Bacterial and Fungal Co-Infections in Patients with COVID-19 Related Pneumonia: A Retrospective Cohort Study

Background: The study analyzed risk factors for bacterial and fungal coinfection in patients with COVID-19 and the impact on mortality. Methods: This is a single-center retrospective study conducted on 387 patients with confirmed COVID-19 pneumonia admitted to an Italian Tertiarycare hospital, between 21 February 2020 and 31 May 2020. Bacterial/fungal coinfection was determined by the presence of characteristic clinical features and positive culture results. Multivariable logistic regression was used to analyze risk factors for the development of bacterial/fungal co-infection after adjusting for demographic characteristics and comorbidities. Thirty-day survival of the patients with or without co-infections was analyzed by Kaplan- Meier method. Results: In 53/387 (13.7%) patients with COVID-19 pneumonia, 67 episodes of bacterial/fungal co-infection occurred (14 presented >1 episode). Pneumonia was the most frequent co-infection (47.7%), followed by BSI (34.3%) and UTI (11.9%). S. aureus was responsible for 24 episodes (35.8%), E. coli for 7 (10.4%), P. aerugionsa and Enterococcus spp. for 5 episodes each (7.4%). Five (7.4%) pulmonary aspergillosis, 3 (4.4%) pneumocystosis and 5 (7.4%) invasive candidiasis were observed. Multivariable analysis showed a higher risk of infection in patients with an age >65 years (csHR 2.680; 95% CI: 1.254-5.727; p=0.054), with cancer (csHR 5.243; 95% CI: 1.173-23.423; p=0.030), with a LOS >10 days (csHR 12.507; 95% CI: 2.659 - 58.830; p=0.001), early (within 48h) admitted in ICU (csHR 11.766; 95% CI: 4.353-31.804; p<0.001), and with a SOFA score >5 (csHR 3.397; 95% CI: 1.091-10.581; p=0.035). Estimated cumulative risk of developing at least 1 bacterial/fungal co-infection episode was of 15% and 27% after 15 and 30 days from admission, respectively. Kaplan-Meier estimated a higher cumulative probability of death in patients with bacterial/fungal co-infection (log-rank=0.031). Thirty-day mortality rate of patients with pneumonia was 38.7%, higher than those with BSI (30.4%). Conclusions: Bacterial and fungal infections are a serious complication affecting the survival of patients with COVID-19- related pneumonia. Some issues need to be investigated, such as the best empirical antibiotic therapy and the need for possible antifungal prophylaxis.