Procalcitonin and Ventilator-associated Pneumonia

The effect of vitamin C on procalcitonin biomarker in community-acquired pneumonia

Introduction

Community acquired pneumonia (CAP) is a prevalent low respiratory infection. Diagnosis is based on clinical symptoms, radiologic evidence and culture. Biomarkers such as IL6, CRP and procalcitonin are helpful in diagnosis. Procalcitonin is a soluble biomarker in serum that increase in systemic inflammation and bacterial infections. People with normal procalcitonin have low risk to infect pneumonia. Patient with CAP have more oxidative stress than normal people. Studies show that receiving vitamin C can reduce incidence of pneumonia. The present study was designed to evaluate the effect of vitamin C supplement on procalcitonin biomarker in patient with CAP.

Methods

Patients with CAP who passed inclusion and exclusion criteria after obtaining informed consent, were assigned randomly in two groups of drug and placebo. The drug group received vitamin C (1000 mg/d) daily and medications that physician prescribed for treating CAP for 10 days and placebo group received placebo and medications that physician prescribed. The serum level of procalcitonin was measured at the beginning of the study and after 10 days of intervention.

Results

35 patients finished the study. Serum level of procalcitonin on the first and tenth day did not show any significant difference between drug and placebo groups.

Conclusions

To clarify the relationship between the effects of vitamin C on procalcitonin in CAP, a larger sample size is required.

Diagnostic value of procalcitonin in ventilator-associated pneumonia

BACKGROUND AND OBJECTIVE

Procalcitonin (PCT) can help the early diagnosis of bacterial infections and estimate the response obtained. The objective is to study the value of PCT for the diagnosis of ventilator-associated pneumonia (VAP).

PATIENTS AND METHOD

Prospective and observational study, carried out for 18 months, in a polyvalent Intensive Care Unit (ICU). Those included were over 18 years of age, with suspected pneumonia after 48h of mechanical ventilation (MV). Collected were demographic characteristics; admission pathology; reason for beginning MV; gravity scores (APACHE II, SAPS II and SOFA); C-reactive protein (CRP) and PCT. At the time of suspicion of VAP: early or late, radiological severity, presence of septic shock, SOFA, CRP, PCT and microbiology.

RESULTS

Ninety-one patients with suspected VAP were included. The mean age was 42 (17.76) and that of hospitalisation in the ICU was 18.59 (11.69) days. VAP was confirmed in 74 patients, of which 19 (25.7%) presented septic shock. The mortality was 28.4%. There were no significant differences of the PCT in the patients who presented VAP versus those who did not present VAP (P=.449). When patients without VAP, with VAP and VAP with shock, were compared, the PCT median was 0.38 (CI95%: 0.22-1.90), 0.56 (CI95%: 0.19-1.77) and 1.93 (CI95%: 0.38-10.07), respectively (P=.169).

CONCLUSIONS

In our study, PCT did not prove useful for the diagnosis of VAP.

Biomarkers in the management of pneumonia

A novel approach to improve diagnosis and prognosis of pneumonia is the use of biomarkers. An ideal diagnostic biomarker for pneumonia should allow an early diagnosis and differential diagnosis from other, noninfectious conditions. Procalcitonin (PCT) has emerged as a reliable diagnostic marker in pneumonia, and is better when compared with other markers, namely C-reactive protein, leukocyte count and proinflammatory cytokines. A PCT-based diagnostic and therapeutic strategy can reduce antibiotic usage in patients with pneumonia, mainly by reducing the duration of antibiotic courses. However, PCT should not be used as a substitute for a careful clinical assessment. PCT levels may remain low in localized infections in the context of pneumonia, especially in patients with localized empyema. An ideal prognostic biomarker should be informative about the course and outcome of a disease. Various biomarkers, namely pro-adrenomedullin, natriuretic peptides, endothelin-1 precursor peptides, as well as copeptin and cortisol levels, are promising in this respect. Future studies will show whether an assessment with those novel biomarkers is able to guide prognostic decision-making and improve the allocation of healthcare resources and hospitalization costs.

Procalcitonin and pneumonia: is it a useful marker?

An ideal biomarker for pneumonia should allow an early diagnosis and differential diagnosis from noninfectious conditions and should inform about the course and prognosis of the disease. Procalcitonin (PCT) covers these features better as compared to more commonly used biomarkers like C-reactive protein or leukocyte count. PCT complements and improves the assessment of pneumonia based on careful patient history, dedicated physical examination, and appropriate cultures. Importantly, a PCT-based therapeutic strategy can safely and markedly reduce antibiotic courses in community-acquired pneumonia. However, as is the cast with all diagnostic surrogate markers, PCT can be increased in noninfectious conditions and may remain low in bacterial infections, especially localized infections. This stresses the importance of follow-up measurements, because PCT levels in these patients often show a gradual increase during follow-up. Although PCT is -better than more common biomarkers for the prognosis of pneumonia and to predict survival and outcome, novel biomarkers show an even better prognostic accuracy.

Procalcitonin Guidance of Antibiotic Therapy in Community-acquired Pneumonia

RATIONALE

In patients with community-acquired pneumonia, guidelines recommend antibiotic treatment for 7 to 21 d. Procalcitonin is elevated in bacterial infections, and its dynamics have prognostic implications.

OBJECTIVE

To assess procalcitonin guidance for the initiation and duration of antibiotic therapy in community-acquired pneumonia.

METHODS

In a randomized intervention trial, 302 consecutive patients with suspected community-acquired pneumonia were included. Data were assessed at baseline, after 4, 6, and 8 d, and after 6 wk. The control group (n = 151) received antibiotics according to usual practice. In the procalcitonin group (n = 151), antibiotic treatment was based on serum procalcitonin concentrations as follows: strongly discouraged, less than 0.1 microg/L; discouraged, less than 0.25 microg/L; encouraged, greater than 0.25 microg/L; strongly encouraged, greater than 0.5 microg/L. The primary endpoint was antibiotic use; secondary endpoints were measures of clinical, laboratory, and radiographic outcome.

RESULTS

At baseline, both groups were similar regarding clinical, laboratory, and microbiology characteristics, and Pneumonia Severity Index. Procalcitonin guidance reduced total antibiotic exposure (relative risk, 0.52; 95% confidence interval, 0.48-0.55; p < 0.001), antibiotic prescriptions on admission (85 vs. 99%; p < 0.001), and antibiotic treatment duration (median, 5 vs. 12 d; p < 0.001) compared with patients treated according to guidelines. After adjustment for Pneumonia Severity Index, the hazard ratio of antibiotic discontinuation was higher in the procalcitonin group than in the control group (3.2; 95% confidence interval, 2.5 to 4.2). Outcome was similar in both groups, with an overall success rate of 83%.

CONCLUSIONS

Procalcitonin guidance substantially reduces antibiotic use in community-acquired pneumonia. These findings may have important clinical and public health implications.