scholarly journals In Vitro Antifungal Drug Resistance Profiles of Clinically Relevant Members of the Mucorales (Mucoromycota) Especially with the Newer Triazoles

2021 ◽  
Vol 7 (4) ◽  
pp. 271
Author(s):  
Andrew M. Borman ◽  
Mark Fraser ◽  
Zoe Patterson ◽  
Michael D. Palmer ◽  
Elizabeth M. Johnson
Keyword(s):  
Amphotericin B ◽  
Fungal Pathogens ◽  
Treatment Guidelines ◽  
Antifungal Susceptibility ◽  
Human Infection ◽  
Antifungal Drug ◽  
Concentration Data ◽  
Accurate Identification ◽  
Broth Microdilution Method

Mucoromycoses (infections caused by members of the order Mucorales, phylum Mucoromycota [ex-Zygomycota]) are highly destructive, rapidly progressive infections, with dire prognoses especially when they occur in immunocompromised hosts. Current treatment guidelines recommend liposomal formulations of amphotericin B with adjunctive surgery as first line therapy, with the newer triazoles posaconazole or isavuconazole as alternative treatments, or as salvage therapy. Among the many organisms belonging to this order, a limited number of species in the genera Rhizopus, Mucor, Lichtheimia and Rhizomucor are responsible for most cases of human infection. Here, we present the minimum inhibitory concentration data (MICs) for amphotericin B, posaconazole, isavuconazole, itraconazole and voriconazole with a panel of over 300 isolates of the five most common agents of human infection (Lichtheimia corymbifera, Rhizopus arrhizus, R. microsporus, Rhizomucor pusillus and Mucor spp.) determined using the CLSI broth microdilution method. In agreement with previous studies, the most active antifungal drug for all Mucorales was amphotericin B, with MICs within the range that would predict susceptibility with Aspergillus fumigatus. Conversely, MICs for voriconazole against all species tested were high, and above the range associated with clinical efficacy with A. fumigatus. Interestingly, whilst isavuconazole and posaconazole MIC distributions indicated in vitro activity against some members of the Mucorales, activity was species-dependent for both agents. These data underscore the importance of accurate identification of the causative agents of mucoromycosis, coupled with antifungal susceptibility testing of individual isolates, in determining the optimal treatment of infections caused by these aggressive opportunistic human fungal pathogens.

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 Relationship between the Antifungal Susceptibility Profile and the Production of Virulence-Related Hydrolytic Enzymes in Brazilian Clinical Strains ofCandida glabrata

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Maria Helena Galdino Figueiredo-Carvalho ◽  
Lívia de Souza Ramos ◽  
Leonardo Silva Barbedo ◽  
Jean Carlos Almeida de Oliveira ◽  
André Luis Souza dos Santos ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Antifungal Susceptibility ◽  
Hydrolytic Enzymes ◽  
Antifungal Drug ◽  
Clinical Strains ◽  
Antifungal Drug Resistance ◽  
Opportunistic Fungal Pathogen ◽  
Esterase Production ◽  
In Vitro Antifungal Susceptibility

Candida glabratais a facultative intracellular opportunistic fungal pathogen in human infections. Several virulence-associated attributes are involved in its pathogenesis, host-pathogen interactions, modulation of host immune defenses, and regulation of antifungal drug resistance. This study evaluated the in vitro antifungal susceptibility profile to five antifungal agents, the production of seven hydrolytic enzymes related to virulence, and the relationship between these phenotypes in 91 clinical strains ofC. glabrata. AllC. glabratastrains were susceptible to flucytosine. However, some of these strains showed resistance to amphotericin B (9.9%), fluconazole (15.4%), itraconazole (5.5%), or micafungin (15.4%). Overall,C. glabratastrains were good producers of catalase, aspartic protease, esterase, phytase, and hemolysin. However, caseinase and phospholipase in vitro activities were not detected. Statistically significant correlations were identified between micafungin minimum inhibitory concentration (MIC) and esterase production, between fluconazole and micafungin MIC and hemolytic activity, and between amphotericin B MIC and phytase production. These results contribute to clarify some of theC. glabratamechanisms of pathogenicity. Moreover, the association between some virulence attributes and the regulation of antifungal resistance encourage the development of new therapeutic strategies involving virulence mechanisms as potential targets for effective antifungal drug development for the treatment ofC. glabratainfections.

scholarly journals Trends in Antifungal Drug Susceptibility of Cryptococcus neoformans Isolates in the United States: 1992 to 1994 and 1996 to 1998

2001 ◽  
Vol 45 (11) ◽  
pp. 3065-3069 ◽  
Author(s):  
Mary E. Brandt ◽  
Michael A. Pfaller ◽  
Rana A. Hajjeh ◽  
Richard J. Hamill ◽  
Peter G. Pappas ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Amphotericin B ◽  
Antifungal Agents ◽  
Clinical Laboratory ◽  
The United States ◽  
Drug Susceptibility ◽  
Antifungal Drug ◽  
National Committee ◽  
Broth Microdilution Method

ABSTRACT The antifungal drug susceptibilities of two collections ofCryptococcus 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 (MIC50s), and the MIC90s 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 (≥2 μg/ml) for 2 isolates, and the MICs of flucytosine were elevated (≥32 μg/ml) for 14 isolates. Among the azoles, the fluconazole MIC was elevated (≥64 μg/ml) for 8 isolates and the itraconazole MIC (≥1 μg/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.

scholarly journals Genetic Diversity and In Vitro Antifungal Susceptibility of 200 Clinical and Environmental Aspergillus flavus Isolates

2017 ◽  
Vol 61 (5) ◽  
Author(s):  
Mojtaba Taghizadeh-Armaki ◽  
Mohammad Taghi Hedayati ◽  
Saham Ansari ◽  
Saeed Mahdavi Omran ◽  
Sasan Saber ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Aspergillus Flavus ◽  
Susceptibility Testing ◽  
Antifungal Susceptibility ◽  
Content Type ◽  
Microdilution Method ◽  
Microsatellite Genotype ◽  
Broth Microdilution Method ◽  
In Vitro Antifungal Susceptibility

ABSTRACT Aspergillus flavus has been frequently reported as the leading cause of invasive aspergillosis in certain tropical and subtropical countries. Two hundred A. flavus strains originating from clinical and environmental sources and collected between 2008 and 2015 were phylogenetically identified at the species level by analyzing partial β-tubulin and calmodulin genes. In vitro antifungal susceptibility testing was performed against antifungals using the European Committee on Antimicrobial Susceptibility Testing (EUCAST) broth microdilution method. In addition, genotyping was performed using a short-tandem-repeat (STR) assay of a panel of six microsatellite markers (A. flavus 2A, 2B, 2C, 3A, 3B, and 3C), in order to determine the genetic variation and the potential relationship between clinical and environmental isolates. The geometric means of the minimum inhibitory concentrations/minimum effective concentrations (MICs/MECs) of the antifungals across all isolates were (in increasing order): posaconazole, 0.13 mg/liter; anidulafungin, 0.16 mg/liter; itraconazole, 0.29 mg/liter; caspofungin, 0.42 mg/liter; voriconazole, 0.64 mg/liter; isavuconazole, 1.10 mg/liter; amphotericin B, 3.35 mg/liter; and flucytosine, 62.97 mg/liter. All of the clinical isolates were genetically different. However, an identical microsatellite genotype was found between a clinical isolate and two environmental strains. In conclusion, posaconazole and anidulafungin showed the greatest in vitro activity among systemic azoles and echinocandins, respectively. However, the majority of the A. flavus isolates showed reduced susceptibility to amphotericin B. Antifungal susceptibility of A. flavus was not linked with the clinical or environmental source of isolation. Microsatellite genotyping may suggest an association between clinical and environmental strains, although this requires further investigation.

scholarly journals Oral Candidiasis among Cancer Patients Attending a Tertiary Care Hospital in Chennai, South India: An Evaluation of Clinicomycological Association and Antifungal Susceptibility Pattern

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Abirami Lakshmy Jayachandran ◽  
Radhika Katragadda ◽  
Ravinder Thyagarajan ◽  
Leela Vajravelu ◽  
Suganthi Manikesi ◽  
...  
Keyword(s):  
Cancer Patients ◽  
Amphotericin B ◽  
Oral Candidiasis ◽  
Antifungal Susceptibility ◽  
Tertiary Care ◽  
Antifungal Drug ◽  
Dilution Method ◽  
Care Hospital ◽  
Susceptibility Pattern

Oropharyngeal candidiasis is one of the common manifestations seen in cancer patients on cytotoxic therapy and invasion into deeper tissues can occur if not treated promptly. Emergence of antifungal drug resistance is of serious concern owing to the associated morbidity and mortality. The present study aims at evaluation of clinicomycological association and antifungal drug susceptibility among the 180 recruited patients with cancer on chemotherapy and/or radiotherapy with signs or symptoms suggestive of oral candidiasis. Speciation and antifungal susceptibility was done by Microbroth dilution method for fluconazole, Itraconazole, and Amphotericin B as per standard microbiological techniques. Chi-square test was used for statistical analysis (p<0.05was considered statistically significant).Candida albicanswas the predominant species isolated (94) (58%) followed byCandida tropicalis(34) (20.9%). Fluconazole and Itraconazole showed an overall resistance rate of 14% and 14.8%, respectively. All the isolates were susceptible to Amphotericin B. There was a significant association between the presence of dry mouth and isolation ofCandida(p<0.001). Such clinicomicrobiological associations can help in associating certain symptoms with the isolation ofCandida. Species level identification with in vitro antifungal susceptibility pattern is essential to choose the appropriate drug and to predict the outcome of therapy.

scholarly journals Molecular Identification, Antifungal Susceptibility Profile, and Biofilm Formation of Clinical and Environmental Rhodotorula Species Isolates

2012 ◽  
Vol 57 (1) ◽  
pp. 382-389 ◽  
Author(s):  
Jorge Meneses Nunes ◽  
Fernando César Bizerra ◽  
Renata Carmona e Ferreira ◽  
Arnaldo Lopes Colombo
Keyword(s):  
Amphotericin B ◽  
Biofilm Formation ◽  
Fungal Pathogens ◽  
Antifungal Susceptibility ◽  
Nitrate Assimilation ◽  
Clinical Isolates ◽  
Its Sequencing ◽  
Environmental Isolates ◽  
Content Type

ABSTRACTRhodotorulaspecies are emergent fungal pathogens capable of causing invasive infections, primarily fungemia. They are particularly problematic in immunosuppressed patients when using a central venous catheter. In this study, we evaluated the species distribution of 51 clinical and 8 environmentalRhodotorulaspecies isolates using the ID32C system and internal transcribed spacer (ITS) sequencing. Antifungal susceptibility testing and biofilm formation capability using a crystal violet staining assay were performed. Using ITS sequencing as the gold standard, the clinical isolates were identified as follows: 44R. mucilaginosaisolates, 2R. glutinisisolates, 2R. minutaisolates, 2R. dairenensisisolates, and 1Rhodosporidium fluvialeisolate. The environmental isolates included 7R. mucilaginosaisolates and 1R. slooffiaeisolate. Using the ID32C system, along with a nitrate assimilation test, only 90.3% of the isolates tested were correctly identified. In the biofilm formation assay,R. mucilaginosaandR. minutaexhibited greater biofilm formation ability compared to the otherRhodotorulaspecies; the clinical isolates ofR. mucilaginosashowed greater biofilm formation compared to the environmental isolates (P= 0.04). Amphotericin B showed goodin vitroactivity (MIC ≤ 1 μg/ml) against planktonic cells, whereas voriconazole and posaconazole showed poor activity (MIC50/MIC90, 2/4 μg/ml). Caspofungin and fluconazole MICs were consistently high for all isolates tested (≥64 μg/ml and ≥ 4 μg/ml, respectively). In this study, we emphasized the importance of molecular methods to correctly identifyRhodotorulaspecies isolates and non-R. mucilaginosaspecies in particular. The antifungal susceptibility profile reinforces amphotericin B as the antifungal drug of choice for the treatment ofRhodotorulainfections. To our knowledge, this is the first study evaluating putative differences in the ability of biofilm formation among differentRhodotorulaspecies.

scholarly journals In Vitro Susceptibility ofCandidaSpecies to Four Antifungal Agents Assessed by the Reference Broth Microdilution Method

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Fahriye Eksi ◽  
Efgan Dogan Gayyurhan ◽  
Iclal Balci
Keyword(s):  
Amphotericin B ◽  
Antifungal Agents ◽  
Antifungal Susceptibility ◽  
Resistance Rate ◽  
Broth Microdilution ◽  
In Vitro Susceptibility ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Dose Dependent

This study was performed to determine the distribution ofCandidaspecies isolated from the blood cultures of the patients hospitalized in our hospital and to investigate their antifungal susceptibility.Candidastrains were identified at species level by using classical methods and API ID 32C (bioMerieux, France) identification kits. The susceptibility of the strains to amphotericin B, fluconazole, voriconazole, and caspofungin was evaluated by using the reference broth microdilution method in document M27-A3 of the Clinical and Laboratory Standards Institute. Of the 111Candidastrains isolated, 47.7% were identified asC. albicansand 52.3% as non-albicansCandidastrains. The MIC ranges were 0.03–1 μg/mL for amphotericin B, 0.125–≥64 μg/mL for fluconazole, 0.03–16 μg/mL for voriconazole, and 0.015–0.25 μg/mL for caspofungin. AllCandidastrains were susceptible to amphotericin B and caspofungin. 10.8% isolates were resistant to fluconazole and 8.1% isolates were dose-dependent susceptible. While 0.9% isolate was resistant to voriconazole, 0.9% isolate was dose-dependent susceptible. In our study,C. albicansandC. parapsilosiswere the most frequently encountered agents of candidemia and it was detected that voriconazole with a low resistance rate might also be used with confidence in the treatment of infections occurring with these agents, primarily besides amphotericin B and caspofungin.

scholarly journals Trends in Antifungal Drug Susceptibility of Cryptococcus neoformans Isolates Obtained through Population-Based Surveillance in South Africa in 2002-2003 and 2007-2008

2011 ◽  
Vol 55 (6) ◽  
pp. 2606-2611 ◽  
Author(s):  
Nelesh P. Govender ◽  
Jaymati Patel ◽  
Marelize van Wyk ◽  
Tom M. Chiller ◽  
Shawn R. Lockhart ◽  
...  
Keyword(s):  
South Africa ◽  
Cryptococcus Neoformans ◽  
Amphotericin B ◽  
Fungal Infections ◽  
Antifungal Susceptibility ◽  
Drug Susceptibility ◽  
Population Based ◽  
Content Type ◽  
Microdilution Method ◽  
Broth Microdilution Method

ABSTRACTCryptococcus neoformansis the most common cause of meningitis among adult South Africans with HIV infection/AIDS. Widespread use of fluconazole for treatment of cryptococcal meningitis and other HIV-associated opportunistic fungal infections in South Africa may lead to the emergence of isolates with reduced fluconazole susceptibility. MIC testing using a reference broth microdilution method was used to determine if isolates with reduced susceptibility to fluconazole or amphotericin B had emerged among cases of incident disease. Incident isolates were tested from two surveillance periods (2002-2003 and 2007-2008) when population-based surveillance was conducted in Gauteng Province, South Africa. These isolates were also tested for susceptibility to flucytosine, itraconazole, voriconazole, and posaconazole. Serially collected isolate pairs from cases at several large South African hospitals were also tested for susceptibility to fluconazole. Of the 487 incident isolates tested, only 3 (0.6%) demonstrated a fluconazole MIC of ≥16 μg/ml; all of these isolates were from 2002-2003. All incident isolates were inhibited by very low concentrations of amphotericin B and exhibited very low MICs to voriconazole and posaconazole. Of 67 cases with serially collected isolate pairs, only 1 case was detected where the isolate collected more than 30 days later had a fluconazole MIC value significantly higher than the MIC of the corresponding incident isolate. Although routine antifungal susceptibility testing of incident isolates is not currently recommended in clinical settings, it is still clearly important for public health to periodically monitor for the emergence of resistance.

scholarly journals Flow Cytometry Antifungal Susceptibility Testing of Pathogenic Yeasts other than Candida albicans and Comparison with the NCCLS Broth Microdilution Test

2000 ◽  
Vol 44 (10) ◽  
pp. 2752-2758 ◽  
Author(s):  
Rama Ramani ◽  
Vishnu Chaturvedi
Keyword(s):  
Flow Cytometry ◽  
Candida Albicans ◽  
Amphotericin B ◽  
Susceptibility Testing ◽  
Antifungal Susceptibility ◽  
Antifungal Susceptibility Testing ◽  
Broth Microdilution ◽  
Nitrogen Base ◽  
Microdilution Method ◽  
Broth Microdilution Method

ABSTRACT Candida species other than Candida albicansfrequently cause nosocomial infections in immunocompromised patients. Some of these pathogens have either variable susceptibility patterns or intrinsic resistance against common azoles. The availability of a rapid and reproducible susceptibility-testing method is likely to help in the selection of an appropriate regimen for therapy. A flow cytometry (FC) method was used in the present study for susceptibility testing ofCandida glabrata, Candida guilliermondii,Candida krusei, Candida lusitaniae,Candida parapsilosis, Candida tropicalis, andCryptococcus neoformans based on accumulation of the DNA binding dye propidium iodide (PI). The results were compared with MIC results obtained for amphotericin B and fluconazole using the NCCLS broth microdilution method (M27-A). For FC, the yeast inoculum was prepared spectrophotometrically, the drugs were diluted in either RPMI 1640 or yeast nitrogen base containing 1% dextrose, and yeast samples and drug dilutions were incubated with amphotericin B and fluconazole, respectively, for 4 to 6 h. Sodium deoxycholate and PI were added at the end of incubation, and fluorescence was measured with a FACScan flow cytometer (Becton Dickinson). The lowest drug concentration that showed a 50% increase in mean channel fluorescence compared to that of the growth control was designated the MIC. All tests were repeated once. The MICs obtained by FC for all yeast isolates except C. lusitaniae were in very good agreement (within 1 dilution) of the results of the NCCLS broth microdilution method. Paired ttest values were not statistically significant (P = 0.377 for amphotericin B; P = 0.383 for fluconazole). Exceptionally, C. lusitaniae isolates showed higher MICs (2 dilutions or more) than in the corresponding NCCLS broth microdilution method for amphotericin B. Overall, FC antifungal susceptibility testing provided rapid, reproducible results that were statistically comparable to those obtained with the NCCLS method.

scholarly journals Evaluation of a Modified EUCAST Fragmented-Mycelium Inoculum Method forIn VitroSusceptibility Testing of Dermatophytes and the Activity of Novel Antifungal Agents

2015 ◽  
Vol 59 (6) ◽  
pp. 3675-3682 ◽  
Author(s):  
B. Risslegger ◽  
C. Lass-Flörl ◽  
G. Blum ◽  
M. Lackner
Keyword(s):  
Antifungal Agents ◽  
Susceptibility Testing ◽  
Preparation Method ◽  
Antifungal Susceptibility ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Inoculum Preparation ◽  
Minimal Effective Concentration

ABSTRACTFor antifungal susceptibility testing of nonsporulating or poorly sporulating dermatophytes, a fragmented-mycelium inoculum preparation method was established and compared to broth microdilution testing according to CLSI and EUCAST guidelines. Moreover, thein vitroactivity of new antifungal agents against dermatophytes was evaluated. Agreement between the mycelial inoculum method and the CLSI broth microdilution method was high (93% to 100%). Echinocandins (minimal effective concentration [MEC], ≤0.5 mg/liter) and posaconazole (MIC, ≤3.00 mg/liter) showed good activity against all tested dermatophytes.

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