Procalcitonin to Guide Antibacterial Prescribing in Patients Hospitalised with COVID- 19

Abstract Background: Antibacterial prescribing in patients presenting with COVID-19 remains discordant to rates of bacterial co-infection. Implementing diagnostic tests to exclude bacterial infection may aid reduction in antibacterial prescribing. Method: A retrospective observational analysis was undertaken of all hospitalised patients with COVID-19 across a single-site NHS acute Trust (London, UK) from 01/12/20-28/2/21. Electronic patient records were used to identify patients, clinical data, and outcomes. Procalcitonin (PCT) serum assays, where available on admission, were analysed against electronic prescribing records for antibacterial prescribing to determine relationships with a negative PCT result (<0.25mg/L) and antibacterial course length. Results: Antibacterial agents were initiated on admission in 310/624 (49.7%) of patients presenting with COVID-19. 33/74 (44.5%) patients with a negative PCT on admission had their treatment stopped within 24 hours. 6/49 (12.2%) patients who had antibacterials started but a positive PCT had their treatment stopped. Microbiologically confirmed bacterial infection was low (19/594; 3.2%); no correlation was seen with PCT and culture positivity (p=1). Lower mortality (15.6% vs 31.4%;p=0.049), length of hospital stay (7.9days vs 10.1days;p=0.044), and intensive care unit (ICU) admission (13.9% vs 40.8%;p=0.001) were seen among patients with low PCT. Conclusion: This retrospective analysis of community acquired COVID-19 patients demonstrates the potential role of PCT in excluding bacterial co-infection. A negative PCT on admission correlates with shorter antimicrobial courses, early cessation of therapy and predicts lower frequency of ICU admission. Low PCT may support decision making in cessation of antibacterials at the 48-72 hour review.