Serum PCT Provides Antibiotic Prescribing Strategies for COVID-19

Serum procalcitonin (PCT) testing was associated with reduced empiric antibiotic prescribing among patients with COVID-19, according to findings from a retrospective study at Emory Health.

In data presented last week at the Making A Difference in Infectious Disease (MAD-ID) 2021 Annual Meeting, investigators from Emory Saint Joseph’s Hospital in Atlanta reported that their reliance on PCT evaluation during the second wave of the COVID-19 pandemic in 2020 resulted in improved clinical decision-making among clinicians quick to prescribe antibiotic therapy in patients testing positive for SARS-CoV-2.

Led by Katie McCrory, PharmD, investigators had sought to observe the impact of PCT levels on the antibiotic therapy prescribing patterns among patients presenting with COVID-19 at their institution. Their retrospective study followed education provided to physicians which touched on the observed low rates of bacterial co-infection being reported in patients with COVID-19.

The education, they added, also highlighted the benefit of PCT for interpreting empiric antibiotic prioritization in individual patients—an element of prescribing that had been neglected in the early outbreak of COVID-19 in the US.

“Current literature reports rates of bacterial coinfections in patients hospitalized with COVID-19 to be low, however, the majority of these patients receive empiric antibiotics,” they wrote. “Unnecessary antibiotics can be associated with adverse effects and antimicrobial resistance.”

Their study included a chart review of patients admitted for COVID-19 treatment during the first and second peaks of the pandemic—defined as April 1 – June 30 and July 1 – September 30 of 2020, respectively.

Patients were excluded from the review if they had been previously hospitalized for COVID-19, or if they had been incidentally found to be COVID-19 positive without symptoms.

McCrory and colleagues collected patient demographics, days of antibiotic therapy, initial PCT levels, and positive culture result data. They sought a primary outcome of antibiotic therapy duration in patients stratified by the following: no PCT level collected, normal initial PCT level (< 0.5 ng/mL), and elevated initial PCT (≥ 0.5 ng/mL).

They additionally sought secondary outcomes including time to positive blood and respiratory cultures, and relationship between such metrics and initial PCT; negative predictive value of PCT; and impact of physician education provided between the COVID-19 waves.

The team’s final assessment included 170 patients, of whom 37 (22%) had no PCT level, 106 (62%) had a normal initial PCT, and 27 (16%) had an elevated PCT. Mean antibiotic therapy duration was 0.7 days among patients with no PCT, 4.5 in patients with normal initial PCT, and 9.4 days in patients with elevated initial PCT (P = .005).

The proportion of patients with positive bacterial cultures in the elevated PCT group was greater than that of the lower PCT group—though the difference was not statistically significant.

Investigators reported a negative predictive value of 82.1% for PCT in the observed dataset.

In their conclusion, McCrory and colleagues noted that serum PCT had a “significant impact” on the Emory institution’s antibiotic prescribing during the second wave of COVID-19.

“The number of patients with positive bacterial cultures was slightly higher than previously seen in the COVID-19 population, however this may be due to false positive blood culture results,” they wrote. “The high negative predictive value seen emphasized that PCT was helpful in clinical decision-making regarding empiric antibiotics.”