Galactomannan in bronchoalveolar lavage fluid: a tool for diagnosing aspergillosis in intensive care unit patients

Abstract

Rationale: Invasive aspergillosis (IA) is an important cause of mortality in patients with hematologic malignancies. However, IA appears to be gaining a foothold in the intensive care unit (ICU) in patients without classical risk factors. A recent study described 89 cases of IA in patients in a medical ICU without leukemia or cancer. The diagnosis of IA remains difficult and is often established too late. Galactomannan (GM) is an exo-antigen released from Aspergillus hyphae while they invade host tissue.

Objectives: This prospective single-center study was conducted to investigate the role of GM in bronchoalveolar lavage (BAL) fluid as a tool for early diagnosis of IA in the ICU.

Methods: All patients with risk factors identified in our earlier study were evaluated. BAL for culture and GM detection, serum GM levels, and computed tomography scan were obtained for all included patients with signs of pneumonia. Patients were classified as having proven, probable, or possible IA.

Measurements and main results: A total of 110 patients out of 1,109 admissions were eligible. There were 26 proven IA cases. Using a cutoff index of 0.5, the sensitivity and specificity of GM detection in BAL fluid was 88 and 87%, respectively. The sensitivity of serum GM was only 42%. In 11 of 26 proven cases, BAL culture and serum GM remained negative, whereas GM in BAL was positive.

Conclusions: IA is common in immunocompromised, critically ill patients. GM detection in BAL fluid seems to be useful in establishing or excluding the diagnosis of IA in the ICU.