Bacterial and fungal coinfection among hospitalised patients with COVID-19: A retrospective cohort study in a UK secondary care setting

Abstract

Objectives We investigate the incidence of bacterial and fungal co-infection of hospitalised patients with confirmed SARS-CoV-2 in this retrospective observational study across two London hospitals during the first UK wave of COVID-19. Methods A retrospective case-series of hospitalised patients with confirmed SARS-CoV-2 by PCR was analysed across two acute NHS hospitals (February 20–April 20; each isolate reviewed independently in parallel). This was contrasted to a control group of influenza positive patients admitted during 2019/20 flu season. Patient demographics, microbiology, and clinical outcomes were analysed. Results 836 patients with confirmed SARS-CoV-2 were included; 27/836(3.2%) had early confirmed bacterial isolates identified (0-5 days post-admission) rising to 51/836(6.1%) throughout admission. Blood cultures, respiratory samples, pneumococcal or legionella urinary antigens, and respiratory viral PCR panels were obtained from 643(77%), 112(13%), 249(30%), 246(29%) and 250(30%) COVID-19 patients, respectively. A positive blood culture was identified in 60(7.1%) patients, of which 39/60 were classified as contaminants. Bacteraemia secondary to respiratory infection was confirmed in two cases (1 community-acquired K. pneumoniae and 1 ventilator-associated E. cloacae). Line-related bacteraemia was identified in six patients (3 candida, 2 Enterococcus spp. and 1 Pseudomonas aeruginosa). All other community acquired bacteraemias(16) were attributed to non-respiratory infection. Zero concomitant pneumococcal, legionella or influenza infection was detected. A low yield of positive respiratory cultures was identified; S. aureus the most common respiratory pathogen isolated in community-acquired coinfection (4/24;16.7%) with pseudomonas and yeast identified in late-onset infection. Invasive fungal infections (n=3) were attributed to line related infections. Comparable rates of positive co-infection were identified in the control group of confirmed influenza infection; clinically relevant bacteraemias (2/141;1.4%), respiratory cultures (10/38;26.1%) and pneumococcal-positive antigens (1/19;5.2%) were low. Conclusion We find a low frequency of bacterial co-infection in early COVID hospital presentation, and no evidence of concomitant fungal infection, at least in the early phase of COVID-19.