From Aspergillus fumigatus pathogen surveillance to Aspergillus disease surveillance

The aim of this study was to determine which mycological diagnostic test(s) and clinical data are required for detecting and classifying Aspergillus disease cases for surveillance purposes.

This pilot study for an Aspergillus disease surveillance programme was performed in two academic medical centres in the Netherlands in collaboration with the National Institute for Public Health with data from 2019. Patients with a positive bronchoalveolar lavage (BAL) Aspergillus fumigatus culture, Aspergillus polymerase chain reaction (PCR), or galactomannan (GM) immune assay were included in the study. Data were retrospectively collected from the laboratory information system and supplemented with clinical and treatment data from electronic patient records (EPRs). Using mycology and clinical data, cases were classified using international definitions for disease classification (considered gold standard).

In total, 89 patients with a positive diagnostic test for Aspergillus were included in the cohort (53 culture positive; 36 PCR/GM positive only). Of these by-pathogen-identified patients, 38 (43%) had classifiable Aspergillus disease (24 culture positive). 32 of 38 (84%) Aspergillus disease cases were detected if a positive diagnostic test in combination with antifungal treatment was considered indicative of disease. The most complete detection and classification was obtained when EPR data were extracted.

Positive Aspergillus BAL results and additional antifungal treatment data resulted in a good estimate of Aspergillus disease cases. However, EPR data provided the most accurate case identification but - at present - require manual chart review which is laborious and less feasible for surveillance. Future research should focus on systems for automated data extraction from the EPR to allow reliable case classification with minimal workload.