Table 1. Characteristics of the patient and environmental route of resistance selection in A. fumigatus.

Patient route	Environmental route
Resistance is primarily found in patients with a pulmonary cavity	Resistance is found in all aspergillus diseases: invasive aspergillosis, ABPA, chronic colonization, aspergilloma
Recent or ongoing triazole therapy	Two-thirds of patients are triazole naïve
Isolates may have a fitness cost in culture	Isolates have no apparent fitness cost
Isogenic wild-type and resistant isolates may be found in consecutive samples from the same patient	Isogenic wild-type and resistant isolates are not found in consecutive samples from the same patient
*Resistance mutations include single mutations in the Cyp51A gene and non-Cyp51A (unknown) mutations	*Resistance mechanisms include single mutations in the Cyp51A gene combined with tandem repeats in the gene promoter
*Resistance mutations are found in clinical samples only	*Resistance mutations are found both in clinical samples and in the environment
Clinical samples may contain multiple different resistance mutations	Clinical samples generally contain one single-resistance mechanism but may also harbor wild-type isolates
Genetic typing shows high diversity in resistant isolates from different patients	Genetic typing shows low diversity in resistant isolates from different patients

*These statements are challenged by recent studies.

Abbreviation: ABPA, allergic bronchopulmonary aspergillosis.