Procalcitonin levels and antibiotic use associations with COVID-19 disease severity in hospitalized adults and the potential for an increase in antibiotic resistance: a cross-sectional clinical and public health analysis

Background: Elevated procalcitonin (PCT) levels guide clinicians in antibiotic use for suspected bacterial infections and subsequent need for antimicrobial therapy. Our aim was to ascertain the usefulness of this laboratory marker in patients hospitalized with COVID-19, its effect on patterns of antibiotic use in this subset of patients and the public health implications of these use patterns. Methods: Electronic medical records (EMRs) were interrogated in a cohort of hospitalized adults with COVID-19 (n=78) who experienced moderate and severe disease as defined by the Yale Impact Score. Patients were recruited from the Northern Colorado region from July 2020 to March 2021 and multiple data metrics were gathered on 55 patients, including demographics, PCT level on admission, disease severity, bacterial co-infections (BcI), and antibiotic usage. T-tests, ANCOVA, and ANOVA were used for continuous data while Fisher's exact or chi square were used to analyze categorical data. Results: Antibiotics were administered to 37 (47.4%) of all patients enrolled in the biorepository, while the rate of BcI in this patient population was 8 (18.7%). Of the 55 hospitalized patients with PCT levels, those with severe COVID-19 had significantly higher LnPCT levels 0.18 (0.12-0.26) ng/mL than those with moderate disease 0.12 (0.09-0.15) ng/mL, P=0.048. Thirty (54.5%) of the 55 were given antibiotics while 25 (45.5%) were not, and only 7 patients had BcI, confirmed by blood, respiratory, or urine culture positivity. Conclusions: In the setting of COVID-19 infection, PCT is more closely linked to viral disease severity and less associated with BcI. This association is driving an increase in antibiotic use in patients with COVID-19 regardless of a confirmed co-infection leading to antibiotic overuse, potential for resistance and associated increase in multidrug resistant organisms (MDROs). Currently available lower respiratory tract infection (LRTI) guidelines for the use of PCT to initiate and de-escalate antibiotics can safely be followed in the setting of COVID-19 infection, although modification of blood-level cutoffs require further study. Such an approach would minimize the public health impact of antibiotic overuse.