Optimization of antibiotic therapy by procalcitonin

Introduction

Procalcitonin (PCT) is routinely used as a specific marker of severe bacterial infections and sepsis. The highly sensitive method of PCT measurement allows using PCT as a marker of local bacterial infections. By this method, the normal value of PCT is defined as < 0.25 ng/ml – but according to some publications PCT < 0.1 ng/ml is a more reliable cutoff point to reject diagnosis of local bacterial infection. Some patients after major surgery have nonspecific signs of infection (for example, fever, leukocytosis) that is usually discussed as true infection and antibiotic therapy (ABT) is provided. We tried to optimize ABT in patients undergoing cardiac surgery with cardiopulmonary bypass using PCT.

Methods

Sixty-six patients aged from 2 days to 72 years (39 adults, 27 children) with nonspecific signs of infection without its focus were studied. Seventy-six PCT tests from blood plasma were made (PCT sensitive LIA; BRAHMS, Germany) to decide whether ABT is sufficient or antibiotics should be prescribed/changed/discontinued.

Results

Based on PCT testing results we have made following decisions (see Figure 1). As Figure 1 shows, when PCT was < 0.1 ng/ml antibiotics were discontinued or not prescribed in 61% of cases. In 30% of cases we prolonged ABT for several days. Only in 9% cases were antibiotics changed. In patients who had PCT of 0.1 to 0.25 ng/ml we tended to continue or change ABT (77%). If elevated PCT levels (> 0.25 ng/ml) were detected, we prescribed (20%) or reinforced (73%) ABT in the majority of cases. In total we discontinued or did not prescribe antibiotics in 31/76 cases (41%) taking into consideration the results of PCT testing. We did not register progression of bacterial infection in those cases with the exception of one 10-month patient with mild exacerbation of bronchitis.

Figure 1

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Conclusion

There is a big need to optimize ABT in postoperative period in cardiac surgery patients due to significant overuse of antibiotics. PCT-guided tactics are safe and allowed reduction of unnecessary antibiotic usage in patients with nonspecific signs of infection. At the same time, supernormal PCT levels are a strong indicator to prescribe or change ABT.