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Zhai B, Liao C, Jaggavarapu S, Tang Y, Rolling T, Ning Y, Sun T, Bergin SA, Gjonbalaj M, Miranda E, Babady NE, Bader O, Taur Y, Butler G, Zhang L, Xavier JB, Weiss DS, Hohl TM. Antifungal heteroresistance causes prophylaxis failure and facilitates breakthrough Candida parapsilosis infections. Nat Med 2024:10.1038/s41591-024-03183-4. [PMID: 39095599 DOI: 10.1038/s41591-024-03183-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2022] [Accepted: 07/08/2024] [Indexed: 08/04/2024]
Abstract
Breakthrough fungal infections in patients on antimicrobial prophylaxis during allogeneic hematopoietic cell transplantation (allo-HCT) represent a major and often unexplained cause of morbidity and mortality. Candida parapsilosis is a common cause of invasive candidiasis and has been classified as a high-priority fungal pathogen by the World Health Organization. In high-risk allo-HCT recipients on micafungin prophylaxis, we show that heteroresistance (the presence of a phenotypically unstable, low-frequency subpopulation of resistant cells (~1 in 10,000)) underlies breakthrough bloodstream infections by C. parapsilosis. By analyzing 219 clinical isolates from North America, Europe and Asia, we demonstrate widespread micafungin heteroresistance in C. parapsilosis. Standard antimicrobial susceptibility tests, such as broth microdilution or gradient diffusion assays, which guide drug selection for invasive infections, fail to detect micafungin heteroresistance in C. parapsilosis. To facilitate rapid detection of micafungin heteroresistance in C. parapsilosis, we constructed a predictive machine learning framework that classifies isolates as heteroresistant or susceptible using a maximum of ten genomic features. These results connect heteroresistance to unexplained antifungal prophylaxis failure in allo-HCT recipients and demonstrate a proof-of-principle diagnostic approach with the potential to guide clinical decisions and improve patient care.
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Affiliation(s)
- Bing Zhai
- Key Laboratory of Quantitative Synthetic Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China.
- Infectious Disease Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
- Immunology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
| | - Chen Liao
- Computational and Systems Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Siddharth Jaggavarapu
- Emory Antibiotic Resistance Center, Atlanta, GA, USA
- Department of Microbiology and Immunology, Emory University, Atlanta, GA, USA
- Emory Vaccine Center, Atlanta, GA, USA
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA, USA
| | - Yuanyuan Tang
- Key Laboratory of Quantitative Synthetic Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Thierry Rolling
- Infectious Disease Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
- Immunology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Yating Ning
- Department of Laboratory Medicine, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
- Beijing Key Laboratory for Mechanisms Research and Precision Diagnosis of Invasive Fungal Diseases, Beijing, China
| | - Tianshu Sun
- Beijing Key Laboratory for Mechanisms Research and Precision Diagnosis of Invasive Fungal Diseases, Beijing, China
- Clinical Biobank, Medical Research Center, National Science and Technology Key Infrastructure on Translational Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Sean A Bergin
- School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin, Ireland
| | - Mergim Gjonbalaj
- Infectious Disease Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
- Immunology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Edwin Miranda
- Clinical Microbiology Service, Department of Laboratory Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - N Esther Babady
- Infectious Disease Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
- Clinical Microbiology Service, Department of Laboratory Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Oliver Bader
- Institute for Medical Microbiology and Virology, University Medical Center Göttingen, Göttingen, Germany
| | - Ying Taur
- Infectious Disease Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
- Department of Medicine, Weill Cornell Medical College, New York, NY, USA
| | - Geraldine Butler
- School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin, Ireland
| | - Li Zhang
- Department of Laboratory Medicine, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
- Beijing Key Laboratory for Mechanisms Research and Precision Diagnosis of Invasive Fungal Diseases, Beijing, China
| | - Joao B Xavier
- Computational and Systems Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - David S Weiss
- Emory Antibiotic Resistance Center, Atlanta, GA, USA.
- Department of Microbiology and Immunology, Emory University, Atlanta, GA, USA.
- Emory Vaccine Center, Atlanta, GA, USA.
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA, USA.
| | - Tobias M Hohl
- Infectious Disease Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
- Department of Medicine, Weill Cornell Medical College, New York, NY, USA.
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
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2
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Huang Y, Zhang Y, Yang S, Lu H, Yu H, Wang X, Jia X, Tang D, Wu L, Huang S, Yang P. Epidemiology of cryptococcal meningitis and fluconazole heteroresistance in Cryptococcus neoformans isolates from a teaching hospital in southwestern China. Microbiol Spectr 2024; 12:e0072524. [PMID: 39007718 DOI: 10.1128/spectrum.00725-24] [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: 03/20/2024] [Accepted: 06/30/2024] [Indexed: 07/16/2024] Open
Abstract
Cryptococcal meningitis (CM), a common and serious opportunistic infection mostly caused by Cryptococcus neoformans, is primarily treated with fluconazole. Nevertheless, Cryptococcus neoformans strains that undergo repeated exposure to azoles can gradually acquire heteroresistance to fluconazole. The management of this specific CM infection poses a substantial challenge. Determining a globally accepted definition for fluconazole heteroresistance and developing effective and prompt methods for identifying heteroresistance is of utmost importance. We collected data on the clinical and epidemiological characteristics of patients diagnosed with CM. All the available Cryptococcus neoformans strains isolated from these patients were collected and subjected to antifungal susceptibility testing and evaluation of fluconazole heteroresistance. AIDS was present in 40.5% of the patients, whereas 24.1% did not have any underlying diseases. Patients with chronic diseases or impaired immune systems are susceptible to infection by Cryptococcus neoformans, a fungus that frequently (39.6%, 19/48) shows heteroresistance to fluconazole, as confirmed by population analysis profile (PAP).IMPORTANCEFluconazole heteroresistance poses a significant threat to the efficacy of fluconazole in treating cryptococcal meningitis (CM). Unfortunately, the standard broth microdilution method often misses the subtle percentages of subpopulations exhibiting heteroresistance. While the population analysis profile (PAP) method is esteemed as the gold standard, its time-consuming and labor-intensive nature makes it impractical for routine clinical use. In contrast, the Kirby-Bauer (KB) disk diffusion method offers a simple and effective screening solution. Our study highlights the value of KB over PAP and minimum inhibitory concentration (MIC) by demonstrating that when adjusting the inoculum concentration to 1.0 McFarland and subjecting samples to a 72-hour incubation period at 35°C, the KB method closely mirrors the outcomes of the PAP approach in detecting fluconazole heteroresistance. This optimization of the KB method not only enhances assay efficiency but also provides a blueprint for developing a timely and effective strategy for identifying heteroresistance.
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Affiliation(s)
- Yunfei Huang
- Department of Clinical Laboratory Medicine, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Yongqi Zhang
- Department of Clinical Laboratory Medicine, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Shuangshuang Yang
- Department of Clinical Laboratory Medicine, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Hongling Lu
- Department of Clinical Laboratory Medicine, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Hanbing Yu
- Department of Laboratory Medicine, Fujian Key Clinical Specialty of Laboratory Medicine, Women and Children's Hospital, School of Medicine, Xiamen University, Xiamen, China
| | - Xingyue Wang
- Department of Clinical Laboratory Medicine, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Xiaojiong Jia
- Division of Allergy and Clinical Immunology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Dijiao Tang
- Department of Clinical Laboratory Medicine, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Linhong Wu
- Department of Clinical Laboratory Medicine, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Shifeng Huang
- Department of Clinical Laboratory Medicine, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Ping Yang
- Department of Clinical Laboratory Medicine, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
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Wake RM, Allebone-Salt PE, John LLH, Caswall BA, Govender NP, Ben-Ami R, Murray LW, Logan C, Harrison TS, Bicanic TA. Optimizing the Treatment of Invasive Candidiasis-A Case for Combination Therapy. Open Forum Infect Dis 2024; 11:ofae072. [PMID: 38887482 PMCID: PMC11181177 DOI: 10.1093/ofid/ofae072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Accepted: 02/20/2024] [Indexed: 06/20/2024] Open
Abstract
Invasive candidiasis is a rising global health threat with increasing incidence, persistently high mortality, and diminishing treatment options. Antifungal resistance has rapidly emerged and spread, with multidrug-resistant species deemed an urgent and serious threat. While acknowledging the key role of antifungal stewardship and infection control in curbing spread, we examine the role of antifungal monotherapy in driving resistance and the potential for combination therapy to prevent stress adaptation and emergence of drug resistance. In addition to its role in mitigating resistance, combination treatment may improve drug penetration, expedite fungal clearance, and allow lower, less toxic doses of individual drugs to be used. A growing body of laboratory-based evidence suggests that antifungal combinations can yield synergistic activity against Candida spp., including against frequently multidrug-resistant Candida auris. It is imperative to test these combinations in clinical trials, incorporating resistance end points as a marker of success.
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Affiliation(s)
- Rachel M Wake
- Institute for Infection and Immunity, St George's University of London, London, UK
- Clinical Academic Group, St George's Hospital NHS Trust, London, UK
| | - Phoebe E Allebone-Salt
- Institute for Infection and Immunity, St George's University of London, London, UK
- Clinical Academic Group, St George's Hospital NHS Trust, London, UK
| | - Larissa L H John
- MRC Centre for Medical Mycology, University of Exeter, Exeter, UK
| | - Ben A Caswall
- Institute for Infection and Immunity, St George's University of London, London, UK
| | - Nelesh P Govender
- Institute for Infection and Immunity, St George's University of London, London, UK
- National Institute for Communicable Diseases, A Division of the National Health Laboratory Service, Johannesburg, South Africa
- School of Pathology, University of Witwatersrand, Johannesburg, South Africa
- Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, South Africa
- MRC Centre for Medical Mycology, University of Exeter, Exeter, UK
| | - Ronen Ben-Ami
- Infectious Diseases Unit, Tel-Aviv Sourasky Medical Center, and the Sackler, Tel-Aviv, Israel
| | - Lyle W Murray
- Division of Infectious Diseases, Department of Internal Medicine, University of the Witwatersrand, Johannesburg, South Africa
| | - Clare Logan
- Institute for Infection and Immunity, St George's University of London, London, UK
- Clinical Academic Group, St George's Hospital NHS Trust, London, UK
| | - Thomas S Harrison
- Institute for Infection and Immunity, St George's University of London, London, UK
- Clinical Academic Group, St George's Hospital NHS Trust, London, UK
- MRC Centre for Medical Mycology, University of Exeter, Exeter, UK
| | - Tihana A Bicanic
- Institute for Infection and Immunity, St George's University of London, London, UK
- Clinical Academic Group, St George's Hospital NHS Trust, London, UK
- MRC Centre for Medical Mycology, University of Exeter, Exeter, UK
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4
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Gautier C, Maciel EI, Ene IV. Approaches for identifying and measuring heteroresistance in azole-susceptible Candida isolates. Microbiol Spectr 2024; 12:e0404123. [PMID: 38483474 PMCID: PMC10986555 DOI: 10.1128/spectrum.04041-23] [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: 11/27/2023] [Accepted: 02/23/2024] [Indexed: 04/06/2024] Open
Abstract
Heteroresistance to antifungal agents poses a significant challenge in the treatment of fungal infections. Currently, the absence of established methods for detecting and measuring heteroresistance impedes progress in understanding this phenomenon in fungal pathogens. In response to this gap, we present a comprehensive set of new and optimized methods designed to detect and quantify azole heteroresistance in Candida albicans. Here, we define two primary assays for measuring heteroresistance: population analysis profiling, based on growth on solid medium, and single-cell assays, based on growth in liquid culture. We observe good correlations between the measurements obtained with liquid and solid assays, validating their utility for studying azole heteroresistance. We also highlight that disk diffusion assays could serve as an additional tool for the rapid detection of heteroresistance. These methods collectively provide a versatile toolkit for researchers seeking to assess heteroresistance in C. albicans. They also serve as a critical step forward in the characterization of antifungal heteroresistance, providing a framework for investigating this phenomenon in diverse fungal species and in the context of other antifungal agents. Ultimately, these advancements will enhance our ability to effectively measure antifungal drug responses and combat fungal infections.IMPORTANCEHeteroresistance involves varying antimicrobial susceptibility within a clonal population. This phenomenon allows the survival of rare resistant subpopulations during drug treatment, significantly complicating the effective management of infections. However, the absence of established detection methods hampers progress in understanding this phenomenon in human fungal pathogens. We propose a comprehensive toolkit to address this gap in the yeast Candida albicans, encompassing population analysis profiling, single-cell assays, and disk diffusion assays. By providing robust and correlated measurements through both solid and liquid assays, this work will provide a framework for broader applications across clinically relevant Candida species. These methods will enhance our ability to understand this phenomenon and the failure of antifungal therapy.
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Affiliation(s)
- Cécile Gautier
- Fungal Heterogeneity Group, Institut Pasteur, Université Paris Cité, Paris, France
| | - Eli I. Maciel
- Fungal Heterogeneity Group, Institut Pasteur, Université Paris Cité, Paris, France
| | - Iuliana V. Ene
- Fungal Heterogeneity Group, Institut Pasteur, Université Paris Cité, Paris, France
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5
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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 PMCID: PMC7616270 DOI: 10.1016/j.mib.2024.102439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [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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Longshaw C, Santerre Henriksen A, Dressel D, Malysa M, Silvestri C, Takemura M, Yamano Y, Baba T, Slover CM. Heteroresistance to cefiderocol in carbapenem-resistant Acinetobacter baumannii in the CREDIBLE-CR study was not linked to clinical outcomes: a post hoc analysis. Microbiol Spectr 2023; 11:e0237123. [PMID: 37966262 PMCID: PMC10714777 DOI: 10.1128/spectrum.02371-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 10/09/2023] [Indexed: 11/16/2023] Open
Abstract
IMPORTANCE The population analysis profiling (PAP) test is considered the "gold standard" method to detect heteroresistance. It exposes bacteria to increasing concentrations of antibiotics at high cell densities to detect any minority resistant subpopulations that might be missed by the low inoculums used for reference susceptibility tests. However, its clinical relevance has not been well established. In the CREDIBLE-CR study, a numerically increased all-cause mortality was observed in the cefiderocol arm relative to the best available therapy arm for patients with Acinetobacter spp. infections. Heteroresistance has independently been proposed by another research group as a potential explanation of the mortality difference. An analysis of the baseline carbapenem-resistant Acinetobacter calcoaceticus-baumannii complex isolates from patients treated with cefiderocol in the CREDIBLE-CR study showed the highest clinical cure rate and the lowest mortality for patients with PAP-heteroresistant isolates compared with PAP-susceptible or PAP-resistant isolates. These findings contradict the abovementioned hypothesis that heteroresistance contributed to the increased mortality.
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Affiliation(s)
| | | | | | | | | | - Miki Takemura
- Laboratory for Drug Discovery and Disease Research, Shionogi & Co., Ltd., Osaka, Japan
| | - Yoshinori Yamano
- Laboratory for Drug Discovery and Disease Research, Shionogi & Co., Ltd., Osaka, Japan
| | - Takamichi Baba
- Biostatistics Center, Shionogi & Co., Ltd., Osaka, Japan
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Franconi I, Rizzato C, Poma N, Tavanti A, Lupetti A. Candida parapsilosis sensu stricto Antifungal Resistance Mechanisms and Associated Epidemiology. J Fungi (Basel) 2023; 9:798. [PMID: 37623569 PMCID: PMC10456088 DOI: 10.3390/jof9080798] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 07/18/2023] [Accepted: 07/25/2023] [Indexed: 08/26/2023] Open
Abstract
Fungal diseases cause millions of deaths per year worldwide. Antifungal resistance has become a matter of great concern in public health. In recent years rates of non-albicans species have risen dramatically. Candida parapsilosis is now reported to be the second most frequent species causing candidemia in several countries in Europe, Latin America, South Africa and Asia. Rates of acquired azole resistance are reaching a worrisome threshold from multiple reports as in vitro susceptibility testing is now starting also to explore tolerance and heteroresistance to antifungal compounds. With this review, the authors seek to evaluate known antifungal resistance mechanisms and their worldwide distribution in Candida species infections with a specific focus on C. parapsilosis.
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Affiliation(s)
- Iacopo Franconi
- Department of Translational Research on New Technologies in Medicine and Surgery, University of Pisa, Via San Zeno, 37, 56127 Pisa, Italy; (I.F.); (C.R.)
| | - Cosmeri Rizzato
- Department of Translational Research on New Technologies in Medicine and Surgery, University of Pisa, Via San Zeno, 37, 56127 Pisa, Italy; (I.F.); (C.R.)
| | - Noemi Poma
- Department of Biology, University of Pisa, Via San Zeno, 37, 56127 Pisa, Italy; (N.P.); (A.T.)
| | - Arianna Tavanti
- Department of Biology, University of Pisa, Via San Zeno, 37, 56127 Pisa, Italy; (N.P.); (A.T.)
| | - Antonella Lupetti
- Department of Translational Research on New Technologies in Medicine and Surgery, University of Pisa, Via San Zeno, 37, 56127 Pisa, Italy; (I.F.); (C.R.)
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Naicker SD, Shuping L, Zulu TG, Mpembe RS, Mhlanga M, Tsotetsi EM, Maphanga TG, Govender NP. Epidemiology and susceptibility of Nakaseomyces (formerly Candida) glabrata bloodstream isolates from hospitalised adults in South Africa. Med Mycol 2023; 61:myad057. [PMID: 37336590 DOI: 10.1093/mmy/myad057] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 06/07/2023] [Accepted: 06/14/2023] [Indexed: 06/21/2023] Open
Abstract
During 2016-2017, Nakaseomyces glabrata (formerly Candida glabrata) caused 14% of cases of candidaemia in South Africa. We aimed to describe the clinical characteristics of adults with N. glabrata candidaemia at 20 sentinel hospitals (accounting for 20% (172/917) of cases) and the antifungal susceptibility of the corresponding isolates. A higher proportion of patients with N. glabrata candidaemia were older (median age: 55 years [interquartile range (IQR): 41-65 years] vs. 49 years [IQR: 35-63 years]; p = 0.04), female (87/164, 53% vs. 283/671, 42%; p = 0.01), admitted to a public-sector hospital (152/172, 88% vs. 470/745, 63%; p < 0.001), treated with fluconazole only (most with suboptimal doses) (51/95, 54% vs. 139/361, 39%; p < 0.001), and had surgery (47/172, 27% vs. 123/745, 17%; p = 0.001) and a shorter hospital stay (median 7 days [IQR: 2-20 days] vs. 13 days [IQR: 4-27 days]; p < 0.001) compared to patients with other causes of candidaemia. Eight N. glabrata isolates (6%, 8/131) had minimum inhibitory concentrations in the intermediate or resistant range for ≥ 1 echinocandin and a R1377K amino acid substitution encoded by the hotspot 2 region of the FKS2 gene. Only 11 isolates (8%, 11/131) were resistant to fluconazole. Patients with confirmed N. glabrata candidaemia are recommended to be treated with an echinocandin (or polyene), thus further guideline training is required.
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Affiliation(s)
- Serisha D Naicker
- Centre for Healthcare-Associated Infections, Antimicrobial Resistance and Mycoses, National Institute for Communicable Diseases, a Division of the National Health Laboratory Service, Johannesburg, South Africa
| | - Liliwe Shuping
- Centre for Healthcare-Associated Infections, Antimicrobial Resistance and Mycoses, National Institute for Communicable Diseases, a Division of the National Health Laboratory Service, Johannesburg, South Africa
| | - Thokozile G Zulu
- Centre for Healthcare-Associated Infections, Antimicrobial Resistance and Mycoses, National Institute for Communicable Diseases, a Division of the National Health Laboratory Service, Johannesburg, South Africa
| | - Ruth S Mpembe
- Centre for Healthcare-Associated Infections, Antimicrobial Resistance and Mycoses, National Institute for Communicable Diseases, a Division of the National Health Laboratory Service, Johannesburg, South Africa
| | - Mabatho Mhlanga
- Centre for Healthcare-Associated Infections, Antimicrobial Resistance and Mycoses, National Institute for Communicable Diseases, a Division of the National Health Laboratory Service, Johannesburg, South Africa
| | - Ernest M Tsotetsi
- Centre for Healthcare-Associated Infections, Antimicrobial Resistance and Mycoses, National Institute for Communicable Diseases, a Division of the National Health Laboratory Service, Johannesburg, South Africa
| | - Tsidiso G Maphanga
- Centre for Healthcare-Associated Infections, Antimicrobial Resistance and Mycoses, National Institute for Communicable Diseases, a Division of the National Health Laboratory Service, Johannesburg, South Africa
| | - Nelesh P Govender
- Centre for Healthcare-Associated Infections, Antimicrobial Resistance and Mycoses, National Institute for Communicable Diseases, a Division of the National Health Laboratory Service, Johannesburg, South Africa
- School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Division of Medical Microbiology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
- Institute of Infection and Immunity, St George's University of London, London and Medical Research Council Centre for Medical Mycology, University of Exeter, Exeter, United Kingdom
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9
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Delaney C, Short B, Rajendran R, Kean R, Burgess K, Williams C, Munro CA, Ramage G. An integrated transcriptomic and metabolomic approach to investigate the heterogeneous Candida albicans biofilm phenotype. Biofilm 2023; 5:100112. [PMID: 36969800 PMCID: PMC10034394 DOI: 10.1016/j.bioflm.2023.100112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 02/16/2023] [Accepted: 03/09/2023] [Indexed: 03/14/2023] Open
Abstract
Candida albicans is the most prevalent and notorious of the Candida species involved in bloodstream infections, which is characterised by its capacity to form robust biofilms. Biofilm formation is an important clinical entity shown to be highly variable among clinical isolates. There are various environmental and physiological factors, including nutrient availability which influence the phenotype of Candida species. However, mechanisms underpinning adaptive biofilm heterogeneity have not yet been fully explored. Within this study we have profiled previously characterised and phenotypically distinct C. albicans bloodstream isolates. We assessed the dynamic susceptibility of these differing populations to antifungal treatments using population analysis profiling in addition to assessing biofilm formation and morphological changes. High throughput methodologies of RNA-Seq and LC-MS were employed to map and integrate the transcriptional and metabolic reprogramming undertaken by heterogenous C. albicans isolates in response to biofilm and hyphal inducing serum. We found a significant relationship between biofilm heterogeneity and azole resistance (P < 0.05). In addition, we observed that in response to serum our low biofilm forming (LBF) C. albicans exhibited a significant increase in biofilm formation and hyphal elongation. The transcriptional reprogramming of LBF strains compared to high biofilm forming (HBF) was distinct, indicating a high level of plasticity and variation in stress responses by heterogenous strains. The metabolic responses, although variable between LBF and HBF, shared many of the same responses to serum. Notably, a high upregulation of the arachidonic acid cascade, part of the COX pathway, was observed and this pathway was found to induce biofilm formation in LBF 3-fold. C. albicans is a highly heterogenous bloodstream pathogen with clinical isolates varying in antifungal tolerance and biofilm formation. In addition to this, C. albicans is capable of highly complex and variable regulation of transcription and metabolic pathways and heterogeneity across isolates further increases the complexity of these pathways. Here we have shown with a dual and integrated approach, the importance of studying a diverse panel of C. albicans isolates, which has the potential to reveal distinct pathways that can harnessed for drug discovery.
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10
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Gow NAR, Johnson C, Berman J, Coste AT, Cuomo CA, Perlin DS, Bicanic T, Harrison TS, Wiederhold N, Bromley M, Chiller T, Edgar K. The importance of antimicrobial resistance in medical mycology. Nat Commun 2022; 13:5352. [PMID: 36097014 PMCID: PMC9466305 DOI: 10.1038/s41467-022-32249-5] [Citation(s) in RCA: 80] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 07/22/2022] [Indexed: 01/08/2023] Open
Abstract
Prior to the SARS-CoV-2 pandemic, antibiotic resistance was listed as the major global health care priority. Some analyses, including the O'Neill report, have predicted that deaths due to drug-resistant bacterial infections may eclipse the total number of cancer deaths by 2050. Although fungal infections remain in the shadow of public awareness, total attributable annual deaths are similar to, or exceeds, global mortalities due to malaria, tuberculosis or HIV. The impact of fungal infections has been exacerbated by the steady rise of antifungal drug resistant strains and species which reflects the widespread use of antifungals for prophylaxis and therapy, and in the case of azole resistance in Aspergillus, has been linked to the widespread agricultural use of antifungals. This review, based on a workshop hosted by the Medical Research Council and the University of Exeter, illuminates the problem of antifungal resistance and suggests how this growing threat might be mitigated.
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Affiliation(s)
- Neil A R Gow
- MRC Centre for Medical Mycology, School of Biosciences, University of Exeter, Geoffrey Pope Building, Exeter, EX4 4QD, UK.
| | - Carolyn Johnson
- Medical Research Council, Polaris House, Swindon, SN2 1FL, UK.
| | - Judith Berman
- Shmunis School of Biomedical and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, 418 Britannia Building, Ramat Aviv, 69978, Israel
| | - Alix T Coste
- Microbiology Institute, University Hospital Lausanne, rue du Bugnon 48, 1011, Lausanne, Switzerland
| | - Christina A Cuomo
- (CAC) Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA
| | - David S Perlin
- Center for Discovery and Innovation, Hackensack Meridian health, Nutley, NJ, 07110, USA
| | - Tihana Bicanic
- Institute of Infection and Immunity, St George's University of London, London, SW17 0RE, UK
- Clinical Academic Group in Infection, St George's University Hospitals NHS Foundation Trust, London, SW17 0QT, UK
| | - Thomas S Harrison
- MRC Centre for Medical Mycology, School of Biosciences, University of Exeter, Geoffrey Pope Building, Exeter, EX4 4QD, UK
- Institute of Infection and Immunity, St George's University of London, London, SW17 0RE, UK
- Clinical Academic Group in Infection, St George's University Hospitals NHS Foundation Trust, London, SW17 0QT, UK
| | - Nathan Wiederhold
- Department of Pathology and Laboratory Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA
| | - Mike Bromley
- Manchester Fungal Infection Group, Division of Evolution, Infection, and Genomics, Faculty of Biology, Medicine and Health, University of Manchester, CTF Building, 46 Grafton Street, Manchester, M13 9NT, UK
| | - Tom Chiller
- Center for Disease Control and Prevention Mycotic Disease Branch 1600 Clifton Rd, MSC-09, Atlanta, 30333, GA, USA
| | - Keegan Edgar
- Center for Disease Control and Prevention Mycotic Disease Branch 1600 Clifton Rd, MSC-09, Atlanta, 30333, GA, USA
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11
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Evaluation of Inoculum Preparation for Etest and EUCAST Broth Dilution to Detect Anidulafungin Polyresistance in Candida glabrata. Antimicrob Agents Chemother 2022; 66:e0016822. [PMID: 35862737 PMCID: PMC9380570 DOI: 10.1128/aac.00168-22] [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] [Indexed: 11/20/2022] Open
Abstract
The influence of inoculum preparation in EUCAST broth dilution and Etest to detect the coexistence of resistant and susceptible Candida subpopulations (defined as polyresistance [PR]) was evaluated. Cocultures of two echinocandin-resistant and susceptible clinical C. glabrata strains were used to simulate the occurrence of mixed populations in clinical samples, and antifungal susceptibility testing was performed with standard and modified approaches of inoculum preparation. Polyresistant results manifested as microcolonies or double ellipses in Etest and in single reduced optical density (OD) values (dip in OD) in microdilution. The strict inclusion of five distinct colonies of 1:5 and 1:10 resistant and susceptible cocultures led to higher rates of PR and R results compared to including one to two colonies in inoculum preparation (30% and 26% for Etest and broth dilution, respectively). Modifying the inoculum preparation by increasing the turbidity from a 2 to a 4 McFarland standard before redilution to a 0.5 McFarland standard reliably enabled the detection of resistance, with better identification of PR by Etest than by broth dilution (82% versus 32%, respectively) and of resistant minimum inhibitory concentration (MIC) values in 18% of Etests and 67% of microdilutions. The highest identification of PR succeeded with Etest and a modified 3 McFarland standard approach of inoculum preparation. Our data demonstrate that inoculum preparation as recommended and practiced does not reliably identify resistant subpopulations in polyresistant Candida cultures. By increasing the inoculum size for Etest assays from a 2 to a 4 McFarland standard with subsequent redilution, we propose a simple adaptation to increase reliability.
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12
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Multiple colony antifungal susceptibility testing detects polyresistance in clinical Candida cultures: an ECMM Excellence centers study. Clin Microbiol Infect 2022; 28:1288.e1-1288.e7. [DOI: 10.1016/j.cmi.2022.04.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 04/13/2022] [Accepted: 04/16/2022] [Indexed: 12/21/2022]
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13
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Murphy SE, Bicanic T. Drug Resistance and Novel Therapeutic Approaches in Invasive Candidiasis. Front Cell Infect Microbiol 2022; 11:759408. [PMID: 34970504 PMCID: PMC8713075 DOI: 10.3389/fcimb.2021.759408] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 11/08/2021] [Indexed: 12/12/2022] Open
Abstract
Candida species are the leading cause of invasive fungal infections worldwide and are associated with acute mortality rates of ~50%. Mortality rates are further augmented in the context of host immunosuppression and infection with drug-resistant Candida species. In this review, we outline antifungal drugs already in clinical use for invasive candidiasis and candidaemia, their targets and mechanisms of resistance in clinically relevant Candida species, encompassing not only classical resistance, but also heteroresistance and tolerance. We describe novel antifungal agents and targets in pre-clinical and clinical development, including their spectrum of activity, antifungal target, clinical trial data and potential in treatment of drug-resistant Candida. Lastly, we discuss the use of combination therapy between conventional and repurposed agents as a potential strategy to combat the threat of emerging resistance in Candida.
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Affiliation(s)
- Sarah E Murphy
- Institute of Infection & Immunity, St George's University of London, London, United Kingdom
| | - Tihana Bicanic
- Institute of Infection & Immunity, St George's University of London, London, United Kingdom.,Clinical Academic Group in Infection and Immunity, St. George's University Hospital National Health Service (NHS) Foundation Trust, London, United Kingdom
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14
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Bacterial heteroresistance: an evolving novel way to combat antibiotics. Biologia (Bratisl) 2021. [DOI: 10.1007/s11756-021-00820-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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15
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de Sousa ESO, Pinheiro SB, Cortez ACA, Cruz KS, de Souza ÉS, Melhem MDSC, Frickmann H, de Souza JVB. Modifications of antifungal sensibility testing as suggested by CLSI document M27-A4: proposal for using different culture medium and buffer. Diagn Microbiol Infect Dis 2021; 101:115488. [PMID: 34461499 DOI: 10.1016/j.diagmicrobio.2021.115488] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 07/05/2021] [Accepted: 07/07/2021] [Indexed: 11/24/2022]
Abstract
A common strategy in antifungal susceptibility testing is the utilization of the standardized protocol based on the microbroth dilution assay approach as described by the Clinical Laboratory Standards Institute (CLSI) (M27-A4). One major problem for laboratories in resource-limited countries with this protocol arises from the use of expensive culture media like RPMI-1640 and 3-N-morpholinopropanesulfonic acid (MOPS) buffer. One approach of circumventing this problem in cases of economic need is the evaluation of alternative culture media and buffers. The overall goal of this work was to investigate the influence of modifications in the protocol M27-A4 on diagnostic reliability. We performed univariate analyses evaluating (1) 2 different culture media (YNB and modified SAB); (2) three different buffers (sodium bicarbonate, Tris-HCL, and phosphate), as well as the influence of inoculum concentration (102, 103, 104, 105 cells/mL), the influence of incubation time, and the influence of the assessment mode (visual, biological dye, and spectrophotometer). Our results suggested that (1) RPMI-1640 may be substituted by modified SAB and (2) MOPS buffer may be substituted by Tris-HCl buffer for defined analyses. By comparing the CLSI protocol and the alternative protocol proposed in the present study (modified SAB and Tris-HCl buffer) for the assessment of fluconazole susceptibility of eighteen yeasts (clinical isolates), similar results with both methodologies were recorded. We feel that this study should stimulate a discussion on the feasibility and evolution of the M27-A4 protocol in order to include pragmatic alternatives for resource-limited settings.
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Affiliation(s)
| | - Silviane Bezerra Pinheiro
- Programa de Pós-graduação em Ciências Farmacêuticas - Universidade Federal do Amazonas - UFAM, Amazonas, Brasil
| | - Ana Cláudia Alves Cortez
- Departamento de Microbiologia Médica, Instituto Nacional de Pesquisa da Amazônia - INPA. Av. André Araújo, Amazonas, Brasil
| | - Kátia Santana Cruz
- Fundação de Medicina Tropical Doutor Heitor Vieira Dourado - AM, Manaus, Amazonas, Brasil
| | | | - Marcia de Souza Carvalho Melhem
- The School of Medicine, Federal University of Mato Grosso do Sul, Campo Grande, Brazil; Departamento de Micologia, Instituto Adolfo Lutz. Av. Dr Arnaldo, São Paulo, Brasil
| | - Hagen Frickmann
- Department of Microbiology and Hospital Hygiene, Bundeswehr Hospital Hamburg, Hamburg, Germany; Institute for Medical Microbiology, Virology and Hygiene, University Medicine Rostock, Rostock, Germany
| | - João Vicente Braga de Souza
- Departamento de Microbiologia Médica, Instituto Nacional de Pesquisa da Amazônia - INPA. Av. André Araújo, Amazonas, Brasil.
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16
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Abstract
Pathogenic fungi have several mechanisms of resistance to antifungal drugs, driven by the genetic plasticity and versatility of their homeostatic responses to stressful environmental cues. We critically review the molecular mechanisms of resistance and cellular adaptations of pathogenic fungi in response to antifungals and discuss the factors contributing to such resistance. We offer suggestions for the translational and clinical research agenda of this rapidly evolving and medically important field. A better understanding of antifungal resistance should assist in developing better detection tools and inform optimal strategies for preventing and treating refractory mycoses in the future.
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Affiliation(s)
- Ronen Ben-Ami
- Infectious Diseases Department, Sackler School of Medicine, Tel Aviv University, Tel Aviv Sourasky Medical Center, 6 Weizmann, Tel Aviv 64239, Israel
| | - Dimitrios P Kontoyiannis
- Infectious Diseases, University of Texas M D Anderson Cancer Center, 1515 Holcombe, Houston, TX 77030, USA.
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17
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Chen YR, Ziv I, Swaminathan K, Elias JE, Jarosz DF. Protein aggregation and the evolution of stress resistance in clinical yeast. Philos Trans R Soc Lond B Biol Sci 2021; 376:20200127. [PMID: 33866806 DOI: 10.1098/rstb.2020.0127] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Protein aggregation, particularly in its prion-like form, has long been thought to be detrimental. However, recent studies have identified multiple instances where protein aggregation is important for normal physiological functions. Combining mass spectrometry and cell biological approaches, we developed a strategy for the identification of protein aggregates in cell lysates. We used this approach to characterize prion-based traits in pathogenic strains of the yeast Saccharomyces cerevisiae isolated from immunocompromised human patients. The proteins that we found, including the metabolic enzyme Cdc19, the translation elongation factor Yef3 and the fibrillarin homologue Nop1, are known to assemble under certain physiological conditions. Yet, such assemblies have not been reported to be stable or heritable. Our data suggest that some proteins which aggregate in response to stress have the capacity to acquire diverse assembled states, certain ones of which can be propagated across generations in a form of protein-based epigenetics. This article is part of the theme issue 'How does epigenetics influence the course of evolution?'
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Affiliation(s)
- Yiwen R Chen
- Department of Chemical and Systems Biology, Stanford University, Stanford, CA 94305, USA
| | - Inbal Ziv
- Department of Chemical and Systems Biology, Stanford University, Stanford, CA 94305, USA
| | - Kavya Swaminathan
- Department of Chemical and Systems Biology, Stanford University, Stanford, CA 94305, USA
| | - Joshua E Elias
- Department of Chemical and Systems Biology, Stanford University, Stanford, CA 94305, USA
| | - Daniel F Jarosz
- Department of Chemical and Systems Biology, Stanford University, Stanford, CA 94305, USA.,Department of Developmental Biology, Stanford University, Stanford, CA 94305, USA
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18
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Lopes SP, Jorge P, Sousa AM, Pereira MO. Discerning the role of polymicrobial biofilms in the ascent, prevalence, and extent of heteroresistance in clinical practice. Crit Rev Microbiol 2021; 47:162-191. [PMID: 33527850 DOI: 10.1080/1040841x.2020.1863329] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Antimicrobial therapy is facing a worrisome and underappreciated challenge, the phenomenon of heteroresistance (HR). HR has been gradually documented in clinically relevant pathogens (e.g. Pseudomonas aeruginosa, Staphylococcus aureus, Burkholderia spp., Acinetobacter baumannii, Klebsiella pneumoniae, Candida spp.) towards several drugs and is believed to complicate the clinical picture of chronic infections. This type of infections are typically mediated by polymicrobial biofilms, wherein microorganisms inherently display a wide range of physiological states, distinct metabolic pathways, diverging refractory levels of stress responses, and a complex network of chemical signals exchange. This review aims to provide an overview on the relevance, prevalence, and implications of HR in clinical settings. Firstly, related terminologies (e.g. resistance, tolerance, persistence), sometimes misunderstood and overlapped, were clarified. Factors generating misleading HR definitions were also uncovered. Secondly, the recent HR incidences reported in clinically relevant pathogens towards different antimicrobials were annotated. The potential mechanisms underlying such occurrences were further elucidated. Finally, the link between HR and biofilms was discussed. The focus was to recognize the presence of heterogeneous levels of resistance within most biofilms, as well as the relevance of polymicrobial biofilms in chronic infectious diseases and their role in resistance spreading. These topics were subject of a critical appraisal, gaining insights into the ascending clinical implications of HR in antimicrobial resistance spreading, which could ultimately help designing effective therapeutic options.
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Affiliation(s)
- Susana Patrícia Lopes
- CEB - Centre of Biological Engineering, LIBRO - Laboratory of Research in Biofilms Rosário Oliveira, University of Minho, Braga, Portugal
| | - Paula Jorge
- CEB - Centre of Biological Engineering, LIBRO - Laboratory of Research in Biofilms Rosário Oliveira, University of Minho, Braga, Portugal
| | - Ana Margarida Sousa
- CEB - Centre of Biological Engineering, LIBRO - Laboratory of Research in Biofilms Rosário Oliveira, University of Minho, Braga, Portugal
| | - Maria Olívia Pereira
- CEB - Centre of Biological Engineering, LIBRO - Laboratory of Research in Biofilms Rosário Oliveira, University of Minho, Braga, Portugal
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19
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Ponde NO, Lortal L, Ramage G, Naglik JR, Richardson JP. Candida albicans biofilms and polymicrobial interactions. Crit Rev Microbiol 2021; 47:91-111. [PMID: 33482069 PMCID: PMC7903066 DOI: 10.1080/1040841x.2020.1843400] [Citation(s) in RCA: 89] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 10/05/2020] [Accepted: 10/25/2020] [Indexed: 12/16/2022]
Abstract
Candida albicans is a common fungus of the human microbiota. While generally a harmless commensal in healthy individuals, several factors can lead to its overgrowth and cause a range of complications within the host, from localized superficial infections to systemic life-threatening disseminated candidiasis. A major virulence factor of C. albicans is its ability to form biofilms, a closely packed community of cells that can grow on both abiotic and biotic substrates, including implanted medical devices and mucosal surfaces. These biofilms are extremely hard to eradicate, are resistant to conventional antifungal treatment and are associated with high morbidity and mortality rates, making biofilm-associated infections a major clinical challenge. Here, we review the current knowledge of the processes involved in C. albicans biofilm formation and development, including the central processes of adhesion, extracellular matrix production and the transcriptional network that regulates biofilm development. We also consider the advantages of the biofilm lifestyle and explore polymicrobial interactions within multispecies biofilms that are formed by C. albicans and selected microbial species.
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Affiliation(s)
- Nicole O. Ponde
- Centre for Host-Microbiome Interactions, Faculty of Dentistry, Oral & Craniofacial Sciences, King’s College London, London, SE1 9RT, United Kingdom
| | - Léa Lortal
- Centre for Host-Microbiome Interactions, Faculty of Dentistry, Oral & Craniofacial Sciences, King’s College London, London, SE1 9RT, United Kingdom
| | - Gordon Ramage
- School of Medicine, Dentistry & Nursing, Glasgow Dental School and Hospital, Faculty of Medicine, University of Glasgow, G2 3JZ, United Kingdom
| | - Julian R. Naglik
- Centre for Host-Microbiome Interactions, Faculty of Dentistry, Oral & Craniofacial Sciences, King’s College London, London, SE1 9RT, United Kingdom
| | - Jonathan P. Richardson
- Centre for Host-Microbiome Interactions, Faculty of Dentistry, Oral & Craniofacial Sciences, King’s College London, London, SE1 9RT, United Kingdom
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20
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Chen M, Zhong G, Wang S, Zhu J, Tang L, Li L. tpo3 and dur3, Aspergillus fumigatus Plasma Membrane Regulators of Polyamines, Regulate Polyamine Homeostasis and Susceptibility to Itraconazole. Front Microbiol 2021; 11:563139. [PMID: 33391196 PMCID: PMC7772357 DOI: 10.3389/fmicb.2020.563139] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 11/25/2020] [Indexed: 11/13/2022] Open
Abstract
Aspergillus fumigatus is a well-known opportunistic pathogen that causes invasive aspergillosis (IA) infections, which have high mortality rates in immunosuppressed individuals. Long-term antifungal drug azole use in clinical treatment and agriculture results in loss of efficacy or drug resistance. Drug resistance is related to cellular metabolites and the corresponding gene transcription. In this study, through untargeted metabolomics and transcriptomics under itraconazole (ITC) treatment, we identified two plasma membrane-localized polyamine regulators tpo3 and dur3, which were important for polyamine homeostasis and susceptibility to ITC in A. fumigatus. In the absence of tpo3 and/or dur3, the levels of cytoplasmic polyamines had a moderate increase, which enhanced the tolerance of A. fumigatus to ITC. In comparison, overexpression of tpo3 or dur3 induced a drastic increase in polyamines, which increased the sensitivity of A. fumigatus to ITC. Further analysis revealed that polyamines concentration-dependently affected the susceptibility of A. fumigatus to ITC by scavenging reactive oxygen species (ROS) at a moderate concentration and promoting the production of ROS at a high concentration rather than regulating drug transport. Moreover, inhibition of polyamine biosynthesis reduced the intracellular polyamine content, resulted in accumulation of ROS and enhanced the antifungal activity of ITC. Interestingly, A. fumigatus produces much lower levels of ROS under voriconazole (VOC) treatment than under ITC-treatment. Accordingly, our study established the link among the polyamine regulators tpo3 and dur3, polyamine homeostasis, ROS content, and ITC susceptibility in A. fumigatus.
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Affiliation(s)
- Mingcong Chen
- Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, China
| | - Guowei Zhong
- Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, China
| | - Sha Wang
- Key Laboratory of Vector Biology and Pathogen Control of Zhejiang Province, Huzhou Central Hospital, Huzhou University, Huzhou, China
| | - Jun Zhu
- Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, China
| | - Lei Tang
- Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, China
| | - Lei Li
- Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, China
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21
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Galocha M, Costa IV, Teixeira MC. Carrier-Mediated Drug Uptake in Fungal Pathogens. Genes (Basel) 2020; 11:genes11111324. [PMID: 33182427 PMCID: PMC7697741 DOI: 10.3390/genes11111324] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 11/03/2020] [Accepted: 11/07/2020] [Indexed: 12/22/2022] Open
Abstract
Candida, Aspergillus, and Cryptococcus species are the most frequent cause of severe human fungal infections. Clinically relevant antifungal drugs are scarce, and their effectiveness are hampered by the ability of fungal cells to develop drug resistance mechanisms. Drug effectiveness and drug resistance in human pathogens is very often affected by their “transportome”. Many studies have covered a panoply of drug resistance mechanisms that depend on drug efflux pumps belonging to the ATP-Binding Cassette and Major Facilitator Superfamily. However, the study of drug uptake mechanisms has been, to some extent, overlooked in pathogenic fungi. This review focuses on discussing current knowledge on drug uptake systems in fungal pathogens, highlighting the need for further studies on this topic of great importance. The following subjects are covered: (i) drugs imported by known transporter(s) in pathogenic fungi; and (ii) drugs imported by known transporter(s) in the model yeast Saccharomyces cerevisiae or in human parasites, aimed at the identification of their homologs in pathogenic fungi. Besides its contribution to increase the understanding of drug-pathogen interactions, the practical implications of identifying drug importers in human pathogens are discussed, particularly focusing on drug development strategies.
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Affiliation(s)
- Mónica Galocha
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; (M.G.); (I.V.C.)
- Biological Sciences Research Group, iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
| | - Inês Vieira Costa
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; (M.G.); (I.V.C.)
- Biological Sciences Research Group, iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
| | - Miguel Cacho Teixeira
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; (M.G.); (I.V.C.)
- Biological Sciences Research Group, iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
- Correspondence: ; Tel.: +351-21-841-7772; Fax: +351-21-841-9199
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22
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Levinson T, Dahan A, Novikov A, Paran Y, Berman J, Ben-Ami R. Impact of tolerance to fluconazole on treatment response in Candida albicans bloodstream infection. Mycoses 2020; 64:78-85. [PMID: 33000505 DOI: 10.1111/myc.13191] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 09/04/2020] [Indexed: 01/05/2023]
Abstract
BACKGROUND Treatment of Candida albicans bloodstream infection with fluconazole is associated with significant mortality despite in vitro susceptibility to the drug. OBJECTIVES We sought to determine whether tolerance to fluconazole is predictive of treatment failure. METHODS We reviewed patients with monomicrobial C albicans bloodstream infection who received primary monotherapy with fluconazole. Tolerance to fluconazole, defined as the fraction of growth above the MIC, was quantified using the disc diffusion assay and digital image analyses. Survival analyses were performed with host and treatment factors as predictive variables. RESULTS Among 44 patients included in the study, all-cause mortality was 29.5% at 30 days and 43.1% at 12 weeks. Forty-one isolates (93%) were susceptible to fluconazole (MIC50, 0.5 mg/L). Fluconazole tolerance was strongly associated with death for patients treated with fluconazole within 24 h of candidemia onset (33.3% vs 0%; p = .007), but not among patients whose treatment was started later. MIC did not correlate with survival, regardless of treatment delay. A Cox regression model including time to treatment, tolerance to fluconazole, fluconazole exposure and Pitt bacteraemia score provided good prediction of treatment outcome (area under the receiver-operator curve, 0.82). CONCLUSIONS In patients with C albicans bloodstream infection, tolerance testing was predictive of fluconazole efficacy if the drug was started early. Further study is required to validate the utility of this metric to guide treatment choices.
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Affiliation(s)
- Tal Levinson
- Infectious Diseases Unit, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Alon Dahan
- The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Anna Novikov
- Infectious Diseases Unit, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
| | - Yael Paran
- Infectious Diseases Unit, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Judith Berman
- The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Ronen Ben-Ami
- Infectious Diseases Unit, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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23
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Caenorhabditis elegans as a Model System To Assess Candida glabrata, Candida nivariensis, and Candida bracarensis Virulence and Antifungal Efficacy. Antimicrob Agents Chemother 2020; 64:AAC.00824-20. [PMID: 32718968 DOI: 10.1128/aac.00824-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 07/19/2020] [Indexed: 12/18/2022] Open
Abstract
Although Candida albicans remains the major etiological agent of invasive candidiasis, Candida glabrata and other emerging species of Candida are increasingly isolated. This species is the second most prevalent cause of candidiasis in many regions of the world. However, clinical isolates of Candida nivariensis and Candida bracarensis can be misidentified and are underdiagnosed due to phenotypic traits shared with C. glabrata Little is known about the two cryptic species. Therefore, pathogenesis studies are needed to understand their virulence traits and their susceptibility to antifungal drugs. The susceptibility of Caenorhabditis elegans to different Candida species makes this nematode an excellent model for assessing host-fungus interactions. We evaluated the usefulness of C. elegans as a nonconventional host model to analyze the virulence of C. glabrata, C. nivariensis, and C. bracarensis The three species caused candidiasis, and the highest virulence of C. glabrata was confirmed. Furthermore, we determined the efficacy of current antifungal drugs against the infection caused by these species in the C. elegans model. Amphotericin B and azoles showed the highest activity against C. glabrata and C. bracarensis infections, while echinocandins were more active for treating those caused by C. nivariensis C. elegans proved to be a useful model system for assessing the pathogenicity of these closely related species.
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24
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Farquhar KS, Flohr H, Charlebois DA. Advancing Antimicrobial Resistance Research Through Quantitative Modeling and Synthetic Biology. Front Bioeng Biotechnol 2020; 8:583415. [PMID: 33072732 PMCID: PMC7530828 DOI: 10.3389/fbioe.2020.583415] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 09/02/2020] [Indexed: 11/13/2022] Open
Abstract
Antimicrobial resistance (AMR) is an emerging global health crisis that is undermining advances in modern medicine and, if unmitigated, threatens to kill 10 million people per year worldwide by 2050. Research over the last decade has demonstrated that the differences between genetically identical cells in the same environment can lead to drug resistance. Fluctuations in gene expression, modulated by gene regulatory networks, can lead to non-genetic heterogeneity that results in the fractional killing of microbial populations causing drug therapies to fail; this non-genetic drug resistance can enhance the probability of acquiring genetic drug resistance mutations. Mathematical models of gene networks can elucidate general principles underlying drug resistance, predict the evolution of resistance, and guide drug resistance experiments in the laboratory. Cells genetically engineered to carry synthetic gene networks regulating drug resistance genes allow for controlled, quantitative experiments on the role of non-genetic heterogeneity in the development of drug resistance. In this perspective article, we emphasize the contributions that mathematical, computational, and synthetic gene network models play in advancing our understanding of AMR to discover effective therapies against drug-resistant infections.
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Affiliation(s)
| | - Harold Flohr
- Department of Physics, University of Alberta, Edmonton, AB, Canada
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25
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Jenks JD, Cornely OA, Chen SCA, Thompson GR, Hoenigl M. Breakthrough invasive fungal infections: Who is at risk? Mycoses 2020; 63:1021-1032. [PMID: 32744334 DOI: 10.1111/myc.13148] [Citation(s) in RCA: 96] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 07/17/2020] [Accepted: 07/18/2020] [Indexed: 12/18/2022]
Abstract
The epidemiology of invasive fungal infections (IFIs) in immunocompromised individuals has changed over the last few decades, partially due to the increased use of antifungal agents to prevent IFIs. Although this strategy has resulted in an overall reduction in IFIs, a subset of patients develop breakthrough IFIs with substantial morbidity and mortality in this population. Here, we review the most significant risk factors for breakthrough IFIs in haematology patients, solid organ transplant recipients, and patients in the intensive care unit, focusing particularly on host factors, and highlight areas that require future investigation.
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Affiliation(s)
- Jeffrey D Jenks
- Division of General Internal Medicine, Department of Medicine, University of California San Diego, La Jolla, California, USA.,Division of Infectious Diseases and Global Public Health, Department of Medicine, University of California San Diego, La Jolla, California, USA.,Clinical and Translational Fungal-Working Group, University of California San Diego, La Jolla, California, USA
| | - Oliver A Cornely
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany.,Department I of Internal Medicine, ECMM Center of Excellence for Medical Mycology, German Centre for Infection Research, Partner Site Bonn-Cologne (DZIF), University of Cologne, Cologne, Germany.,Clinical Trials Centre Cologne (ZKS Köln), University of Cologne, Cologne, Germany
| | - Sharon C-A Chen
- Centre for Infectious Diseases and Microbiology, Westmead Hospital, and Sydney Medical School, The University of Sydney, Camperdown, NSW, Australia
| | - George R Thompson
- Department of Internal Medicine Division of Infectious Diseases and Department of Medical Microbiology and Immunology, UC-Davis Medical Center, Sacramento, California, USA
| | - Martin Hoenigl
- Division of Infectious Diseases and Global Public Health, Department of Medicine, University of California San Diego, La Jolla, California, USA.,Clinical and Translational Fungal-Working Group, University of California San Diego, La Jolla, California, USA.,Division of Pulmonology and Section of Infectious Diseases, Medical University of Graz, Graz, Austria
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26
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Fuller J, Dingle TC, Bull A, Shokoples S, Laverdière M, Baxter MR, Adam HJ, Karlowsky JA, Zhanel GG. Species distribution and antifungal susceptibility of invasive Candida isolates from Canadian hospitals: results of the CANWARD 2011-16 study. J Antimicrob Chemother 2020; 74:iv48-iv54. [PMID: 31505645 DOI: 10.1093/jac/dkz287] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
OBJECTIVES Understanding the epidemiology of invasive Candida infections is essential to patient management decisions and antifungal stewardship practices. This study characterized the species distribution and antifungal susceptibilities of prospectively collected isolates of Candida species causing bloodstream infections (BSIs) in patients admitted to tertiary care hospitals located in 14 cities across 8 of the 10 Canadian provinces between 2011 and 2016. METHODS Antifungal susceptibility testing was performed by broth microdilution using CLSI methods, breakpoints and epidemiological cut-off values. DNA sequencing of fks loci was performed on all echinocandin-non-susceptible isolates. RESULTS Candida albicans (49.6%), Candida glabrata (20.8%) and Candida parapsilosis complex (12.0%) were the most common species out of 1882 isolates associated with BSIs. Candida tropicalis (5.2%), Candida krusei (4.3%), Candida dubliniensis (4.1%), Candida lusitaniae (1.4%) and Candida guilliermondii (1.1%) were less frequently isolated. Between 2011 and 2016, the proportion of C. albicans significantly decreased from 60.9% to 42.1% (P < 0.0001) while that of C. glabrata significantly increased from 16.4% to 22.4% (P = 0.023). C. albicans (n = 934), C. glabrata (n = 392) and C. parapsilosis complex (n = 225) exhibited 0.6%, 1.0% and 4.9% resistance to fluconazole and 0.1%, 2.5% and 0% resistance to micafungin, respectively. Mutations in fks hot-spot regions were confirmed in all nine micafungin non-susceptible C. glabrata. CONCLUSIONS Antifungal resistance in contemporary isolates of Candida causing BSIs in Canada is uncommon. However, the proportion of C. glabrata isolates has increased and echinocandin resistance in this species has emerged. Ongoing surveillance of local hospital epidemiology and appropriate antifungal stewardship practices are necessary to preserve the utility of available antifungal agents.
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Affiliation(s)
- Jeff Fuller
- Department of Pathology and Laboratory Medicine, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada.,Division of Microbiology, London Health Sciences Centre, 800 Commissioners Road E, London, Ontario, Canada
| | - Tanis C Dingle
- Provincial Laboratory, Alberta Health Services, 8440-112 Street, Edmonton, Alberta, Canada.,Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada
| | - Amy Bull
- Provincial Laboratory, Alberta Health Services, 8440-112 Street, Edmonton, Alberta, Canada
| | - Sandy Shokoples
- Provincial Laboratory, Alberta Health Services, 8440-112 Street, Edmonton, Alberta, Canada
| | - Michel Laverdière
- Department of Medicine, Microbiology and Infectious Diseases, Hôpital Maisonneuve-Rosemont, Montreal, Quebec, Canada
| | - Melanie R Baxter
- Department of Medical Microbiology/Infectious Diseases, Max Rady College of Medicine, University of Manitoba, Room 543-745 Bannatyne Avenue, Winnipeg, Manitoba, Canada
| | - Heather J Adam
- Department of Medical Microbiology/Infectious Diseases, Max Rady College of Medicine, University of Manitoba, Room 543-745 Bannatyne Avenue, Winnipeg, Manitoba, Canada.,Clinical Microbiology, Diagnostic Services Manitoba, MS673-820 Sherbrook Street, Winnipeg, Manitoba, Canada
| | - James A Karlowsky
- Department of Medical Microbiology/Infectious Diseases, Max Rady College of Medicine, University of Manitoba, Room 543-745 Bannatyne Avenue, Winnipeg, Manitoba, Canada.,Clinical Microbiology, Diagnostic Services Manitoba, MS673-820 Sherbrook Street, Winnipeg, Manitoba, Canada
| | - George G Zhanel
- Department of Medical Microbiology/Infectious Diseases, Max Rady College of Medicine, University of Manitoba, Room 543-745 Bannatyne Avenue, Winnipeg, Manitoba, Canada
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27
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Todd RT, Selmecki A. Expandable and reversible copy number amplification drives rapid adaptation to antifungal drugs. eLife 2020; 9:e58349. [PMID: 32687060 PMCID: PMC7371428 DOI: 10.7554/elife.58349] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 07/09/2020] [Indexed: 12/13/2022] Open
Abstract
Previously, we identified long repeat sequences that are frequently associated with genome rearrangements, including copy number variation (CNV), in many diverse isolates of the human fungal pathogen Candida albicans (Todd et al., 2019). Here, we describe the rapid acquisition of novel, high copy number CNVs during adaptation to azole antifungal drugs. Single-cell karyotype analysis indicates that these CNVs appear to arise via a dicentric chromosome intermediate and breakage-fusion-bridge cycles that are repaired using multiple distinct long inverted repeat sequences. Subsequent removal of the antifungal drug can lead to a dramatic loss of the CNV and reversion to the progenitor genotype and drug susceptibility phenotype. These findings support a novel mechanism for the rapid acquisition of antifungal drug resistance and provide genomic evidence for the heterogeneity frequently observed in clinical settings.
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Affiliation(s)
- Robert T Todd
- Department of Microbiology and Immunology, University of Minnesota Medical SchoolMinneapolis, MinnesotaUnited States
| | - Anna Selmecki
- Department of Microbiology and Immunology, University of Minnesota Medical SchoolMinneapolis, MinnesotaUnited States
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28
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Duxbury SJN, Bates S, Beardmore RE, Gudelj I. Evolution of drug-resistant and virulent small colonies in phenotypically diverse populations of the human fungal pathogen Candida glabrata. Proc Biol Sci 2020; 287:20200761. [PMID: 32673559 DOI: 10.1098/rspb.2020.0761] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Antimicrobial resistance frequently carries a fitness cost to a pathogen, measured as a reduction in growth rate compared to the sensitive wild-type, in the absence of antibiotics. Existing empirical evidence points to the following relationship between cost of resistance and virulence. If a resistant pathogen suffers a fitness cost in terms of reduced growth rate it commonly has lower virulence compared to the sensitive wild-type. If this cost is absent so is the reduction in virulence. Here we show, using experimental evolution of drug resistance in the fungal human pathogen Candida glabrata, that reduced growth rate of resistant strains need not result in reduced virulence. Phenotypically heterogeneous populations were evolved in parallel containing highly resistant sub-population small colony variants (SCVs) alongside sensitive sub-populations. Despite their low growth rate in the absence of an antifungal drug, the SCVs did not suffer a marked alteration in virulence compared with the wild-type ancestral strain, or their co-isolated sensitive strains. This contrasts with classical theory that assumes growth rate to positively correlate with virulence. Our work thus highlights the complexity of the relationship between resistance, basic life-history traits and virulence.
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Affiliation(s)
- Sarah J N Duxbury
- Department of Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, Devon EX4 4QD, UK.,Laboratory of Genetics, Wageningen University, 6708 PB Wageningen, The Netherlands
| | - Steven Bates
- Department of Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, Devon EX4 4QD, UK
| | - Robert E Beardmore
- Department of Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, Devon EX4 4QD, UK
| | - Ivana Gudelj
- Department of Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, Devon EX4 4QD, UK
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29
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Hauzer M, Cohen MJ, Polacheck I, Moses A, Korem M. The prevalence and clinical significance of microcolonies when tested according to contemporary interpretive breakpoints for fluconazole against Candida species using E-test. Med Mycol 2020; 57:718-723. [PMID: 30576514 DOI: 10.1093/mmy/myy130] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 10/28/2018] [Accepted: 11/06/2018] [Indexed: 12/21/2022] Open
Abstract
Changes in the interpretive-breakpoints for antifungals against various Candida species have raised the need to examine the significance of the phenomenon of the growth of microcolonies in agar diffusion inhibition zones, which has generally been considered negligible. The objective was to determine the incidence of cases in which microcolonies demonstrate fluconazole resistance according to current interpretive-breakpoints and whether their growth is associated with therapeutic failure. The fluconazole minimum inhibitory concentrations (MICs) of 100 blood culture isolates of Candida were performed by E-test on Roswell Park Memorial Institute (RPMI) agar and examined for the appearance of microcolonies. Fluconazole MICs of microcolonies were then determined over three generations. The significance of the phenomenon of microcolonies was determined according to clinical data retrieved from electronic files. Microcolonies were a common phenomenon among Candida isolates following incubation on RPMI agar, with a higher frequency among C. albicans isolates as compared to non-albicans Candida across generations (57-93% vs 31-93%, respectively) and a similar fluconazole susceptibility rate over three generations. The rate of microcolonies was similar in both patients with successful and unsuccessful outcome (41% vs 42%, respectively). Microcolonies are a common phenomenon. No increase in MIC was demonstrated throughout three generations of microcolony inoculation on RPMI, and no difference in clinical outcome was observed.
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Affiliation(s)
- Michael Hauzer
- Department of Clinical Microbiology and Infectious Diseases, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | | | - Itzhack Polacheck
- Department of Clinical Microbiology and Infectious Diseases, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Allon Moses
- Department of Clinical Microbiology and Infectious Diseases, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Maya Korem
- Department of Clinical Microbiology and Infectious Diseases, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
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30
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Abstract
Systemic fungal infections pose a serious clinical problem. Treatment options are limited, and antifungal drug resistance is increasing. In addition, a substantial proportion of patients do not respond to therapy despite being infected with fungi that are susceptible to the drug. The discordance between overall treatment outcome and low levels of clinical resistance may be attributable to antifungal drug tolerance. In this Review, we define and distinguish resistance and tolerance and discuss the current understanding of the molecular, genetic and physiological mechanisms that contribute to those phenomena. Distinguishing tolerance from resistance might provide important insights into the reasons for treatment failure in some settings.
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31
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Zangl I, Pap IJ, Aspöck C, Schüller C. The role of Lactobacillus species in the control of Candida via biotrophic interactions. MICROBIAL CELL 2019; 7:1-14. [PMID: 31921929 PMCID: PMC6946018 DOI: 10.15698/mic2020.01.702] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Microbial communities have an important role in health and disease. Candida spp. are ubiquitous commensals and sometimes opportunistic fungal pathogens of humans, colonizing mucosal surfaces of the genital, urinary, respiratory and gastrointestinal tracts and the oral cavity. They mainly cause local mucosal infections in immune competent individuals. However, in the case of an ineffective immune defense, Candida infections may become a serious threat. Lactobacillus spp. are part of the human microbiome and are natural competitors of Candida in the vaginal environment. Lactic acid, low pH and other secreted metabolites are environmental signals sensed by fungal species present in the microbiome. This review briefly discusses the ternary interaction between host, Lactobacillus species and Candida with regard to fungal infections and the potential antifungal and fungistatic effect of Lactobacillus species. Our understanding of these interactions is incomplete due to the variability of the involved species and isolates and the complexity of the human host.
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Affiliation(s)
- Isabella Zangl
- University of Natural Resources and Life Sciences Vienna (BOKU), Department of Applied Genetics and Cell Biology (DAGZ), Tulln, Austria
| | - Ildiko-Julia Pap
- University Hospital of St. Pölten, Institute for Hygiene and Microbiology, St Pölten, Austria
| | - Christoph Aspöck
- University Hospital of St. Pölten, Institute for Hygiene and Microbiology, St Pölten, Austria
| | - Christoph Schüller
- University of Natural Resources and Life Sciences Vienna (BOKU), Department of Applied Genetics and Cell Biology (DAGZ), Tulln, Austria.,Bioactive Microbial Metabolites (BiMM), BOKU, Tulln, Austria
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32
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Cornely OA, Hoenigl M, Lass-Flörl C, Chen SCA, Kontoyiannis DP, Morrissey CO, Thompson GR. Defining breakthrough invasive fungal infection-Position paper of the mycoses study group education and research consortium and the European Confederation of Medical Mycology. Mycoses 2019; 62:716-729. [PMID: 31254420 PMCID: PMC6692208 DOI: 10.1111/myc.12960] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 06/26/2019] [Accepted: 06/27/2019] [Indexed: 12/14/2022]
Abstract
Breakthrough invasive fungal infections (IFIs) have emerged as a significant problem in patients receiving systemic antifungals; however, consensus criteria for defining breakthrough IFI are missing. This position paper establishes broadly applicable definitions of breakthrough IFI for clinical research. Representatives of the Mycoses Study Group Education and Research Consortium (MSG-ERC) and the European Confederation of Medical Mycology (ECMM) reviewed the relevant English literature for definitions applied and published through 2018. A draft proposal for definitions was developed and circulated to all members of the two organisations for comment and suggestions. The authors addressed comments received and circulated the updated document for approval. Breakthrough IFI was defined as any IFI occurring during exposure to an antifungal drug, including fungi outside the spectrum of activity of an antifungal. The time of breakthrough IFI was defined as the first attributable clinical sign or symptom, mycological finding or radiological feature. The period defining breakthrough IFI depends on pharmacokinetic properties and extends at least until one dosing interval after drug discontinuation. Persistent IFI describes IFI that is unchanged/stable since treatment initiation with ongoing need for antifungal therapy. It is distinct from refractory IFI, defined as progression of disease and therefore similar to non-response to treatment. Relapsed IFI occurs after treatment and is caused by the same pathogen at the same site, although dissemination can occur. These proposed definitions are intended to support the design of future clinical trials and epidemiological research in clinical mycology, with the ultimate goal of increasing the comparability of clinical trial results.
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Affiliation(s)
- Oliver A Cornely
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
- Department I of Internal Medicine, ECMM Center of Excellence for Medical Mycology, German Centre for Infection Research, Partner Site Bonn-Cologne (DZIF), University of Cologne, Cologne, Germany
- Clinical Trials Centre Cologne (ZKS Köln), University of Cologne, Cologne, Germany
| | - Martin Hoenigl
- Division of Infectious Diseases, University of California San Diego, San Diego, CA, USA
- Division of Pulmonology and Section of Infectious Diseases, Medical University of Graz, Graz, Austria
| | - Cornelia Lass-Flörl
- Division of Hygiene and Microbiology, ECMM Excellence Center for Medical Mycology, Medical University Innsbruck, Innsbruck, Austria
| | - Sharon C-A Chen
- Centre for Infectious Diseases and Microbiology, Laboratory Services, ICPMR, New South Wales Health Pathology, Westmead Hospital, Centre for Infectious Diseases and Microbiology, Sydney Medical School, The University of Sydney, Sydney, NSW, Australia
| | - Dimitrios P Kontoyiannis
- Department of Infectious Diseases, Infection Control, and Employee Health, University of Texas M. D. Anderson Cancer Center, Houston, TX, USA
| | - C Orla Morrissey
- Infectious Diseases, Alfred Health and Monash University, Melbourne, VIC, Australia
| | - George R Thompson
- Departments of Medical Microbiology and Immunology and Internal Medicine Division of Infectious Diseases, UC-Davis Medical Center, Sacramento, CA, USA
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33
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Nitroglycerin-Citrate-Ethanol Catheter Lock Solution Is Highly Effective for In Vitro Eradication of Candida auris Biofilm. Antimicrob Agents Chemother 2019; 63:AAC.00299-19. [PMID: 31036689 DOI: 10.1128/aac.00299-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 04/20/2019] [Indexed: 12/23/2022] Open
Abstract
Candida auris poses emerging risks for causing severe central line-associated bloodstream infections. We tested in vitro the ability of antifungal lock solutions to rapidly eradicate C. auris biofilms. Liposomal amphotericin B, amphotericin B deoxycholate, fluconazole, voriconazole, micafungin, caspofungin, and anidulafungin failed to completely eradicate all 10 tested C. auris biofilms. Conversely, nitroglycerin-citrate-ethanol (NiCE) catheter lock solution completely eradicated all replicates for all of C. auris biofilms tested.
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34
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Stone NR, Rhodes J, Fisher MC, Mfinanga S, Kivuyo S, Rugemalila J, Segal ES, Needleman L, Molloy SF, Kwon-Chung J, Harrison TS, Hope W, Berman J, Bicanic T. Dynamic ploidy changes drive fluconazole resistance in human cryptococcal meningitis. J Clin Invest 2019; 129:999-1014. [PMID: 30688656 PMCID: PMC6391087 DOI: 10.1172/jci124516] [Citation(s) in RCA: 102] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 11/30/2018] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Cryptococcal meningitis (CM) causes an estimated 180,000 deaths annually, predominantly in sub-Saharan Africa, where most patients receive fluconazole (FLC) monotherapy. While relapse after FLC monotherapy with resistant strains is frequently observed, the mechanisms and impact of emergence of FLC resistance in human CM are poorly understood. Heteroresistance (HetR) - a resistant subpopulation within a susceptible strain - is a recently described phenomenon in Cryptococcus neoformans (Cn) and Cryptococcus gattii (Cg), the significance of which has not previously been studied in humans. METHODS A cohort of 20 patients with HIV-associated CM in Tanzania was prospectively observed during therapy with either FLC monotherapy or in combination with flucytosine (5FC). Total and resistant subpopulations of Cryptococcus spp. were quantified directly from patient cerebrospinal fluid (CSF). Stored isolates underwent whole genome sequencing and phenotypic characterization. RESULTS Heteroresistance was detectable in Cryptococcus spp. in the CSF of all patients at baseline (i.e., prior to initiation of therapy). During FLC monotherapy, the proportion of resistant colonies in the CSF increased during the first 2 weeks of treatment. In contrast, no resistant subpopulation was detectable in CSF by day 14 in those receiving a combination of FLC and 5FC. Genomic analysis revealed high rates of aneuploidy in heteroresistant colonies as well as in relapse isolates, with chromosome 1 (Chr1) disomy predominating. This is apparently due to the presence on Chr1 of ERG11, which is the FLC drug target, and AFR1, which encodes a drug efflux pump. In vitro efflux levels positively correlated with the level of heteroresistance. CONCLUSION Our findings demonstrate for what we believe is the first time the presence and emergence of aneuploidy-driven FLC heteroresistance in human CM, association of efflux levels with heteroresistance, and the successful suppression of heteroresistance with 5FC/FLC combination therapy. FUNDING This work was supported by the Wellcome Trust Strategic Award for Medical Mycology and Fungal Immunology 097377/Z/11/Z and the Daniel Turnberg Travel Fellowship.
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Affiliation(s)
- Neil R.H. Stone
- Centre for Global Health, Institute for Infection and Immunity, St. George’s, University of London, United Kingdom
| | - Johanna Rhodes
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, United Kingdom
| | - Matthew C. Fisher
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, United Kingdom
| | - Sayoki Mfinanga
- National Institute of Medical Research, Dar es Salaam, Tanzania
- Liverpool School of Tropical Medicine, United Kingdom
| | - Sokoine Kivuyo
- National Institute of Medical Research, Dar es Salaam, Tanzania
| | | | - Ella Shtifman Segal
- School of Molecular Cell Biology and Biotechnology, Tel Aviv University, Israel
| | - Leor Needleman
- School of Molecular Cell Biology and Biotechnology, Tel Aviv University, Israel
| | - Síle F. Molloy
- Centre for Global Health, Institute for Infection and Immunity, St. George’s, University of London, United Kingdom
| | | | - Thomas S. Harrison
- Centre for Global Health, Institute for Infection and Immunity, St. George’s, University of London, United Kingdom
| | - William Hope
- Institute of Translational Medicine, University of Liverpool, United Kingdom
| | - Judith Berman
- School of Molecular Cell Biology and Biotechnology, Tel Aviv University, Israel
| | - Tihana Bicanic
- Centre for Global Health, Institute for Infection and Immunity, St. George’s, University of London, United Kingdom
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35
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Pais P, Galocha M, Viana R, Cavalheiro M, Pereira D, Teixeira MC. Microevolution of the pathogenic yeasts Candida albicans and Candida glabrata during antifungal therapy and host infection. MICROBIAL CELL 2019; 6:142-159. [PMID: 30854392 PMCID: PMC6402363 DOI: 10.15698/mic2019.03.670] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Infections by the pathogenic yeasts Candida albicans and Candida glabrata are among the most common fungal diseases. The success of these species as human pathogens is contingent on their ability to resist antifungal therapy and thrive within the human host. C. glabrata is especially resilient to azole antifungal treatment, while C. albicans is best known for its wide array of virulence features. The core mechanisms that underlie antifungal resistance and virulence in these pathogens has been continuously addressed, but the investigation on how such mechanisms evolve according to each environment is scarcer. This review aims to explore current knowledge on micro-evolution experiments to several treatment and host-associated conditions in C. albicans and C. glabrata. The analysis of adaptation strategies that evolve over time will allow to better understand the mechanisms by which Candida species are able to achieve stable phenotypes in real-life scenarios, which are the ones that should constitute the most interesting drug targets.
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Affiliation(s)
- Pedro Pais
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal.,iBB - Institute for Bioengineering and Biosciences, Biological Sciences Research Group, Instituto Superior Técnico, Lisboa, Portugal
| | - Mónica Galocha
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal.,iBB - Institute for Bioengineering and Biosciences, Biological Sciences Research Group, Instituto Superior Técnico, Lisboa, Portugal
| | - Romeu Viana
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal.,iBB - Institute for Bioengineering and Biosciences, Biological Sciences Research Group, Instituto Superior Técnico, Lisboa, Portugal
| | - Mafalda Cavalheiro
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal.,iBB - Institute for Bioengineering and Biosciences, Biological Sciences Research Group, Instituto Superior Técnico, Lisboa, Portugal
| | - Diana Pereira
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal.,iBB - Institute for Bioengineering and Biosciences, Biological Sciences Research Group, Instituto Superior Técnico, Lisboa, Portugal
| | - Miguel Cacho Teixeira
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal.,iBB - Institute for Bioengineering and Biosciences, Biological Sciences Research Group, Instituto Superior Técnico, Lisboa, Portugal
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36
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Anticandidal Potential of Endophytic Bacteria Isolated from Dryopteris Uniformis (Makino). Jundishapur J Microbiol 2018. [DOI: 10.5812/jjm.69878] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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37
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Ksiezopolska E, Gabaldón T. Evolutionary Emergence of Drug Resistance in Candida Opportunistic Pathogens. Genes (Basel) 2018; 9:genes9090461. [PMID: 30235884 PMCID: PMC6162425 DOI: 10.3390/genes9090461] [Citation(s) in RCA: 114] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 09/14/2018] [Accepted: 09/17/2018] [Indexed: 01/08/2023] Open
Abstract
Fungal infections, such as candidiasis caused by Candida, pose a problem of growing medical concern. In developed countries, the incidence of Candida infections is increasing due to the higher survival of susceptible populations, such as immunocompromised patients or the elderly. Existing treatment options are limited to few antifungal drug families with efficacies that vary depending on the infecting species. In this context, the emergence and spread of resistant Candida isolates are being increasingly reported. Understanding how resistance can evolve within naturally susceptible species is key to developing novel, more effective treatment strategies. However, in contrast to the situation of antibiotic resistance in bacteria, few studies have focused on the evolutionary mechanisms leading to drug resistance in fungal species. In this review, we will survey and discuss current knowledge on the genetic bases of resistance to antifungal drugs in Candida opportunistic pathogens. We will do so from an evolutionary genomics perspective, focusing on the possible evolutionary paths that may lead to the emergence and selection of the resistant phenotype. Finally, we will discuss the potential of future studies enabled by current developments in sequencing technologies, in vitro evolution approaches, and the analysis of serial clinical isolates.
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Affiliation(s)
- Ewa Ksiezopolska
- Bioinformatics and Genomics Programme, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), 08003 Barcelona, Spain.
- Universitat Pompeu Fabra (UPF), 08003 Barcelona, Spain.
| | - Toni Gabaldón
- Bioinformatics and Genomics Programme, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), 08003 Barcelona, Spain.
- Universitat Pompeu Fabra (UPF), 08003 Barcelona, Spain.
- Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Spain.
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38
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Fungal Resistance to Echinocandins and the MDR Phenomenon in Candida glabrata. JOURNAL OF FUNGI (BASEL, SWITZERLAND) 2018; 4:jof4030105. [PMID: 30200517 PMCID: PMC6162769 DOI: 10.3390/jof4030105] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 08/28/2018] [Accepted: 08/30/2018] [Indexed: 12/17/2022]
Abstract
Candida glabrata has thoroughly adapted to successfully colonize human mucosal membranes and survive in vivo pressures. prior to and during antifungal treatment. Out of all the medically relevant Candida species, C. glabrata has emerged as a leading cause of azole, echinocandin, and multidrug (MDR: azole + echinocandin) adaptive resistance. Neither mechanism of resistance is intrinsic to C. glabrata, since stable genetic resistance depends on mutation of drug target genes, FKS1 and FKS2 (echinocandin resistance), and a transcription factor, PDR1, which controls expression of major drug transporters, such as CDR1 (azole resistance). However, another hallmark of C. glabrata is the ability to withstand drug pressure both in vitro and in vivo prior to stable "genetic escape". Additionally, these resistance events can arise within individual patients, which underscores the importance of understanding how this fungus is adapting to its environment and to drug exposure in vivo. Here, we explore the evolution of echinocandin resistance as a multistep model that includes general cell stress, drug adaptation (tolerance), and genetic escape. The extensive genetic diversity reported in C. glabrata is highlighted.
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Kumari S, Kumar M, Khandelwal NK, Kumari P, Varma M, Vishwakarma P, Shahi G, Sharma S, Lynn AM, Prasad R, Gaur NA. ABC transportome inventory of human pathogenic yeast Candida glabrata: Phylogenetic and expression analysis. PLoS One 2018; 13:e0202993. [PMID: 30153284 PMCID: PMC6112666 DOI: 10.1371/journal.pone.0202993] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 08/12/2018] [Indexed: 12/25/2022] Open
Abstract
ATP-binding cassette (ABC) is one of the two major superfamilies of transporters present across the evolutionary scale. ABC superfamily members came to prominence due to their ability to extrude broad spectrum of substrates and to confer multi drug resistance (MDR). Overexpression of some ABC transporters in clinical isolates of Candida species was attributed to the development of MDR phenotypes. Among Candida species, Candida glabrata is an emerging drug resistant species in human fungal infections. A comprehensive analysis of such proteins in C. glabrata is required to untangle their role not only in MDR but also in other biological processes. Bioinformatic analysis of proteins encoded by genome of human pathogenic yeast C. glabrata identified 25 putative ABC protein coding genes. On the basis of phylogenetic analysis, domain organization and nomenclature adopted by the Human Genome Organization (HUGO) scheme, these proteins were categorized into six subfamilies such as Pleiotropic Drug Resistance (PDR)/ABCG, Multi Drug Resistance (MDR)/ABCB, Multi Drug Resistance associated Protein (MRP)/ABCC, Adrenoleukodystrophy protein (ALDp)/ABCD, RNase L Inhibitor (RLI)/ABCE and Elongation Factor 3 (EF3)/ABCF. Among these, only 18 ABC proteins contained transmembrane domains (TMDs) and were grouped as membrane proteins, predominantly belonging to PDR, MDR, MRP, and ALDp subfamilies. A comparative phylogenetic analysis of these ABC proteins with other yeast species revealed their orthologous relationship and pointed towards their conserved functions. Quantitative real time PCR (qRT-PCR) analysis of putative membrane localized ABC protein encoding genes of C. glabrata confirmed their basal expression and showed variable transcriptional response towards antimycotic drugs. This study presents first comprehensive overview of ABC superfamily proteins of a human fungal pathogen C. glabrata, which is expected to provide an important platform for in depth analysis of their physiological relevance in cellular processes and drug resistance.
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Affiliation(s)
- Sonam Kumari
- Yeast Biofuel Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
| | - Mohit Kumar
- Yeast Biofuel Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
- Amity Institute of Integrative Science and Health, Amity University Gurgaon, Haryana, India
| | - Nitesh Kumar Khandelwal
- Yeast Biofuel Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
| | - Priya Kumari
- Yeast Biofuel Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
| | - Mahendra Varma
- Yeast Biofuel Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
| | - Poonam Vishwakarma
- School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Garima Shahi
- Amity Institute of Integrative Science and Health, Amity University Gurgaon, Haryana, India
| | - Suman Sharma
- Amity Institute of Integrative Science and Health, Amity University Gurgaon, Haryana, India
| | - Andrew M. Lynn
- School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Rajendra Prasad
- Amity Institute of Integrative Science and Health, Amity University Gurgaon, Haryana, India
| | - Naseem A. Gaur
- Yeast Biofuel Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
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Ben-Ami R. Treatment of Invasive Candidiasis: A Narrative Review. J Fungi (Basel) 2018; 4:jof4030097. [PMID: 30115843 PMCID: PMC6162658 DOI: 10.3390/jof4030097] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 08/08/2018] [Accepted: 08/12/2018] [Indexed: 12/29/2022] Open
Abstract
Invasive candidiasis occurs frequently in hospitalized patients, and is associated with high mortality rates due to delays in recognition and initiation of appropriate antifungals. Management of invasive candidiasis must take into account multiple host, pathogen, and drug-related factors, including the site of infection, host immune status, severity of sepsis, resistance and tolerance to antifungal agents, biofilm formation, and pharmacokinetic/pharmacodynamic considerations. Recent treatment directives have been shaped by the widespread introduction of echinocandins, highly potent and safe antifungals, into clinical use, as well as important changes in drug susceptibility patterns and the emergence of known and novel drug-resistant Candida species. Advances in molecular diagnostics have the potential to guide early targeted treatment of high-risk patients.
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Affiliation(s)
- Ronen Ben-Ami
- Infectious Diseases Unit, Tel Aviv Sourasky Medical Center, and the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 64239, Israel.
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41
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Antifungal tolerance is a subpopulation effect distinct from resistance and is associated with persistent candidemia. Nat Commun 2018; 9:2470. [PMID: 29941885 PMCID: PMC6018213 DOI: 10.1038/s41467-018-04926-x] [Citation(s) in RCA: 139] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 06/05/2018] [Indexed: 11/23/2022] Open
Abstract
Tolerance to antifungal drug concentrations above the minimal inhibitory concentration (MIC) is rarely quantified, and current clinical recommendations suggest it should be ignored. Here, we quantify antifungal tolerance in Candida albicans isolates as the fraction of growth above the MIC, and find that it is distinct from susceptibility/resistance. Instead, tolerance is due to the slow growth of subpopulations of cells that overcome drug stress more efficiently than the rest of the population, and correlates inversely with intracellular drug accumulation. Many adjuvant drugs used in combination with fluconazole, a widely used fungistatic drug, reduce tolerance without affecting resistance. Accordingly, in an invertebrate infection model, adjuvant combination therapy is more effective than fluconazole in treating infections with highly tolerant isolates and does not affect infections with low tolerance isolates. Furthermore, isolates recovered from immunocompetent patients with persistent candidemia display higher tolerance than isolates readily cleared by fluconazole. Thus, tolerance correlates with, and may help predict, patient responses to fluconazole therapy. The authors show that antifungal tolerance, defined as the fraction of growth of a fungal pathogen above the minimal inhibitory concentration, is due to the slow growth of subpopulations of cells that overcome drug stress, and that high tolerance is often associated with persistent infections.
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Van Dijck P, Sjollema J, Cammue BPA, Lagrou K, Berman J, d’Enfert C, Andes DR, Arendrup MC, Brakhage AA, Calderone R, Cantón E, Coenye T, Cos P, Cowen LE, Edgerton M, Espinel-Ingroff A, Filler SG, Ghannoum M, Gow NA, Haas H, Jabra-Rizk MA, Johnson EM, Lockhart SR, Lopez-Ribot JL, Maertens J, Munro CA, Nett JE, Nobile CJ, Pfaller MA, Ramage G, Sanglard D, Sanguinetti M, Spriet I, Verweij PE, Warris A, Wauters J, Yeaman MR, Zaat SA, Thevissen K. Methodologies for in vitro and in vivo evaluation of efficacy of antifungal and antibiofilm agents and surface coatings against fungal biofilms. MICROBIAL CELL (GRAZ, AUSTRIA) 2018; 5:300-326. [PMID: 29992128 PMCID: PMC6035839 DOI: 10.15698/mic2018.07.638] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 05/24/2018] [Indexed: 12/13/2022]
Abstract
Unlike superficial fungal infections of the skin and nails, which are the most common fungal diseases in humans, invasive fungal infections carry high morbidity and mortality, particularly those associated with biofilm formation on indwelling medical devices. Therapeutic management of these complex diseases is often complicated by the rise in resistance to the commonly used antifungal agents. Therefore, the availability of accurate susceptibility testing methods for determining antifungal resistance, as well as discovery of novel antifungal and antibiofilm agents, are key priorities in medical mycology research. To direct advancements in this field, here we present an overview of the methods currently available for determining (i) the susceptibility or resistance of fungal isolates or biofilms to antifungal or antibiofilm compounds and compound combinations; (ii) the in vivo efficacy of antifungal and antibiofilm compounds and compound combinations; and (iii) the in vitro and in vivo performance of anti-infective coatings and materials to prevent fungal biofilm-based infections.
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Affiliation(s)
- Patrick Van Dijck
- VIB-KU Leuven Center for Microbiology, Leuven, Belgium
- KU Leuven Laboratory of Molecular Cell Biology, Leuven, Belgium
| | - Jelmer Sjollema
- University of Groningen, University Medical Center Groningen, Department of BioMedical Engineering, Groningen, The Netherlands
| | - Bruno P. A. Cammue
- Centre for Microbial and Plant Genetics, KU Leuven, Leuven, Belgium
- Department of Plant Systems Biology, VIB, Ghent, Belgium
| | - Katrien Lagrou
- Department of Microbiology and Immunology, KU Leuven, Leuven, Belgium
- Clinical Department of Laboratory Medicine and National Reference Center for Mycosis, UZ Leuven, Belgium
| | - Judith Berman
- School of Molecular Cell Biology and Biotechnology, Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Israel
| | - Christophe d’Enfert
- Institut Pasteur, INRA, Unité Biologie et Pathogénicité Fongiques, Paris, France
| | - David R. Andes
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Department of Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Maiken C. Arendrup
- Unit of Mycology, Statens Serum Institut, Copenhagen, Denmark
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen, Denmark
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Axel A. Brakhage
- Leibniz Institute for Natural Product Research and Infection Biology - Hans Knoell Institute (HKI), Dept. Microbiology and Molecular Biology, Friedrich Schiller University Jena, Institute of Microbiology, Jena, Germany
| | - Richard Calderone
- Department of Microbiology & Immunology, Georgetown University Medical Center, Washington DC, USA
| | - Emilia Cantón
- Severe Infection Research Group: Medical Research Institute La Fe (IISLaFe), Valencia, Spain
| | - Tom Coenye
- Laboratory of Pharmaceutical Microbiology, Ghent University, Ghent, Belgium
- ESCMID Study Group for Biofilms, Switzerland
| | - Paul Cos
- Laboratory for Microbiology, Parasitology and Hygiene (LMPH), University of Antwerp, Belgium
| | - Leah E. Cowen
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Mira Edgerton
- Department of Oral Biology, School of Dental Medicine, University at Buffalo, Buffalo, NY USA
| | | | - Scott G. Filler
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA
| | - Mahmoud Ghannoum
- Center for Medical Mycology, Department of Dermatology, University Hospitals Cleveland Medical Center and Case Western Re-serve University, Cleveland, OH, USA
| | - Neil A.R. Gow
- MRC Centre for Medical Mycology, Institute of Medical Sciences, University of Aberdeen, Aberdeen, UK
| | - Hubertus Haas
- Biocenter - Division of Molecular Biology, Medical University Innsbruck, Innsbruck, Austria
| | - Mary Ann Jabra-Rizk
- Department of Oncology and Diagnostic Sciences, School of Dentistry; Department of Microbiology and Immunology, School of Medicine, University of Maryland, Baltimore, USA
| | - Elizabeth M. Johnson
- National Infection Service, Public Health England, Mycology Reference Laboratory, Bristol, UK
| | | | | | - Johan Maertens
- Department of Microbiology and Immunology, KU Leuven, Leuven, Belgium and Clinical Department of Haematology, UZ Leuven, Leuven, Belgium
| | - Carol A. Munro
- MRC Centre for Medical Mycology, Institute of Medical Sciences, University of Aberdeen, Aberdeen, UK
| | - Jeniel E. Nett
- University of Wisconsin-Madison, Departments of Medicine and Medical Microbiology & Immunology, Madison, WI, USA
| | - Clarissa J. Nobile
- Department of Molecular and Cell Biology, School of Natural Sciences, University of California, Merced, Merced, USA
| | - Michael A. Pfaller
- Departments of Pathology and Epidemiology, University of Iowa, Iowa, USA
- JMI Laboratories, North Liberty, Iowa, USA
| | - Gordon Ramage
- ESCMID Study Group for Biofilms, Switzerland
- College of Medical, Veterinary and Life Sciences, University of Glasgow, UK
| | - Dominique Sanglard
- Institute of Microbiology, University of Lausanne and University Hospital, CH-1011 Lausanne
| | - Maurizio Sanguinetti
- Institute of Microbiology, Università Cattolica del Sacro Cuore, IRCCS-Fondazione Policlinico "Agostino Gemelli", Rome, Italy
| | - Isabel Spriet
- Pharmacy Dpt, University Hospitals Leuven and Clinical Pharmacology and Pharmacotherapy, Dpt. of Pharmaceutical and Pharma-cological Sciences, KU Leuven, Belgium
| | - Paul E. Verweij
- Center of Expertise in Mycology Radboudumc/CWZ, Radboud University Medical Center, Nijmegen, the Netherlands (omit "Nijmegen" in Radboud University Medical Center)
| | - Adilia Warris
- MRC Centre for Medical Mycology, Aberdeen Fungal Group, University of Aberdeen, Foresterhill, Aberdeen, UK
| | - Joost Wauters
- KU Leuven-University of Leuven, University Hospitals Leuven, Department of General Internal Medicine, Herestraat 49, B-3000 Leuven, Belgium
| | - Michael R. Yeaman
- Geffen School of Medicine at the University of California, Los Angeles, Divisions of Molecular Medicine & Infectious Diseases, Har-bor-UCLA Medical Center, LABioMed at Harbor-UCLA Medical Center
| | - Sebastian A.J. Zaat
- Department of Medical Microbiology, Amsterdam Infection and Immunity Institute, Academic Medical Center, University of Am-sterdam, Netherlands
| | - Karin Thevissen
- Centre for Microbial and Plant Genetics, KU Leuven, Leuven, Belgium
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Enhanced Efflux Pump Activity in Old Candida glabrata Cells. Antimicrob Agents Chemother 2018; 62:AAC.02227-17. [PMID: 29311061 DOI: 10.1128/aac.02227-17] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 01/01/2018] [Indexed: 12/11/2022] Open
Abstract
We investigated the effect of replicative aging on antifungal resistance in Candida glabrata Our studies demonstrate significantly increased transcription of ABC transporters and efflux pump activity in old versus young C. glabrata cells of a fluconazole-sensitive and -resistant strain. In addition, higher tolerance to killing by micafungin and amphotericin B was noted and is associated with higher transcription of glucan synthase gene FKS1 and lower ergosterol content in older cells.
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Aspergillus fumigatus Afssn3-Afssn8 Pair Reverse Regulates Azole Resistance by Conferring Extracellular Polysaccharide, Sphingolipid Pathway Intermediates, and Efflux Pumps to Biofilm. Antimicrob Agents Chemother 2018; 62:AAC.01978-17. [PMID: 29311083 DOI: 10.1128/aac.01978-17] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2017] [Accepted: 12/21/2017] [Indexed: 11/20/2022] Open
Abstract
Antifungal treatment is often ineffectual, partly because of biofilm formation. In this study, by using a combined forward and reverse genetic strategy, we identified that nucleus-localized AfSsn3 and its partner AfSsn8, which constitute a Cdk8-cyclin pair, are required for azole resistance in Aspergillus fumigatus Deletion of Afssn3 led to increased absorption and utilization of glucose and amino acids. Interestingly, absorption and utilization of glucose accelerated the extracellular polysaccharide formation, while utilization of the amino acids serine, threonine, and glycine increased sphingolipid pathway intermediate accumulation. In addition, the absence of Afssn3 induced the activity of the efflux pump proteins. These factors indicate the mature biofilm is responsible for the major mechanisms of A. fumigatus resistance to azoles in the ΔAfssn3 mutant. Collectively, the loss of Afssn3 led to two "barrier" layers between the intracellular and extracellular spaces, which consequently decreased drug penetration into the cell.
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45
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Gaining Insights from Candida Biofilm Heterogeneity: One Size Does Not Fit All. J Fungi (Basel) 2018; 4:jof4010012. [PMID: 29371505 PMCID: PMC5872315 DOI: 10.3390/jof4010012] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 01/03/2018] [Accepted: 01/09/2018] [Indexed: 12/17/2022] Open
Abstract
Despite their clinical significance and substantial human health burden, fungal infections remain relatively under-appreciated. The widespread overuse of antibiotics and the increasing requirement for indwelling medical devices provides an opportunistic potential for the overgrowth and colonization of pathogenic Candida species on both biological and inert substrates. Indeed, it is now widely recognized that biofilms are a highly important part of their virulence repertoire. Candida albicans is regarded as the primary fungal biofilm forming species, yet there is also increasing interest and growing body of evidence for non-Candida albicans species (NCAS) biofilms, and interkingdom biofilm interactions. C. albicans biofilms are heterogeneous structures by definition, existing as three-dimensional populations of yeast, pseudo-hyphae, and hyphae, embedded within a self-produced extracellular matrix. Classical molecular approaches, driven by extensive studies of laboratory strains and mutants, have enhanced our knowledge and understanding of how these complex communities develop, thrive, and cause host-mediated damage. Yet our clinical observations tell a different story, with differential patient responses potentially due to inherent biological heterogeneity from specific clinical isolates associated with their infections. This review explores some of the recent advances made in an attempt to explore the importance of working with clinical isolates, and what this has taught us.
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Healey KR, Nagasaki Y, Zimmerman M, Kordalewska M, Park S, Zhao Y, Perlin DS. The Gastrointestinal Tract Is a Major Source of Echinocandin Drug Resistance in a Murine Model of Candida glabrata Colonization and Systemic Dissemination. Antimicrob Agents Chemother 2017; 61:e01412-17. [PMID: 28971865 PMCID: PMC5700336 DOI: 10.1128/aac.01412-17] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 09/23/2017] [Indexed: 12/22/2022] Open
Abstract
Candida species are a part of the human microbiome and can cause systemic infection upon immune suppression. Candida glabrata infections are increasing and have greater rates of antifungal resistance than other species. Here, we present a C. glabrata gastrointestinal (GI) colonization model to explore whether colonized yeast exposed to caspofungin, an echinocandin antifungal, develop characteristic resistance mutations and, upon immunosuppression, breakthrough causing systemic infection. Daily therapeutic dosing (5 mg/kg of body weight) of caspofungin resulted in no reduction in fecal burdens, organ breakthrough rates similar to control groups, and resistance rates (0 to 10%) similar to those reported clinically. Treatment with 20 mg/kg caspofungin initially reduced burdens, but a rebound following 5 to 9 days of treatment was accompanied by high levels of resistance (FKS1/FKS2 mutants). Although breakthrough rates decreased in this group, the same FKS mutants were recovered from organs. In an attempt to negate drug tolerance that is critical for resistance development, we cotreated mice with daily caspofungin and the chitin synthase inhibitor nikkomycin Z. The largest reduction (3 log) in GI burdens was obtained within 3 to 5 days of 20 mg/kg caspofungin plus nikkomycin treatment. Yet, echinocandin resistance, characterized by a novel Fks1-L630R substitution, was identified following 5 to 7 days of treatment. Therapeutic caspofungin plus nikkomycin treatment left GI burdens unchanged but significantly reduced organ breakthrough rates (20%; P < 0.05). Single-dose pharmacokinetics demonstrated low levels of drug penetration into the GI lumen posttreatment with caspofungin. Overall, we show that C. glabrata echinocandin resistance can arise within the GI tract and that resistant mutants can readily disseminate upon immunosuppression.
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Affiliation(s)
- Kelley R Healey
- Public Health Research Institute, New Jersey Medical School, Rutgers Biomedical and Health Sciences, Newark, New Jersey, USA
| | - Yoji Nagasaki
- Public Health Research Institute, New Jersey Medical School, Rutgers Biomedical and Health Sciences, Newark, New Jersey, USA
| | - Matthew Zimmerman
- Public Health Research Institute, New Jersey Medical School, Rutgers Biomedical and Health Sciences, Newark, New Jersey, USA
| | - Milena Kordalewska
- Public Health Research Institute, New Jersey Medical School, Rutgers Biomedical and Health Sciences, Newark, New Jersey, USA
| | - Steven Park
- Public Health Research Institute, New Jersey Medical School, Rutgers Biomedical and Health Sciences, Newark, New Jersey, USA
| | - Yanan Zhao
- Public Health Research Institute, New Jersey Medical School, Rutgers Biomedical and Health Sciences, Newark, New Jersey, USA
| | - David S Perlin
- Public Health Research Institute, New Jersey Medical School, Rutgers Biomedical and Health Sciences, Newark, New Jersey, USA
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47
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Morio F, Jensen RH, Le Pape P, Arendrup MC. Molecular basis of antifungal drug resistance in yeasts. Int J Antimicrob Agents 2017; 50:599-606. [DOI: 10.1016/j.ijantimicag.2017.05.012] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 05/04/2017] [Accepted: 05/06/2017] [Indexed: 01/05/2023]
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48
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Biofilms Formed by Isolates from Recurrent Vulvovaginal Candidiasis Patients Are Heterogeneous and Insensitive to Fluconazole. Antimicrob Agents Chemother 2017; 61:AAC.01065-17. [PMID: 28696240 DOI: 10.1128/aac.01065-17] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 07/04/2017] [Indexed: 12/16/2022] Open
Abstract
Vulvovaginal candidiasis (VVC) is a global health problem affecting ∼75% of women at least once in their lifetime. Here we examined the epidemiology of VVC in a patient cohort to identify the causative organisms associated with VVC. Biofilm-forming capacity and antifungal sensitivity profiles were also assessed. We report a shifting prevalence of Candida species with heterogeneous biofilm-forming capacity, which is associated with altered antifungal drug sensitivity.
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49
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Benhamou RI, Bibi M, Steinbuch KB, Engel H, Levin M, Roichman Y, Berman J, Fridmana M. Real-Time Imaging of the Azole Class of Antifungal Drugs in Live Candida Cells. ACS Chem Biol 2017; 12:1769-1777. [PMID: 28472585 PMCID: PMC7030953 DOI: 10.1021/acschembio.7b00339] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Azoles are the most commonly used class of antifungal drugs, yet where they localize within fungal cells and how they are imported remain poorly understood. Azole antifungals target lanosterol 14α-demethylase, a cytochrome P450, encoded by ERG11 in Candida albicans, the most prevalent fungal pathogen. We report the synthesis of fluorescent probes that permit visualization of antifungal azoles within live cells. Probe 1 is a dansyl dye-conjugated azole, and probe 2 is a Cy5-conjugated azole. Docking computations indicated that each of the probes can occupy the active site of the target cytochrome P450. Like the azole drug fluconazole, probe 1 is not effective against a mutant that lacks the target cytochrome P450. In contrast, the azole drug ketoconazole and probe 2 retained some antifungal activity against mutants lacking the target cytochrome P450, implying that both act against more than one target. Both fluorescent azole probes colocalized with the mitochondria, as determined by fluorescence microscopy with MitoTracker dye. Thus, these fluorescent probes are useful molecular tools that can lead to detailed information about the activity and localization of the important azole class of antifungal drugs.
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Affiliation(s)
- Raphael I. Benhamou
- School of Chemistry, Raymond & Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Maayan Bibi
- Dept. of Molecular Microbiology & Biotechnology, School of Molecular Cell Biology and Biotechnology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Kfir B. Steinbuch
- School of Chemistry, Raymond & Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Hamutal Engel
- BLAVATNIK CENTER for Drug Discovery, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Maayan Levin
- School of Chemistry, Raymond & Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Yael Roichman
- School of Chemistry, Raymond & Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Judith Berman
- Dept. of Molecular Microbiology & Biotechnology, School of Molecular Cell Biology and Biotechnology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Micha Fridmana
- School of Chemistry, Raymond & Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel
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50
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Ferreira GF, Santos DA. Heteroresistance and fungi. Mycoses 2017; 60:562-568. [PMID: 28660647 DOI: 10.1111/myc.12639] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 04/07/2017] [Accepted: 05/10/2017] [Indexed: 11/27/2022]
Abstract
The concept of heteroresistance refers to the heterogeneous susceptibility to an antimicrobial drug in a microorganism population, meaning that some clones may be resistant and others are susceptible. This phenomenon has been widely studied in bacteria, but little attention has been given to its expression in fungi. We review the available literature on heteroresistance in fungi and invite the reader to recognise this phenomenon as a fungal mechanism to adapt to environmental stress, which may interfere both in resistance and virulence. Finally, heteroresistance may explain the treatment failures to eradicate mycosis in some patients treated with a seemingly appropriate antifungal.
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Affiliation(s)
- Gabriella F Ferreira
- Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Governador Valadares, Brazil.,Departamento de Farmácia, Universidade Federal de Juiz de Fora - Campus Governador Valadares, Governador Valadares, Brazil
| | - Daniel A Santos
- Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Governador Valadares, Brazil
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