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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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2
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de Sousa ESO, Cortez ACA, de Souza Carvalho Melhem M, Frickmann H, de Souza JVB. Factors influencing susceptibility testing of antifungal drugs: a critical review of document M27-A4 from the Clinical and Laboratory Standards Institute (CLSI). Braz J Microbiol 2020; 51:1791-1800. [PMID: 32757139 DOI: 10.1007/s42770-020-00354-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 07/29/2020] [Indexed: 12/24/2022] Open
Abstract
Due to the increasing numbers of fungal infections and the emergence of drug-resistant fungi, optimization and standardization of diagnostic methods for the measurement of antifungal susceptibility are ongoing. The M27-A4 document by the US Clinical and Laboratory Standards Institute (CLSI) is presently used for the interpretation of minimum inhibitory concentrations of major opportunistic yeast species as measured by broth microdilution testing in many countries. Although microdilution is considered a benchmark for reproducible and accurate results, increased testing capacity, and limited human bias, the method is often inaccessible to routine clinical laboratories and researchers, especially in low-income countries. Furthermore, several studies suggest that there are still a considerable number of factors that make the estimation of in vitro activity of antifungal agents challenging. This review article summarizes the limitations of the M27-A4 standard which, despite the advances and improvements obtained by the standardization of antimicrobial resistance testing methods by CLSI, still persist.
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Affiliation(s)
| | - Ana Claúdia Alves Cortez
- Department of Medical Microbiology, National Institute for Amazonian Research - INPA, André Araújo Avenue, Manaus, Amazonas, Brazil
| | - Marcia de Souza Carvalho Melhem
- Department of Mycology, Adolfo Lutz Institute, Av. Dr. Arnaldo, Sao Paulo, Brazil
- School of Medicine, Federal University of Mato Grosso do Sul, Campo Grande, Mato Grosso do Sul, Brazil
| | - Hagen Frickmann
- Department of Tropical Medicine at the Bernhard Nocht Institute, German Armed Forces Hospital of Hamburg, Hamburg, Germany, Institute for Medical Microbiology, Virology and Hygiene, University Medicine Rostock, Rostock, Germany
| | - João Vicente Braga de Souza
- Department of Medical Microbiology, National Institute for Amazonian Research - INPA, André Araújo Avenue, Manaus, Amazonas, Brazil.
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3
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de-Souza-Silva CM, Guilhelmelli F, Zamith-Miranda D, de Oliveira MA, Nosanchuk JD, Silva-Pereira I, Albuquerque P. Broth Microdilution In Vitro Screening: An Easy and Fast Method to Detect New Antifungal Compounds. J Vis Exp 2018. [PMID: 29553507 DOI: 10.3791/57127] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Fungal infections have become an important medical condition in the last decades, but the number of available antifungal drugs is limited. In this scenario, the search for new antifungal drugs is necessary. The protocol reported here details a method to screen peptides for their antifungal properties. It is based on the broth microdilution susceptibility test from the Clinical and Laboratory Standards Institute (CLSI) M27-A3 guidelines with modifications to suit the research of antimicrobial peptides as potential new antifungals. This protocol describes a functional assay to evaluate the activity of antifungal compounds and may be easily modified to suit any particular class of molecules under investigation. Since the assays are performed in 96-well plates using small volumes, a large-scale screening can be completed in a short amount of time, especially if carried out in an automation setting. This procedure illustrates how a standardized and adjustable clinical protocol can help the bench-work pursuit of new molecules to improve the therapy of fungal diseases.
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Affiliation(s)
| | - Fernanda Guilhelmelli
- Laboratory of Molecular Biology, Department of Cellular Biology, Institute of Biological Sciences, University of Brasília
| | - Daniel Zamith-Miranda
- Department of Microbiology and Immunology, Albert Einstein College of Medicine; Division of Infectious Diseases, Department of Medicine, Albert Einstein College of Medicine
| | - Marco Antônio de Oliveira
- Laboratory of Molecular Biology, Department of Cellular Biology, Institute of Biological Sciences, University of Brasília
| | - Joshua Daniel Nosanchuk
- Department of Microbiology and Immunology, Albert Einstein College of Medicine; Division of Infectious Diseases, Department of Medicine, Albert Einstein College of Medicine
| | - Ildinete Silva-Pereira
- Laboratory of Molecular Biology, Department of Cellular Biology, Institute of Biological Sciences, University of Brasília;
| | - Patrícia Albuquerque
- Laboratory of Molecular Biology, Department of Cellular Biology, Institute of Biological Sciences, University of Brasília; Faculty of Ceilândia, University of Brasília;
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4
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Comparison of Different In Vitro Tests to Detect Cryptococcus neoformans Not Susceptible to Amphotericin B. Mycopathologia 2015; 179:359-71. [DOI: 10.1007/s11046-015-9871-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 02/03/2015] [Indexed: 01/05/2023]
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5
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Taverna CG, Cordoba S, Murisengo OA, Vivot W, Davel G, Bosco-Borgeat ME. Molecular identification, genotyping, and antifungal susceptibility testing of clinically relevant Trichosporon species from Argentina. Med Mycol 2014; 52:356-66. [DOI: 10.1093/mmy/myt029] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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6
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Córdoba S, Afeltra J, Vitale RG. Evaluation of the in vitro activity of amphotericin B by time-kill curve methodology against large and small capsulate C. neoformans isolates. Diagn Microbiol Infect Dis 2011; 71:260-2. [PMID: 21917396 DOI: 10.1016/j.diagmicrobio.2011.08.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Revised: 07/31/2011] [Accepted: 08/02/2011] [Indexed: 11/18/2022]
Abstract
We have evaluated and compared the activity of amphotericin B (AMB) by time-kill curve methodology against 20 clinical Cryptococcus neoformans isolates in which capsule induction in vitro was performed. Overall, large capsulated isolates were more resistant to killing by AMB over time when compared with those small capsulate ones.
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Affiliation(s)
- Susana Córdoba
- Departamento de Micologia; Instituto Nacional de Enfermedades Infecciosas, (INEI), ANLIS Dr. C.G. Malbrán, Buenos Aires 1281, Argentina
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7
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Process analysis of variables for standardization of antifungal susceptibility testing of nonfermentative yeasts. Antimicrob Agents Chemother 2011; 55:1563-70. [PMID: 21245438 DOI: 10.1128/aac.01631-10] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nonfermentative yeasts, such as Cryptococcus spp., have emerged as fungal pathogens during the last few years. However, standard methods to measure their antifungal susceptibility (antifungal susceptibility testing [AST]) are not completely reliable due to the impaired growth of these yeasts in standard media. In this work, we have compared the growth kinetics and the antifungal susceptibilities of representative species of nonfermentative yeasts such as Cryptococcus neoformans, Cryptococcus gattii, Cryptococcus albidus, Rhodotorula spp., Yarrowia lipolytica, Geotrichum spp., and Trichosporon spp. The effect of the growth medium (RPMI medium versus yeast nitrogen base [YNB]), glucose concentration (0.2% versus 2%), nitrogen source (ammonium sulfate), temperature (30°C versus 35°C), shaking, and inoculum size (10(3), 10(4), and 10(5) cells) were analyzed. The growth rate, lag phase, and maximum optical density were obtained from each growth experiment, and after multivariate analysis, YNB-based media demonstrated a significant improvement in the growth of yeasts. Shaking, an inoculum size of 10(5) CFU/ml, and incubation at 30°C also improved the growth kinetics of organisms. Supplementation with ammonium sulfate and with 2% glucose did not have any effect on growth. We also tested the antifungal susceptibilities of all the isolates by the reference methods of the CLSI and EUCAST, the EUCAST method with shaking, YNB under static conditions, and YNB with shaking. MIC values obtained under different conditions showed high percentages of agreement and significant correlation coefficient values between them. MIC value determinations according to CLSI and EUCAST standards were rather complicated, since more than half of isolates tested showed a limited growth index, hampering endpoint determinations. We conclude that AST conditions including YNB as an assay medium, agitation of the plates, reading after 48 h of incubation, an inoculum size of 10(5) CFU/ml, and incubation at 30°C made MIC determinations easier without an overestimation of MIC values.
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Cuenca-Estrella M, Gomez-Lopez A, Alastruey-Izquierdo A, Bernal-Martinez L, Cuesta I, Buitrago MJ, Rodriguez-Tudela JL. Comparison of the Vitek 2 antifungal susceptibility system with the clinical and laboratory standards institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) Broth Microdilution Reference Methods and with the Sensititre YeastOne and Etest techniques for in vitro detection of antifungal resistance in yeast isolates. J Clin Microbiol 2010; 48:1782-6. [PMID: 20220169 PMCID: PMC2863906 DOI: 10.1128/jcm.02316-09] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Revised: 01/04/2010] [Accepted: 02/25/2010] [Indexed: 11/20/2022] Open
Abstract
The commercial technique Vitek 2 system for antifungal susceptibility testing of yeast species was evaluated. A collection of 154 clinical yeast isolates, including amphotericin B- and azole-resistant organisms, was tested. Results were compared with those obtained by the reference procedures of both the CLSI and the European Committee on Antimicrobial Susceptibility Testing (EUCAST). Two other commercial techniques approved for clinical use, the Etest and the Sensititre YeastOne, were included in the comparative exercise as well. The average essential agreement (EA) between the Vitek 2 system and the reference procedures was >95%, comparable with the average EAs observed between the reference procedures and the Sensititre YeastOne and Etest. The EA values were >97% for Candida spp. and stood at 92% for Cryptococcus neoformans. Intraclass correlation coefficients (ICC) between the commercial techniques and the reference procedures were statistically significant (P<0.01). Percentages of very major errors were 2.6% between Vitek 2 and the EUCAST technique and 1.6% between Vitek 2 and the CLSI technique. The Vitek 2 MIC results were available after 14 to 18 h of incubation for all Candida spp. (average time to reading, 15.5 h). The Vitek 2 system was shown to be a reliable technique to determine antifungal susceptibility testing of yeast species and a more rapid and easier alternative for clinical laboratories than the procedures developed by either the CLSI or EUCAST.
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Affiliation(s)
- Manuel Cuenca-Estrella
- Mycology Department, Spanish National Center for Microbiology, Instituto de Salud Carlos III, Madrid, Spain.
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9
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Bernal-Martinez L, Gomez-Lopez A, Castelli MV, Mesa-Arango AC, Zaragoza O, Rodriguez-Tudela JL, Cuenca-Estrella M. Susceptibility profile of clinical isolates of non-Cryptococcus neoformans/non-Cryptococcus gattii Cryptococcusspecies and literature review. Med Mycol 2010; 48:90-6. [DOI: 10.3109/13693780902756073] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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10
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Moranova Z, Kawamoto S, Raclavsky V. HYPOXIA SENSING IN CRYPTOCOCCUS NEOFORMANS: BIOFILM-LIKE ADAPTATION FOR DORMANCY? Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub 2009; 153:189-93. [DOI: 10.5507/bp.2009.031] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
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11
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de Oliveira Silva RB, Fusco-Almeida AM, Matsumoto MT, Baeza LC, Benaducci T, Mendes-Giannini MJS. Genetic diversity and antifungal susceptibility testing of Trichosporon asahii isolated of Intensive Care Units patients. Braz J Microbiol 2008; 39:585-92. [PMID: 24031270 PMCID: PMC3768427 DOI: 10.1590/s1517-838220080003000033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2007] [Revised: 02/08/2007] [Accepted: 07/05/2008] [Indexed: 11/21/2022] Open
Abstract
Trichosporon asahii is an opportunistic pathogen, associated with a high mortality rate in immunocompromised patients. In this study, ten isolates, recovered from oral cavity and urine of patients in Intensive Care Units (ICU) over six months, were identified by classical and molecular methods, typed by RAPD and tested in vitro for susceptibility to fluconazole, itraconazole, 5-flucytosine and amphotericin B. A total agreement between the identification of Trichosporon sp by PCR based on sequences of the Internal Transcribed Spacer Regions (ITS) and on the sequences of small-subunit (SSU) ribosomal DNA (rDNA) was found. Randomly amplified of polymorphic DNA (RAPD), with primers P6 and M13, was used to determine the genomic profiles. The dendogram analysis indicated that almost all strains showed similarity >0.9 among them and all strains were multidrug-resistant. This study brings new results on the identification and genotyping of T. asahii isolated from Brazilian ICU patients and information about their antifungal drugs susceptibility.
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Affiliation(s)
- Rosana Bellan de Oliveira Silva
- Instituto Adolfo Lutz , Rio Claro, SP , Brasil ; Departamento de Análises Clínicas, Faculdade de Ciências Farmacêuticas, Universidade Estadual Paulista , Araraquara, SP , Brasil
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12
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Kantarcioğlu AS, Boekhout T, Yücel A, Altas K. Susceptibility testing of Cryptococcus diffluens against amphotericin B, flucytosine, fluconazole, itraconazole, voriconazole and posaconazole. Med Mycol 2008; 47:169-76. [PMID: 18654925 DOI: 10.1080/13693780802213407] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Cryptococcus diffluens is a recently re-established species that shares several phenotypic features with Cryptococcus neoformans. We evaluated the application of the Clinical Laboratory Standards Institute (CLSI, formerly NCCLS) macro- and microbroth dilution methods and the E-test agar diffusion method to determine the in vitro susceptibilities of known strains of C. diffluens against amphotericin B (AMB), flucytosine (5-FC), fluconazole (FLC), itraconazole (ITC) and the novel triazoles, voriconazole (VRC) and posaconazole (PSC). Seven strains were found to be resistant in vitro to AMB (MICs >/=2 microg/ml), five were resistant to 5-FC (MICs of >/=32 microg/ml), four were resistant to FLC (MICs of FLC >/=32 microg/ml) and nine were resistant to ITC (MICs of ITC >1 microg/ml). In contrast, VRC and PSC showed good in vitro activity against C.diffluens strains, even those with elevated MICs to amphotericin B and/or established azoles. Most of the isolates were inhibited by 0.5 microg/ml of both VRC and PSC. A clinical isolate showing phenotypic switching exhibited elevated MICs to both agents, i.e., VRC (>16 microg/ml) and PSC (>8 microg/ml).
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Affiliation(s)
- A Serda Kantarcioğlu
- Cerrahpasa Medical Faculty, Dept. of Microbiology and Clinical Microbiology, Deep Mycosis Laboratory, Istanbul University, Istanbul, Turkey
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13
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Reliability of the WIDERYST susceptibility testing system for detection of in vitro antifungal resistance in yeasts. Antimicrob Agents Chemother 2008; 52:1062-5. [PMID: 18195057 DOI: 10.1128/aac.01016-07] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
This study evaluated the WIDERYST system, a commercially available computer-assisted image-processing device for the antifungal susceptibility testing of yeasts. A collection of 90 clinical isolates selected to represent ranges of susceptibilities in vitro as broad as possible was tested. An evaluation compared the results obtained by the new system with those achieved by both the Clinical and Laboratory Standards Institute (CLSI) microdilution reference procedure and the antifungal susceptibility standard of the European Committee for Antimicrobial Susceptibility Testing (EUCAST). Overall, the agreement and the correlation index between results obtained by the EUCAST method and the WIDERYST system were 89% and 0.84 (P < 0.01), respectively, and agreement and correlation index between data obtained by the CLSI procedure and the WIDERYST system were 90% and 0.86 (P < 0.01), respectively. The system was able to detect amphotericin B-resistant isolates. All Candida sp. isolates with resistance in vitro to azole agents were detected as well. The system misclassified some isolates belonging to the slowly growing genera Dipodascus and Pichia. A total of 2.7% very major errors were detected for fluconazole. The WIDERYST system is an alternative to reference procedures for antifungal susceptibility testing of clinical isolates of yeasts, particularly for Candida and Cryptococcus species.
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Kantarcioğlu AS, Boekhout T, De Hoog GS, Theelen B, Yücel A, Ekmekci TR, Fries BC, Ikeda R, Koslu A, Altas K. Subcutaneous cryptococcosis due to Cryptococcus diffluens in a patient with sporotrichoid lesions case report, features of the case isolate and in vitro antifungal susceptibilities. Med Mycol 2007; 45:173-81. [PMID: 17365654 PMCID: PMC2714484 DOI: 10.1080/13693780601045166] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Environmental fungi, in particular primary pathogens and Cryptococcus spp. can be responsible for skin lesions mimicking sporotrichosis. In this paper, we report a case of subcutaneous cryptococcosis in an apparently healthy, young male patient due to a non-C. neoformans Cryptococcus species, C. diffluens. The isolate showed in vitro phenotypic switching that may affect virulence and host inflammatory and immune responses, and in vitro resistance to amphotericin B and 5-flucytosin. This species shares several phenotypic traits with C. neoformans, and, therefore, decisive diagnosis should be based on biopsy and culturing results followed by molecular identification.
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MESH Headings
- Adolescent
- Amphotericin B/pharmacology
- Antifungal Agents/pharmacology
- Base Sequence
- Cryptococcosis/diagnosis
- Cryptococcosis/microbiology
- Cryptococcosis/pathology
- Cryptococcus/cytology
- Cryptococcus/drug effects
- Cryptococcus/isolation & purification
- Cryptococcus/physiology
- DNA, Fungal/chemistry
- DNA, Fungal/genetics
- DNA, Ribosomal/chemistry
- DNA, Ribosomal/genetics
- DNA, Ribosomal Spacer/chemistry
- DNA, Ribosomal Spacer/genetics
- Diagnosis, Differential
- Drug Resistance, Fungal
- Flucytosine/pharmacology
- Humans
- Male
- Microbial Sensitivity Tests
- Molecular Sequence Data
- RNA, Ribosomal, 28S/genetics
- Sequence Analysis, DNA
- Sporotrichosis/diagnosis
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Affiliation(s)
- A Serda Kantarcioğlu
- Cerrahpasa Medical Faculty, Department of Microbiology and Clinical Microbiology, Deep Mycosis Laboratory, Istanbul University, Istanbul,Turkey.
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15
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Rodriguez-Tudela JL, Gomez-Lopez A, Alastruey-Izquierdo A, Mellado E, Bernal-Martinez L, Cuenca-Estrella M. Genotype distribution of clinical isolates of Trichosporon asahii based on sequencing of intergenic spacer 1. Diagn Microbiol Infect Dis 2007; 58:435-40. [PMID: 17509802 DOI: 10.1016/j.diagmicrobio.2007.03.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2007] [Revised: 02/20/2007] [Accepted: 03/02/2007] [Indexed: 11/28/2022]
Abstract
The sequence polymorphisms of intergenic transcribed spacer and the antifungal susceptibility profile of 18 Trichosporon asahii isolates from Spain, Argentina, and Brazil together with 43 intergenic transcribed spacer 1 sequences deposited in the GenBank were analyzed. Six genotypes were detected instead of 5 genotypes described previously. Genotype 1 was the most common found comprising 57.3% of all strains, followed by genotype 3 (14.7%) and genotype 5 (13.1%). Spanish strains had members in all genotypes except 2, whereas South American isolates were grouped with genotypes 1, 3, and 6. Our results indicate that all genotypes are present in at least 2 countries suggesting a worldwide distribution. On the other hand, genotype 6 was not previously described but was only composed of 2 South American strains isolated from a subcutaneous abscess and skin. All isolates showed amphotericin B MICs>or=2 mg/L supporting the in vitro resistance of this species to this antifungal. Three isolates from South America showed high MICs to all antifungals analyzed. The true epidemiologic usefulness of classifying T. asahii in genotypes should be ascertaining analyzing a high number of isolates from many countries.
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Affiliation(s)
- Juan L Rodriguez-Tudela
- Servicio de Micología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda (Madrid), Spain.
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16
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Gadea I, Cuenca-Estrella M, Martín E, Pemán J, Pontón J, Rodríguez-Tudela JL. Procedimientos de diagnóstico microbiológico de las micosis y estudios de sensibilidad a los antifúngicos. Enferm Infecc Microbiol Clin 2007; 25:336-40. [PMID: 17504688 DOI: 10.1157/13102270] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Fungal infections are a diagnostic and therapeutic problem of increasing concern due to the frequency and severity of disseminated infection in immunocompromised patients. Culture-based methods are characteristically slow and have poor sensitivity; hence, other methods, based on the detection of fungus-specific genetic, antigenic and metabolic components are being developed to enable early diagnosis and specific treatment. Moreover, reproducible antifungal susceptibility methods that can be adapted for use in clinical laboratories have been standardized to allow in vitro detection of resistance, which correlates with a less favorable clinical outcome. In this paper we review the main microbiological procedures available for the diagnosis of fungal infections and for antifungal susceptibility testing.
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Affiliation(s)
- Ignacio Gadea
- Departamento de Microbiología Médica, Fundación Jiménez Díaz, UTE, Madrid, España.
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17
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Cuenca-Estrella M, Gomez-Lopez A, Mellado E, Buitrago MJ, Monzon A, Rodriguez-Tudela JL. Head-to-head comparison of the activities of currently available antifungal agents against 3,378 Spanish clinical isolates of yeasts and filamentous fungi. Antimicrob Agents Chemother 2006; 50:917-21. [PMID: 16495251 PMCID: PMC1426453 DOI: 10.1128/aac.50.3.917-921.2006] [Citation(s) in RCA: 221] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2005] [Revised: 12/10/2005] [Accepted: 01/03/2006] [Indexed: 11/20/2022] Open
Abstract
We have compared the activities of posaconazole and other currently available antifungal agents against a collection of 3,378 clinical isolates of yeasts and filamentous fungi. A total of 1,997 clinical isolates of Candida spp., 359 of other yeast species, 697 strains of Aspergillus spp., and 325 nondermatophyte non-Aspergillus spp. were included. The average geometric means of the MICs of agents that were tested against Candida spp. were 0.23 microg/ml for amphotericin B, 0.29 microg/ml for flucytosine, 0.97 microg/ml for fluconazole, 0.07 microg/ml for itraconazole, 0.04 microg/ml for voriconazole, 0.15 microg/ml for caspofungin, and 0.03 microg/ml for posaconazole. Voriconazole and posaconazole were active in vitro against the majority of isolates, with resistance to fluconazole and itraconazole, and against Cryptococcus neoformans and other Basidiomycota yeasts. Posaconazole was the most active of antifungal agents tested against Aspergillus spp., with an average geometric mean of 0.10 microg/ml. It was active against Paecilomyces spp., Penicillium spp., Scedosporium apiospermum, and some black fungi, such as Alternaria spp. Multiresistant filamentous fungi, such as Scedosporium prolificans, Scopulariopsis brevicaulis, and Fusarium solani, were also resistant to voriconazole, caspofungin, and posaconazole. Amphotericin B and posaconazole were found to be active against most of the Mucorales strains tested. Posaconazole and currently available antifungal agents exhibit a potent activity in vitro against the majority of pathogenic fungal species.
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Affiliation(s)
- Manuel Cuenca-Estrella
- Servicio de Micología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Ctra Majadahonda-Pozuelo Km 2, 28220 Majadahonda (Madrid), Spain.
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Perkins A, Gomez-Lopez A, Mellado E, Rodriguez-Tudela JL, Cuenca-Estrella M. Rates of antifungal resistance among Spanish clinical isolates of Cryptococcus neoformans var. neoformans. J Antimicrob Chemother 2005; 56:1144-7. [PMID: 16282208 DOI: 10.1093/jac/dki393] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES Activities in vitro of six antifungal agents were tested against a collection of 317 Cryptococcus neoformans var. neoformans clinical isolates. METHODS The procedure described in document 7.1 by the European Committee on Antibiotic Susceptibility Testing with minor modifications was employed. RESULTS Amphotericin B, itraconazole, voriconazole and ravuconazole exhibited a potent activity with geometric mean (GM) MICs under 0.26 mg/L. The GM MIC of flucytosine was 7.33 mg/L and that of fluconazole was 4.16 mg/L. The rates of antifungal resistance were 5.3% for amphotericin B, 0.9% for voriconazole and 3.1% for ravuconazole. Fifteen point eight per cent of strains had itraconazole MICs > or = 1 mg/L, and 46% of strains had flucytosine MICs > or = 8 mg/L. Fluconazole susceptibility (MIC < or = 8 mg/L) stood at 53.4%. CONCLUSIONS The percentage of fluconazole susceptibility was significantly lower than that in other surveys. Cross-resistance to itraconazole was common (33.8%) but almost the whole collection was susceptible to voriconazole and ravuconazole. These results should be confirmed with prospective and population-based surveillance programmes.
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Affiliation(s)
- Alexander Perkins
- Servicio de Micología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Ctra Majadahonda-Pozuelo Km 2. 28220 Majadahonda (Madrid), Spain
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Rodriguez-Tudela JL, Diaz-Guerra TM, Mellado E, Cano V, Tapia C, Perkins A, Gomez-Lopez A, Rodero L, Cuenca-Estrella M. Susceptibility patterns and molecular identification of Trichosporon species. Antimicrob Agents Chemother 2005; 49:4026-34. [PMID: 16189076 PMCID: PMC1251560 DOI: 10.1128/aac.49.10.4026-4034.2005] [Citation(s) in RCA: 138] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2005] [Revised: 07/05/2005] [Accepted: 07/11/2005] [Indexed: 11/20/2022] Open
Abstract
The physiological patterns, the sequence polymorphisms of the internal transcriber spacer (ITS), and intergenic spacer regions (IGS) of the rRNA genes and the antifungal susceptibility profile were evaluated for their ability to identify Trichosporon spp. and their specificity for the identification of 49 clinical isolates of Trichosporon spp. Morphological and biochemical methodologies were unable to differentiate among the Trichosporon species. ITS sequencing was also unable to differentiate several species. However, IGS1 sequencing unambiguously identified all Trichosporon isolates. Following the results of DNA-based identification, Trichosporon asahii was the species most frequently isolated from deep sites (15 of 25 strains; 60%). In the main, other Trichosporon species were recovered from cutaneous samples. The majority of T. asahii, T. faecale, and T. coremiiforme clinical isolates exhibited resistance in vitro to amphotericin B, with geometric mean (GM) MICs >4 mug/ml. The other species of Trichosporon did not show high MICs of amphotericin B, and GM MICs were <1 mug/ml. Azole agents were active in vitro against the majority of clinical strains. The most potent compound in vitro was voriconazole, with a GM MIC =0.14 mug/ml. The sequencing of IGS correctly identified Trichosporon isolates; however, this technique is not available in many clinical laboratories, and strains should be dispatched to reference centers where these complex methods are available. Therefore, it seems to be more practical to perform antifungal susceptibility testing of all isolates belonging to Trichosporon spp., since correct identification could take several weeks, delaying the indication of an antifungal agent which exhibits activity against the infectious strain.
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MESH Headings
- Amphotericin B/pharmacology
- Antifungal Agents/pharmacology
- Argentina/epidemiology
- DNA, Fungal/analysis
- DNA, Fungal/genetics
- DNA, Intergenic/analysis
- DNA, Intergenic/genetics
- DNA, Ribosomal/analysis
- DNA, Ribosomal/genetics
- DNA, Ribosomal Spacer/analysis
- DNA, Ribosomal Spacer/genetics
- Disease Susceptibility
- Drug Resistance, Fungal/genetics
- Humans
- Microbial Sensitivity Tests
- Phylogeny
- Polymorphism, Genetic
- RNA, Fungal/analysis
- RNA, Fungal/genetics
- RNA, Ribosomal/analysis
- RNA, Ribosomal/genetics
- Retrospective Studies
- Sequence Analysis, DNA
- Spain/epidemiology
- Trichosporon/classification
- Trichosporon/drug effects
- Trichosporon/genetics
- Trichosporon/growth & development
- Trichosporon/isolation & purification
- Trichosporon/physiology
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Affiliation(s)
- Juan L Rodriguez-Tudela
- Servicio de Micología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain.
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Gomez-Lopez A, Mellado E, Rodriguez-Tudela JL, Cuenca-Estrella M. Susceptibility profile of 29 clinical isolates of Rhodotorula spp. and literature review. J Antimicrob Chemother 2005; 55:312-6. [PMID: 15695538 DOI: 10.1093/jac/dki020] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVE In vitro susceptibility results of 29 clinical isolates of Rhodotorula spp. were analysed. In addition, the susceptibility profile of another 102 Rhodotorula isolates was reviewed. METHODS The review included studies using antifungal susceptibility testing reference procedures or commercial methods exhibiting high correlation rates with reference procedures (Etest and Sensititre YeastOne). The 131 organisms analysed were 77 Rhodotorula mucilaginosa, 45 Rhodotorula glutinis and nine Rhodotorula spp. RESULTS AND CONCLUSIONS Fluconazole, itraconazole and voriconazole were inactive in vitro against the majority of isolates. Amphotericin B and flucytosine exhibited good activity, being reasonable alternatives for empirical treatment. Ravuconazole was more active in vitro than other azole agents and it could be considered as an extended-spectrum triazole and maybe as a therapeutic alternative in treating infections caused by Rhodotorula species.
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Affiliation(s)
- Alicia Gomez-Lopez
- Servicio de Micología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Ctra Majadahonda-Pozuelo Km 2, 28220 Majadahonda, Madrid, Spain
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Cuenca-Estrella M, Gomez-Lopez A, Mellado E, Garcia-Effron G, Rodriguez-Tudela JL. In vitro activities of ravuconazole and four other antifungal agents against fluconazole-resistant or -susceptible clinical yeast isolates. Antimicrob Agents Chemother 2004; 48:3107-11. [PMID: 15273127 PMCID: PMC478504 DOI: 10.1128/aac.48.8.3107-3111.2004] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2004] [Revised: 04/02/2004] [Accepted: 04/18/2004] [Indexed: 11/20/2022] Open
Abstract
The activities of ravuconazole and four other antifungal agents were tested against a collection of 1,796 clinical yeast isolates, including fluconazole-susceptible and -resistant strains. Ravuconazole was active against the majority of fluconazole-resistant isolates; but for 102 of 562 (18%) resistant isolates, mainly Candida tropicalis, Candida glabrata, and Cryptococcus neoformans, ravuconazole MICs were > or =1 microg/ml.
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Affiliation(s)
- Manuel Cuenca-Estrella
- Servicio de Micología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda (Madrid), Spain.
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22
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Gadea I, Cuenca-Estrella M, Prieto E, Diaz-Guerra TM, Garcia-Cia JI, Mellado E, Tomas JF, Rodriguez-Tudela JL. Genotyping and antifungal susceptibility profile of Dipodascus capitatus isolates causing disseminated infection in seven hematological patients of a tertiary hospital. J Clin Microbiol 2004; 42:1832-6. [PMID: 15071063 PMCID: PMC387620 DOI: 10.1128/jcm.42.4.1832-1836.2004] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Seven cases of disseminated infection due to Dipodascus capitatus are reported. Infections occurred in a hematological unit of a tertiary hospital during a period of 5 years. Five cases were refractory to antifungal therapy. Antifungal susceptibility testing of seven isolates was performed, and strains were typed by PCR fingerprinting with the core sequence of phage M13 and by random amplification of polymorphic DNA with two primers, Ap12h and W-80A. A very short range of MICs of each antifungal agent was observed. The MICs of amphotericin B ranged between 0.50 and 2 microg/ml. Strains were susceptible in vitro to flucytosine and susceptible (dose-dependent) to fluconazole and itraconazole. Voriconazole exhibited an activity in vitro comparable to that of itraconazole. Typing techniques allowed seven additional isolates of D. capitatus neither geographically nor temporally related to be classified into two different genomic patterns. The genomic type of the seven strains from the hematological unit was identical regardless of typing technique utilized. It would indicate that the seven cases of disseminated infection could be related epidemiologically.
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Rodero L, Mellado E, Rodriguez AC, Salve A, Guelfand L, Cahn P, Cuenca-Estrella M, Davel G, Rodriguez-Tudela JL. G484S amino acid substitution in lanosterol 14-alpha demethylase (ERG11) is related to fluconazole resistance in a recurrent Cryptococcus neoformans clinical isolate. Antimicrob Agents Chemother 2004; 47:3653-6. [PMID: 14576140 PMCID: PMC253790 DOI: 10.1128/aac.47.11.3653-3656.2003] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Five sequential Cryptococcus neoformans isolates recovered from an AIDS patient with recurrent meningitis were analyzed. Four isolates were fluconazole susceptible, while the fifth isolate developed fluconazole resistance. Analysis of the 14-alpha lanosterol demethylase gene (ERG11) showed a point mutation in the resistant strain responsible for the amino acid substitution G484S.
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Affiliation(s)
- Laura Rodero
- Departamento Micología, Instituto Nacional de Enfermedades Infecciosas, ANLIS Dr. Carlos G. Malbrán, Hospital J. A. Fernandez, Buenos Aires, Argentina.
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24
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Ramos JM, Cuenca-Estrella M, Gutierrez F, Elia M, Rodriguez-Tudela JL. Clinical case of endocarditis due to Trichosporon inkin and antifungal susceptibility profile of the organism. J Clin Microbiol 2004; 42:2341-4. [PMID: 15131229 PMCID: PMC404682 DOI: 10.1128/jcm.42.5.2341-2344.2004] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2003] [Revised: 01/14/2004] [Accepted: 02/10/2004] [Indexed: 11/20/2022] Open
Abstract
A fatal case of Trichosporon inkin prosthetic endocarditis is reported. The isolation sites and susceptibility profiles of 10 other isolates are also reviewed. Four strains were recovered from cutaneous or subcutaneous samples, four were recovered from urine, one was recovered from peritoneal liquid, and one was recovered from bone. Voriconazole and amphotericin B had the most potent activities in vitro against the isolates, with MIC geometric means of 0.11 and 0.30 microg/ml, respectively.
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Affiliation(s)
- Jose M Ramos
- Unidad de Enfermedades Infecciosas, Servicio de Medicina, Hospital General Universitario de Elche, Alicante, Spain
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Pappalardo MCSM, Melhem MSC. Cryptococcosis: a review of the Brazilian experience for the disease. Rev Inst Med Trop Sao Paulo 2004; 45:299-305. [PMID: 14762626 DOI: 10.1590/s0036-46652003000600001] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Cryptococcosis is a systemic mycosis caused by Cryptococcus neoformans. The disease occurs in patients with cellular immunodeficiency. The incidence of cryptococcosis arises with aids, and mycosis is one of the opportunistic infections that defines AIDS. After the HAART era the occurrence of cryptococcosis decreased all over the world, but it still continues to be a prevalent disease in Brazil. Thus, we consider this paper to be very important as a result of our reviewing of Brazilian literature regarding some relevant aspects of that disease.
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Cuenca-Estrella M, Moore CB, Barchiesi F, Bille J, Chryssanthou E, Denning DW, Donnelly JP, Dromer F, Dupont B, Rex JH, Richardson MD, Sancak B, Verweij PE, Rodríguez-Tudela JL. Multicenter evaluation of the reproducibility of the proposed antifungal susceptibility testing method for fermentative yeasts of the Antifungal Susceptibility Testing Subcommittee of the European Committee on Antimicrobial Susceptibility Testing (AFST-EUCAST). Clin Microbiol Infect 2003; 9:467-74. [PMID: 12848721 DOI: 10.1046/j.1469-0691.2003.00592.x] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To evaluate the intra- and inter-laboratory reproducibility of a new standard for susceptibility testing of fermentative yeasts. This standard is based on the M27-A procedure of the National Committee for Clinical Laboratory Standards (NCCLS), but incorporates several modifications, including spectrophotometric growth-dependent endpoint reading. METHODS Nine laboratories participated in the study. Common material lots were used to test six Candida species (one each of C. albicans, C. tropicalis, C. parapsilosis, C. glabrata, C. krusei, and C. lusitaniae), and two quality control strains (C. krusei ATCC6258 and C. parapsilosis ATCC22019). Triplicate testing on three separate days was performed in microtiter format with RPMI-2% glucose, pH 7.0. Flucytosine, fluconazole and itraconazole were tested. In total, 3888 MIC values were included in the analyses. Reproducibility was calculated by means of agreement (percentage of MICs within one two-fold dilution of the mode) and intraclass correlation coefficient (ICC, maximum value of 1). RESULTS The average intra-laboratory agreements were 99% and 96% after 24 h and 48 h of incubation, respectively, with ICCs of 0.98 and 0.97 (P < 0.05). Two strains exhibiting a trailing effect showed intra-laboratory agreement of 92% and ICCs of < 0.91 at 48 h. The inter-laboratory agreement was 94% and 88% after 24 h and 48 h, respectively, with ICCs of 0.93 and 0.91 (P < 0.05). Lower values of agreement and ICCs were obtained for strains exhibiting trailing after 48 h of incubation. Itraconazole yielded the lowest values of reproducibility. CONCLUSION The new procedure of EUCAST for antifungal susceptibility testing is a reproducible method within and between laboratories and offers several advantages over the NCCLS approved method.
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Gil E, Durán MT, Rodríguez-Tudela JL, Cuenca-Estrella M, Cartelle M, Molina F, Guerrero A. [Pseudozyma sp.: colonizer of the respiratory tract in critical patients]. Enferm Infecc Microbiol Clin 2003; 21:65. [PMID: 12550051 DOI: 10.1016/s0213-005x(03)72881-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Kantarcioglu AS, Yücel A. A flucytosine-resistant Cryptococcus neoformans (serotype D) strain isolated in turkey from cutaneous lesions. Med Mycol 2002; 40:519-23. [PMID: 12462532 DOI: 10.1080/mmy.40.5.519.523] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
A Cryptococcus neoformans strain from cutaneous lesions of a patient with thrombotic thrombocytopenia purpura was tested for in vitro susceptibility against seven conventional antifungal agents. The strain was susceptible to fluconazole, itraconazole, ketoconazole and miconazole but was resistant to 5-fluorocytosine (5-FC). Minimal inhibitory concentration (MIC) values obtained against amphotericin B and terbinafine were 1 and 4 microg ml(-1), respectively. The isolate belonged to serotype D. Few human cases of cryptococcosis have been reported over the last 50 years in Turkey. This is the first C. neoformans isolate in Turkey shown to have primary resistance to 5-FC. Primary resistance to flucytosine is rarely reported in C. neoformans and may be associated with treatment failure in some cases.
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Affiliation(s)
- A S Kantarcioglu
- Department of Microbiology and Clinical Microbiology, Cerrahpasa Medical Faculty, Istanbul University, 34303 Cerrahpasa, Istanbul, Turkey.
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Cuenca-Estrella M, Rodríguez-Tudela JL. Present status of the detection of antifungal resistance: the perspective from both sides of the ocean. Clin Microbiol Infect 2002; 7 Suppl 2:46-53. [PMID: 11525218 DOI: 10.1111/j.1469-0691.2001.tb00009.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The NCCLS reference methodology for antifungal susceptibility testing is a new milestone of the evolution of medical mycology. The use of this methodology however, is not problem-free. At present, major limitations are a trailing phenomenon with azoles, unreliable detection of resistance to amphotericin B, poor growth of some organisms and unpractical procedures for the clinical laboratory. Herein a overview of NCCLS guidelines for yeasts and filamentous fungi is presented. Likewise, a review of studies conducted trying to overcome the limitations of reference procedures is also included. Several alternative approaches are reviewed as alternative media, inoculum size and incubation time. Modifications of reading procedure and endpoint determination are also evaluated. Agar diffusion methods and other methods for susceptibility testing are cited. Finally, we discuss the data on correlation of the in vitro results with the in vivo activity.
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Affiliation(s)
- M Cuenca-Estrella
- Servicio de Micrología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain.
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Brandt ME, Pfaller MA, Hajjeh RA, Hamill RJ, Pappas PG, Reingold AL, Rimland D, Warnock DW. Trends in antifungal drug susceptibility of Cryptococcus neoformans isolates in the United States: 1992 to 1994 and 1996 to 1998. Antimicrob Agents Chemother 2001; 45:3065-9. [PMID: 11600357 PMCID: PMC90783 DOI: 10.1128/aac.45.11.3065-3069.2001] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The antifungal drug susceptibilities of two collections of Cryptococcus neoformans isolates obtained through active laboratory-based surveillance from 1992 to 1994 (368 isolates) and 1996 to 1998 (364 isolates) were determined. The MICs of fluconazole, itraconazole, and flucytosine were determined by the National Committee for Clinical Laboratory Standards broth microdilution method; amphotericin B MICs were determined by the E-test. Our results showed that the MIC ranges, the MICs at which 50% of isolates are inhibited (MIC(50)s), and the MIC(90)s of these four antifungal agents did not change from 1992 to 1998. In addition, very small numbers of isolates showed elevated MICs suggestive of in vitro resistance. The MICs of amphotericin B were elevated (>or=2 microg/ml) for 2 isolates, and the MICs of flucytosine were elevated (>or=32 microg/ml) for 14 isolates. Among the azoles, the fluconazole MIC was elevated (>or=64 microg/ml) for 8 isolates and the itraconazole MIC (>or=1 microg/ml) was elevated for 45 isolates. Analysis of 172 serial isolates from 71 patients showed little change in the fluconazole MIC over time. For isolates from 58 patients (82% of serial cases) there was either no change or a twofold change in the fluconazole MIC. In contrast, for isolates from seven patients (12% of serial cases) the increase in the MIC was at least fourfold. For isolates from another patient there was a 32-fold decrease in the fluconazole MIC over a 1-month period. We conclude that in vitro resistance to antifungal agents remains uncommon in C. neoformans and has not significantly changed with time during the past decade.
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Affiliation(s)
- M E Brandt
- Mycotic Diseases Branch, Division of Bacterial and Mycotic Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA.
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Rex JH, Pfaller MA, Walsh TJ, Chaturvedi V, Espinel-Ingroff A, Ghannoum MA, Gosey LL, Odds FC, Rinaldi MG, Sheehan DJ, Warnock DW. Antifungal susceptibility testing: practical aspects and current challenges. Clin Microbiol Rev 2001; 14:643-58, table of contents. [PMID: 11585779 PMCID: PMC88997 DOI: 10.1128/cmr.14.4.643-658.2001] [Citation(s) in RCA: 278] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Development of standardized antifungal susceptibility testing methods has been the focus of intensive research for the last 15 years. Reference methods for yeasts (NCCLS M27-A) and molds (M38-P) are now available. The development of these methods provides researchers not only with standardized methods for testing but also with an understanding of the variables that affect interlaboratory reproducibility. With this knowledge, we have now moved into the phase of (i) demonstrating the clinical value (or lack thereof) of standardized methods, (ii) developing modifications to these reference methods that address specific problems, and (iii) developing reliable commercial test kits. Clinically relevant testing is now available for selected fungi and drugs: Candida spp. against fluconazole, itraconazole, flucytosine, and (perhaps) amphotericin B; Cryptococcus neoformans against (perhaps) fluconazole and amphotericin B; and Aspergillus spp. against (perhaps) itraconazole. Expanding the range of useful testing procedures is the current focus of research in this area.
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Affiliation(s)
- J H Rex
- Division of Infectious Diseases, Department of Internal Medicine, Center for the Study of Emerging and Reemerging Pathogens, University of Texas Medical School, Houston, Texas 77030, USA.
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Cuenca-Estrella M, Díaz-Guerra TM, Mellado E, Rodríguez-Tudela JL. Influence of glucose supplementation and inoculum size on growth kinetics and antifungal susceptibility testing of Candida spp. J Clin Microbiol 2001; 39:525-32. [PMID: 11158101 PMCID: PMC87770 DOI: 10.1128/jcm.39.2.525-532.2001] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The influences of inoculum size and glucose supplementation on the growth kinetics of 60 Candida spp. clinical isolates (Candida albicans, Candida tropicalis, Candida parapsilosis, Candida glabrata, Candida krusei, and Candida lusitaniae [10 isolates each]) are assessed. The combined influence of growth and reading method (visual or spectrophotometric) on the determination of the MICs of amphotericin B, flucytosine, fluconazole, itraconazole, ketoconazole, and voriconazole is also analyzed, and the MICs are compared with those determined by the National Committee for Clinical Laboratory Standards standard microdilution method (NCCLS document M27-A). Glucose supplementation and inoculum size had a significant influence on the growth cycles of these yeasts, and a statistically significant denser growth (optical density at 540 nm) was seen for both incubation periods, 24 and 48 h (P < 0.01). A longer exponential phase and shorter lag phase were also observed. The A540 values at 24 h of incubation with medium containing glucose and an inoculum of 10(5) CFU/ml were >0.4 U for all species, with the exception of that for C. parapsilosis (A540 = 0.26 +/- 0.025). The MICs at 24 h determined by testing with 2% glucose and an inoculum of 10(5) CFU/ml showed the strongest agreement (96.83%) with MICs determined by the reference method. MICs were not falsely elevated, and good correlation indexes were obtained. The reproducibility of results with this medium-inoculum combination was high (intraclass correlation coefficient, 0.955). The best agreement and reproducibility of results for spectrophotometric readings were achieved with endpoints of 50% growth inhibition for flucytosine and azoles and 95% for amphotericin B. Supplementation of test media with glucose and an inoculum size of 10(5) CFU/ml yielded a reproducible technique that shows elevated agreement with the reference procedures and a shorter incubation period for obtaining reliable MIC determinations. The spectrophotometric method offers an advantage over the visual method by providing a more objective and automated MIC determination.
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Affiliation(s)
- M Cuenca-Estrella
- Servicio de Micología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda, Madrid, Spain.
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Meletiadis J, Meis JF, Mouton JW, Verweij PE. Analysis of growth characteristics of filamentous fungi in different nutrient media. J Clin Microbiol 2001; 39:478-84. [PMID: 11158093 PMCID: PMC87762 DOI: 10.1128/jcm.39.2.478-484.2001] [Citation(s) in RCA: 130] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A microbroth kinetic model based on turbidity measurements was developed in order to analyze the growth characteristics of three species of filamentous fungi (Rhizopus microsporus, Aspergillus fumigatus, and Scedosporium prolificans) characterized by different growth rates in five nutrient media (antibiotic medium 3, yeast nitrogen base medium, Sabouraud broth, RPMI 1640 alone, and RPMI 1640 with 2% glucose). In general, five distinct phases in the growth of filamentous fungi could be distinguished, namely, the lag phase, the first transition period, the log phase, the second transition period, and the stationary phase. The growth curves were smooth and were characterized by the presence of long transition periods. Among the different growth phases distinguished, the smallest variability in growth rates among the strains of each species was found during the log phase in all nutrient media. The different growth phases of filamentous fungi were barely distinguishable in RPMI 1640, in which the poorest growth was observed for all fungi even when the medium was supplemented with 2% glucose. R. microsporus and A. fumigatus grew better in Sabouraud and yeast nitrogen base medium than in RPMI 1640, with growth rates three to four times higher. None of the media provided optimal growth of S. prolificans. The germination of Rhizopus spores and Aspergillus and Scedosporium conidia commenced after 2 and 5 h of incubation, respectively. The elongation rates ranged from 39.6 to 26.7, 25.4 to 20.2, and 16.9 to 9.9 microm/h for Rhizopus, Aspergillus, and Scedoporium hyphae, respectively. The germination of conidia and spores and the elongation rates of hyphae were enhanced in antibiotic medium 3 and delayed in yeast nitrogen base medium. In conclusion, the growth curves provide a useful tool to gain insight into the growth characteristics of filamentous fungi in different nutrient media and may help to optimize the methodology for antifungal susceptibility testing.
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Affiliation(s)
- J Meletiadis
- Department of Medical Microbiology, University Medical Center Nijmegen, Nijmegen, The Netherlands
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