Amphotericin B resistance in Aspergillus isolates

Researchers from Brazil who set out to survey azole resistance in Aspergillus species have found a high number of amphotericin B resistant isolates.

In a paper published in the journal ‘Mycoses’, the researchers describe the resistance profiles of 228 isolates from 91 patients treated at the University Clinical Hospital in Brazil. Aspergillus fumigatus and flavus were the most prevalent species isolated, comprising 74% and 12% of the clinical isolates.

Aspergillus flavus showed high Minimum Inhibitory Concentrations (MICs) to Amphotericin B to levels associated with treatment failure in patients with Invasive Aspergillosis. 27% of A. fumigatus isolates had Amphotericin B MICs equal to or exceeding 2 mg/L.

The authors note that their findings suggest that A. fumigatus, A. flavus and A. terreus are developing resistance to one of the most important therapeutic options for invasive aspergillosis. They suggest continued surveillance to monitor resistance of Aspergillus species to azoles and Amphotericin B.