title: Rapid induction of multiple resistance mechanisms in Aspergillus fumigatus during azole therapy: a case study and review of the literature.
abstract: Nine consecutive isogenic Aspergillus fumigatus isolates cultured from a patient with aspergilloma were investigated for azole resistance. The first cultured isolate showed a wild-type phenotype, but four azole-resistant phenotypes were observed in the subsequent eight isolates. Four mutations were found in the cyp51A gene of these isolates, leading to the substitutions A9T, G54E, P216L, and F219I. Only G54 substitutions were previously proved to be associated with azole resistance. Using a Cyp51A homology model and recombination experiments in which the mutations were introduced into a susceptible isolate, we show that the substitutions at codons P216 and F219 were both associated with resistance to itraconazole and posaconazole. A9T was also present in the wild-type isolate and thus considered a Cyp51A polymorphism. Isolates harboring F219I evolved further into a pan-azole-resistant phenotype, indicating an additional acquisition of a non-Cyp51A-mediated resistance mechanism. Review of the literature showed that in patients who develop azole resistance during therapy, multiple resistance mechanisms commonly emerge. Furthermore, the median time between the last cultured wild-type isolate and the first azole-resistant isolate was 4 months (range, 3 weeks to 23 months), indicating a rapid induction of resistance.
authors: Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands. s.camps@mmb.umcn.nl
authors: Simone M T
authors: SM
authors: Camps
authors: Jan W M
authors: JW
authors: van der Linden
authors: Yi
authors: Y
authors: Li
authors: Ed J
authors: EJ
authors: Kuijper
authors: Jaap T
authors: JT
authors: van Dissel
authors: Paul E
authors: PE
authors: Verweij
authors: Willem J G
authors: WJ
authors: Melchers
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000935:Antifungal Agents / Q000008:administration & dosage*; D001228:Aspergillosis / Q000188:drug therapy* / Q000382:microbiology; D001232:Aspergillus fumigatus / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics* / Q000378:metabolism; D025141:Drug Resistance, Fungal / Q000187:drug effects* / Q000235:genetics; D005260:Female; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D005838:Genotype; D006801:Humans; D017964:Itraconazole / Q000008:administration & dosage*; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D059645:Mutation Rate; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide; D013183:Sputum / Q000382:microbiology; D013997:Time Factors; D014230:Triazoles / Q000008:administration & dosage*
chemical_list: D000935:Antifungal Agents; D005656:Fungal Proteins; D014230:Triazoles; D017964:Itraconazole; C101425:posaconazole; D003577:Cytochrome P-450 Enzyme System; C465526:cytochrome P-450 CYP51A, Aspergillus