Aspergillus superinfection and bronchoalveolar lavage galactomannan among patients with severe COVID-19-related respiratory failure

ABSTRACT

Rationale The frequency of superinfection with Aspergillus among patients with severe COVID-19-related respiratory failure is unknown. The association of bronchoalveolar lavage (BAL) fluid markers, such as galactomannan, with the presence of Aspergillus infections is also unclear. Methods: Our cohort included all patients with COVID-19 admitted to the Northwestern Memorial Hospital ICU from March to November 2020 who were intubated and underwent a BAL;patients were identified as having COVID-19 by the presence of a flag in the electronic medical record. We evaluated BAL fluid data for fungal organisms and markers. Data analysis was performed in Excel and Prism, with non-parametric values compared by two-tailed Mann Whitney tests. Results: We identified 274 patients meeting study entry criteria. The median (interquartile range) age was 62 years (47-69), and 93 (34%) were female. 714 BALs were performed on these patients, and 457 galactomannan tests were sent from these BALs. Only six (2.2%) patients grew Aspergillus on BAL fluid culture;one patient never grew Aspergillus but given his significantly elevated BAL galactomannan of 7.81, was empirically treated. The median (IQR) optical density index of galactomannan for the BAL samples that grew Aspergillus was 6.69 (3.37-8.87) compared with 0.08 (0.06-0.13) for those that did not, p<0.001. Using our lab's reported galactomannan index cutoff of >0.5 as positive, with patients who grew Aspergillus on culture as gold standard, the test sensitivity was 91.7% and specificity was 94.6%;using the ATS recommended cutoff of >1.0 as positive, the sensitivity was 75.0% and specificity was 97.5%. The median (IQR) age of patients who grew Aspergillus was 71.5 years (64-80.5) (p=0.02 compared with the overall cohort). Only two were immunocompromised (diffuse large B-cell lymphoma and another was status post liver transplant). Of note, two patients who grew Aspergillus had visible mold or plaque seen during bronchoscopy;three had cavitary findings on imaging;three died. Conclusions: Aspergillus superinfection is uncommon among ventilated patients with COVID-19 but can occur in patients without typical immunocompromising risk factors. BAL fluid galactomannan levels are lower in patients without Aspergillus, and had reasonable specificity especially if cutoff of >1.0 was used. Future analysis should focus on additional factors that differentiate between these two groups.