Characterization of antimicrobial use and co-infections among hospitalized patients with COVID-19: a prospective observational cohort study

Purpose To investigate antimicrobial use and primary and nosocomial infections in hospitalized COVID-19 patients to provide data for guidance of antimicrobial therapy. Methods Prospective observational cohort study conducted at Charite-Universitatsmedizin Berlin, including patients hospitalized with SARS-CoV-2-infection between March and November 2020. Results 309 patients were included, 231 directly admitted and 78 transferred from other centres. Antimicrobial therapy was initiated in 62/231 (26.8%) of directly admitted and in 44/78 (56.4%) of transferred patients. The rate of microbiologically confirmed primary co-infections was 4.8% (11/231). Although elevated in most COVID-19 patients, C-reactive protein and procalcitonin levels were higher in patients with primary co-infections than in those without (median CRP 110 mg/l, IQR 51-222 vs. 36, IQR 11-101, respectively; p < 0.0001). Nosocomial bloodstream and respiratory infections occurred in 47/309 (15.2%) and 91/309 (29.4%) of patients, respectively, and were associated with need for invasive mechanical ventilation (OR 45.6 95%CI 13.7-151.8 and 104.6 95%CI 41.5-263.5, respectively), extracorporeal membrane oxygenation (OR 14.3 95%CI 6.5-31.5 and 16.5 95%CI 6.5-41.6, respectively), and haemodialysis (OR 31.4 95%CI 13.9-71.2 and OR 22.3 95%CI 11.2-44.2, respectively). The event of any nosocomial infection was significantly associated with in-hospital death (33/99 (33.3%) with nosocomial infection vs. 23/210 (10.9%) without, OR 4.1 95%CI 2.2-7.3). Conclusions Primary co-infections are rare, yet antimicrobial use was frequent, mostly based on clinical worsening and elevated inflammation markers without clear evidence for co-infection. More reliable diagnostic prospects may help to reduce overtreatment. Rates of nosocomial infections are substantial in severely ill patients on organ support and associated with worse patient outcome.