Study objectives: As the failure of amphotericin B therapy in patients with invasive aspergillosis often exceeds 50%, we sought to determine the relationship between in vitro amphotericin B resistance and clinical failure of amphotericin B against invasive aspergillosis.
Design: Retrospective study.
Setting: University cancer center.
Patients: One hundred sixteen patients with cancer and invasive aspergillosis.
Measurements and main results: The correlation between in vitro amphotericin B susceptibility, defined by both the National Committee for Clinical Laboratory Standards and Etest methods, and other prognostic factors with failure of initial amphotericin B therapy was retrospectively evaluated. Data for correlation could be clearly assessed in only 18 (16%) of the 116 patients. Admission to the intensive care unit was the only prognostic factor associated with failure of initial amphotericin B treatment in these 18 patients (p = 0.01).
Conclusions: Several important obstacles underlie the correlation of in vitro susceptibility testing with in vivo efficacy of individual antifungal agents in the treatment of invasive aspergillosis. Such correlations could be determined in only a small subset of patients.