scholarly journals Mutation in the Squalene Epoxidase Gene ofTrichophyton interdigitaleandTrichophyton rubrumAssociated with Allylamine Resistance

2018 ◽  
Vol 62 (5) ◽  
Author(s):  
Shivaprakash M. Rudramurthy ◽  
Shamanth A. Shankarnarayan ◽  
Sunil Dogra ◽  
Dipika Shaw ◽  
Khurram Mushtaq ◽  
...  
Keyword(s):  
Antifungal Agents ◽  
Susceptibility Testing ◽  
Trichophyton Rubrum ◽  
Antifungal Susceptibility ◽  
Ergosterol Biosynthesis ◽  
Squalene Epoxidase ◽  
Biosynthesis Pathway ◽  
Wild Type ◽  
Content Type ◽  
Recent Attention

ABSTRACTDermatophytosis, the commonest superficial fungal infection, has gained recent attention due to its change of epidemiology and treatment failures. Despite the availability of several agents effective against dermatophytes, the incidences of chronic infection, reinfection, and treatment failures are on the rise.Trichophyton rubrumandTrichophyton interdigitaleare the two species most frequently identified among clinical isolates in India. Consecutive patients (n= 195) with suspected dermatophytosis during the second half of 2014 were included in this study. Patients were categorized into relapse and new cases according to standard definitions. Antifungal susceptibility testing of the isolatedTrichophytonspecies (n= 127) was carried out with 12 antifungal agents: fluconazole, voriconazole, itraconazole, ketoconazole, sertaconazole, clotrimazole, terbinafine, naftifine, amorolfine, ciclopirox olamine, griseofulvin, and luliconazole. The squalene epoxidase gene was evaluated for mutation (if any) in 15T. interdigitaleand 5T. rubrumisolates exhibiting high MICs for terbinafine. A T1189C mutation was observed in fourT. interdigitaleand twoT. rubrumisolates. This transition leads to the change of phenylalanine to leucine in the 397th position of the squalene epoxidase enzyme. In homology modeling the mutant residue was smaller than the wild type and positioned in the dominant site of squalene epoxidase during drug interaction, which may lead to a failure to block the ergosterol biosynthesis pathway by the antifungal drug.

scholarly journals Rare modification in the ergosterol biosynthesis pathway leads to amphotericin B resistance in Candida auris clinical isolates

2021 ◽  
Author(s):  
Milena Kordalewska ◽  
Kevin D. Guerrero ◽  
Timothy D. Mikulski ◽  
Tony N. Elias ◽  
Rocio Garcia-Rubio ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Susceptibility Testing ◽  
Antifungal Susceptibility ◽  
Clinical Isolates ◽  
Resistant Isolate ◽  
Ergosterol Biosynthesis ◽  
Biosynthesis Pathway ◽  
Wild Type ◽  
Candida Auris ◽  
Key Genes

We determined amphotericin B (AmB) susceptibility and sequenced key genes of the ergosterol biosynthesis pathway implicated in AmB resistance (ERG2, ERG3, ERG6, ERG11) of 321 clinical isolates of Candida auris. In antifungal susceptibility testing, 19 (5.9%) isolates were categorized as AmB-resistant (MIC ≥2 mg/l). Only one AmB-resistant isolate presented a unique non-wild-type ERG6 genotype that was confirmed to confer amphotericin B resistance (MIC >32 mg/l) when introduced into a susceptible strain (MIC = 0.5 mg/l).

scholarly journals Emerging Terbinafine Resistance in Trichophyton: Clinical Characteristics, Squalene Epoxidase Gene Mutations, and a Reliable EUCAST Method for Detection

2019 ◽  
Vol 63 (10) ◽  
Author(s):  
Ditte M. L. Saunte ◽  
Rasmus K. Hare ◽  
Karin M. Jørgensen ◽  
René Jørgensen ◽  
Mette Deleuran ◽  
...  
Keyword(s):  
Homology Modeling ◽  
Susceptibility Testing ◽  
Topical Therapy ◽  
Antifungal Susceptibility ◽  
Acquired Resistance ◽  
Three Dimensional ◽  
Public Health Problem ◽  
Squalene Epoxidase ◽  
Content Type ◽  
The Mean

ABSTRACT In recent years, cases involving terbinafine-resistant Trichophyton isolates have been reported increasingly, particularly in India. We present 14 cases of terbinafine treatment failure in Trichophyton-infected Danish patients due to acquired resistance. Patients infected with Trichophyton rubrum (n = 12) or Trichophyton interdigitale (n = 2) with elevated terbinafine MICs during 2013–2018 were included. Antifungal susceptibility testing (AFST) was performed following a modified EUCAST E.Def 9.3.1 method (5 days of incubation) with or without cycloheximide and chloramphenicol (CC) supplementation of the growth medium. The squalene epoxidase (SE) target gene was sequenced, and 3-dimensional enzyme homology modeling was performed. Most patients (12/14 [86%]) were male. The mean age was 53.5 years (range, 11 to 77 years). The mean duration of infections was 4.8 years at the time of resistance detection. Prior systemic terbinafine treatment was documented for all patients, and topical therapy for 62% (information was missing in one case). Overall, nine isolates (64%) displayed high terbinafine resistance (MICs, 4 to >8 mg/liter), while two (14%) displayed moderate (MICs, 1 to 2 mg/liter) and three (21%) displayed low (MICs, 0.125 to 0.25 mg/liter) terbinafine resistance compared with control isolates. MICs generated with or without CC supplementation were similar, but CC prevented contamination. Known and novel SE amino acid substitutions (F397L, L393F, L393S, F415S, H440Y F484Y, and I121M V237I) were detected in resistant but not control isolates. Three-dimensional homology modeling suggested a role of the novel I121M and V237I alterations. Terbinafine resistance has been detected in Denmark using a modified EUCAST method, which facilitated susceptibility testing of dermatophytes. Action is needed for this emerging public health problem.

scholarly journals Comparison of the Sensititre YeastOne and CLSI M38-A2 Microdilution Methods in Determining the Activity of Amphotericin B, Itraconazole, Voriconazole, and Posaconazole against Aspergillus Species

2018 ◽  
Vol 56 (10) ◽  
Author(s):  
Hsuan-Chen Wang ◽  
Ming-I Hsieh ◽  
Pui-Ching Choi ◽  
Chi-Jung Wu
Keyword(s):  
Aspergillus Fumigatus ◽  
Amphotericin B ◽  
Antifungal Agents ◽  
Susceptibility Testing ◽  
Geometric Mean ◽  
Antifungal Susceptibility ◽  
Reference Method ◽  
Aspergillus Species ◽  
Broth Microdilution ◽  
Content Type

ABSTRACT This study compared the YeastOne and reference CLSI M38-A2 broth microdilution methods for antifungal susceptibility testing of Aspergillus species. The MICs of antifungal agents were determined for 100 Aspergillus isolates, including 54 Aspergillus fumigatus (24 TR34/L98H isolates), 23 A. flavus, 13 A. terreus, and 10 A. niger isolates. The overall agreement (within 2 2-fold dilutions) between the two methods was 100%, 95%, 92%, and 90% for voriconazole, posaconazole, itraconazole, and amphotericin B, respectively. The voriconazole geometric mean (GM) MICs were nearly identical for all isolates using both methods, whereas the itraconazole and posaconazole GM MICs obtained using the YeastOne method were approximately 1 dilution lower than those obtained using the reference method. In contrast, the amphotericin B GM MIC obtained using the YeastOne method was 3.3-fold higher than that observed using the reference method. For the 24 A. fumigatus TR34/L98H isolates assayed, the categorical agreement (classified according to the CLSI epidemiological cutoff values) was 100%, 87.5%, and 83.3% for itraconazole, voriconazole, and posaconazole, respectively. For four A. niger isolates, the itraconazole MICs were >8 μg/ml using the M38-A2 method due to trailing growth, whereas the corresponding itraconazole MICs obtained using the YeastOne method were all ≤0.25 μg/ml without trailing growth. These data suggest that the YeastOne method can be used as an alternative for azole susceptibility testing of Aspergillus species and for detecting the A. fumigatus TR34/L98H isolates but that this method fails to detect A. niger isolates exhibiting trailing growth with itraconazole. Additionally, for isolates with azole MICs that approach or that are at susceptibility breakpoints or with high amphotericin B MICs detected using the YeastOne method, further MIC confirmation using the reference CLSI method is needed.

scholarly journals In VitroActivity of Isavuconazole against Opportunistic Fungal Pathogens from Two Mycology Reference Laboratories

2018 ◽  
Vol 62 (10) ◽  
Author(s):  
Michael A. Pfaller ◽  
Paul R. Rhomberg ◽  
Nathan P. Wiederhold ◽  
Connie Gibas ◽  
Carmita Sanders ◽  
...  
Keyword(s):  
Species Complex ◽  
Fungal Pathogens ◽  
Antifungal Agents ◽  
Antifungal Susceptibility ◽  
Wild Type ◽  
Content Type ◽  
Excellent Activity ◽  
Comparable Activity ◽  
Yeasts And Molds ◽  
Susceptibility Patterns

ABSTRACTMonitoring antifungal susceptibility patterns for new and established antifungal agents seems prudent given the increasing prevalence of uncommon species associated with higher antifungal resistance. We evaluated the activity of isavuconazole against 4,856 invasive yeasts and molds collected worldwide. The 4,856 clinical fungal isolates, including 2,351Candidaspecies isolates, 97 non-Candidayeasts, 1,972Aspergillusspecies isolates, and 361 non-Aspergillusmolds, including 292Mucoralesisolates collected in 2015 to 2016, were tested using CLSI methods. The MIC values for isavuconazole versusAspergillusranged from 0.06 to ≥16 μg/ml. The modal MIC for isavuconazole was 0.5 μg/ml (range, 0.25 [A. nidulansandA. terreusspecies complex] to 4 μg/ml [A. calidoustusandA. tubingensis]). EightA. fumigatusisolates had elevated isavuconazole MIC values at ≥8 μg/ml (non-wild type). Isavuconazole showed comparable activity to itraconazole against theMucorales. The lowest modal isavuconazole MIC values were seen forRhizopusspp.,R. arrhizusvar.arrhizus, andR. microsporus(all 1 μg/ml).Candidaspecies isolates were inhibited by ≤0.25 μg/ml of isavuconazole (range, 96.1% [C. lusitaniae] to 100.0% [C. albicans,C. dubliniensis,C. kefyr, andC. orthopsilosis]). MIC values were ≤1 μg/ml for 95.5% ofC. glabrataisolates and 100.0% ofC. kruseiisolates. Isavuconazole was active against the non-Candidayeasts, includingCryptococcus neoformans(100.0% at ≤0.5 μg/ml). Isavuconazole exhibited excellent activity against most species ofCandidaandAspergillus. Isavuconazole was comparable to posaconazole and voriconazole against the less common yeasts and molds. Isavuconazole was generally less active than posaconazole and more active than voriconazole against the 292Mucoralesisolates. We confirm the potentially useful activity of isavuconazole against species ofRhizopusas determined by CLSI methods.

scholarly journals In VitroActivity of ASP2397 against Aspergillus Isolates with or without Acquired Azole Resistance Mechanisms

2015 ◽  
Vol 60 (1) ◽  
pp. 532-536 ◽  
Author(s):  
Maiken Cavling Arendrup ◽  
Rasmus Hare Jensen ◽  
Manuel Cuenca-Estrella
Keyword(s):  
Amphotericin B ◽  
Target Gene ◽  
Antifungal Agents ◽  
Susceptibility Testing ◽  
Resistance Mechanisms ◽  
Azole Resistance ◽  
Wild Type ◽  
Resistance Mutations ◽  
Content Type

ABSTRACTASP2397 is a new compound with a novel and as-yet-unknown target different from that of licensed antifungal agents. It has activity againstAspergillusandCandida glabrata. We compared itsin vitroactivity against wild-type and azole-resistantA. fumigatusandA. terreusisolates with that of amphotericin B, itraconazole, posaconazole, and voriconazole. Thirty-four isolates, including 4 wild-typeA. fumigatusisolates, 24A. fumigatusisolates with alterations in CYP51A TR/L98H (5 isolates), M220 (9 isolates), G54 (9 isolates), and HapE (1 isolate), andA. terreusisolates (2 wild-type isolates and 1 isolate with an M217I CYP51A alteration), were analyzed. EUCAST E.Def 9.2 and CLSI M38-A2 MIC susceptibility testing was performed. ASP2397 MIC50values (in milligrams per liter, with MIC ranges in parentheses) determined by EUCAST and CLSI were 0.5 (0.25 to 1) and 0.25 (0.06 to 0.25) againstA. fumigatusCYP51A wild-type isolates and were similarly 0.5 (0.125 to >4) and 0.125 (0.06 to >4) against azole-resistantA. fumigatusisolates, respectively. These values were comparable to those for amphotericin B, which were 0.25 (0.125 to 0.5) and 0.25 (0.125 to 0.25) against wild-type isolates and 0.25 (0.125 to 1) and 0.25 (0.125 to 1) against isolates with azole resistance mechanisms, respectively. In contrast, MICs for the azole compounds were elevated and highest for itraconazole: >4 (1 to >4) and 4 (0.5 to >4) against isolates with azole resistance mechanisms compared to 0.125 (0.125 to 0.25) and 0.125 (0.06 to 0.25) against wild-type isolates, respectively. ASP2397 was active againstA. terreusCYP51A wild-type isolates (MIC 0.5 to 1), whereas MICs of both azole and ASP2397 were elevated for the mutant isolate. ASP2397 displayedin vitroactivity againstA. fumigatusandA. terreusisolates which was independent of the presence or absence of azole target gene resistance mutations inA. fumigatus. The findings are promising at a time when azole-resistantA. fumigatusis emerging globally.

scholarly journals Antifungal Susceptibility Testing of Aspergillus spp. by Using a Composite Correlation Index (CCI)-Based Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry Method Appears To Not Offer Benefit over Traditional Broth Microdilution Testing

2017 ◽  
Vol 55 (7) ◽  
pp. 2030-2034 ◽  
Author(s):  
Melissa R. Gitman ◽  
Lisa McTaggart ◽  
Joanna Spinato ◽  
Rahgavi Poopalarajah ◽  
Erin Lister ◽  
...  
Keyword(s):  
Susceptibility Testing ◽  
Antifungal Susceptibility ◽  
Laser Desorption Ionization ◽  
Wild Type ◽  
Ionization Time ◽  
Content Type ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Flight Mass Spectrometry ◽  
Tof Ms

ABSTRACT Aspergillus spp. cause serious invasive lung infections, and Aspergillus fumigatus is the most commonly encountered clinically significant species. Voriconazole is considered to be the drug of choice for treating A. fumigatus infections; however, rising resistance rates have been reported. We evaluated a matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS)-based method for the differentiation between wild-type and non-wild-type isolates of 20 Aspergillus spp. (including 2 isolates of Aspergillus ustus and 1 of Aspergillus calidoustus that were used as controls due their intrinsic low azole susceptibility with respect to the in vitro response to voriconazole). At 30 and 48 h of incubation, there was complete agreement between Cyp51A sequence analysis, broth microdilution, and MALDI-TOF MS classification of isolates as wild type or non-wild type. In this proof-of-concept study, we demonstrated that MALDI-TOF MS can be used to accurately detect A. fumigatus strains with reduced voriconazole susceptibility. However, rather than proving to be a rapid and simple method for antifungal susceptibility testing, this particular MS-based method showed no benefit over conventional testing methods.

scholarly journals Susceptibility Testing of Common and Uncommon Aspergillus Species against Posaconazole and Other Mold-Active Antifungal Azoles Using the Sensititre Method

2017 ◽  
Vol 61 (6) ◽  
Author(s):  
Enrica Mello ◽  
Brunella Posteraro ◽  
Antonietta Vella ◽  
Elena De Carolis ◽  
Riccardo Torelli ◽  
...  
Keyword(s):  
Antifungal Agents ◽  
Susceptibility Testing ◽  
Reference Method ◽  
Aspergillus Species ◽  
Wild Type ◽  
Mutant Genotype ◽  
Cutoff Value ◽  
Content Type

ABSTRACT We tested 59 common and 27 uncommon Aspergillus species isolates for susceptibility to the mold-active azole antifungal agents itraconazole, voriconazole, and posaconazole using the Sensititre method. The overall essential agreement with the CLSI reference method was 96.5% for itraconazole and posaconazole and was 100% for voriconazole. By the Sensititre method as well as the CLSI reference method, all of 10 A. fumigatus isolates with a cyp51 mutant genotype were classified as being non-wild-type isolates (MIC > epidemiological cutoff value [ECV]) with respect to triazole susceptibility.

scholarly journals MIC and Upper Limit of Wild-Type Distribution for 13 Antifungal Agents against a Trichophyton mentagrophytes-Trichophyton interdigitale Complex of Indian Origin

2020 ◽  
Vol 64 (4) ◽  
Author(s):  
Dipika Shaw ◽  
Shreya Singh ◽  
Sunil Dogra ◽  
Jyothi Jayaraman ◽  
Ramesh Bhat ◽  
...  
Keyword(s):  
Antifungal Susceptibility ◽  
Trichophyton Mentagrophytes ◽  
Squalene Epoxidase ◽  
Wild Type ◽  
Content Type ◽  
Ciclopirox Olamine ◽  
Trichophyton Interdigitale ◽  
Medical Centers ◽  
Upper Limit ◽  
Indian Origin

ABSTRACT Dermatophytosis due to the Trichophyton mentagrophytes-Trichophyton interdigitale complex is being increasingly reported across India. Reports of therapeutic failure have surfaced recently, but there are no clinical break points (CBP) or epidemiological cutoffs (ECVs) available to guide the treatment of dermatophytosis. In this study, a total of 498 isolates of the T. mentagrophytes-interdigitale complex were collected from six medical centers over a period of five years (2014 to 2018). Antifungal susceptibility testing of the isolates was carried out for itraconazole, fluconazole, ketoconazole, voriconazole, luliconazole, sertaconazole, miconazole, clotrimazole, terbinafine, amorolfine, naftifine, ciclopirox olamine, and griseofulvin. The MICs (in mg/liter) comprising >95% of the modeled populations were as follows: 0.06 for miconazole, luliconazole, and amorolfine; 0.25 for voriconazole; 0.5 for itraconazole, ketoconazole, and ciclopirox olamine; 1 for clotrimazole and sertaconazole; 8 for terbinafine; 16 for naftifine; 32 for fluconazole; and 64 for griseofulvin. A high percentage of isolates above the upper limit of the wild-type MIC (UL-WT) were observed for miconazole (29%), luliconazole (13.9%), terbinafine (11.4%), naftifine (5.2%), and voriconazole (4.8%), while they were low for itraconazole (0.2%). Since the MICs of itraconazole were low against the T. mentagrophytes-interdigitale complex, this could be considered the choice of first-line treatment. The F397L mutation in the squalene epoxidase (SE) gene was observed in 77.1% of isolates with a terbinafine MIC of ≥1 mg/liter, but no mutation was detected in isolates with a terbinafine MIC of <1 mg/liter. In the absence of CBPs, evaluation of the UL-WT may be beneficial for managing dermatophytosis and monitoring the emergence of isolates with reduced susceptibility.

scholarly journals In Vitro Antifungal Susceptibility Testing of Candida Isolates with the EUCAST Methodology, a New Method for ECOFF Determination

2017 ◽  
Vol 61 (4) ◽  
Author(s):  
J. Meletiadis ◽  
I. Curfs-Breuker ◽  
J. F. Meis ◽  
J. W. Mouton
Keyword(s):  
Susceptibility Testing ◽  
Antifungal Susceptibility ◽  
Antifungal Drugs ◽  
Second Derivative ◽  
Wild Type ◽  
Content Type ◽  
Microdilution Method ◽  
In Vitro Antifungal Susceptibility ◽  
Resistance Rates

ABSTRACT The in vitro susceptibilities of 1,099 molecularly identified clinical Candida isolates against 8 antifungal drugs were determined using the EUCAST microdilution method. A new simple, objective, and mathematically solid method for determining epidemiological cutoff values (ECOFFs) was developed by derivatizing the MIC distribution and determining the derivatized ECOFF (dECOFF) as the highest MIC with the maximum second derivative. The dECOFFs were similar (95% agreement within 1 dilution) to the EUCAST ECOFFs. Overall, low non-wild-type/resistance rates were found. The highest rates were found for azoles with C. parapsilosis (2.7 to 9.8%), C. albicans (7%), and C. glabrata (1.7 to 2.3%) and for echinocandins with C. krusei (3.3%), C. albicans (1%), and C. tropicalis (1.7%).

scholarly journals In VitroActivity of a Novel Broad-Spectrum Antifungal, E1210, Tested against Aspergillus spp. Determined by CLSI and EUCAST Broth Microdilution Methods

2011 ◽  
Vol 55 (11) ◽  
pp. 5155-5158 ◽  
Author(s):  
Michael A. Pfaller ◽  
Frederick Duncanson ◽  
Shawn A. Messer ◽  
Gary J. Moet ◽  
Ronald N. Jones ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Broad Spectrum ◽  
Antifungal Agents ◽  
Susceptibility Testing ◽  
Hyphal Growth ◽  
Wild Type ◽  
Minimum Effective Concentration ◽  
Content Type ◽  
Excellent Activity

ABSTRACTE1210 is a first-in-class broad-spectrum antifungal that suppresses hyphal growth by inhibiting fungal glycophosphatidylinositol (GPI) biosynthesis. In the present study, we extend these findings by examining the activity of E1210 and comparator antifungal agents againstAspergillusspp. by using the methods of the Clinical and Laboratory Standards Institute (CLSI) and the European Committee for Antimicrobial Susceptibility Testing (EUCAST) to test wild-type (WT) as well as amphotericin B (AMB)-resistant (-R) and azole-R strains (as determined by CLSI methods). Seventy-eight clinical isolates ofAspergilluswere tested including 20 isolates ofAspergillus flavusspecies complex (SC), 22 ofA. fumigatusSC, 13 ofA. nigerSC, and 23 ofA. terreusSC. The collection included 15 AMB-R (MIC, ≥2 μg/ml) isolates ofA. terreusSC and 10 itraconazole-R (MIC, ≥4 μg/ml) isolates ofA. fumigatusSC (7 isolates),A. nigerSC (2 isolates), andA. terreusSC (1 isolate). Comparator antifungal agents included anidulafungin, caspofungin, amphotericin B, itraconazole, posaconzole, and voriconazole. Both CLSI and EUCAST methods were highly concordant for E1210 and all comparators. The essential agreement (EA; ±2 log2dilution steps) was 100% for all comparisons with the exception of posaconazole versusA. terreusSC (EA = 91.3%). The minimum effective concentration (MEC)/MIC90values (μg/ml) for E1210, anidulafungin, caspofungin, itraconazole, posaconazole, and voriconazole, respectively, were as follows for each species: forA. flavusSC, 0.03, ≤0.008, 0.12, 1, 1, and 1; forA. fumigatusSC, 0.06, 0.015, 0.12, >8, 1, and 4; forA. nigerSC, 0.015, 0.03, 0.12, 4, 1, and 2; and forA. terreusSC, 0.06, 0.015, 0.12, 1, 0.5, and 1. E1210 was very active against AMB-R strains ofA. terreusSC (MEC range, 0.015 to 0.06 μg/ml) and itraconazole-R strains ofA. fumigatusSC (MEC range, 0.03 to 0.12 μg/ml),A. nigerSC (MEC, 0.008 μg/ml), andA. terreusSC (MEC, 0.015 μg/ml). In conclusion, E1210 was a very potent and broad-spectrum antifungal agent regardless ofin vitromethod applied, with excellent activity against AMB-R and itraconazole-R strains ofAspergillusspp.

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