- Procalcitonin testing can reduce the length of
antibiotic treatment for patients with suspected
community-acquired pneumonia, mainly by permitting
tailored treatment and earlier discontinuation of
antibiotics, new findings indicate.
Circulating levels of procalcitonin are elevated in
bacterial infections and its dynamics have prognostic
implications, note Dr. Beat Muller from University
Hospital Basel, Switzerland and colleagues in the first
issue for July of the American Journal of Respiratory and
Critical Care Medicine.
In a previous study, the investigators showed that
procalcitonin testing was useful in differentiating lower
respiratory tract infections that require antibiotic
therapy from infections that do not.
In the current study, using a sensitive rapid assay for
procalcitonin, the team evaluated the ability of
procalcitonin to guide initiation and duration of
antibiotic therapy in 302 consecutive patients with
suspected CAP. The patients had similar clinical,
laboratory, and microbiology characteristics, and
Pneumonia Severity Index scores at baseline.
Half of the patients received antibiotics according to
usual practice (the control group), while the other half
received antibiotic therapy based on serum procalcitonin
Antibiotics were strongly discouraged if the procalcitonin
level was 0.1 µg/L or lower; discouraged for levels lower
than 0.25 µg/L; encouraged for levels greater than 0.25
µg/L; and strongly encouraged for levels greater than 0.5
µg/L.Antibiotics were withheld on admission in 15% of
patients in the procalcitonin group due to very low
procalcitonin levels, consistent with the absence of
bacterial infection. According to the team, procalcitonin
guidance significantly reduced total antibiotic exposure,
"mainly by individually reducing the duration of
antibiotic courses from a median of 12 days to 5 days."
Supporting the safety of procalcitonin-guided antibiotic
therapy, clinical and laboratory outcomes were similar
between the groups; the overall success rate was 83%. In
an editorial, Dr. Richard G. Wunderink of Northwestern
University in Chicago notes that the "major finding" in
this study was the ability of procalcitonin testing to
decrease the duration of antibiotic therapy. "No other
secondary variables, including hospital length of stay and
mortality, were different when therapy was based on
procalcitonin levels," he notes.
However, 14-day treatment of CAP is no longer the
standard, Dr. Wunderink points out, noting that newer
guidelines recommend 7 days or less of antibiotics.
Therefore, the use of procalcitonin-guided therapy is
unlikely to have a major impact, if current guidelines are
"The major implication of this study," Dr. Wunderink
writes, "is to support putting a cap on the duration of
antibiotic therapy for CAP, similar to that of
The greatest clinical benefit of procalcitonin-directed
therapy," he adds, "still appears to be in the selection
of patients who may not need antibiotics at all, or at
least, not beta-lactam antibiotics."