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. 2020 Feb 21;64(3):e02059-19.
doi: 10.1128/AAC.02059-19. Print 2020 Feb 21.

Aspergillus fumigatus Clinical Isolates Carrying CYP51A with TR34/L98H/S297T/F495I Substitutions Detected after Four-Year Retrospective Azole Resistance Screening in Brazil

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Aspergillus fumigatus Clinical Isolates Carrying CYP51A with TR34/L98H/S297T/F495I Substitutions Detected after Four-Year Retrospective Azole Resistance Screening in Brazil

Laís Pontes et al. Antimicrob Agents Chemother. .

Abstract

Azole antifungal resistance in Aspergillus fumigatus is a worldwide concern. As in most public hospitals in Brazil, antifungal susceptibility tests are not routinely performed for filamentous fungi at our institution. A 4-year retrospective azole antifungal resistance screening revealed two azole-resistant A. fumigatus clinical isolates carrying the CYP51A TR34 (34-bp tandem repeat)/L98H (change of L to H at position 98)/S297T/F495I resistance mechanism mutations, obtained from two unrelated patients. Broth microdilution antifungal susceptibility testing showed high MICs for itraconazole, posaconazole, and miconazole. Short tandem repeat (STR) typing analysis presented high levels of similarity between these two isolates and clinical isolates with the same mutations reported from the Netherlands, Denmark, and China, as well as environmental isolates from Taiwan. Our findings might indicate that active searching for resistant A. fumigatus is necessary. They also represent a concern considering that our hospital provides tertiary care assistance to immunocompromised patients who may be exposed to resistant environmental isolates. We also serve patients who receive prophylactic antifungal therapy or treatment for invasive fungal infections for years. In these two situations, isolates resistant to the antifungal in use may be selected within the patients themselves. We do not know the potential of this azole-resistant A. fumigatus strain to spread throughout our country. In this scenario, the impact on the epidemiology and use of antifungal drugs will significantly alter patient care, as in other parts of the world. In summary, this finding is an important contribution to alert hospital laboratories conducting routine microbiological testing to perform azole resistance surveillance and antifungal susceptibility tests of A. fumigatus isolates causing infection or colonization in patients at high risk for systemic aspergillosis.

Keywords: Aspergillus fumigatus; azole resistance; drug resistance mechanisms.

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Figures

FIG 1
FIG 1
(A) Nucleotide sequence alignment showing TR34 repeat on isolates LIF 2444-6 and LIF 2552-4.9. (B) Protein sequence alignment.
FIG 2
FIG 2
Genotypic relationship between LIF 2444-6 and LIF 2552-4.9 and Aspergillus fumigatus isolates with TR34/L98H/S297T/F495I mutations from China, the Netherlands, Denmark, and Taiwan (16, 17). The dendrogram is based on a categorical analysis of nine microsatellite markers in combination with unweighted pair group method with arithmetic mean (UPGMA) clustering using Phyloviz 2.0a.

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