scholarly journals In Vitro Susceptibilities of Candida andCryptococcus neoformans Isolates from Blood Cultures of Neutropenic Patients

1999 ◽  
Vol 43 (6) ◽  
pp. 1463-1464 ◽  
Author(s):  
Daryl J. Hoban ◽  
George G. Zhanel ◽  
James A. Karlowsky
Keyword(s):  
Risk Factors ◽  
Candida Parapsilosis ◽  
Clinical Laboratory ◽  
Blood Cultures ◽  
Weight Basis ◽  
National Committee ◽  
Fluconazole Resistance ◽  
Neutropenic Patients ◽  
Fluconazole Resistant

ABSTRACT Fluconazole-resistant Candida albicans and intrinsically fluconazole-resistant Candida species have been reported as bloodstream isolates. However, an association between the isolation of fluconazole-resistant Candida from the bloodstream and patient risk factors for fungemia has not been established. The purpose of this study was to determine the prevalence of fluconazole resistance in bloodstream isolates ofCandida species and Cryptococcus neoformanscollected from patients with neutropenia, one of the most important risk factors for fungemia. MICs of voriconazole, fluconazole, itraconazole, ketoconazole, amphotericin B, and flucytosine were determined by the National Committee for Clinical Laboratory Standards M27-A method (1997). Voriconazole, on a per-weight basis, was the most active azole tested. Fluconazole resistance (MIC ≥ 64 μg/ml) was not identified in any of the C. albicans(n = 513), Candida parapsilosis(n = 78), Candida tropicalis(n = 62), or C. neoformans(n = 38) isolates tested.

scholarly journals In Vitro Susceptibilities of Candida dubliniensisIsolates Tested against the New Triazole and Echinocandin Antifungal Agents

1999 ◽  
Vol 37 (3) ◽  
pp. 870-872 ◽  
Author(s):  
M. A. Pfaller ◽  
S. A. Messer ◽  
S. Gee ◽  
S. Joly ◽  
C. Pujol ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Antifungal Agents ◽  
Clinical Laboratory ◽  
National Committee ◽  
Mucosal Disease ◽  
Fluconazole Resistant ◽  
Resistant Strains ◽  
Investigational Agents ◽  
Multidrug Resistance Transporters

Candida dubliniensis is a newly recognized fungal pathogen causing mucosal disease in AIDS patients. Although preliminary studies indicate that most strains of C. dubliniensis are susceptible to established antifungal agents, fluconazole-resistant strains have been detected. Furthermore, fluconazole-resistant strains are easily derived in vitro, and these strains exhibit increased expression of multidrug resistance transporters, especially MDR1. Because of the potential for the development of resistant strains of C. dubliniensis, it is prudent to explore the in vitro activities of several of the newer triazole and echinocandin antifungals against isolates of C. dubliniensis. In this study we tested 71 isolates of C. dubliniensis against the triazoles BMS-207147, Sch 56592, and voriconazole and a representative of the echinocandin class of antifungal agents, MK-0991. We compared the activities of these agents with those of the established antifungal agents fluconazole, itraconazole, amphotericin B, and 5-fluorocytosine (5FC) by using National Committee for Clinical Laboratory Standards microdilution reference methods. Our findings indicate that the vast majority of clinical isolates of C. dubliniensis are highly susceptible to both new and established antifungal agents. Strains with decreased susceptibilities to fluconazole remained susceptible to the investigational agents as well as to amphotericin B and 5FC. The increased potencies of the new triazole and echinocandin antifungal agents may provide effective therapeutic options for the treatment of infections due to C. dubliniensis.

scholarly journals Candida parapsilosis Resistance to Fluconazole: Molecular Mechanisms andIn VivoImpact in Infected Galleria mellonella Larvae

2015 ◽  
Vol 59 (10) ◽  
pp. 6581-6587 ◽  
Author(s):  
Ana Carolina R. Souza ◽  
Beth Burgwyn Fuchs ◽  
Henrique M. S. Pinhati ◽  
Ricardo A. Siqueira ◽  
Ferry Hagen ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Candida Parapsilosis ◽  
Galleria Mellonella ◽  
Common Mutation ◽  
Fluconazole Resistance ◽  
Content Type ◽  
Clonal Origin ◽  
Fluconazole Resistant ◽  
Resistant Strains

ABSTRACTCandida parapsilosisis the main non-albicans Candidaspecies isolated from patients in Latin America. Mutations in theERG11gene and overexpression of membrane transporter proteins have been linked to fluconazole resistance. The aim of this study was to evaluate the molecular mechanisms in fluconazole-resistant strains ofC. parapsilosisisolated from critically ill patients. The identities of the nine collectedC. parapsilosisisolates at the species level were confirmed through molecular identification with a TaqMan qPCR assay. The clonal origin of the strains was checked by microsatellite typing. TheGalleria mellonellainfection model was used to confirmin vitroresistance. We assessed the presence ofERG11mutations, as well as the expression ofERG11and two additional genes that contribute to antifungal resistance (CDR1andMDR1), by using real-time quantitative PCR. All of theC. parapsilosis(sensu stricto) isolates tested exhibited fluconazole MICs between 8 and 16 μg/ml. Thein vitrodata were confirmed by the failure of fluconazole in the treatment ofG. mellonellainfected with fluconazole-resistant strains ofC. parapsilosis. Sequencing of theERG11gene revealed a common mutation leading to a Y132F amino acid substitution in all of the isolates, a finding consistent with their clonal origin. After fluconazole exposure, overexpression was noted forERG11,CDR1, andMDR1in 9/9, 9/9, and 2/9 strains, respectively. We demonstrated that a combination of molecular mechanisms, including the presence of point mutations in theERG11gene, overexpression ofERG11, and genes encoding efflux pumps, are involved in fluconazole resistance inC. parapsilosis.

scholarly journals Comparative Evaluation of FUNGITEST and Broth Microdilution Methods for Antifungal Drug Susceptibility Testing of Candida Species and Cryptococcus neoformans

1998 ◽  
Vol 36 (4) ◽  
pp. 926-930 ◽  
Author(s):  
Kate G. Davey ◽  
Ann D. Holmes ◽  
Elizabeth M. Johnson ◽  
Adrien Szekely ◽  
David W. Warnock
Keyword(s):  
Cryptococcus Neoformans ◽  
Amphotericin B ◽  
Susceptibility Testing ◽  
Clinical Laboratory ◽  
Drug Susceptibility ◽  
Drug Susceptibility Testing ◽  
National Committee ◽  
Broth Microdilution ◽  
Fluconazole Resistant

The FUNGITEST method (Sanofi Diagnostics Pasteur, Paris, France) is a microplate-based procedure for the breakpoint testing of six antifungal agents (amphotericin B, flucytosine, fluconazole, itraconazole, ketoconazole, and miconazole). We compared the FUNGITEST method with a broth microdilution test, performed according to National Committee for Clinical Laboratory Standards document M27-A guidelines, for determining the in vitro susceptibilities of 180 isolates ofCandida spp. (50 C. albicans, 50C. glabrata, 10 C. kefyr, 20C. krusei, 10 C. lusitaniae, 20C. parapsilosis, and 20 C. tropicalisisolates) and 20 isolates of Cryptococcus neoformans. Overall, there was 100% agreement between the methods for amphotericin B, 95% agreement for flucytosine, 84% agreement for miconazole, 83% agreement for itraconazole, 77% agreement for ketoconazole, and 76% agreement for fluconazole. The overall agreement between the methods exceeded 80% for all species tested with the exception ofC. glabrata (71% agreement). The poorest agreement between the results for individual agents was seen with C. glabrata (38% for fluconazole, 44% for ketoconazole, and 56% for itraconazole) and C. tropicalis (50% for miconazole). The FUNGITEST method misclassified as susceptible 2 of 12 (16.6%) fluconazole-resistant isolates, 2 of 10 (20%) itraconazole-resistant isolates, and 4 of 8 (50%) ketoconazole-resistant isolates of several Candida spp. Further development of the FUNGITEST procedure will be required before it can be recommended as an alternative method for the susceptibility testing of Candida spp. or C. neoformans.

scholarly journals In vitro susceptibilities of clinical yeast isolates to a new echinocandin derivative, LY303366, and other antifungal agents.

1997 ◽  
Vol 41 (4) ◽  
pp. 763-766 ◽  
Author(s):  
M A Pfaller ◽  
S A Messer ◽  
S Coffman
Keyword(s):  
Amphotericin B ◽  
Fungicidal Activity ◽  
Antifungal Agents ◽  
Candida Parapsilosis ◽  
Clinical Laboratory ◽  
National Committee ◽  
In Vitro Activity ◽  
Medical Centers

LY303366 is a new semisynthetic echinocandin derivative with potent, broad-spectrum fungicidal activity. We investigated the in vitro activity of LY303366, amphotericin B, flucytosine (5FC), fluconazole, and itraconazole against 435 clinical yeast isolates (413 Candida and 22 Saccharomyces cerevisiae isolates) obtained from over 30 different medical centers. MICs for all five antifungal agents were determined by the National Committee for Clinical Laboratory Standards method with RPMI 1640 test medium. LY303366 was also tested in antibiotic medium 3 as specified by the manufacturer. Overall, LY303366 was quite active against all of the yeast isolates when tested in RPMI 1640 (MIC at which 90% of the isolates are inhibited [MIC90], 1.0 microg/ml) but appeared to be considerably more potent when tested in antibiotic medium 3 (MIC90, 0.03 microg/ml). When tested in antibiotic medium 3, LY303366 was 16- to >2,000-fold more active than itraconazole, fluconazole, amphotericin B, or 5FC against all species except Candida parapsilosis. When tested in RPMI 1640, LY303366 was comparable to amphotericin B and itraconazole and more active than fluconazole and 5FC. All of the isolates for which fluconazole and itraconazole had elevated MICs (> or = 128 and > or = 2.0 microg/ml, respectively) were inhibited by < or = 0.007 microg of LY303366/ml when tested in antibiotic medium 3 and < or = 0.5 microg/ml when tested in RPMI 1640. Based on these studies, LY303366 has promising antifungal activity and warrants further in vitro and in vivo investigation.

scholarly journals In vitro activities of semisynthetic pneumocandin L-733,560 against fluconazole-resistant and -susceptible Candida albicans isolates.

1996 ◽  
Vol 40 (5) ◽  
pp. 1277-1279 ◽  
Author(s):  
J V Martinez-Suarez ◽  
J L Rodriguez-Tudela
Keyword(s):  
Candida Albicans ◽  
Clinical Laboratory ◽  
Active Agent ◽  
Water Soluble ◽  
National Committee ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Fluconazole Resistant ◽  
Reference Strains

Lipopeptide L-733,560 is a water-soluble derivative of pneumocandin B0 that exhibits enhanced anti-Candida activity. We investigated the in vitro activity of L-733,560 compared with those of amphotericin B, flucytosine, and itraconazole, against fluconazole-resistant (n = 44) and fluconazole-susceptible (n = 46) Candida albicans isolates. Tests were performed with a photometer-read broth microdilution method with RPMI-2% glucose and National Committee for Clinical Laboratory Standards reference strains. Except for those of itraconazole, MICs were not significantly different between the two groups of isolates, as expected for agents with different mechanisms of action. L-733,560 was the most active agent against C.albicans, with MICs for 50 and 90% of the strains tested of 0.01 and 0.06 microgram/ml, respectively.

scholarly journals Clonal and Spontaneous Origins of Fluconazole Resistance in Candida albicans

2000 ◽  
Vol 38 (3) ◽  
pp. 1214-1220 ◽  
Author(s):  
Jianping Xu ◽  
Adela R. Ramos ◽  
Rytas Vilgalys ◽  
Thomas G. Mitchell
Keyword(s):  
Candida Albicans ◽  
Clinical Laboratory ◽  
Healthy Person ◽  
The Other ◽  
National Committee ◽  
Pathogenic Yeast ◽  
Fluconazole Resistance ◽  
Distinct Cluster ◽  
Fluconazole Resistant ◽  
Resistant Strains

The genotypes and susceptibilities to fluconazole of 78 strains of the human pathogenic yeast Candida albicans were compared. The strains comprised two sets of samples from Durham, N.C.: one from patients infected with the human immunodeficiency virus (HIV) and the other from healthy volunteers. For each strain, the MIC of fluconazole was determined by the standard National Committee for Clinical Laboratory Standards protocol. Genotypes were determined by PCR fingerprinting with five separate primers. The analysis revealed little evidence for genotypic clustering according to HIV status or body site. However, a small group of fluconazole-resistant strains isolated from patients infected with HIV formed a distinct cluster. In addition, two fluconazole-resistant strains were isolated from individuals who never took fluconazole, one from a patient infected with HIV and the other from a healthy person. The results suggest both clonal and spontaneous origins of fluconazole resistance in C. albicans.

Use of spectrophotometric reading for in vitro antifungal susceptibility testing ofAspergillusspp.

1999 ◽  
Vol 45 (10) ◽  
pp. 871-874 ◽  
Author(s):  
Eric Dannaoui ◽  
Florence Persat ◽  
Marie-France Monier ◽  
Elisabeth Borel ◽  
Marie-Antoinette Piens ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Susceptibility Testing ◽  
Clinical Laboratory ◽  
Antifungal Susceptibility ◽  
Reference Method ◽  
Antifungal Susceptibility Testing ◽  
Aspergillus Species ◽  
National Committee ◽  
Broth Microdilution Method

A comparative study of visual and spectrophotometric MIC endpoint determinations for antifungal susceptibility testing of Aspergillus species was performed. A broth microdilution method adapted from the National Committee for Clinical Laboratory Standards (NCCLS) was used for susceptibility testing of 180 clinical isolates of Aspergillus species against amphotericin B and itraconazole. MICs were determined visually and spectrophotometrically at 490 nm after 24, 48, and 72h of incubation, and MIC pairs were compared. The agreement between the two methods was 99% for amphotericin B and ranged from 95 to 98% for itraconazole. It is concluded that spectrophotometric MIC endpoint determination is a valuable alternative to the visual reference method for susceptibility testing of Aspergillus species.Key words: antifungal, susceptibility testing, Aspergillus, spectrophotometric reading.

scholarly journals Quantitation of Candida albicans Ergosterol Content Improves the Correlation between In Vitro Antifungal Susceptibility Test Results and In Vivo Outcome after Fluconazole Treatment in a Murine Model of Invasive Candidiasis

2000 ◽  
Vol 44 (8) ◽  
pp. 2081-2085 ◽  
Author(s):  
Beth A. Arthington-Skaggs ◽  
David W. Warnock ◽  
Christine J. Morrison
Keyword(s):  
Murine Model ◽  
Invasive Candidiasis ◽  
Clinical Laboratory ◽  
Antifungal Susceptibility ◽  
Resistant Isolate ◽  
National Committee ◽  
Ergosterol Content ◽  
In Vitro Antifungal Susceptibility

ABSTRACT MIC end point determination for the most commonly prescribed azole antifungal drug, fluconazole, can be complicated by “trailing” growth of the organism during susceptibility testing by the National Committee for Clinical Laboratory Standards approved M27-A broth macrodilution method and its modified broth microdilution format. To address this problem, we previously developed the sterol quantitation method (SQM) for in vitro determination of fluconazole susceptibility, which measures cellular ergosterol content rather than growth inhibition after exposure to fluconazole. To determine if SQM MICs of fluconazole correlated better with in vivo outcome than M27-A MICs, we used a murine model of invasive candidiasis and analyzed the capacity of fluconazole to treat infections caused by C. albicansisolates which were trailers (M27-A MICs at 24 and 48 h, ≤1.0 and ≥64 μg/ml, respectively; SQM MIC, ≤1.0 μg/ml), as well as those which were fluconazole sensitive (M27-A and SQM MIC, ≤1.0 μg/ml) and fluconazole resistant (M27-A MIC, ≥64 μg/ml; SQM MIC, 54 μg/ml). Compared with the untreated controls, fluconazole therapy increased the survival of mice infected with a sensitive isolate and both trailing isolates but did not increase the survival of mice infected with a resistant isolate. These results indicate that the SQM is more predictive of in vivo outcome than the M27-A method for isolates that give unclear MIC end points due to trailing growth in fluconazole.

Assessment of Laboratory Performance With Streptococcus pneumoniae Antimicrobial Susceptibility Testing in the United States

1999 ◽  
Vol 123 (4) ◽  
pp. 285-289 ◽  
Author(s):  
Gary V. Doern ◽  
Angela B. Brueggemann ◽  
Michael A. Pfaller ◽  
Ronald N. Jones
Keyword(s):  
United States ◽  
Streptococcus Pneumoniae ◽  
Antimicrobial Agents ◽  
Susceptibility Testing ◽  
Clinical Laboratory ◽  
The United States ◽  
National Committee ◽  
In Vitro Susceptibility ◽  
Susceptibility Tests

Abstract Objective.—To assess the performance of clinical microbiology laboratories in the United States when conducting in vitro susceptibility tests with Streptococcus pneumoniae. Methods.—The results of a nationwide College of American Pathologists Proficiency Survey test sample, in which susceptibility testing of an isolate of S pneumoniae was performed, were assessed with respect to precision and accuracy. Results.—Wide variability was noted among participating laboratories with both minimum inhibitory concentration procedures and disk diffusion susceptibility tests when both methods were applied to S pneumoniae. Despite this high degree of variation, categorical interpretive errors were uncommon. Numerous laboratories reported results for antimicrobial agents that are not recommended by the National Committee for Clinical Laboratory Standards for tests with S pneumoniae. Conclusions.—Current susceptibility testing practices with S pneumoniae in the United States indicate limited precision and a tendency for laboratories to test and report results obtained with antimicrobial agents of questionable therapeutic value against this organism. Continued efforts to standardize susceptibility testing of S pneumoniae in the United States are warranted. In addition, modifications of existing interpretive criteria may be necessary.

Sign in / Sign up

Export Citation Format

Share Document