Bacterial infections in patients with COVID-19: the impact of procalcitonin testing on antibiotics prescription in the real world

Background Bacterial infections are not prevalent among patients hospitalized with COVID-19, while unnecessary prescription of antibiotics was commonly observed. This study aimed to determine the impact of procalcitonin testing on antibiotics prescription in the real-world setting. Methods We performed a territory-wide retrospective cohort study involving all laboratory-confirmed patients hospitalized in public hospitals in Hong Kong in 2020 with COVID-19. We determined the prevalence of bacterial co-infections (documented infections within 72 h of admission) and secondary bacterial infections (infections after 72 h of admission) and antibiotics consumption, and the correlation between procalcitonin testing and antibiotics prescription. Results The cohort included 8666 patients, with mean age 45.3 ± 19.9 years, 48.5% male, and comorbidities in 26.9%. Among 2688 patients with bacterial cultures performed, 147 (5.5%) had bacterial co-infections, and 222 (8.3%) had secondary bacterial infections. Antibiotics were prescribed for 2773 (32.0%) patients during the hospital admission. Procalcitonin tests were performed for 2543 (29.3%) patients. More patients with procalcitonin testing received antibiotics (65.9% vs. 17.9%, p < 0.001). Procalcitonin testing was associated with 5-fold increased risk of antibiotics prescription after adjusting for confounding variables. At hospital level, procalcitonin testing correlated with antibiotics prescription. Patients with procalcitonin level < 0.5 ng/mL had a lower probability of antibiotics initiation and shorter duration of antibiotics therapy. Conclusions Procalcitonin testing was not associated with lower prescription of antibiotics. Patients with low procalcitonin level had lower antibiotics exposure, supporting the use of procalcitonin to exclude bacterial infections aiding early stopping of antibiotics among patients hospitalized with COVID-19.