrated that blocking the membrane location and inactivating Cdr1 by inhibiting sphingolipids biogenesis is beneficial for enhancing the antifungal activity of azoles against azole-resistant C. albicans due to Cdr1 activation.
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Affiliation(s)
- Hongkang Wang
- Institute of Vascular Anomalies, Shanghai TCM-Integrated Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Zhe Ji
- Institute of Vascular Anomalies, Shanghai TCM-Integrated Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Yanru Feng
- Institute of Vascular Anomalies, Shanghai TCM-Integrated Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Tianhua Yan
- Institute of Vascular Anomalies, Shanghai TCM-Integrated Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Yongbing Cao
- Institute of Vascular Anomalies, Shanghai TCM-Integrated Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China,*Correspondence: Yongbing Cao, ; Hui Lu, ; Yuanying Jiang,
| | - Hui Lu
- Institute of Vascular Anomalies, Shanghai TCM-Integrated Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China,*Correspondence: Yongbing Cao, ; Hui Lu, ; Yuanying Jiang,
| | - Yuanying Jiang
- Institute of Vascular Anomalies, Shanghai TCM-Integrated Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China,*Correspondence: Yongbing Cao, ; Hui Lu, ; Yuanying Jiang,
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Wu X, Shen M, Wang H, He X, Tan J, Wang R, Yang L, Yang H, Qi J, Chen Z, Zhu Q. Evaluation of the efficacy and safety of ionic liquids containing ketoconazole in patients with tinea pedis: A randomized controlled clinical trial. Bioeng Transl Med 2022; 8:e10463. [DOI: 10.1002/btm2.10463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 10/21/2022] [Accepted: 11/23/2022] [Indexed: 12/04/2022] Open
Affiliation(s)
- Xiying Wu
- Shanghai Skin Disease Hospital Tongji University School of Medicine Shanghai China
- School of Pharmacy Fudan University Shanghai China
| | - Min Shen
- Shanghai Skin Disease Hospital Tongji University School of Medicine Shanghai China
| | - Huan Wang
- School of Pharmacy Naval Medical University Shanghai China
| | - Xue He
- Shanghai Skin Disease Hospital Tongji University School of Medicine Shanghai China
| | - Jingwen Tan
- Shanghai Skin Disease Hospital Tongji University School of Medicine Shanghai China
| | - Ruiping Wang
- Shanghai Skin Disease Hospital Tongji University School of Medicine Shanghai China
| | - Lianjuan Yang
- Shanghai Skin Disease Hospital Tongji University School of Medicine Shanghai China
| | - Hong Yang
- Shanghai Skin Disease Hospital Tongji University School of Medicine Shanghai China
| | - Jianping Qi
- Shanghai Skin Disease Hospital Tongji University School of Medicine Shanghai China
- School of Pharmacy Fudan University Shanghai China
| | - Zhongjian Chen
- Shanghai Skin Disease Hospital Tongji University School of Medicine Shanghai China
| | - Quangang Zhu
- Shanghai Skin Disease Hospital Tongji University School of Medicine Shanghai China
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Wang X, Wang X, Cai T, Qin Y, Li L, Jiang Y, Han B, Cao Y. Development and validation of a sensitive LC-MS/MS method for determination of intracellular concentration of fluconazole in Candida albicans. Front Microbiol 2022; 13:1007576. [PMID: 36274702 PMCID: PMC9581211 DOI: 10.3389/fmicb.2022.1007576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Accepted: 09/16/2022] [Indexed: 11/22/2022] Open
Abstract
Systemic candidiasis is the fourth leading cause of healthcare-associated infections worldwide. The combination therapy based on existing antifungal agents is well-established to overcome drug resistance and restore antifungal efficacy against drug-resistant strains. In this study, a simple and sensitive liquid chromatography with tandem mass spectrometry (LC-MS/MS) method was developed to quantify the intracellular fluconazole (FLC) content in the opportunistic human fungal pathogen Candida albicans. The cell lysates were prepared by lysing C. albicans cells with Precellys homogenizers and FLC was extracted with methylene chloride. The entire extraction approach was simple, precise and reliable. The extracts were separated on a Zorbax SB-C18 column using a mobile phase of acetonitrile (solvent A) and deionized water plus 0.1% formic acid. FLC and ketoconazole (KCZ, internal standard) were monitored in positive mode using electrospray ionization source. The multiple reaction monitoring transitions (precursor to product) were monitored for FLC m/z 307.1 → 238.2 and for the internal standard KCZ m/z 531.2 → 489.1. The linear for this method were in the range from 5.0 to 1000.0 ng/mL. The precision and accuracy of the samples were relative standard deviations (RSD) < 1.0% for intra-day and RSD < 0.51% for inter-day. The overall recovery of FLC from samples was higher than 77.61%. Furthermore, this method was successfully applied and validated in 36 clinical isolated strains. Taken together, we established a highly accurate, efficient, and reproducible method for quantifying the intracellular content of FLC in C. albicans.
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Affiliation(s)
- Xiaofei Wang
- Institute of Vascular Disease, Shanghai TCM-Integrated Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
- School of Pharmacy, Naval Medical University, Shanghai, China
- Department of Pharmacy, Mudanjiang First People’s Hospital, Mudanjiang, China
| | - Xiaojuan Wang
- School of Pharmacy, Naval Medical University, Shanghai, China
- Department of Pharmacy, Minhang Hospital, Fudan University, Shanghai, China
| | - Tongkai Cai
- Institute of Vascular Disease, Shanghai TCM-Integrated Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
- School of Pharmacy, Naval Medical University, Shanghai, China
| | - Yulin Qin
- School of Pharmacy, Naval Medical University, Shanghai, China
- Department of Pharmacy, Minhang Hospital, Fudan University, Shanghai, China
| | - Ling Li
- Institute of Vascular Disease, Shanghai TCM-Integrated Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Yuanying Jiang
- School of Pharmacy, Naval Medical University, Shanghai, China
- *Correspondence: Yuanying Jiang,
| | - Bing Han
- Department of Pharmacy, Minhang Hospital, Fudan University, Shanghai, China
- Bing Han,
| | - Yongbing Cao
- Institute of Vascular Disease, Shanghai TCM-Integrated Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
- Yongbing Cao,
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Liu NN, Zhou J, Jiang T, Tarsio M, Yu F, Zheng X, Qi W, Liu L, Tan JC, Wei L, Ding J, Li J, Zeng L, Ren B, Huang X, Peng Y, Cao YB, Zhao Y, Zhang XY, Kane PM, Chen C, Wang H. A dual action small molecule enhances azoles and overcomes resistance through co-targeting Pdr5 and Vma1. Transl Res 2022; 247:39-57. [PMID: 35452875 DOI: 10.1016/j.trsl.2022.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Revised: 02/26/2022] [Accepted: 04/12/2022] [Indexed: 11/19/2022]
Abstract
Fungal infection threatens human health worldwide due to the limited arsenal of antifungals and the rapid emergence of resistance. Epidermal growth factor receptor (EGFR) is demonstrated to mediate epithelial cell endocytosis of the leading human fungal pathogen, Candida albicans. However, whether EGFR inhibitors act on fungal cells remains unknown. Here, we discovered that the specific EGFR inhibitor osimertinib mesylate (OSI) potentiates azole efficacy against diverse fungal pathogens and overcomes azole resistance. Mechanistic investigation revealed a conserved activity of OSI by promoting intracellular fluconazole accumulation via inhibiting Pdr5 and disrupting V-ATPase function via targeting Vma1 at serine 274, eventually leading to inactivation of the global regulator TOR. Evaluation of the in vivo efficacy and toxicity of OSI demonstrated its potential clinical application in impeding fluconazole resistance. Thus, the identification of OSI as a dual action antifungal with co-targeting activity proposes a potentially effective therapeutic strategy to treat life-threatening fungal infection and overcome antifungal resistance.
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Affiliation(s)
- Ning-Ning Liu
- State Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell Omics, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
| | - Jia Zhou
- State Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell Omics, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Tong Jiang
- The Center for Microbes, Development and Health, Key Laboratory of Molecular Virology and Immunology, Institute Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China; University of Chinese Academy of Sciences, Beijing, China
| | - Maureen Tarsio
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Feifei Yu
- Institute of Environmental Pollution and Health, School of Environmental and Chemical Engineering, Shanghai University, Shanghai, China
| | - Xuehan Zheng
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Wanjun Qi
- Division of Infectious Diseases, Boston Children's Hospital/Harvard Medical School, Boston, MA, USA
| | - Lin Liu
- State Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell Omics, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jing-Cong Tan
- State Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell Omics, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Luqi Wei
- State Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell Omics, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jun Ding
- Computational biology department, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Jingquan Li
- State Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell Omics, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Lingbing Zeng
- Department of Laboratory Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, China
| | - Biao Ren
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu, Sichuan, China
| | - Xiaotian Huang
- Department of Medical Microbiology, School of Medicine, Nanchang University, Nanchang, Jiangxi, China
| | - Yibing Peng
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Faculty of Medical Laboratory Science, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yong-Bing Cao
- Department of Vascular Disease, Shanghai TCM-Integrated Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China; Shanghai TCM-Integrated Institute of Vascular Disease, Shanghai, China
| | - Yanbin Zhao
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, China
| | - Xin-Yu Zhang
- School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Patricia M Kane
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Changbin Chen
- The Center for Microbes, Development and Health, Key Laboratory of Molecular Virology and Immunology, Institute Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China.
| | - Hui Wang
- State Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell Omics, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
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Aspergillus terreus and the Interplay with Amphotericin B: from Resistance to Tolerance? Antimicrob Agents Chemother 2022; 66:e0227421. [PMID: 35254091 PMCID: PMC9017323 DOI: 10.1128/aac.02274-21] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Aspergillus terreus is an opportunistic causative agent of invasive aspergillosis and, in most cases, it is refractory to amphotericin B (AMB) therapy. Notably, AMB-susceptible Aspergillus terreus sensu stricto (s.s.) representatives exist which are also associated with poor clinical outcomes. Such findings may be attributable to drug tolerance, which is not detectable by antifungal susceptibility testing. Here, we tested in vitro antifungal susceptibility (AFST) and the fungicidal activity of AMB against 100 clinical isolates of A. terreus species complex in RPMI 1640 and antibiotic medium 3 (AM3). MICs ranged from 0.5 to 16 μg/mL for RPMI 1640 and from 1 to >16 mg/L for AM3. AMB showed medium-dependent activity, with fungicidal effects only in antibiotic medium 3, not in RPMI 1640. Furthermore, the presence of AMB-tolerant phenotypes of A. terreus has been examined by assessing the minimum duration for killing 99% of the population (MDK99) and evaluating the data obtained in a Galleria mellonella infection model. A time-kill curve analysis revealed that A. terreus with AMB MICs of ≤1 mg/L (susceptible range) displayed AMB-tolerant phenotypes, exhibiting MDK99s at 18 and 36 h, respectively. Survival rates of infected G. mellonella highlighted that AMB was effective against susceptible A. terreus isolates, but not against tolerant or resistant isolates. Our analysis reveals that A. terreus isolates which are defined as susceptible based on MIC may comprise tolerant phenotypes, which may, in turn, explain the worse outcome of AMB therapy for phenotypically susceptible isolates.
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