Procalcitonin Test Helps to Rationalize Antibiotic Use

Researchers in Switzerland have developed a test for the blood protein procalcitonin that allows the physician to differentiate between viral and bacterial infections and will reduce the inappropriate use of antibiotics.

In microbial infections and in various forms of severe systemic inflammation, circulating levels of calcitonin precursors (CTpr), including the prohormone procalcitonin (ProCT), increase several-fold to several thousand-fold, and this increase often correlates with the severity of the condition and with mortality. Initially, calcitonin is biosynthesized as ProCT, a precursor which is cleaved enzymatically into free aminoprocalcitonin (N-ProCT) and the conjoined calcitonin:calcitonin-carboxypeptide-I (CT:CCP-I). The latter, in turn, is processed into free CCP-I and immature CT. The thirty-three amino acid immature CT is then amidated to yield the thirty-two amino acid mature CT. All these peptides are found in the serum of healthy people. However, in sepsis, with the exception of mature CT, they are increased to a more or less marked extent.

Investigators at University Hospital (Basel, CH) divided a group of 243 patients into two groups based on procalcitonin levels in the blood. Only those with elevated levels of procalcitonin were treated with antibiotics. More than 97% of patients in both groups made complete recoveries, so withholding of antibiotic did not have a detrimental effect on the outcome of the disease. These findings were published in the February 21, 2004, issue of The Lancet.

Senior author Dr. Beat Müller, a researcher in the department of internal medicine at University Hospital, explained, "Procalcitonin guidance substantially reduced antibiotic use in lower respiratory tract infections. Withholding antimicrobial treatment did not compromise outcome. In view of the current overuse of antimicrobial therapy in often self-limiting acute respiratory tract infections, treatment based on procalcitonin measurement could have important clinical and financial implications.”



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University Hospital (Basel)