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      Elevated MIC Values of Imidazole Drugs against Aspergillus fumigatus Isolates with TR 34 /L98H/S297T/F495I Mutation

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          ABSTRACT

          The use of azole fungicides in agriculture is believed to be one of the main reasons for the emergence of azole resistance in Aspergillus fumigatus . Though widely used in agriculture, imidazole fungicides have not been linked to resistance in A. fumigatus . This study showed that elevated MIC values of imidazole drugs were observed against A. fumigatus isolates with TR 34 /L98H/S297T/F495I mutation, but not among isolates with TR 34 /L98H mutation. Short-tandem-repeat (STR) typing analysis of 580 A. fumigatus isolates from 20 countries suggested that the majority of TR 34 /L98H/S297T/F495I strains from China were genetically different from the predominant major clade comprising most of the azole-resistant strains and the strains with the same mutation from the Netherlands and Denmark. Alignments of sterol 14α-demethylase sequences suggested that F495I in A. fumigatus was orthologous to F506I in Penicillium digitatum and F489L in Pyrenophora teres , which have been reported to be associated with imidazole resistance. In vitro antifungal susceptibility testing of different recombinants with cyp51A mutations further confirmed the association of the F495I mutation with imidazole resistance. In conclusion, this study suggested that environmental use of imidazole fungicides might confer selection pressure for the emergence of azole resistance in A. fumigatus .

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          Most cited references46

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          What makes Aspergillus fumigatus a successful pathogen? Genes and molecules involved in invasive aspergillosis.

          Aspergillus fumigatus is an opportunistic pathogen that causes 90% of invasive aspergillosis (IA) due to Aspergillus genus, with a 50-95% mortality rate. It has been postulated that certain virulence factors are characteristic of A. fumigatus, but the "non-classical" virulence factors seem to be highly variable. Overall, published studies have demonstrated that the virulence of this fungus is multifactorial, associated with its structure, its capacity for growth and adaptation to stress conditions, its mechanisms for evading the immune system and its ability to cause damage to the host. In this review we intend to give a general overview of the genes and molecules involved in the development of IA. The thermotolerance section focuses on five genes related with the capacity of the fungus to grow at temperatures above 30°C (thtA, cgrA, afpmt1, kre2/afmnt1, and hsp1/asp f 12). The following sections discuss molecules and genes related to interaction with the host and with the immune responses. These sections include β-glucan, α-glucan, chitin, galactomannan, galactomannoproteins (afmp1/asp f 17 and afmp2), hydrophobins (rodA/hyp1 and rodB), DHN-melanin, their respective synthases (fks1, rho1-4, ags1-3, chsA-G, och1-4, mnn9, van1, anp1, glfA, pksP/alb1, arp1, arp2, abr1, abr2, and ayg1), and modifying enzymes (gel1-7, bgt1, eng1, ecm33, afpigA, afpmt1-2, afpmt4, kre2/afmnt1, afmnt2-3, afcwh41 and pmi); several enzymes related to oxidative stress protection such as catalases (catA, cat1/catB, cat2/katG, catC, and catE), superoxide dismutases (sod1, sod2, sod3/asp f 6, and sod4), fatty acid oxygenases (ppoA-C), glutathione tranferases (gstA-E), and others (afyap1, skn7, and pes1); and efflux transporters (mdr1-4, atrF, abcA-E, and msfA-E). In addition, this review considers toxins and related genes, such as a diffusible toxic substance from conidia, gliotoxin (gliP and gliZ), mitogillin (res/mitF/asp f 1), hemolysin (aspHS), festuclavine and fumigaclavine A-C, fumitremorgin A-C, verruculogen, fumagillin, helvolic acid, aflatoxin B1 and G1, and laeA. Two sections cover genes and molecules related with nutrient uptake, signaling and metabolic regulations involved in virulence, including enzymes, such as serine proteases (alp/asp f 13, alp2, and asp f 18), metalloproteases (mep/asp f 5, mepB, and mep20), aspartic proteases (pep/asp f 10, pep2, and ctsD), dipeptidylpeptidases (dppIV and dppV), and phospholipases (plb1-3 and phospholipase C); siderophores and iron acquisition (sidA-G, sreA, ftrA, fetC, mirB-C, and amcA); zinc acquisition (zrfA-H, zafA, and pacC); amino acid biosynthesis, nitrogen uptake, and cross-pathways control (areA, rhbA, mcsA, lysF, cpcA/gcn4p, and cpcC/gcn2p); general biosynthetic pathway (pyrG, hcsA, and pabaA), trehalose biosynthesis (tpsA and tpsB), and other regulation pathways such as those of the MAP kinases (sakA/hogA, mpkA-C, ste7, pbs2, mkk2, steC/ste11, bck1, ssk2, and sho1), G-proteins (gpaA, sfaD, and cpgA), cAMP-PKA signaling (acyA, gpaB, pkaC1, and pkaR), His kinases (fos1 and tcsB), Ca(2+) signaling (calA/cnaA, crzA, gprC and gprD), and Ras family (rasA, rasB, and rhbA), and others (ace2, medA, and srbA). Finally, we also comment on the effect of A. fumigatus allergens (Asp f 1-Asp f 34) on IA. The data gathered generate a complex puzzle, the pieces representing virulence factors or the different activities of the fungus, and these need to be arranged to obtain a comprehensive vision of the virulence of A. fumigatus. The most recent gene expression studies using DNA-microarrays may be help us to understand this complex virulence, and to detect targets to develop rapid diagnostic methods and new antifungal agents. Copyright © 2010 Revista Iberoamericana de Micología. Published by Elsevier Espana. All rights reserved.
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            Aspergillosis due to voriconazole highly resistant Aspergillus fumigatus and recovery of genetically related resistant isolates from domiciles.

            Azole resistance is an emerging problem in Aspergillus fumigatus and complicates the management of patients with Aspergillus-related diseases. Selection of azole resistance may occur through exposure to azole fungicides in the environment. In the Netherlands a surveillance network was used to investigate the epidemiology of resistance selection in A. fumigatus. Clinical A. fumigatus isolates were screened for azole resistance in 8 university hospitals using azole agar dilution plates. Patient information was collected using an online questionnaire and azole-resistant A. fumigatus isolates were analyzed using gene sequencing, susceptibility testing, and genotyping. Air sampling was performed to investigate the presence of resistant isolates in hospitals and domiciles. Between December 2009 and January 2011, 1315 A. fumigatus isolates from 921 patients were screened. A new cyp51A-mediated resistance mechanism (TR46/Y121F/T289A) was observed in 21 azole-resistant isolates from 15 patients in 6 hospitals. TR46/Y121F/T289A isolates were highly resistant to voriconazole (minimum inhibitory concentration ≥16 mg/L). Eight patients presented with invasive aspergillosis due to TR46/Y121F/T289A, and treatment failed in all 5 patients receiving primary therapy with voriconazole. TR46/Y121F/T289A Aspergillus fumigatus was recovered from 6 of 10 sampled environmental sites. We describe the emergence and geographical migration of a voriconazole highly resistant A. fumigatus that was associated with voriconazole treatment failure in patients with invasive aspergillosis. Recovery of TR46/Y121F/T289A from the environment suggests an environmental route of resistance selection. Exposure of A. fumigatus to azole fungicides may facilitate the emergence of new resistance mechanisms over time, thereby compromising the use of azoles in the management of Aspergillus-related diseases.
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              Azole resistance in Aspergillus fumigatus isolates from the ARTEMIS global surveillance study is primarily due to the TR/L98H mutation in the cyp51A gene.

              We surveyed 497 isolates of Aspergillus fumigatus collected from 2008 to 2009 as part of the ARTEMIS global surveillance study for elevated MIC values to itraconazole, voriconazole, and posaconazole. Sequencing of the cyp51A gene revealed that 8/29 isolates with elevated MIC values to one or more triazoles, all originating in China, contained the TR/L98H mutation associated with resistant European isolates of A. fumigatus. This is the first time the TR/L98H mutation has been identified outside Europe.
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                Author and article information

                Journal
                Antimicrobial Agents and Chemotherapy
                Antimicrob Agents Chemother
                American Society for Microbiology
                0066-4804
                1098-6596
                May 2018
                April 26 2018
                March 05 2018
                : 62
                : 5
                Article
                10.1128/AAC.01549-17
                5923150
                29507067
                65fd620b-59b1-4368-99d0-340f26136181
                © 2018
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