Procalcitonin Levels in Fungal Infections

Introduction to Procalcitonin Response

PCT is an inflammatory biomarker that shows marked elevation during bacterial infections but remains at low levels during viral and fungal infections, as noted by the Intensive Care Medicine guidelines 1
In bacterial infections, particularly gram-negative infections, PCT levels typically rise to 0.5-2.0 ng/mL in systemic inflammatory response syndrome (SIRS), 2-10 ng/mL in severe sepsis, and >10 ng/mL in septic shock, according to Praxis Medical Insights 2

In COVID-19 patients, elevated PCT levels are more indicative of bacterial co-infection rather than the viral infection itself or fungal superinfection, as reported in the Journal of Microbiology, Immunology and Infection 3, 4
A PCT level <0.25 ng/mL has a high negative predictive value for ruling out bacterial co-infections in COVID-19 patients, as found in studies published in the Journal of Microbiology, Immunology and Infection 3, 4
Serial PCT measurements are more valuable than single readings, particularly in critically ill or ICU patients under mechanical ventilation, as rising levels may indicate developing bacterial infection, according to the Journal of Microbiology, Immunology and Infection 3, 4
In patients with suspected invasive fungal disease such as COVID-19-associated pulmonary aspergillosis (CAPA), normal or low PCT levels despite clinical deterioration should raise suspicion for fungal rather than bacterial infection, as suggested by the Journal of Microbiology, Immunology and Infection 5

PCT can be elevated in non-infectious conditions including shock states and certain drug reactions, requiring clinical correlation, as noted by Praxis Medical Insights 2
The diagnostic value of PCT should not be considered in isolation but as part of a comprehensive diagnostic approach including clinical assessment, microbiological cultures, and other biomarkers, as recommended by Intensive Care Medicine 1