Respiratory Tract Infections

When to Order

Order upon presentation. PCT testing is reasonable to reduce unnecessary antibiotic exposure.

PCT Level < 0.10μg/L

Antibiotic initiation strongly discouraged
Alternative diagnosis of viral infection or pulmonary embolism may be considered
Consider antibiotic initiation if patient becomes clinically unstable or has strong evidence of bacterial pathogen

PCT Level 0.10-0.24μg/L

Antibiotic initiation discouraged
Alternative diagnosis of viral infection or pulmonary embolism may be considered
Consider antibiotic initiation if patient becomes clinically unstable or has strong evidence of bacterial pathogen

PCT Level 0.25-0.49 μg/L

PCT Level ≥0.5μg/L

If antibiotics are held on admission

Re-measure PCT is not recommended if patient demonstrates clinical or symptom improvement within 1-2 days
If patient has not improved and bacterial is suspected, recheck PCT in 12-48 hours

If antibiotics are started on admission

Repeat PCT monitoring at 48-72 hours
PCT can be effective every 48-72 hours to reduce duration of antimicrobial therapy in stable patients with concern for respiratory tract infections
See "Thresholds for Antibiotic De-Escalation" below

PCT should not be used in place of standard diagnostic tests.

It is a biomarker to aid a clinician in decision making. Algorithm should not circumvent clinical judgement and patient assessment.