Postmortem analysis of secondary infections in a German cohort of patients following COVID-19 infection.

PURPOSE: This retrospective study analyses secondary infections found in post mortem autopsies in patients with COVID-19 and their contribution to the causes of death. METHODS: Death certificates and reports of clinically requested autopsies of hospitalised COVID-19 positive cases were retrospectively analysed for documented evidence of secondary infections. Type of infections, pathogens, patient demographics and comorbidities were recorded and data analysed using descriptive statistics. RESULTS: A total of 120 COVID-19 deaths underwent a clinically requested autopsy. Most cases (71.6%; 86/120) were hospitalised in the ICU. Within this cohort of deaths 17.5% (21/120) had evidence of a secondary infection of which 57% contributed directly to the cause of death. All secondary infection cases had at least two or more comorbidities and were significantly more immunosuppressed compared to the COVID-19 control group (p = 0.017). A total of 52.4% of the infections were due to bacteria (S. pneumoniae, S. aureus, Staphylococcus sp. Enterococcus spp., K. pneumoniae, K. oxytoca and E. coli) which presented in 47.6% of cases as pneumonia and 14.3% had a documented bacteraemia. Viral pneumonitis was detected in 19% due to viruses such as herpes simplex virus and Cytomegaly virus. Invasive fungal infection made up 47.6% of the infections which were documented as fungal pneumonia (23.8%) including invasive pulmonary aspergillosis, tracheobronchitis (14.3%) and invasive candidiasis (14.3%). CONCLUSION: Secondary infections contribute to the cause of death in a high percentage of hospitalised COVID-19 patients. Autopsies are essential in understanding the role of such infections and may help to guide policies for early diagnosis and therapeutic interventions particularly within high-risk groups.