Although the majority of cases of sepsis in intensive care unit (ICU) patients are due to bacterial infection, fungal infections are common and their early identification is important so that appropriate treatment can be started. Biomarkers have been used to aid diagnosis of bacterial infections, but their role in fungal infections is less defined. In this study we assessed the value of procalcitonin (PCT) levels for the diagnosis of candidemia or bacteremia in septic patients.

We prospectively recorded PCT levels in 48 critically ill surgical patients with signs of sepsis and at high risk for fungal infection, and compared levels in patients with candidemia and bacteremia.

Bacterial species were isolated from blood cultures in 16 patients, Candida species in 17, and mixed bacterial and Candida species in 2 patients. PCT levels were less elevated in patients with candidemia (median 0.71 [IQR 0.5–1.1]) than in those with bacteremia (12.9 [2.6–81.2]). A PCT value less than 2 ng/ml enabled bacteremia to be ruled out with a negative predictive value of 94%, and had a similar positive predictive value for candidemia.

Our data indicate that a low PCT value in a critically ill septic patient is more likely to be related to candidemia than to bacteremia.