Culture may miss most PCR-confirmed, often-resistant Aspergillus

Using PCR testing on BAL fluid, Denning et al (in Manchester UK) found Aspergillus DNA in 4 of 11 (36%) healthy volunteers; 21 of 22 patients with culture/microscopy-proven invasive aspergillosis; and 70-80% of patients with allergic bronchopulmonary aspergillosis or chronic pulmonary aspergillosis. Culture was positive in none of the ABPA patients, and only 17% of the CPA patients. (Other series report much higher culture positivity rates; authors suggest that yields vary widely by lab and technique, so buyer beware when relying on culture.) Most (50-75%) of the isolates from patients with ABPA and CPA had markers of triazole (itraconazole) resistance; authors suggest this may be an important previously unrecognized cause for treatment failure. Clin Infect Dis 2011;52:1123-1129.