Early identification of infectious complications in lung transplant recipients using procalcitonin

Evaluation of procalcitonin (PCT) as a marker of infection in early post living donated liver transplant period

BACKGROUND AND AIM

Procalcitonin (PCT) has been increasingly used as a biomarker of bacterial infection and as a tool to guide antimicrobial therapy. Despite its increased use, data in patients with solid organ transplants are limited. The study aimed to assess the frequency of rising PCT associated with infectious complications in immunosuppressed living donated liver transplantation.

METHODS

A single-center, retrospective observational study. Preoperative patients' demographic data, operative, anesthetic data, and postoperative clinical course were analyzed post-liver transplant (LT) till discharge from the intensive care unit.

RESULTS

Sixty patients were classified according to the culture results' into a positive culture group & a negative one and then followed up the sepsis variables in each group. Total leukocyte count (TLC) was elevated in the positive culture group in comparison to the negative culture one and was statistically significant (P-value <0.05) till the fourth day postoperative. Procalcitonin was higher in the positive culture group than in the negative one on days 1, 3, and 5 postoperative and was statistically significant (P-value <0.05). The cutoff values in the receiver operating characteristic curve (ROC) with >90% specificity to infection post LT were PCT of ≥9 ng/ml and TLC of ≥17.3/mm3 on day one.

CONCLUSIONS

Following up PCT level on day one with TLC is essential and will help to detect sepsis and guide early antimicrobial initiation post-liver transplantation. Combined measurements of PCT and TLC with cutoff values of <9 ng/ml and < 17.3/mm³ respectively will help to exclude infections in 83.7% of patients, thus avoiding unnecessary usage of higher generations empiric antimicrobials.

Diagnostic Value of Procalcitonin in Transplant Patients Receiving Immunosuppressant Drugs: A Retrospective Electronic Medical Record-Based Analysis

OBJECTIVES

To evaluate concentrations of procalcitonin (PCT) in transplant recipients receiving immunosuppressive therapy compared with nonimmunosuppressed patients.

METHODS

We analyzed a data set of 9,500 inpatient encounters to compare levels of PCT and other biomarkers of infection (C-reactive protein [CRP], WBC count, and absolute neutrophil count [ANC]) between immunosuppressed and nonimmunosuppressed cohorts. We also assessed the correlation between PCT and clinical variables in immunosuppressed patients.

RESULTS

Patients receiving immunosuppressive drugs had significantly higher levels of maximal and minimal PCT compared with the nonimmunosuppressed patients (P < .0001 and P = .0019, respectively). However, CRP levels, WBC count, and ANC were significantly lower in immunosuppressed patients compared with the nonimmunosuppressed patients (P = .0003, P < .0019, and P = .0001, respectively).

CONCLUSIONS

Our results from real-world data demonstrated that PCT dynamics remain intact despite immunosuppressive therapy, in contrast to other biomarkers such as CRP, WBC, and ANC. In addition, higher PCT levels are associated with systemic infections and reflect disease severity.

Acute respiratory failure among lung transplant adults requiring intensive care: Changing spectrum of causative organisms and impact of procalcitonin test in the diagnostic workup

BACKGROUND

The aim was to identify the causing organisms and assess the association of procalcitonin (PCT) with bacterial pneumonia within 24 hours of intensive care unit admission (ICU-A) among lung transplant (LT) adult recipients.

METHODS

Secondary analysis from a prospective cohort study. All LT adults admitted to ICU for acute respiratory failure (ARF) over 5 years were included. Patients were followed until hospital discharge or death.

RESULTS

Fifty-eight consecutive LT patients were enrolled. The most important cause of ICU-A due to ARF was pneumonia 29 (50%) followed by acute rejection 3 (5.2%) and bronchiolitis obliterans syndrome exacerbation 3 (5.2%). Microorganisms were isolated from 22/29 cases with pneumonia (75.9%): 17 (77.2%) bacterial, 4 (18.2%) viral, 1 (4.5%) Aspergillus fumigates, with Pseudomonas aeruginosa being the most common cause (45.5%) of pneumonia, with 10 patients presenting chronic colonization by P aeruginosa. Median [Interquartile range (IQR)] PCT levels within 24 hours after admission were higher in pneumonia (1.5 µg/L; IQR:0.3-22.0), than in non-pneumonia cases (0.2 µg/L; IQR:0.1-0.7) (P = .019) and PCT levels within 24 hours helped to discriminate bacterial pneumonia (8.2 µg/L; IQR:0.2-43.0) from viral pneumonia and non-pneumonia cases (0.2 µg/L; IQR:0.1-0.7). The overall negative predictive value for bacterial pneumonia was 85.1%, increasing to 91.6% among episodes after 6 months of LT.

CONCLUSIONS

Causes of severe pneumonia in LT are changing, with predominant role of P aeruginosa and respiratory viruses. PCT ≤ 0.5 μg/L within 24 hours helps to exclude bacterial pneumonia diagnosis in LT adults requiring ICU-A. A negative PCT test allows antimicrobial de-escalation and requires an alternative diagnostic to bacterial pneumonia.

Procalcitonin Kinetics After Heart Transplantation and as a Marker of Infection in Early Postoperative Course

INTRODUCTION

Procalcitonin (PCT) is a biomarker of systemic infection. Specificity of PCT is decreased because PCT is also elevated after heart transplantation (HTx). There is no established normal range of serum PCT concentrations after HTx yet. Our aim was to determine the course of PCT concentrations in patients after HTx in the early postoperative period, if we can discriminate postoperative increase in values from infectious complications.

RESULTS

Of 39 patients we diagnosed infection in 11. These patients develop acute kidney injury significantly more often than in control group (group C) (5 in infection group [group I] and 2 in group C, P < .05), and 1 patient died within 30 days in group C. Seven patients developed primary graft dysfunction (3/4 + ECMO [extracorporeal membrane oxygenation], respectively, group I/group C) and 2 neurologic disorders in group I. Reoperation due to bleeding was 3 in each group. During the 14 days after HTx, serum PCT concentrations increased with maximum on the second postoperative day (group C: 30.6 ± 15.3 ng/mL; group I: 24.9 ± 44.3 ng/mL). Normal values for PCT were reached on day 8 in group C and 11 in group I. Mean PCT levels were similar: 8.7 ± 5.7 ng/mL vs 11.9 ± 13.1 ng/mL in group I vs group C, respectively. Patients in group I stayed longer in the intensive care unit.

CONCLUSIONS

Despite increase in serum concentration of PCT in early postoperative course after HTx there is no marker of infection. Trends in PCT serum concentration may be a valuable tool in diagnosis of infection in patients after HTx, but further investigation is needed.

Host-pathogen interaction during mechanical ventilation: systemic or compartmentalized response?

Patients admitted to the intensive care unit (ICU) often require invasive mechanical ventilation. Ventilator-associated lower respiratory tract infections (VA-LRTI), either ventilator-associated tracheobronchitis (VAT) or ventilator-associated pneumonia (VAP), are the most common complication among this patient cohort. VAT and VAP are currently diagnosed and treated as separate entities, viewed as binary disease elements despite an inherent subjectivity in distinguishing them clinically. This paper describes a new approach to pulmonary infections in critically ill patients. Our conjecture is that the host-pathogen interaction during mechanical ventilation determines a local compartmentalized or systemic de-compartmentalized response, based on host immunity and inflammation, and the pathogenic potential of the infecting organism. This compartmentalized or de-compartmentalized response establishes disease severity along a continuum of colonization, VAT or VAP. This change in approach is underpinned by the dissemination hypothesis, which acknowledges the role of immune and inflammatory systems in determining host response to pathogenic organisms in the lower respiratory tract. Those with intact immune and inflammatory pathways may limit infection to a compartmentalized VAT, while immunosuppressed mechanically ventilated patients are at greater risk of a de-compartmentalized VAP. Taking this model from the realm of theory to the bedside will require a greater understanding of inflammatory and immune pathways, and the development of novel disease-specific biomarkers and diagnostic techniques. Advances will lead to early initiation of optimal bespoke antimicrobial therapy, where the intensity and duration of therapy are tailored to clinical, immune and biomarker response. This approach will benefit towards a personalized treatment.

How Can We Distinguish Ventilator-Associated Tracheobronchitis from Pneumonia?

Ventilator-associated tracheobronchitis (VAT) might represent an intermediate process between lower respiratory tract colonization and ventilator-associated pneumonia (VAP), or even a less severe spectrum of VAP. There is an urgent need for new concepts in the arena of ventilator-associated lower respiratory tract infections. Ideally, the gold standard of care is based on prevention rather than treatment of respiratory infection. However, despite numerous and sometimes imaginative efforts to validate the benefit of these measures, most clinicians now accept that currently available measures have failed to eradicate VAP. Stopping the progression from VAT to VAP could improve patient outcomes.

Pneumonia in solid organ transplantation: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These guidelines from the AST Infectious Diseases Community of Practice review the diagnosis and management of pneumonia in the post-transplant period. Clinical presentations and differential diagnosis for pneumonia in the solid organ transplant recipient are reviewed. A two-tier approach is proposed based on the net state of immunosuppression and the severity of presentation. With a lower risk of opportunistic, hospital-acquired, or exposure-specific pathogens and a non-severe presentation, empirical therapy may be initiated under close clinical observation. In all other patients, or those not responding to the initial therapy, a more aggressive diagnostic approach including sampling of tissue for microbiological and pathological testing is warranted. Given the broad range of potential pathogens, a microbiological diagnosis is often key for optimal care. Given the limited literature comparatively evaluating diagnostic approaches to pneumonia in the solid organ transplant recipient, much of the proposed diagnostic algorithm reflects clinical experience rather than evidence-based data. It should serve as a template which may be modified according to local needs. The same holds true for the suggested empiric therapies, which need to be adapted to the local resistance patterns. Further study is needed to comparatively evaluate diagnostic and empiric treatment strategies in SOT recipients.

Procalcitonin as Biomarker of Infection: Implications for Evaluation and Treatment

Procalcitonin (PCT) is a quickly measurable marker, assumed to have high sensitivity and specificity for sepsis and infection. A literature search was conducted to evaluate PCT ability as a diagnostic and prognostic tool in infectious processes and its ability to monitor the antibiotic therapy. PCT level is increased in bacterial and fungal infections, but not in viral infections, with a significantly higher level in patients with bacteremia compared with uninfected patients (2.5 vs. 0.3 ng/mL; P < 0.0001). A PCT value of ≤0.1 ng/mL discards bacteremia and microbiological tests (negative predictive value of 96.3%), >0.1 ng/mL needs microbiological tests, and >1.0 ng/mL is indicative of bacteremia. Antibiotic treatment algorithms guided by PCT decreased the need for antibiotic treatment in approximately 50%. PCT is a promising test in clinical practice to decide the introduction of antibiotic therapy in addition to the existing tools, without neglecting the clinical assessment, with a significant decrease in costs.

Role of biomarkers in early infectious complications after lung transplantation

Background

Infections and primary graft dysfunction are devastating complications in the immediate postoperative period following lung transplantation. Nowadays, reliable diagnostic tools are not available. Biomarkers could improve early infection diagnosis.

Methods

Multicentre prospective observational study that included all centres authorized to perform lung transplantation in Spain. Lung infection and/or primary graft dysfunction presentation during study period (first postoperative week) was determined. Biomarkers were measured on ICU admission and daily till ICU discharge or for the following 6 consecutive postoperative days.

Results

We included 233 patients. Median PCT levels were significantly lower in patients with no infection than in patients with Infection on all follow up days. PCT levels were similar for PGD grades 1 and 2 and increased significantly in grade 3. CRP levels were similar in all groups, and no significant differences were observed at any study time point. In the absence of PGD grade 3, PCT levels above median (0.50 ng/ml on admission or 1.17 ng/ml on day 1) were significantly associated with more than two- and three-fold increase in the risk of infection (adjusted Odds Ratio 2.37, 95% confidence interval 1.06 to 5.30 and 3.44, 95% confidence interval 1.52 to 7.78, respectively).

Conclusions

In the absence of severe primary graft dysfunction, procalcitonin can be useful in detecting infections during the first postoperative week. PGD grade 3 significantly increases PCT levels and interferes with the capacity of PCT as a marker of infection. PCT was superior to CRP in the diagnosis of infection during the study period.

The utility of C-reactive protein and procalcitonin for sepsis diagnosis in critically burned patients: A preliminary study

Objective

To assess the utility of C-reactive protein (CRP) and procalcitonin (PCT) as biomarkers of infection in patients with severe burn injury.

Methods

The present study included severe burn injury patients consecutively admitted to the Virgen del Rocío University Hospital (Andalucia, Spain) intensive care unit during a 12-month period. The variables of interest were: age, sex, mechanism of injury, percentage of burned body surface area, the Abbreviated Burn Severity Index (ABSI) and the absence/presence of sepsis. The authors analyzed serum levels of CRP and PCT at admission and every 48 h thereafter until intensive care unit discharge or death. Each determination was considered to be a sample or unit of analysis.

Results

A total of 157 determinations were analyzed from 17 severe burn injury patients. Fifty-four samples were considered to be septic, 25 of which corresponded to the first day of a new onset of sepsis. The mean duration of these symptoms was four days (interquartile range two to five days). Significant differences were found in the distributions of CRP and PCT values between sepsis and no-sepsis samples. Analysis of the changes in these biomarkers over time showed that PCT increase (ΔPCT) differentiated these diagnoses, whereas CRP increase (ΔCRP) did not. ROC curve analysis revealed that ΔPCT could predict positive sepsis samples (area under the curve 0.75 [95% CI 0.58 to 0.90]; P=0.003).

Conclusion

These preliminary results showed that PCT had a better discriminatory capacity than CRP for identifying infectious processes in patients with severe burn injury. A larger sample size would be needed to confirm these results.

The use and value of procalcitonin in solid organ transplantation

Procalcitonin (PCT) has been increasingly used as a biomarker of bacterial infection and as a tool to guide antimicrobial therapy, especially in lower respiratory tract and bloodstream infections. Despite its increased use, data in patients with solid organ transplants are limited. Even without the presence of infection, PCT increases as a result of surgical procedures during transplantation, implantation of devices, and use of induction immunosuppressive therapy. The risk of infection is also higher in solid organ transplant recipients when compared to the general population. Monitoring PCT in the early post-transplant period seems to be a promising method for early detection of infectious complications. It has been shown that elevated PCT levels after one wk of transplantation are correlated with infectious complications. PCT may be a useful adjunctive biomarker that may improve early identification and guide appropriate treatment of infection or rejection, with the potential to further improve clinical outcomes. The use of serial PCT measurements may be more reliable than single values. It is important to recognize which factors may lead to PCT increases in the post-transplantation period, which in turn will help understand the kinetics and utility of this biomarker in this important patient population.

Diagnostic value of serum procalcitonin in solid organ transplant recipients: a systematic review and meta-analysis

PURPOSE

To perform a systematic review and meta-analysis to define the role of procalcitonin (PCT) in identifying infectious complication in organ transplant recipients.

METHODS

We searched EMBASE, MEDLINE, the Cochrane database, and reference lists of relevant articles, with no language restrictions, published from inception through May 2013. We selected original research that reported the diagnostic performance of PCT alone or when compared with other biomarkers to diagnose infectious complication among organ transplant recipients. We summarized test performance characteristics with the use of forest plots, hierarchical summary receiver operating characteristic curves, and bivariate random-effects models.

RESULTS

We found 7 qualifying studies (studying 1226 episodes of suspected infection with 186 confirmed infectious episodes) from 4 countries. The patients were lung, kidney, liver, and heart transplant recipients. Bivariate pooled sensitivity, specificity, positive likelihood ratios, and negative likelihood ratios for identification of bacterial infections in patients after transplantation were 85% (95% confidence interval [CI], 75%-92%), 81% (95% CI, 72%-88%), 4.41 (95% CI, 2.86-6.81), and 0.18 (95% CI, 0.10-0.33), respectively. Of the 4 studies that reported the experience of liver transplant patients, the pooled sensitivity, specificity, positive likelihood ratios, and negative likelihood ratios were 90% (95% CI, 75%-97%), 85% (95% CI, 77%-91%), 6.12 (95% CI, 3.79-9.88), and 0.11 (95% CI, 0.04-0.32), respectively. There was no evidence of significant heterogeneity.

CONCLUSION

The existing literature suggests reasonable sensitivity and specificity for the PCT test in identifying infection complications among patients undergoing solid organ transplantation. Given the imperfect sensitivity and specificity of the PCT test, medical decisions should be based on both PCT test results and clinical findings.

Utility of Procalcitonin as a Biomarker for Rejection and Differentiation of Infectious Complications in Lung Transplant Recipients

Objective: To evaluate the utility of procalcitonin (PCT) as a biomarker for rejection and differentiation of infectious complications in lung transplant recipients. Data Sources: An English-language literature search was conducted using MEDLINE (1966-September 2013) using the terms procalcitonin, transplantation, and lung transplantation. Additional articles were identified through a manual search of reference lists of the articles obtained. Study Selection and Data Extraction: All articles evaluating PCT use in lung transplant recipients, including those where lung transplant patients were a subgroup of immunocompromised patients, were included. Data Synthesis: Infection and rejection are leading causes of mortality in lung transplant recipients, with similar clinical presentations; PCT could be a valuable biomarker to differentiate between these complications. Five prospective and 2 retrospective single-center observational evaluations were reviewed. Study populations were diverse, with only 3 focused solely on lung transplant recipients. PCT levels were not elevated during episodes of rejection and viral infections, whereas elevations were seen with bacterial infections. The effect of colonization or fungal infection on PCT varied. Conclusions: Current data suggest that PCT can be used to differentiate bacterial infections from rejection in lung transplant recipients, with unclear utility in colonization or fungal infection. It is reasonable to conclude that PCT values more than 8.18 ng/mL and PCT area under receiver operating curve greater than 0.97 indicate bacterial infection in this population, and PCT trends may increase predictive value. Because of the lack of randomized controlled trials, PCT should only be utilized in conjunction with standard tests for infection and rejection diagnosis.