High procalcitonin, longer antibiotics? Not so fast

Clinical takeaway: In patients with uncomplicated bloodstream infection who are already planned for a short antibiotic course, an elevated procalcitonin level at day 7 should not automatically prompt extension to 14 days. The study supports using clinical stability, source control, pathogen, infection source, and host factors to guide decisions rather than treating a persistently high procalcitonin value as evidence that more antibiotics are needed.

A planned secondary analysis of the BALANCE (Bacteremia Antibiotic Length Actually Needed for Clinical Effectiveness) trial found that elevated procalcitonin (PCT) at day 7 was associated with higher 90-day mortality in patients with bloodstream infections, but longer antibiotic treatment did not improve outcomes in those patients.

The original BALANCE trial showed that 7 days of antibiotics was noninferior to 14 days for most patients with bacteremia. The new secondary analysis asked a practical bedside question: if a patient still has an elevated PCT level after 7 days, should clinicians extend antibiotics?

Researchers evaluated day-7 PCT in 125 patients with bacteremia. Nearly half had high levels, defined as 250 pg/mL or higher. Ninety-day mortality was higher in the high-PCT group than in the low-PCT group: 21.6% vs 6.2%.

However, among patients with high day-7 PCT levels, extending antibiotics to 14 days was not associated with lower mortality than stopping at 7 days. Mortality was 10.3% in the 7-day group and 32.3% in the 14-day group, with wide confidence intervals. Secondary outcomes were also not improved with longer treatment.

The result matters because PCT is often used to help clinicians feel more comfortable stopping antibiotics. This study suggests the reverse should not be assumed: a persistently elevated PCT level near the end of a planned short course may mark a sicker patient, but it does not necessarily mean ongoing bacterial infection that will respond to additional antibiotics.

The authors noted that patients with higher day-7 PCT levels had higher baseline Sequential Organ Failure Assessment (SOFA) scores, a measure of acute organ dysfunction, and more comorbidities, including diabetes and dialysis dependence. They suggested that persistent PCT elevation may reflect the intensity of the host inflammatory response rather than the remaining bacterial burden.

For clinicians, the finding supports a simple antimicrobial stewardship message: in most uncomplicated bloodstream infections, PCT measurement is not needed to justify stopping antibiotics at 7 days. A high PCT level should prompt reassessment of the patient, source control, complications, and alternative causes of inflammation, but not reflexive antibiotic prolongation.

The accompanying commentary by Brad Spellberg, MD, of Los Angeles General Medical Center, framed PCT as more useful when it is low than when it is high. He noted that a low PCT can reassure clinicians that stopping or withholding antibiotics is safe, but an elevated PCT often does not change management because clinicians were already likely to continue antibiotics.

“Overall, the results are compelling that there is no role for testing procalcitonin toward end of preplanned course of therapy to determine whether antibiotic treatment should be prolonged or not,” Spellberg wrote in the commentary.

Source: Ramendra R, et al. 2026 June 29 JAMA Netw Open. Procalcitonin to guide 7 vs 14 days of antibiotics in bloodstream infections: a secondary analysis of the BALANCE trial