Procalcitonin

Excerpt

In current clinical practice, procalcitonin (PCT) has developed into a promising new biomarker for the early detection of systemic bacterial infections. PCT is a 116-amino acid residue first explained by Le Moullec et al. in 1984; its diagnostic significance was not recognized until 1993. In 1993, Assicot et al. demonstrated a positive correlation between high serum levels of PCT and patients with positive findings for bacterial infection and sepsis (e.g., positive blood cultures). Further, they demonstrated that PCT did not elevate in viral infections and that serum levels of PCT would decrease following the administration of appropriate antibiotic therapies.

Other inflammatory biomarkers, such as C-reactive protein, lack the specificity to accurately distinguish between bacterial and non-bacterial infections. Therefore, PCT assays, with a specificity of 79%, have been developed and utilized to more accurately determine if a systemic inflammatory reaction is caused by a bacterial species.

The United States Food and Drug Administration has approved using PCT assays for initiating or discontinuing antibiotics in lower respiratory tract infections (LRTIs) and for discontinuing antibiotics in patients with sepsis. Numerous studies have evaluated PCT-based treatment algorithms in these settings and found them safe compared to standard care. In particular, using PCT assays allows cessation of antibiotic therapy without increased morbidity and mortality. This makes PCT a potentially helpful tool for preventing the emergence of antibiotic-resistant organisms while still ensuring appropriate treatment for serious bacterial infections.

PCT should not be used as the sole determinant for antimicrobial therapy. The results of a PCT assay should be placed in the context of the clinical scenario considering the possible site of infection, the likelihood of bacterial infection, the severity of illness, and other pertinent clinical data.