Invasive pulmonary aspergillosis (IPA) is difficult to diagnose. The detection of galactomannan (GM) in serum samples is useful for diagnosing IPA. A positive test for GM antigen in BAL has also been proposed as a criterion of IPA, although it has not been fully validated. The aim of our study was to evaluate the contribution of GM antigen detection in BAL to the diagnosis of IPA in hematologic patients.
One hundred one consecutive patients treated for hematologic malignancy were explored by bronchoscopy and BAL for new pulmonary infiltrates. Both BAL fluid and serum samples were evaluated for GM using an enzyme-linked immunosorbent assay test, with an optical density index ≥ 0.5 considered positive. Respiratory samples were also examined for the presence of fungi.
IPA was diagnosed in 33 patients according to European Organization for Research and Treatment of Cancer and Mycoses Study Group consensus group criteria (six proven, 23 probable, four possible). Nineteen of these 33 patients had a positive BAL GM test, whereas three patients without IPA had false-positive results. GM detection in BAL had a sensitivity of 57.6% (95% CI, 40.8%-72.8%) and a specificity of 95.6% (95% CI, 87.8%-98.5%). Among the 19 patients with IPA whose BAL was positive for GM, 15 also had a positive serum GM test. In 11 of these 19 patients, Aspergillus was identified in the respiratory samples.
Detection of GM in BAL is complementary of serum GM testing and mycologic evaluation of the respiratory samples for the diagnosis of IPA. Positive GM BAL was the sole microbiologic criterion in two of 33 patients studied.