scholarly journals Antifungal susceptibility and mutations in the squalene epoxidase gene in dermatophytes of the Trichophyton mentagrophytes species complex

2021 ◽  
Author(s):  
Xue Kong ◽  
Chao Tang ◽  
Ashutosh Singh ◽  
Sarah A. Ahmed ◽  
Abdullah M.S. Al-Hatmi ◽  
...  
Keyword(s):  
Species Complex ◽  
Novel Species ◽  
Antifungal Susceptibility ◽  
Trichophyton Mentagrophytes ◽  
Squalene Epoxidase ◽  
Free Medium ◽  
Serial Transfer ◽  
The Past ◽  
Drug Free ◽  
High Mics

Background: During the past decade, a prolonged and serious outbreak of dermatophytosis due to a terbinafine-resistant novel species in the Trichophyton mentagrophytes/T. interdigitale complex is ongoing in India, and it spreads to several European countries. Objective: To investigate the molecular background of the squalene epoxidase (SQLE) gene in order to understand the risk of emergence and spread of multi-resistance in dermatophytes. Methods: Antifungal susceptibility for fluconazole, griseofulvin, itraconazole, ketoconazole, miconazole, naftifine, sertaconazole, and terbinafine was tested in 135 isolates from India, China, Australia, Germany and The Netherlands. Based on the latest taxonomic insights, strains were identified as three species: T. mentagrophytes s. str. (n=35), T. indotineae (n=64 representing the Indian clone) and T. interdigitale s. str. (n=36). Results: High minimum inhibitory concentrations (MICs) of terbinafine (>16 mg/L) were found in 34 (53%) T. indotineae isolates. These isolates showed an amino acid substitution in the 397th position of the SQLE gene. Elevated MICs of terbinafine (0.5 mg/L) were noted in 2 (3%) T. indotineae isolates; these isolates lead to Phe415Val and Leu393Ser of the SQLE gene. Stability of the effect of the mutations was proven by serial transfer on drug-free medium. Substitutions of Lys276Asn and Leu419Phe were found in susceptible T. mentagrophytes strains. The double mutant Phe377Leu/Ala448Thr showed higher MIC values for triazoles. Conclusions: High MICs of terbinafine are as yet limited to T. indotineae, and are unlikely to be distributed through the T. mentagrophytes species complex by genetic exchange.

scholarly journals Intrinsic resistance to terbinafine among human and animal isolates of Trichophyton mentagrophytes related to amino acid substitution in the squalene epoxidase

Infection ◽  
2020 ◽  
Vol 48 (6) ◽  
pp. 889-897 ◽  
Author(s):  
Dominik Łagowski ◽  
Sebastian Gnat ◽  
Aneta Nowakiewicz ◽  
Marcelina Osińska ◽  
Mariusz Dyląg
Keyword(s):  
Amino Acid ◽  
Fungal Infections ◽  
Single Point ◽  
Antifungal Susceptibility ◽  
Point Mutations ◽  
Trichophyton Mentagrophytes ◽  
Single Amino Acid ◽  
Squalene Epoxidase ◽  
Intrinsic Resistance ◽  
Resistant Strains

Abstract Background Dermatomycoses are the most common fungal infections in the world affecting a significant part of the human and animal population. The majority of zoophilic infections in humans are caused by Trichophyton mentagrophytes. Currently, the first-line drug for both oral and topical therapy is terbinafine. However, an increasing number of cases that are difficult to be cured with this drug have been noted in Europe and Asia. Resistance to terbinafine and other allylamines is very rare and usually correlated with point mutations in the squalene epoxidase gene resulting in single amino acid substitutions in the enzyme, which is crucial in the ergosterol synthesis pathway. Purpose Here, we report terbinafine-resistant T. mentagrophytes isolates among which one was an etiological factor of tinea capitis in a man and three were obtained from asymptomatic foxes in Poland. Methods We used the CLSI protocol to determine antifungal susceptibility profiles of naftifine, amphotericin B, griseofulvin, ketoconazole, miconazole, itraconazole, voriconazole, and ciclopirox. Moreover, the squalene epoxidase gene of the terbinafine-resistant strains was sequenced and analysed. Results In the genomes of all four resistant strains exhibiting elevated MICs to terbinafine (16 to 32 µg/ml), single-point mutations leading to Leu393Phe substitution in the squalene epoxidase enzyme were revealed. Among the other tested substances, a MIC50 value of 1 µg/ml was shown only for griseofulvin. Conclusion Finally, our study revealed that the terbinafine resistance phenomenon might not be acquired by exposure to the drug but can be intrinsic. This is evidenced by the description of the terbinafine-resistant strains isolated from the asymptomatic animals.

scholarly journals cyp51A Mutations, Extrolite Profiles, and Antifungal Susceptibility in Clinical and Environmental Isolates of the Aspergillus viridinutans Species Complex

2019 ◽  
Vol 63 (11) ◽  
Author(s):  
Jessica J. Talbot ◽  
Jens C. Frisvad ◽  
Jacques F. Meis ◽  
Ferry Hagen ◽  
Paul E. Verweij ◽  
...  
Keyword(s):  
Species Complex ◽  
Antifungal Susceptibility ◽  
Gene Mutations ◽  
Azole Resistance ◽  
Wild Type ◽  
Environmental Isolates ◽  
Content Type ◽  
The Past ◽  
Agar Plug ◽  
Very High

ABSTRACT The past decade has seen an increase in aspergillosis in humans and animals due to Aspergillus viridinutans species complex members. Azole resistance is common to these infections, carrying a poor prognosis. cyp51A gene mutations are the main cause of acquired azole resistance in Aspergillus fumigatus. This study aimed to determine if the azole-resistant phenotype in A. viridinutans complex members is associated with cyp51A mutations or extrolite profiles. The cyp51A gene of clinical and environmental isolates was amplified using novel primers, antifungal susceptibility was tested using the Clinical and Laboratory Standards Institute methodology, and extrolite profiling was performed using agar plug extraction. Very high azole MICs were detected in 84% of the isolates (31/37). The MICs of the newer antifungals luliconazole and olorofim (F901318) were low for all isolates. cyp51A sequences revealed 113 nonsynonymous mutations compared to the sequence of wild-type A. fumigatus. M172A/V and D255G, previously associated with A. fumigatus azole resistance, were common among all isolates but were not correlated with azole MICs. Two environmental isolates with nonsusceptibility to itraconazole and high MICs of voriconazole and isavuconazole harbored G138C, previously associated with azole-resistant A. fumigatus. Some novel mutations were identified only among isolates with high azole MICs. However, cyp51A homology modeling did not cause a significant protein structure change for these mutations. There was no correlation between extrolite patterns and susceptibility. For A. viridinutans complex isolates, cyp51A mutations and the extrolites that they produced were not major causes of antifungal resistance. Luliconazole and olorofim show promise for treating azole-resistant infections caused by these cryptic species.

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 Infections due to Rare Cryptococcus Species. A Literature Review

2021 ◽  
Vol 7 (4) ◽  
pp. 279
Author(s):  
Soraya E. Morales-López ◽  
Guillermo Garcia-Effron
Keyword(s):  
Nervous System ◽  
Literature Review ◽  
Species Complex ◽  
Antifungal Susceptibility ◽  
Epidemiological Data ◽  
Laboratory Findings ◽  
Comprehensive Literature Review ◽  
Cryptococcus Species ◽  
Cryptococcus Spp ◽  
High Mics

Infections due to rare Cryptococcus species (other than C. neoformans species complex, C. gattii species complex, C. albidus or C. laurentii) are barely reported. The aim of this work is to present a comprehensive literature review of all the papers describing infections due to these species referenced in the main databases (PubMed/MEDLINE, ScienceDirect, Scopus, and Google Scholar). Clinical and epidemiological data together with laboratory findings (identification and antifungal susceptibility) of each isolate were analyzed. Fifty-eight cryptococosis due to rare species were described in 46 papers between 1934–2018. These reports included 16 rare Cryptococcus spp. that were generally associated with nervous system infections and fungemias. Some species are non-capsulated and are not able to grow at 37 °C. Few species were identified by commercially available methods, making internal transcriber spacer (ITS) and D1/D2 regions sequencing mandatory. The most potent antifungal was amphotericin B (although some species showed high MIC values). The studied strains showed high MICs values to 5-fluorocytosine (all >64 µg/mL), echinocandins (all >8 µg/mL), and fluconazole (>80% of the MICs >4 µg/mL). Due to the scarcity of the data and the absence of guidelines for the treatment of these infections, this review could be informative and could help in the diagnosis and treatment of these infections.

scholarly journals Molecular Epidemiology and Antifungal Susceptibility of Trichophyton Isolates in Greece: Emergence of Terbinafine-Resistant Trichophytonmentagrophytes Type VIII Locally and Globally

2021 ◽  
Vol 7 (6) ◽  
pp. 419
Author(s):  
Maria Siopi ◽  
Ioanna Efstathiou ◽  
Konstantinos Theodoropoulos ◽  
Spyros Pournaras ◽  
Joseph Meletiadis
Keyword(s):  
Molecular Epidemiology ◽  
Antifungal Susceptibility ◽  
Reference Method ◽  
Cross Resistance ◽  
Squalene Epoxidase ◽  
In Vitro Susceptibility ◽  
Type Viii ◽  
In Vitro Antifungal Susceptibility ◽  
Resistance Rates

Trichophyton isolates with reduced susceptibility to antifungals are now increasingly reported worldwide. We therefore studied the molecular epidemiology and the in vitro antifungal susceptibility patterns of Greek Trichophyton isolates over the last 10 years with the newly released EUCAST reference method for dermatophytes. Literature was reviewed to assess the global burden of antifungal resistance in Trichophyton spp. The in vitro susceptibility of 112 Trichophyton spp. molecularly identified clinical isolates (70 T. rubrum, 24 T. mentagrophytes, 12 T. interdigitale and 6 T. tonsurans) was tested against terbinafine, itraconazole, voriconazole and amorolfine (EUCAST E.DEF 11.0). Isolates were genotyped based on the internal transcribed spacer (ITS) sequences and the target gene squalene epoxidase (SQLE) was sequenced for isolates with reduced susceptibility to terbinafine. All T. rubrum, T. interdigitale and T. tonsurans isolates were classified as wild-type (WT) to all antifungals, whereas 9/24 (37.5%) T. mentagrophytes strains displayed elevated terbinafine MICs (0.25–8 mg/L) but not to azoles and amorolfine. All T. interdigitale isolates belonged to ITS Type II, while T. mentagrophytes isolates belonged to ITS Type III* (n = 11), VIII (n = 9) and VII (n = 4). All non-WT T. mentagrophytes isolates belonged to Indian Genotype VIII and harbored Leu393Ser (n = 5) and Phe397Leu (n = 4) SQLE mutations. Terbinafine resistance rates ranged globally from 0–44% for T. rubrum and 0–76% for T. interdigitale/T. mentagrophytes with strong endemicity. High incidence (37.5%) of terbinafine non-WT T. mentagrophytes isolates (all belonging to ITS Type VIII) without cross-resistance to other antifungals was found for the first time in Greece. This finding must alarm for susceptibility testing of dermatophytes at a local scale particularly in non-responding dermatophytoses.

scholarly journals The Emerging Terbinafine-Resistant Trichophyton Epidemic: What Is the Role of Antifungal Susceptibility Testing?

Dermatology ◽  
2021 ◽  
pp. 1-20
Author(s):  
Julia J. Shen ◽  
Maiken C. Arendrup ◽  
Shyam Verma ◽  
Ditte Marie L. Saunte
Keyword(s):  
Gene Mutation ◽  
Susceptibility Testing ◽  
Geometric Mean ◽  
Antifungal Susceptibility ◽  
Antifungal Susceptibility Testing ◽  
Squalene Epoxidase ◽  
Exclusion Criteria ◽  
Huge Variation

<b><i>Background:</i></b> Dermatophytosis is commonly encountered in the dermatological clinics. The main aetiological agents in dermatophytosis of skin and nails in humans are <i>Trichophyton</i> (<i>T</i>.) <i>rubrum</i>, <i>T. mentagrophytes</i> and <i>T. interdigitale</i> (former <i>T. mentagrophytes-</i>complex). Terbinafine therapy is usually effective in eradicating infections due to these species by inhibiting their squalene epoxidase (SQLE) enzyme, but increasing numbers of clinically resistant cases and mutations in the SQLE gene have been documented recently. Resistance to antimycotics is phenotypically determined by antifungal susceptibility testing (AFST). However, AFST is not routinely performed for dermatophytes and no breakpoints classifying isolates as susceptible or resistant are available, making it difficult to interpret the clinical impact of a minimal inhibitory concentration (MIC). <b><i>Summary:</i></b> PubMed was systematically searched for terbinafine susceptibility testing of dermatophytes on October 20, 2020, by two individual researchers. The inclusion criteria were <i>in vitro</i> terbinafine susceptibility testing of <i>Trichophyton (T.) rubrum</i>, <i>T. mentagrophytes</i> and <i>T. interdigitale</i> with the broth microdilution technique. The exclusion criteria were non-English written papers. Outcomes were reported as MIC range, geometric mean, modal MIC and MIC<sub>50</sub> and MIC<sub>90</sub> in which 50 or 90% of isolates were inhibited, respectively. The reported MICs ranged from &#x3c;0.001 to &#x3e;64 mg/L. The huge variation in MIC is partly explained by the heterogeneity of the <i>Trichophyton</i> isolates, where some originated from routine specimens (wild types) whereas others came from non-responding patients with a known SQLE gene mutation. Another reason for the great variation in MIC is the use of different AFST methods where MIC values are not directly comparable. High MICs were reported particularly in isolates with SQLE gene mutation. The following SQLE alterations were reported: F397L, L393F, L393S, H440Y, F393I, F393V, F415I, F415S, F415V, S443P, A448T, L335F/A448T, S395P/A448T, L393S/A448T, Q408L/A448T, F397L/A448T, I121M/V237I and H440Y/F484Y in terbinafine-resistant isolates.

scholarly journals UTERINE ADENOMATA IN THE RABBIT

1938 ◽  
Vol 67 (5) ◽  
pp. 691-708 ◽  
Author(s):  
Harry S. N. Greene ◽  
John A. Saxton
Keyword(s):  
Present Report ◽  
Pathological Study ◽  
Serial Transfer ◽  
Continuous Growth ◽  
The Past ◽  
Tumor Bearing ◽  
Uterine Mucosa ◽  
Intraocular Transplantation ◽  
Transplantation Experiments ◽  
Uterine Fundus

83 cases of an adenomatous tumor of the uterine mucosa have been observed in a colony of rabbits during the past 4 years The results of a clinical and pathological study of the tumor, together with a description of transplantation experiments are included in the present report. The clinical histories of tumor bearing animals are similar in all cases. Discovery of the tumor is preceded by a long period of reproductive disturbance, and its subsequent course is one of slow, continuous growth which has terminated in death with metastasis in all animals held under observation for longer than 1 year. Microscopically, the tumor shows an atypical alveolar structure, and its characteristics closely resemble those of an adenocarcinoma of the uterine fundus in women. Pathological changes similar to those observed in mice after treatment with estrogenic substances occur in the thyroid, suprarenal, pituitary and mammary glands. Intraocular transplantation of the tumor has been successful, and at the present time the growth has been carried through 6 generations by serial transfer.

Ethidium bromide-induced loss of mitochondrial DNA from primary chicken embryo fibroblasts

1985 ◽  
Vol 5 (5) ◽  
pp. 1163-1169
Author(s):  
P Desjardins ◽  
E Frost ◽  
R Morais
Keyword(s):  
Mitochondrial Dna ◽  
Ethidium Bromide ◽  
Chicken Embryo ◽  
Blot Hybridization ◽  
Cell Populations ◽  
Free Medium ◽  
Reassociation Kinetics ◽  
Embryo Fibroblasts ◽  
Drug Free ◽  
Chicken Embryo Fibroblasts

Chicken embryo fibroblasts in uridine-containing medium are inherently resistant to the growth-inhibitory effect of ethidium bromide. The drug was found to inhibit the incorporation of [3H]thymidine into mitochondrial DNA circular molecules. Mitochondrial DNA was quantitated by DNA-DNA reassociation kinetics with a probe of chicken liver mitochondrial DNA. A mean number of 604 copies of mitochondrial DNA per cell was found. This number decreased progressively in cells exposed to ethidium bromide, and by day 13 ca. one copy of mitochondrial DNA was detected per cell. When the cells were then transferred to drug-free medium, the number of copies increased very slowly as a function of time. On the other hand, analyses of DNA extracted from cell populations exposed to ethidium bromide for 20 or more days, with or without subsequent transfer to drug-free medium, revealed very little or no mitochondrial DNA by reassociation kinetics or by Southern blot hybridization of AvaI- or HindIII-digested total cellular DNA. As a result of the elimination of mitochondrial DNA molecules, the establishment of cell populations with a respiration-deficient phenotype was confirmed by measuring cytochrome c oxidase activity as a function of the number of cell generations and the absorption spectrum of mitochondrial cytochromes.

scholarly journals A Revised Species Concept for OpportunisticMucorSpecies Reveals Species-Specific Antifungal Susceptibility Profiles

2019 ◽  
Vol 63 (8) ◽  
Author(s):  
Lysett Wagner ◽  
Sybren de Hoog ◽  
Ana Alastruey-Izquierdo ◽  
Kerstin Voigt ◽  
Oliver Kurzai ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Susceptibility Testing ◽  
Species Concept ◽  
Antifungal Susceptibility ◽  
Content Type ◽  
Mucor Indicus ◽  
Species Specific ◽  
Susceptibility Profiles ◽  
High Mics

ABSTRACTRecently, the species concept of opportunisticMucor circinelloidesand its relatives has been revised, resulting in the recognition of its classical formae as independent species and the description of new species. In this study, we used isolates of all clinically relevantMucorspecies and performed susceptibility testing using the EUCAST reference method to identify potential species-specific susceptibility patterns.In vitrosusceptibility profiles of 101 mucoralean strains belonging to the genusMucor(72), the closely related speciesCokeromyces recurvatus(3),Rhizopus(12),Lichtheimia(10), andRhizomucor(4) to six antifungals (amphotericin B, natamycin, terbinafine, isavuconazole, itraconazole, and posaconazole) were determined. The most active drug for all Mucorales was amphotericin B. Antifungal susceptibility profiles of pathogenicMucorspecies were specific for isavuconazole, itraconazole, and posaconazole. The species formerly united inM. circinelloidesshowed clear differences in their antifungal susceptibilities.Cokeromyces recurvatus,Mucor ardhlaengiktus,Mucor lusitanicus(M. circinelloidesf.lusitanicus), andMucor ramosissimusexhibited high MICs to all azoles tested.Mucor indicuspresented high MICs for isavuconazole and posaconazole, andMucor amphibiorumandMucor irregularisshowed high MICs for isavuconazole. MIC values ofMucorspp. for posaconazole, isavuconazole, and itraconazole were high compared to those forRhizopusand the Lichtheimiaceae (LichtheimiaandRhizomucor). Molecular identification combined within vitrosusceptibility testing is recommended forMucorspecies, especially if azoles are applied in treatment.

Sign in / Sign up

Export Citation Format

Share Document