Comparison of diagnostic techniques in patients with COVID-19-associated pulmonary aspergillosis (CAPA) in a Venezuelan population

Abstract

Background: Invasive aspergillosis related to COVID-19 or CAPA is defined by the association of a group of histological, mycological, radiological and clinical criteria that establish this disease as a secondary infection of high morbidity without timely diagnosis. Clinical and histological methods, due to the non-specific characterization of the disease, have been supported by techniques based on microbiological methods, such as culture and direct examination, with a sensitivity close to 50%, allowing the identification of biomarkers such as the GM of the pathogen, being the immunological techniques of greater sensitivity and specificity, the use of radial immunodiffusion and ELISA with antigens secreted by Aspergillus spp. are recommended. The objective of this article was to compare three different serological diagnostic methods used in the mycology laboratory to diagnose CAPA in a Venezuelan population. Methods: Based on a longitudinal study, 77 patient samples diagnosed as positive for SARS-CoV-2 by RT-PCR were analyzed, of which 24 CAPA BAL samples were subsequently evaluated by conventional mycological diagnostic methods (direct examination and culture) and corresponding CAPA serum samples by three serological methods: DID, ELISA with Aspergillus pool antigen, and the Galactomannan detection with Lateral flow (GM- LFA) essay. Results: By microscopy, fungal structures were observed in 18/24 patients and 16/24 were positive for GM-LFA. Regarding the DID assays, precipitating bands were obtained in 21/24 patients with 86% sensitivity; and 97% specificity. To use ELISA technique, shows that 16/24 sera from patients with aspergillosis were positive, which represents 66% sensitivity and 97% specificity. As for GM- LFA, all sera were tested and 16/24 positive sera were obtained with the commercial kit, representing 66% sensitivity and 97% specificity. Conclusions: Finally, when comparing the three tests studied, all techniques were found to be highly sensitive and have excellent specificity, recommending that the diagnosis of CAPA and IPA be based on a combination of diagnostic assays.