The Procalcitonin (PCT) regulation differs in viral and bacterial infection. Pure viral infections are characterized by interferon signalling which in essence suppresses the PCT production; in contrast, the bacterial infection induces the PCT production. The rules of PCT usage in COVID-19 patients are based on measurement at the admission, followed by daily measurements to detect the viral infection associated PCT values (less than 0.1 ng/ml) or higher PCT values (0.25-8 ng/ml) which identify a bacterial co-infection.
The pathologically exaggerated and prolonged anti-inflammatory phenotype, plus the steroid therapy as part of COVID-19 treatment is associated with a higher nosocomial infection rate (MDR bugs). It is vital to diagnose the secondary bacterial infection as early as possible in COVID-19 because the initiation time of an appropriate treatment is shorter in these patients.
The daily PCT measurements detect the increasing PCT levels and help the medical team to react promptly and start antibiotic therapy. In addition, the daily PCT measurements distinguish the maximum PCT value and the PCT value reduction thanks to the appropriate AB therapy. The AB treatment discontinuation always had to be based on 3 criteria: clinical, microbiological and inflammatory triggered PCT kinetics. The CRP levels are better correlated to the viral component of the inflammation and have a slower kinetics, compared to the PCT.
1. Procalcitonin helps to distinguish bacterial infection from other.
2. Antibiotic initiation can be reduced with PCT plasma level monitoring.
3. Antibiotic treatment duration can be reduced with PCT plasma level follow up.
4. Low PCT levels are found in pure viral infection eg influenza SARS Cov2, RSV.