Tracheal Aspirate Galactomannan Testing in COVID-19-Associated Pulmonary Aspergillosis

Abstract

Among critically ill patients, COVID-19-associated pulmonary aspergillosis (CAPA) is a challenging complication. The recommended diagnostic methods for this disease are bronchoalveolar lavage (BAL) culture and galactomannan (GM) testing, which were not widely available during the pandemic. There is scarce information regarding GM testing in other respiratory specimens. Our objective was to compare the agreement of GM between BAL and tracheal aspirate (TA) samples. We selected patients with COVID-19 and those with suspected CAPA who were admitted in the intensive care unit (ICU). GM was routinely done in BAL. We performed GM in TA samples and compared the results. The agreement was evaluated with Cohen's Kappa coefficient. GM was considered positive when an OD index ≥ 1 in BAL and ≥ 2 in TA were found. Probable CAPA was considered when the ECMM/ISHAM criteria were met. A descriptive analysis of clinical characteristics and mortality was made. We included 20 patients with suspected CAPA from 54 patients with critical COVID-19, of which 5 (9%) met the probable category. Aspergillus fumigatus was the most frequent isolate. We found moderate agreement between BAL and TA GM (Kappa = 0.47, p = 0.01, 95% CI.04-0.9), whereas TA GM had 75% sensitivity (95% CI 19.4-99.4%), 81.2% specificity (95% CI 54.4-95.9%), 50% positive predictive value (95% CI 23.8-76.3%),] and 92.8% negative predictive value (95% CI 70.1-98.6%), and 80% accuracy (95% CI 56.3-94.3%). Lastly, three (60%) patients with CAPA died during hospitalization compared to 40% (6/15) without CAPA (p = 0.4). In conclusion, a moderate agreement between TA GM and BAL was found. Therefore, TA testing may aid in ruling out CAPA due to high negative predictive value when bronchoscopies are unavailable.

Keywords: Aspergillus; CAPA; COVID-19; galactomannan; tracheal aspirate.