A recent study conducted by Austin Health, Australia, has revealed that the serum level of procalcitonin can be a strong indicator of bacterial co-infection with coronavirus disease 2019 (COVID-19). The study is currently available on the medRxiv* preprint server.
Since its emergence in December 2019, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative pathogen of COVID-19, has already infected more than 92 million people and claimed about 2 million lives globally. Alike other respiratory infections, the presence of microbial co-infection can increase the disease severity and mortality in critically ill COVID-19 patients. To prevent adverse outcomes of microbial co-infection, empiric antibiotics are frequently used as a part of the standard of care treatment for in-hospital COVID-19 patients. However, several clinical studies have shown that the risk of bacterial co-infection in COVID-19 patients is lower compared to other viral infections.
The level of procalcitonin, which is a precursor of the hormone calcitonin, in the blood can increase significantly in response to systemic bacterial infection. This means that it can be used as a biomarker to guide antimicrobial stewardship, which specifies the appropriate use of antimicrobial medicines, including antibiotics. In in-hospitalized COVID-19 patients, the serum level of procalcitonin has been associated with disease severity, duration of stay in intensive care units (ICU), and mortality. Clinical measurement of procalcitonin levels at the time of hospital admission or clinical deterioration can serve as a valuable indicator for identifying bacterial co-infection and can inform appropriate treatments.
Current study design
The current study was designed to investigate whether procalcitonin can be a useful marker in predicting the severity of COVID-19, initiation of antibiotic treatment, duration of antibiotic treatment, and intravenous to oral antibiotic switch.
A total of 55 hospitalized COVID-19 patients were investigated in the study. Based on the serum levels of procalcitonin measured at the time of admission, these patients were categorized into normal, medium, and high procalcitonin groups.
Of the 55 patients, 44 received antibiotic therapy at the time of admission. Around 60%, 81%, and 100% of the patients with normal, medium, and high procalcitonin levels, respectively, received antibiotic therapy. Although a significant association was observed between the procalcitonin level and antibiotic use, no such association was found for the total duration of antibiotic therapy. However, a significant association was observed between the procalcitonin level and intravenous to oral switch of antibiotics. The patients with high procalcitonin levels received intravenous antibiotics for an additional 1.5 days compared to the patients with normal or medium procalcitonin levels.
As a part of their routine examinations, blood cultures were conducted for 42 of the patients, where three positive reports were obtained.
Regarding other clinical indicators of COVID-19 severity, the study findings revealed that nearly all patients with high procalcitonin levels received supplemental oxygen during the hospital admission. In contrast, only 35% of patients with normal procalcitonin required oxygen supplementation. However, no association has been observed between the procalcitonin level and need for admission to ICUs.
Regarding biochemical markers of COVID-19 severity, significant associations were observed between the serum levels of procalcitonin and C-reactive protein, lymphocyte, ferritin, and lactate dehydrogenase.
The study findings suggest that the serum level of procalcitonin in COVID-19 patients can be a good indicator of disease severity. By measuring procalcitonin levels at the time of hospital admission, physicians can more accurately evaluate antibiotic therapy requirements, and potentially avoid unnecessary use of antibiotics.
medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.