PCT-Guided Antibiotic Therapy

Lower respiratory tract infections can present in many different ways, including acute bronchitis, community-acquired pneumonia, and acute exacerbation of chronic obstructive pulmonary disease.

In the past, this ambiguity was met with almost-automatic antibiotic therapy. Today, we have better information and better ways to decide if antibiotics are warranted.

Procalcitonin (PCT) provides critical biomarker information. PCT is produced by numerous organs at a cellular level after bacterial pro-inflammatory stimulation.1,2

Procalcitonin is a host response to bacterial insult.3-5

Viral Infections inhibit PCT expression, enhancing the ability to distinguish bacterial infections from non-bacterial infections (PCT is not specifically indicated as a viral marker).

  • Bacterial infection stimulates PCT
  • Viral infection blocks PCT

PCT Algorithm

Lower Respiratory Tract Infections (LTRI): PCT-Guided Therapy

LRTI Antibiotic Initiation Algorithm

For patients with suspected or confirmed lower respiratory tract infection (LRTI), defined as community-acquired pneumonia (CAP), acute bronchitis, and acute exacerbation of chronic obstructive pulmonary disease (AECOPD).

PCT Value <0.1 ng/mL 0.1 - 0.25 ng/mL 0.26 - 0.5 ng/mL >0.5 ng/mL
Initiation of Antibiotic Use Recommendation Strongly Discourage Discourage Encourage Strongly Encourage
Clinical Considerations
  • Inpatients: If antibiotics are withheld, repeat measurement within 6 - 24 hours
  • Outpatients: reassess and/or repeat test if symptoms persist/worsen
  • Antibiotic therapy should be considered if clinical context indicates it is warranted
  • Follow-up samples should be tested at regular intervals and antibiotic therapy may be adjusted using algorithm for discontinuation

LRTI Antibiotic Discontinuation Algorithm

PCT Value <0.25 ng/mL ↓ >80% from peak
Discontinuation of Antibiotic Use Recommendation Encourage
Clinical Considerations
  • Consider continuing antibiotic therapy if clinical instability or disease progress present
  • If PCT remains high, consider treatment failure

PCT-Guided Antibiotic Therapy is Safe and Effective for Patients 

Significant reduction in antibiotic initiation

  • 19% reduction in relative antibiotic initiation in all patients
  • 39% reduction in initiation of antibiotics in ED patients

Significant reduction in exposure to antibiotics

  • 38% reduction in overall antibiotic exposure for inpatients
  • 51% reduction in overall antibiotic exposure for patients in ED

No adverse safety signals associated with PCT guidance for LRTI

  • No signal for increase in 30-day mortality, complications or length of stay

Sepsis: PCT-Guided Antibiotic Therapy

For more information, please see full package insert for VIDAS B•R•A•H•M•S PCT (30450-01).

In conjunction with clinical assessments, use of PCT can increase accuracy of early diagnosis and enable more appropriate clinical decisions.

1. Evaluate: Assess Sepsis Risk & Severity

In just 20 minutes, you can get results from a proven, sensitive biomarker that provides specific information that adds to physician acumen, and enables more appropriate triage decisions.

>2.0 ng/mL High risk for progression to severe sepsis and/or septic shock
0.5 - 2.0 ng/mL Sepsis should be considered
<0.5 ng/mL Low risk for progression to severe sepsis and/or septic shock

2. Monitor: Assess Risk Over Time

Assessing PCT values over time provides valuable information regarding patient disposition, response to treatment, and likelihood of survival.

Follow up samples should be tested once every 1-2 days, based upon physician discretion to support decision to discontinue antibiotic therapy.

3. Discontinue: Assess When to Discontinue Antibiotics

VIDAS B•R•A•H•M•S PCT has been cleared by the FDA to aid in decision making on antibiotic discontinuation for patients with suspected or confirmed sepsis.

Discontinuation of antibiotics is encouraged if the PCT concentration is ≤0.50 ng/mL or if the ∆PCT >80%.

Antibiotic therapy may be continued based upon other clinical findings, such as failure to control a local infection, or ongoing physiologic instability.

PCT is an Important Part of the Solution

For Critically Ill Patients:

  • Antibiotic therapy is of great importance 
  • Prolonged duration is associated with development of antimicrobial resistance
  • PCT-guided antibiotic therapy reduces antibiotic exposure and patient length of stay (a 23% reduction in antibiotic exposure)
  • No adverse safety signals associated with PCT-guided antibiotic therapy for sepsis

PCT & Antibiotic Stewardship

  • Monitor PCT levels
  • Gain needed data to make better, more informed decisions
  • Additional guidance for initiation and discontinuation of antibiotic therapy
  • Improve prescribing practices to slow rise of resistant bacteria
  • Support CMS guidelines for antibiotic stewardship and infection prevention

So you can achieve the goal of giving antibiotics to the right patients, at the right time, for the right duration.

Useful Material for Interpreting PCT Results

Clinical Guide to Use of Procalcitonin  

VIDAS B•R•A•M•H•S PCT Wall Chart    

Learn More About VIDAS® B•R•A•H•M•S PCT™

VIDAS® 3 is a benchtop immunoassay system designed specifically for low throughput testing.  Fully automated, it is based on the proven and robust ELFA technology that makes VIDAS a gold standard worldwide for high quality on-demand test results.

  • Full traceability
  • Specialty menu available in single-test ready-to-use format
  • Bidirectional connectivity to internal and external networks


Visit VIDAS 3

Order Online


1. Kumar A, Roberts D, Wood KE, et al. Duration of hypotension before initiation of effective antimicrobial therapy is the critical determinant of survival in human septic shock. Crit Care Med. 2006;34(6):1589-1596.
2. Müller B, White JC, Nylén ES, Snider RH, Becker KL, Habener JF. Ubiquitous expression of the calcitonin-I gene in multiple tissues in response to sepsis. J Clin Endocrinol Metab. 2001;86(1):396-404.
3. Linscheid P, Seboek D, Schaer DJ, Zulewski H, Keller U, Müller B. Expression and secretion of procalcitonin and calcitonin gene-related peptide by adherent monocytes and by macrophage-activated adipocytes. Crit Care Med. 2004;32(8):1715-1721.
4. Linscheid P, Seboek D, Nylen ES, et al. In vitro and in vivo calcitonin-I gene expression in parenchymal cells: a novel product of human adipose tissue. Endocrinology. 2003;144(12):5578-5584.
5. Linscheid P, Seboek D , Zulewski H, Keller U, Müller B. Autocrine/Paracrine role of inflammation-mediated calcitonin gene-related peptide and adrenomedullin expression in human adipose tissue. Endocrinology. 2005;146(6):2699-2708.
Pioneering Diagnostics