First Detection of TR34 L98H and TR46 Y121F T289A Cyp51 Mutations in Aspergillus fumigatus Isolates in the United States

Abstract

dAzole resistance in Aspergillus fumigatus is an increasing problem. The TR34 L98H and TR46 Y121F T289A mutations that can occur in patients without previous azole exposure have been reported in Europe, Asia, the Middle East, Africa, and Australia. Here, we report the detection of both the TR34 L98H and TR46 Y121F T289A mutations in confirmed A. fumigatus isolates collected in institutions in the United States. These mutations, other mutations known to cause azole resistance, and azole MICs are reported here. Invasive aspergillosis remains a major problem in immunocompromised individuals, including solid organ transplant recipients, those undergoing hematopoietic stem cell transplant, and patients receiving highly immunosuppressive chemotherapies (1-3). In patients with structural damage to the lungs, such as those who have had tuberculosis or sarcoidosis, chronic pulmonary aspergillosis is also a significant problem, the prevalence of which has been estimated to be approximately 3 million patients worldwide (4-7). The azoles are a mainstay in the treatment of invasive aspergillosis, as the members of this class that have activity against Aspergillus species, itraconazole, posaconazole, voriconazole, and isavuconazole, may be given orally, and the treatment of this invasive fungal infection is often prolonged. However, prolonged therapy may predispose patients to adverse effects and drug interactions associated with these agents and increase the potential for the development of drug-resistant organisms (8). Over the last several years, concern has been growing regarding azole resistance in Aspergillus fumigatus (9, 10). Azole-resistant A. fumigatus isolates recovered from patients failing therapy have been reported in several countries around the world. Mutations in the CYP51A gene, which encodes the Cyp51 enzyme responsible for the last step in ergosterol biosynthesis, have been the resistance mechanism documented in clinical isolates, and these mutations have been found in isolates recovered from patients who have had long exposures to azoles (11, 12). However, resistant isolates harboring tandem repeats of various sizes in the promoter region of the CYP51A gene, along with nonsynonymous point mutations leading to amino acid changes in the Cyp51 enzyme, have been recovered from azole-naive patients with invasive aspergillosis (8, 12, 13). These resistance mechanisms, which include TR34 L98H and TR46 Y121F T289A, have been linked to the environmental use of azoles in agriculture and the preservation of various materials (14, 15), and they have been found in various countries, including many in Europe, India, China, Iran, Tanzania, and Australia (13, 16-21). However, these mutations have not yet been reported in isolates collected in the United States (22). Our objective was to evaluate the Cyp51-associated mechanisms of azole resistance in a collection of A. fumigatus isolates from institutions across the United States.The antifungal susceptibility database in the Fungus Testing Laboratory at the University of ...

Quantitative Analysis of Single-Nucleotide Polymorphism for Rapid Detection of TR 34 /L98H- and TR 46 /Y121F/T289A-Positive Aspergillus fumigatus Isolates Obtained from Patients in Iran from 2010 to 2014

“…Two common genetic variants associated with resistance to azoles are the TR 34 /L98H mutation and the TR 46 /Y121F/T289A mutation (1,2). Both mutations are predominantly found in the environment, show a strong tendency to migrate, and have now been reported in many countries from several continents (3,23,(40)(41)(42). In addition, the clinical implications of infection due to A. fumigatus isolates harboring these mutations are significant, as they cause both diagnostic challenges and azole treatment failure (8,43).…”

“…Surveillance studies indicate that the incidence of azole resistance is increasing (2)(3)(4)(5)(6), with the TR 34 /L98H mutation (a 34-bp tandem repeat mutation in the promoter region of the cyp51A gene in combination with a substitution at codon L98) emerging in multiple European countries and in the Middle East, Asia, and Africa and with a new resistance mechanism, the TR 46 /Y121F/ T289A mutation (a 46-bp tandem repeat mutation in the promoter region of the cyp51A gene in combination with substitutions at codons Y121 and T289), emerging more recently in Europe and India (2)(3)(4)(5)(6). We also previously reported the occurrence of the TR 34 /L98H mutation in 3.2% of clinical Aspergillus fumigatus isolates obtained from patients in Iran to the end of 2009 (5).…”

Epidemiology and Molecular Characterizations of Azole Resistance in Clinical and Environmental Aspergillus fumigatus Isolates from China

“…The most common resistance mechanism is characterized by combinations of a tandem repeat (TR 34 ) in the cyp51A promoter and a concomitant mutation in the cyp51A gene itself (L98H), which is believed to be primarily driven by the use of azole fungicides in the environment (4,5). A new environmental cyp51A-mediated resistance mechanism (TR 46 / Y121F/T289A), which might confer high level resistance to voriconazole (VRC), has been reported recently in countries from many continents (6)(7)(8)(9)(10)(11).…”

In Vivo Efficacy of Liposomal Amphotericin B against Wild-Type and Azole-Resistant Aspergillus fumigatus Isolates in Two Different Immunosuppression Models of Invasive Aspergillosis

“…However, the management of IA has become more complicated due to the emergence of azole resistance in A. fumigatus (8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18). Surveillance studies indicate that azole resistance is increasing in Europe, the Middle East, Asia, Africa, and Australia and, most recently, in North and South America as well (19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30). Azole-resistant IA has been shown to be associated with a very high mortality rate; therefore, alternative treatment regimens need to be investigated to improve the outcome of patients (18,31,32).…”