Bronchoalveolar lavage (BAL) galactomannan in the diagnosis of pulmonary aspergillosis among non-immunocompromised hosts

Author: 

Nguyen MH, Jaber R, Leather HL, Wingard JR, Staley B, Wheat LJ, Cline CL, Baz M, Rand KH, Clancy CJ
J Clin Microbiol. 2007 Sep;45(9):2787-92

Abstract: 

Pulmonary aspergillosis (PA) in non-immunocompromised hosts, although rare, is increasingly recognized. The diagnosis of PA is difficult, since recovery of Aspergillus from respiratory samples cannot differentiate colonization from invasion. We assessed the role of BAL galactomannan (GM) in diagnosing PA in 73 non-immunocompromised patients with pulmonary infiltrates for whom the test was ordered. Six patients had PA, two each with acute invasive pulmonary aspergillosis (IPA), chronic necrotizing pulmonary aspergillosis and aspergilloma. All six patients had BAL GM >/= 1.18. The sensitivity, specificity, and negative predictive values for BAL GM >/= 1.0 were 100%, 88.1%, and 100%, respectively. Notably, the positive predictive value was only 42.9%, likely reflecting the low prevalence of PA among non-immunosuppressed patients. The combination of BAL microscopy and culture had sensitivity and NPV similar to BAL GM, but higher specificity and PPV (92.5% and 54.6%, respectively). Moreover, BAL GM did not identify any cases that were not diagnosed by conventional methods like microscopy and culture. In conclusion, there was no conclusive benefit of BAL GM in the diagnosis of PA among non-immunocompromised hosts. Given the likelihood of false positive results, BAL GM should not be ordered routinely in this population.