Use of Bronchoalveolar Lavage To Detect Galactomannan for Diagnosis of Pulmonary Aspergillosis among Nonimmunocompromised Hosts

Abstract

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

Diagnostic Value of Galactomannan Antigen Test in Serum and Bronchoalveolar Lavage Fluid Samples from Patients with Nonneutropenic Invasive Pulmonary Aspergillosis

“…Currently, few studies of patients with nonneutropenic pulmonary aspergillosis have been reported. At a cutoff value of Ն0.5 or Ն1.0, BALF GM detection test sensitivities of 57.1% to 100% for the diagnosis of nonneutropenic IPA and specificities ranging from 47.1% to 92.1% have been reported (16)(17)(18). The BALF GM detection test sensitivities and specificities recorded in our study were within the ranges reported in these studies.…”

“…By ROC curve analysis, we found that the optimal cutoff value for BALF GM detection was 0.70, at which level the sensitivity and specificity of the test were 72.97% and 89.16%, respectively. Other studies in which ROC curve analysis was applied have reported optimal BALF GM cutoff values ranging from 0.5 to 1.18 in nonneutropenic patients with pulmonary aspergillosis (16)(17)(18)(19). Among these studies, one reported the same optimal cutoff value of 0.7 as our study (19), while another found that the optimal cutoff value was 0.8 (16), which was higher than that of our study.…”

“…As the pulmonary structures and defense functions of these patients were severely damaged, Aspergillus may have been able to colonize the airway and lung parenchyma more readily and result in IPA. A study that had a mixed population that mainly included patients with chronic necrotizing pulmonary aspergillosis (CNPA) and allergic bronchopulmonary aspergillosis (ABPA) rather than IPA found that the minimum optimal cutoff value was 0.5 (17), while the maximum optimal cutoff value reported in another study was 1.18 (18). However, the latter study had a very low prevalence rate (8.22%), as only 6 of 73 nonimmunocompromised patients had pulmonary aspergillosis.…”

Biomarkers for Invasive Aspergillosis: The Challenges Continue

“…BAL fluid has been investigated thoroughly, since it was reported that detection of GM in BAL fluid increased the diagnostic sensitivity from 47% in serum to 85% [66], a comparison of 33 cases found that all 33 BAL specimens, but only nine serum specimens, were positive [67] and that BAL fluid from an established guinea pig model of IA gave a positive result more than 2 days sooner with BAL fluid than with serum [68]. This approach has been investigated for early diagnosis of IA following hematopoietic stem cell transplants [69], after solid organ transplantation [70], in patients with hematological malignancies and pulmonary infiltrates [71], chronic pulmonary disease [72][73][74] as well as in intensive care units [75] and in nonimmunocompromised patients [76]. Nevertheless, its impact on clinical outcome is uncertain: our analysis of the assay sensitivity reported in these studies shows variation from 57 to 88%, with the specificity ranging from 87 to 95.8%, and positive-predictive values in the range of 41.7 to 92.5%, when using a GMI cut-off of 0.5.…”

Capítulo 1: diagnóstico laboratorial das micoses pulmonares

“…Its efficacy for other clinical specimens and for different invasive aspergillosis risk groups is currently under study. (39,40) When serially monitored, the detection of galactomannan allows the diagnosis of invasive diffuse in the agar and, when they meet, they react and precipitate, forming an opaque line that can be visualized through indirect illumination against a dark back. A positive control serum sample (standard serum) should be used in this reaction to facilitate the reading and final interpretation of the test.…”