Procalcitonin Levels in Identifying Bacterial Infections in Children with and without COVID-19

Elevated procalcitonin levels have been associated with bacterial infection in children. Observational studies reported high procalcitonin values in COVID-19. Data on bacterial coinfections in pediatric COVID-19 is sparse; small studies suggest a low coinfection rate. In this study, we aimed to quantify the positive predictive value (PPV) of procalcitonin in identifying bacterial infection in children with and without COVID-19.

A retrospective chart review was performed for 215 children <21 years admitted to our tertiary children's hospital between February 1, 2013, and July 15, 2020, who had procalcitonin levels measured within 48 hours of admission. Confirmed bacterial infection was defined as positive blood, urine, or cerebrospinal fluid (CSF) culture, positive endotracheal culture with evidence of leukocytosis on Gram stain, or pneumonia by chest radiograph. Suspected bacterial infection was defined as confirmed bacterial infection or administration of antibiotics for >48 hours.

Of the 215 patients, 73 were admitted for COVID-19 (66% multisystem inflammatory syndrome in children [MIS-C], 34% acute COVID-19). The PPV of an elevated procalcitonin level >1.0 ng/mL in identifying suspected bacterial infections for those with MIS-C was 6.3% (95% CI=0-15), in acute COVID-19 was 29% (95% CI=0-62%), and in the non-COVID-19 cohort was 75% (95% CI=62-88%). For identification of confirmed bacterial infection, PPV of an elevated procalcitonin level was 0% in MIS-C, 14% (95% CI=0-40%) in acute COVID-19, and 55% (95% CI=40-69%) in the non-COVID-19 cohort.

We found a low PPV of elevated procalcitonin level above 1 ng/mL in identifying either culture-confirmed or presumed bacterial infection in children hospitalized with COVID-19-related illness.