Implementation of a Procalcitonin Assay Requires Appropriate Stewardship to Result in Improved Antimicrobial Use

Abstract

Elevation of procalcitonin (PCT) has a high correlation for the presence of sepsis because of bacterial infection. Levels of PCT have been shown to increase within 6 to 12 hours of the initial bacterial infection, and circulating PCT levels are expected to decrease by half daily when the infection is controlled by the host immune system and antibiotics (ABX).1 Procalcitonin has a high degree of discrimination between viral and bacterial infection and has been shown to be a very useful tool in the decision to shorten the duration of ABX therapy in patients hospitalized with community-acquired pneumonia.2 It is used extensively in Europe to assist decisions for use of antimicrobials and for duration of antimicrobial use because the value of PCT quickly increases or decreases with bacterial burden. There has been less experience, but there is increased interest and ongoing studies in the United States. We have found this test to be very useful in reducing duration of ABX. Ramanathan et al3 presented their experience after introducing PCT in a veterans affairs hospital (primarily in the intensive care unit). They found a suboptimal result of antimicrobial discontinuation or de-escalation on the basis of a low PCT level. This is not surprising because there was no systematic education provided to practitioners before introduction of the test. Other studies of PCT have demonstrated that, without some type of stewardship oversight or defined algorithmic interpretation of the results, there has been little change in the use of antimicrobials. 4,5 We have published our experience in PCT in the intensive care unit whereby we initially educated practitioners as to the appropriate interpretation and found in an observational study a significant decrease in duration of ABX, length of hospital stay, and 30-day readmission rate.6 Since then, our antimicrobial stewardship program has been prospectively following PCT and giving recommendations for the de-escalation of ABX at 48 to 72 hours and has observed a reduction of ABX use. In our study and in current practice, we recommend PCT determination at the onset of sepsis and 48 hours later because there is often a rapid change on the basis of bacterial response to therapy. In addition, in difference to the study by Ramanathan et al,3 we prefer to use the lower level of less than 0.1 μg/L for indication of unlikelihood of bacterial infection. An antimicrobial stewardship team that reviews rapid diagnostic testing results (ie, PNA FISH® (a fluorescence in-situ hybridization (FISH) method using PNA probes), PCT, MALDI-TOF (Matrix Assisted Laser Desorption Ionization Time-of-Flight), and antimicrobial orders) and provides feedback to providers can help clinicians understand and act upon these results. Without this oversight, there may be little change in behavior of practitioners.7 Procalcitonin does not replace clinical judgment but can be a valuable tool regarding the duration of ABX in bacterial infections, including sepsis.