scholarly journals Hmg1 Gene Mutation Prevalence in Triazole-Resistant Aspergillus fumigatus Clinical Isolates

2020 ◽  
Vol 6 (4) ◽  
pp. 227
Author(s):  
Agustin Resendiz-Sharpe ◽  
Margriet W.J. Hokken ◽  
Toine Mercier ◽  
Rita Merckx ◽  
Kamiel Verhagen ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Gene Mutation ◽  
Gene Mutations ◽  
Clinical Isolates ◽  
In Vitro Susceptibility ◽  
In Vitro Susceptibility Testing ◽  
Center Of Expertise ◽  
Clinical Records ◽  
National Reference Center

Recently, mutations in the 3-hydroxy-3-methylglutaryl-coenzyme-A-reductase-encoding gene (hmg1), a gene involved in ergosterol production, were associated with triazole-resistance in Aspergillus fumigatus. In this study, we determined the prevalence and characteristics of hmg1 mutations in a collection of clinical triazole-resistant A. fumigatus isolates collected during 2001–2019 from two international mycology reference centers: the Belgian National Reference Center for Mycosis and the Center of Expertise in Mycology Radboudumc/CWZ. Clinical isolates with and without cyp51A gene mutations and randomly selected wild-type (WT) controls were included. Isolates were characterized by in vitro susceptibility testing, cyp51A and hmg1 sequencing, and short tandem repeat typing. Available clinical records were analyzed for previous triazole exposure. In 23 isolates (24%) of the 95 triazole-resistant A. fumigatus isolates, hmg1 gene mutations were observed; including 5/23 (22%) isolates without cyp51A gene mutations and 18/72 (25%) with cyp51A mutations. Four previously described hmg1 gene mutations (E105K, G307R/D, G466V, and S541G) and two novel mutations (W273S and L304P) were found; 4/23 (17%) in the sterol-sensing-domain region. No triazole-antifungal exposure was reported in 75% (9/12) of patients harboring an isolate with hmg1 gene mutations. Three of 39 WT isolates (8%) contained a hmg1 gene mutation; E105K (2-isolates) and S541G. Hmg1 gene mutations were predominantly found in A. fumigatus with cyp51A mutations with voriconazole MICs ≥ 8 mg/L.

Azole resistance among clinical isolates of Aspergillus fumigatus in Lima-Peru

2019 ◽  
Vol 58 (1) ◽  
pp. 54-60 ◽  
Author(s):  
Beatriz Bustamante ◽  
Luis Ricardo Illescas ◽  
Andrés Posadas ◽  
Pablo E Campos
Keyword(s):  
Aspergillus Fumigatus ◽  
Latin American ◽  
Pcr Amplification ◽  
Sensu Stricto ◽  
Clinical Isolates ◽  
Azole Resistance ◽  
Molecular Testing ◽  
Naive Patient ◽  
In Vitro Susceptibility

Abstract Azole resistance among Aspergillus fumigatus isolates, which is mainly related to mutations in the cyp51A gene, is a concern because it is rising, worldwide disseminated, and associated with treatment failure and death. Data on azole resistance of aspergillus from Latin American countries is very scarce and do not exist for Peru. Two hundred and seven Aspergillus clinical isolates collected prospectively underwent mycology and molecular testing for specie identification, and 143 isolates were confirmed as A. fumigatus sensu stricto (AFSS). All AFSS were tested for in vitro azole susceptibility, and resistant isolates underwent PCR amplification and sequencing of the whole cyp51A gene and its promoter. The in vitro susceptibility showed a minimal inhibitory concentration (MIC) range, MIC50 and MIC90 of 0.125 to >16, 0.25, and 0.5 μg/ml for itraconazole; 0.25 to 2, 0.5, and 0.5 μg/ml for voriconazole; and 0.003 to 1, 0.06, and 0.125 μg/ml for posaconazole. Three isolates (2%) showed resistance to itraconazole and exhibited different mutations of the cyp51A gene. One isolate harbored the mutation M220K, while a second one exhibited the G54 mutation plus a modification in the cyp51A gene promoter. The third isolate, from an azole naive patient, presented an integration of a 34-bp tandem repeat (TR34) in the promoter region of the gene and a substitution of leucine 98 by histidine (L98H). The three source patients had a diagnosis or suspicion of chronic pulmonary aspergillosis.

scholarly journals In Vitro Comparative Efficacy of Voriconazole and Itraconazole against Fluconazole-Susceptible and -Resistant Cryptococcus neoformans Isolates

1998 ◽  
Vol 42 (2) ◽  
pp. 471-472 ◽  
Author(s):  
M. Hong Nguyen ◽  
Christine Y. Yu
Keyword(s):  
Cryptococcus Neoformans ◽  
Susceptibility Testing ◽  
Clinical Isolates ◽  
Comparative Efficacy ◽  
In Vitro Susceptibility ◽  
In Vitro Susceptibility Testing ◽  
Fluconazole Resistant ◽  
Dose Dependent

ABSTRACT In vitro susceptibility testing for 50 clinical isolates of fluconazole-susceptible or -resistant Cryptococcus neoformans was performed with itraconazole and voriconazole. Voriconazole was more potent than itraconazole for fluconazole-susceptible isolates and as potent as itraconazole for fluconazole-susceptible dose-dependent isolates and for fluconazole-resistant isolates. For fluconazole-resistant isolates, the voriconazole and itraconazole MICs ranged from 1 to 2 μg/ml.

scholarly journals Molecular Studies Reveal Frequent Misidentification of Aspergillus fumigatus by Morphotyping

2006 ◽  
Vol 5 (10) ◽  
pp. 1705-1712 ◽  
Author(s):  
S. Arunmozhi Balajee ◽  
David Nickle ◽  
Janos Varga ◽  
Kieren A. Marr
Keyword(s):  
Aspergillus Fumigatus ◽  
Amphotericin B ◽  
Distinct Species ◽  
Enzyme Polymorphism ◽  
Antifungal Drugs ◽  
Clinical Isolates ◽  
Polymorphism Analysis ◽  
In Vitro Susceptibility ◽  
Epidemiological Surveys

ABSTRACT Aspergillus fumigatus has been understood to be the most common cause of invasive aspergillosis (IA) in all epidemiological surveys. However, recent studies have uncovered a large degree of genetic heterogeneity between isolates morphologically identified as A. fumigatus, leading to the description of a new species, Aspergillus lentulus. Here, we examined the genetic diversity of clinical isolates identified as A. fumigatus using restriction enzyme polymorphism analysis and sequence-based identification. Analysis of 50 clinical isolates from geographically diverse locations recorded the presence of at least three distinct species: A. lentulus, Aspergillus udagawae, and A. fumigatus. In vitro, A. lentulus isolates demonstrated decreased susceptibility to antifungal drugs currently used for IA, including amphotericin B, voriconazole, and caspofungin; A. udagawae isolates demonstrated decreased in vitro susceptibility to amphotericin B. Results of the present study demonstrate that current phenotypic methods to identify fungi do not differentiate between genetically distinct species in the A. fumigatus group. Differential antifungal susceptibilities of these species may account for some of the reported poor outcomes of therapy in clinical studies.

scholarly journals Mutations in a 23S rRNA Gene of Chlamydia trachomatis Associated with Resistance to Macrolides

2004 ◽  
Vol 48 (4) ◽  
pp. 1347-1349 ◽  
Author(s):  
O. Y. Misyurina ◽  
E. V. Chipitsyna ◽  
Y. P. Finashutina ◽  
V. N. Lazarev ◽  
T. A. Akopian ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Chlamydia Trachomatis ◽  
Gene Mutations ◽  
Clinical Isolates ◽  
23S Rrna ◽  
Rrna Gene ◽  
In Vitro Susceptibility ◽  
23S Rrna Gene ◽  
Mixed Populations

ABSTRACT For six clinical isolates of Chlamydia trachomatis, in vitro susceptibility to erythromycin, azithromycin, and josamycin has been determined. Four isolates were resistant to all the antibiotics and had the mutations A2058C and T2611C (Escherichia coli numbering) in the 23S rRNA gene. All the isolates had mixed populations of bacteria that did and did not carry 23S rRNA gene mutations.

A comparative study of the broth micro- and macro-dilution techniques for the determination of the in vitro susceptibility ofAspergillus fumigatus

1996 ◽  
Vol 42 (9) ◽  
pp. 960-964 ◽  
Author(s):  
Elias K. Manavathu ◽  
George J. Alangaden ◽  
Stephen A. Lerner
Keyword(s):  
Aspergillus Fumigatus ◽  
Amphotericin B ◽  
Medical Center ◽  
Acquired Resistance ◽  
Inoculum Size ◽  
Clinical Isolates ◽  
Medium Temperature ◽  
In Vitro Susceptibility ◽  
Broth Macrodilution

The effects of inoculum size, medium, temperature, and duration of growth on the in vitro susceptibility testing of Aspergillus fumigatus were investigated using broth micro- and macro-dilution techniques. The minimum inhibitory concentrations (MICs) of ketoconazole, miconazole, itraconazole, fluconazole, and amphotericin B were significantly influenced by the inoculum size, regardless of the techniques used. Two- to four-fold higher MIC values were obtained when the inoculum size was increased 100-fold. The use of peptone yeast extract glucose and RPMI 1640 media provided essentially identical MIC values at 30 and 35 °C after incubation for 48 h or longer. A comparison of broth micro- and macro-dilution techniques revealed that, under equivalent conditions, the latter with an inoculum size between 1 × 103and 1 × 104conidia (strain W73355)/mL consistently provided the lowest MICs of fluconazole (256 μg/mL), ketoconazole (8 μg/mL), miconazole (2 μg/mL), itraconazole (0.25 μg/mL), and amphotericin B (0.25 μg/mL). Using the broth macrodilution technique, we screened 24 clinical isolates of A. fumigatus obtained from the Detroit Medical Center in 1994. The MIC values of fluconazole, ketoconazole, miconazole, itraconazole and amphotericin B for all the isolates were 128–256, 8–16, 1–2, 0.25–0.5, and 0.25–1.0 μg/mL, respectively, indicating that none of the clinical isolates that we tested shows acquired resistance to the antifungals used.Key words: Aspergillus fumigatus, susceptibility test, antifungals, drug resistance, broth macrodilution.

scholarly journals Comparative Study of Susceptibilities of Germinated and Ungerminated Conidia of Aspergillus fumigatus to Various Antifungal Agents

1999 ◽  
Vol 37 (3) ◽  
pp. 858-861 ◽  
Author(s):  
Elias K. Manavathu ◽  
Jessica Cutright ◽  
Pranatharthi H. Chandrasekar
Keyword(s):  
Comparative Study ◽  
Growth Inhibition ◽  
Aspergillus Fumigatus ◽  
Mycelial Growth ◽  
Fungicidal Activity ◽  
Antifungal Agents ◽  
Susceptibility Testing ◽  
In Vitro Susceptibility ◽  
In Vitro Susceptibility Testing

Conidia are used as inocula for the in vitro susceptibility testing of Aspergillus fumigatus. Since the MIC is defined on the basis of visible mycelial growth, conidia should germinate and produce sporelings (germinated conidia) for monitoring of the growth inhibition and fungicidal activity of a drug. If a compound is capable of inhibiting germination of conidia while affecting or not affecting the growth of the organism, the MIC obtained will be the concentration of the drug required for the inhibition of conidial germination but not necessarily that required for inhibition of the growth of the organism. We investigated the susceptibility of germinated and ungerminated conidia to amphotericin B, itraconazole, voriconazole, and SCH56592. The MICs of various antifungal agents for germinated conidia were almost identical to those obtained for ungerminated conidia. In addition, both the germinated and ungerminated conidia were killed with almost equal efficiency by all of the compounds tested when exposed to the drugs for 24 h. These results suggest that either germinated or ungerminated conidia could be used as inocula for in vitro susceptibility studies of A. fumigatus with identical results.

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