In a recent study by Kolwijck et al (Am J Resp Crit Care Med 2016;193-927-9) three patients are described with proven invasive aspergillosis due to a voriconazole-susceptible and voriconazole-resistant Aspergillus fumigatus co-infection. All patients had evidence for the presence of both voriconazole-susceptible and voriconazole-resistant A. fumigatus colonies in culture.
Genetic analysis of individual colonies and lung lesions indicated that lung lesions may originate from genetically distinct A. fumigatus spores. Patients are believed to inhale genetically diverse spores, which, in regions with environmental resistance, may result in lesions caused by azole-susceptible A. fumigatus and others by azole-resistant spores. During voriconazole monotherapy the patients’ condition and radiology improved. However, in one patient the infection disseminated to the brain, and azole-resistant A. fumigatus was recovered from the brain lesion. As a consequence ruling out of azole resistance will be very difficult and intensive monitoring of patients during antifungal therapy is warranted even if initial culture suggests azole-susceptible disease. It appears appropriate to analyse all A. fumigatus colonies for azole-resistance in culture-positive patients, although the frequency of coinfections remains unknown.