Clinical implications of globally emerging azole resistance in Aspergillus fumigatus

Antifungal susceptibility testing is an essential tool for guiding therapy, although EUCAST and CLSI reference methods are often available only in specialized centers. We studied the performance of an agar-based screening method for the detection of azole resistance in Aspergillus fumigatus cultures. The VIPcheck consists of four wells containing voriconazole, itraconazole, posaconazole, or a growth control. Ninety-six A. fumigatus isolates were used. Thirty-three isolates harbored a known resistance mechanism: TR 34 /L98H (11 isolates), TR 46 /Y121F/T289A (6 isolates), TR 53 (2 isolates), and 14 isolates with other cyp51A gene point mutations. Eighteen resistant isolates had no cyp51A-mediated azole resistance. Forty-five isolates had a wild-type (WT) azole phenotype. Four technicians and two inexperienced interns, blinded to the genotype/phenotype, read the plates visually after 24 h and 48 h and documented minimal growth, uninhibited growth, and no growth. The performance was compared to the EUCAST method. After 24 h of incubation, the mean sensitivity and specificity were 0.54 and 1.00, respectively, with uninhibited growth as the threshold. After 48 h of incubation, the performance mean sensitivity and specificity were 0.98 and 0.93, respectively, with minimal growth. The performance was not affected by observer experience in mycology. The interclass correlation coefficient was 0.87 after 24 h and 0.85 after 48 h. VIPcheck enabled the selection of azole-resistant A. fumigatus colonies, with a mean sensitivity and specificity of 0.98 and 0.93, respectively. Uninhibited growth on any azole-containing well after 24 h and minimal growth after 48 h were indicative of resistance. These results indicate that the VIPcheck is an easy-to-use tool for azole resistance screening and the selection of colonies that require MIC testing.KEYWORDS VIPcheck, broth microdilution, antifungal resistance, susceptibility, azole resistance, antifungal susceptibility testing A zole resistance is an emerging problem in Aspergillus fumigatus (1), with increasing evidence that patients with azole-resistant aspergillosis fail azole therapy (2-5). Two routes of resistance selection have been signified, through patient therapy and through the exposure of A. fumigatus to azole fungicides in the environment. There are important differences between these routes of resistance selection, including patient risk factors and fungal resistance mechanisms. Resistance mechanisms that are associated with the environmental route include TR 34 /L98H and TR 46 /Y121F/T289A (6-8).Surveillance studies in The Netherlands show that of the clinical isolates that are azole resistant, between 83% and 95% harbor mutations associated with the environmental route, while approximately 15% exhibit an azole-resistant phenotype without known resistance mutations (9). As patients inhale these airborne azole-resistant spores, a resistant infection may occur in any Aspergillus disease and in patients who have never been treated with medical triazoles (3, 7, 10,...

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confidence: 99%

Single-Center Evaluation of an Agar-Based Screening for Azole Resistance in Aspergillus fumigatus by Using VIPcheck

Buil

Lee

Rijs

et al. 2017

“…While the most common TR34/L98H mutation confers resistance to all azoles, TR46/Y121F/T289A confers resistance to voriconazole and isavuconazole but shows a variable influence on the MICs of itraconazole and posaconazole. The point mutations G54 and M220 in cyp51A induce resistance mainly to itraconazole and posaconazole (21). Only limited data are available on the effect and related toxicity of systemic use of luliconazole and lanoconazole.…”

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confidence: 99%

Potent Activities of Novel Imidazoles Lanoconazole and Luliconazole against a Collection of Azole-Resistant and -Susceptible Aspergillus fumigatus Strains

Abastabar

Rahimi

Meis

et al. 2016

Self Cite

A collection of azole-susceptible (n ‫؍‬ 141) and azole-resistant (n ‫؍‬ 27) Aspergillus fumigatus isolates was tested against seven antifungal drugs, including the new imidazoles lanoconazole and luliconazole. The luliconazole and lanoconazole MIC 90 values for the azole-susceptible strains were 0.001 g/ml and 0.008 g/ml, and those for the azole-resistant strains were 0.016 g/ml and 0.032 g/ml.

“…This case is instructive because it highlights the increasing problem of azole resistance in patients with invasive aspergillosis (28,29), which is thought to be related to the use of agricultural pesticides and the selection of these strains in the environment as well as increasing azole use in clinical settings. It also highlights invaluable diagnostic tools, such as CT and both serum and bronchio-alveolar lavage fluid GM (30,31), as part of the contemporary management of this disease, both in terms of diagnosis and monitoring for progression or resolution of the disease (32).…”

Section: Commentarymentioning

confidence: 97%

“…Finally, it also reminds us of the importance of postmortem studies, a disappearing trend, in determining the cause of death and quantifying the burden of disease that the patient experienced. The message is loud and clear: azole resistance is on the rise (28,33), and centers that routinely deal with these complex hosts should be screening for these organisms.…”

Section: Commentarymentioning

confidence: 99%

Progressive Dispersion of Azole Resistance in Aspergillus fumigatus: Fatal Invasive Aspergillosis in a Patient with Acute Myeloid Leukemia Infected with an A. fumigatus Strain with a cyp51A TR ₄₆ Y121F M172I T289A Allele

Rößler

Bader

Stölzel

et al. 2017

This Journal section presents a real, challenging case involving a multidrugresistant organism. The case authors present the rationale for their therapeutic strategy and discuss the impact of mechanisms of resistance on clinical outcome. An expert clinician then provides a commentary on the case.ABSTRACT Patients with hematologic malignancies as well as allogeneic hematopoietic stem cell transplantation (HSCT) patients are at high risk for invasive aspergillosis. Here, we report a culture-and autopsy-proven fatal invasive aspergillosis in an allogeneic HSTC patient which he developed despite posaconazole prophylaxis. The agent was determined to be an azole-resistant Aspergillus fumigatus strain bearing the cyp51A mutation combination TR 46 Y121F M172I T289A. At increasing frequency, the azole resistance of A. fumigatus is being reported globally, limiting treatment options and complicating regimens.