Biological Markers to Determine Eligibility in Trials for Community‐Acquired Pneumonia: A Focus on Procalcitonin

A cytokine/PTX3 prognostic index as a predictor of mortality in sepsis

Background

Early prognostic stratification of patients with sepsis is a difficult clinical challenge. Aim of this study was to evaluate novel molecules in association with clinical parameters as predictors of 90-days mortality in patients admitted with sepsis at Humanitas Research Hospital.

Methods

Plasma samples were collected from 178 patients, diagnosed based on Sepsis-3 criteria, at admission to the Emergency Department and after 5 days of hospitalization. Levels of pentraxin 3 (PTX3), soluble IL-1 type 2 receptor (sIL-1R2), and of a panel of pro- and anti-inflammatory cytokines were measured by ELISA. Cox proportional-hazard models were used to evaluate predictors of 90-days mortality.

Results

Circulating levels of PTX3, sIL-1R2, IL-1β, IL-6, IL-8, IL-10, IL-18, IL-1ra, TNF-α increased significantly in sepsis patients on admission, with the highest levels measured in shock patients, and correlated with SOFA score (PTX3: r=0.44, p<0.0001; sIL-1R2: r=0.35, p<0.0001), as well as with 90-days mortality. After 5 days of hospitalization, PTX3 and cytokines, but not sIL-1R2 levels, decreased significantly, in parallel with a general improvement of clinical parameters. The combination of age, blood urea nitrogen, PTX3, IL-6 and IL-18, defined a prognostic index predicting 90-days mortality in Sepsis-3 patients and showing better apparent discrimination capacity than the SOFA score (AUC=0.863, 95% CI: 0.780−0.945 vs. AUC=0.727, 95% CI: 0.613-0.840; p=0.021 respectively).

Conclusion

These data suggest that a prognostic index based on selected cytokines, PTX3 and clinical parameters, and hence easily adoptable in clinical practice, performs in predicting 90-days mortality better than SOFA. An independent validation is required.

Procalcitonin and C-reactive protein predict infection in hematopoietic stem cell transplantation patients

INTRODUCTION

Procalcitonin (PCT) and C-reactive protein (CRP) are known inflammatory markers of severe infection; however, their ability to differentiate between infections of different origins is not clear yet. In this study, we evaluated PCT and CRP as markers of infection in hematopoietic stem cell transplantation (HSCT) patients.

METHODS

Blood samples were collected to determine serum concentrations of PCT, CRP, d-Dimer, and to perform blood culture analysis. Based on blood culture results, the patients were divided into two groups-positive blood culture (n = 271) patients and negative blood culture patients (n = 668); the negative blood culture group served as the control. The positive blood culture group was further divided into three groups based on the etiological agent of infection. PCT and CRP concentrations were compared, and ROC curve, sensitivity, specificity, and cutoff values were calculated.

RESULTS

PCT levels in infected patients were significantly higher than those in control patients (p < 0.001); similarly, CRP and d-Dimer levels were also higher among infected patients when compared with those in the controls. A PCT level of 0.51 ng/mL was the best threshold for detecting the infection, with an AUC-ROC of 0.877, whereas the best threshold for CRP was 49.20 mg/L. PCT levels were the highest in patients with gram-negative bacteremia as compared to in those with gram-positive bacteremia and fungal infection. The optimal cutoff value of PCT for the detection of gram-negative and gram-positive infection was 1.63 ng/mL.

CONCLUSION

PCT seems to be a useful marker for the diagnosis of systemic infection in HSCT patients, probably better than CRP and d-Dimer.

Use of procalcitonin and C-reactive protein in the diagnosis of bacterial infection in infants with severe bronchiolitis

The objective was to evaluate the use of procalcitonin (PCT) and C-reactive protein (CRP) for the diagnosis of bacterial infection in bronchiolitis patients. A prospective, single-centre, descriptive, and comparative observational study was carried out on patients with severe bronchiolitis admitted to the paediatric intensive care unit (PICU), from January 2011 to July 2017. Two cohorts were compared: patients with invasive bacterial infection (IBI) and patients with no bacterial infection (NBI). We included 675 patients, 399 of whom were males (59.1%), with median age of 47 days (IQR 25-100.3). Of them, 181 patients were diagnosed with IBI (26.8%). Seventy-two had sepsis (10.7%), 106 had pneumonia (15.7%), and 41 had a urinary tract infection (6.1%). PCT and CRP values were significantly higher in patients with IBI. ROC curves compared the ability of PCT and CRP to diagnose IBI at admission, 24 h, and 48 h. PCT showed a better AUC for diagnosing IBI, with statistically significant differences at all time points (p < 0.001). The best PCT cut-off for IBI diagnosis at admission was 1.4 ng/mL, with a sensitivity of 69% (95% CI 58.4-74.9) and a specificity of 91% (95% CI 88.1-92.5). Procalcitonin showed a better AUC for diagnosing both sepsis and pneumonia, which makes it an excellent predictor.Conclusion: We present PCT as a novel test in comparison with the traditional CRP screening test to discern which bronchiolitis patients have IBI. We highlight the importance of PCT for the diagnosis of pneumonia and sepsis, as it proved to be more sensitive and specific than CRP, with statistically significant differences. What is Known: • Bronchiolitis should be treated with antibiotics only when a bacterial infection is present. • The rate of antibiotic prescription in severe bronchiolitis is extremely high, so diagnostic tools are needed. What is New: • PCT is a good biomarker to discern which bronchiolitis patients have IBI, specially for pneumonia and sepsis diagnoses. It is more sensitive and specific than CRP, with statistically significant differences. • Implementation of PCT cut-off values may prevent unnecessary antibiotic use.

Diagnostic Accuracy of Routinely Available Biomarkers to Predict Bacteremia in Children With Community-Acquired Pneumonia: A Secondary Analysis of the GPIP/ACTIV Pneumonia Study in France, 2009-2018

Objective(s): Blood cultures (BC), when performed in children seen in the emergency department with community-acquired pneumonia (CAP), are most of the time sterile. We described the diagnostic accuracy of white blood cells (WBC), absolute neutrophils count (ANC), C-reactive protein (CRP), and procalcitonin (PCT) to predict blood culture (BC) result in childhood CAP. Study Design: Secondary analysis of a prospective study carried out in eight pediatric emergency departments (France, 2009-2018), including children (≤15 years) with CAP. Analyses involved univariate comparisons and ROC curves. Results: We included 13,752 children with CAP. BC was positive in 137 (3.6%) of the 3,829 children (mean age 3.7 years) in whom it was performed, mostly with Streptococcus pneumoniae (n = 107). In children with bacteremia, ANC, CRP and PCT levels were higher (median 12,256 vs. 9,251/mm³, 223 vs. 72 mg/L and 8.6 vs. 1.0 ng/mL, respectively; p ≤ 0.002), but WBC levels were not. The area under the ROC curve of PCT (0.73 [95%CI 0.64-0.82]) was significantly higher (p ≤ 0.01) than that of WBC (0.51 [0.43-0.60]) and of ANC (0.55 [0.46-0.64]), but not than that of CRP (0.66 [0.56-0.76]; p = 0.21). CRP and PCT thresholds that provided a sensitivity of at least 90% were 30 mg/L and 0.25 ng/mL, respectively, for a specificity of 25.4 and 23.4%, respectively. CRP and PCT thresholds that provided a specificity of at least 90% were 300 mg/L and 20 ng/mL, respectively, for a sensitivity of 31.3 and 28.9%, respectively. Conclusions: PCT and CRP are the best routinely available predictive biomarkers of bacteremia in childhood CAP.

Procalcitonin: The marker of pediatric bacterial infection

Timely recognition of systemic bacterial infections in pediatric care setting is the basis for effective treatment and control. This review provides an overview of procalcitonin (PCT) as an early marker for the detection of severe, invasive bacterial infection in children. Almost all articles on biochemical property and clinical studies in PubMed and Scopus databases regarding their use in pediatric infections and the use of PCT as a marker of bacterial infections were examined. Various methods and analyzers are currently available for the evaluation of PCT. Employment of PCT in the identification of neonatal bacterial infection is a complex process in some conditions. Age specific cut-off, underlying syndrome, and maternal antibiotics usage should be considered when PCT is to be applied in neonates. PCT might be false-negative in these conditions. However, if used appropriately, it can lead to a higher specificity than other immunologic markers. Due to its correlation with the severity of infection, PCT can consequently be used as a prognostic indicator especially for sepsis and urinary tract infection. It is, therefore, a practical supplementary means for the identification of bacterial infections in pediatric health settings.

A new sensitive automated assay for procalcitonin detection: LIAISON® BRAHMS PCT® II GEN

Objectives

To assess the performance of LIAISON^® BRAHMS PCT^® II GEN (DiaSorin, Saluggia, Italy) in procalcitonin (PCT) determination by comparing it to the assay reference method B·R·A·H·M·S PCT KRYPTOR (Thermo Fisher Scientific Clinical Diagnostics, Hennigsdorf, Germany) and assessing its ability to discriminate between healthy subjects and patients with suspected infection.

Methods

Diagnostic performance was evaluated on: a) 193 selected samples covering the assay range, whose procalcitonin levels were already evaluated with the B·R·A·H·M·S PCT^® KRYPTOR; b) prospective samples: 150 apparently healthy specimens obtained from a blood bank, 161 hospitalized patients (not with specific pathologies), 243 apparently healthy children.

Results

The comparison of LIAISON^® BRAHMS PCT^® II GEN to the reference method B·R·A·H·M·S PCT KRYPTOR yielded high correlation coefficients: slope of Deming fit equal to 1.04 (95% CI: 0.99–1.09) with an intercept equal to 0.05 (95% CI: −0.09 to 0.19) and a high concordance (98.4% (95% CI: 95.5–99.7%)) at the 0.5 ng/mL cut-off. Moreover, the results obtained using prospective samples showed: (i) no samples with PCT concentration >0.5 ng/mL (cut-off) for the apparently healthy adults (highest value=0.033 ng/mL, 95th percentile and 97.5th percentile <0.02 ng/mL); (ii) 2 samples >0.5 ng/mL for hospitalized patients (highest value=0.715 ng/mL, 95th percentile: 0.054 ng/mL; 97.5th percentile: 0.088 ng/mL); (iii) 3 samples >0.5 ng/mL for the healthy children population (highest value=0.713 ng/mL, 95th percentile: 0.155 ng/mL; 97.5th percentile: 0.275 ng/mL).

Conclusion

The fully automated LIAISON^® BRAHMS PCT^® II GEN agrees well with the reference method and is suitable for early diagnosis of sepsis, severe bacterial infection and guiding antibiotic therapy.

Serum Procalcitonin for Differential Diagnosis of Acute Exacerbation and Bacterial Pneumonia in Patients With Interstitial Lung Disease

BACKGROUND

Acute exacerbation and bacterial pneumonia are major life-threatening conditions in patients with interstitial lung disease (ILD). The rapid recognition of these 2 different conditions is important for their proper treatment. An elevated procalcitonin (PCT) level is commonly detected in patients with bacterial infections. This study assessed the usefulness of the serum PCT level as a biomarker for the differential diagnosis of acute exacerbation and bacterial pneumonia in patients with ILD.

MATERIALS AND METHODS

In this prospective observational study, we enrolled patients with ILD who had experienced recently progressive dyspnea and exhibited new infiltrations on chest radiographs. We classified these patients into an acute exacerbation group and a bacterial pneumonia group and compared their baseline characteristics and laboratory parameters, including the PCT level.

RESULTS

Of 21 patients with ILD, 9 patients had bacterial pneumonia. Both the groups showed similar baseline characteristics. The bacterial pneumonia group demonstrated a high PCT level. The PCT level in the acute exacerbation group was significantly lower than that in the bacterial pneumonia group (0.05 versus 0.91ng/mL, respectively; P < 0.001). Other parameters, such as the C-reactive protein level, leukocyte count and body temperature, were also lower in the acute exacerbation group. At a cutoff value of 0.1ng/mL, the sensitivity, specificity and negative predictive values of the serum PCT level were 88.9%, 100.0% and 92.3%, respectively.

CONCLUSIONS

These findings suggest that the serum PCT level is useful in the differential diagnosis of acute exacerbation and bacterial pneumonia in patients with ILD.

A review of the role of Haemophilus influenzae in community-acquired pneumonia

In an era when Haemophilus influenzae type b (Hib) conjugate vaccine is widely used, the incidence of Hib as a cause of community-acquired pneumonia (CAP) has dramatcally declined. Non-typeable H. influenzae (NTHi) strains and, occasionally, other encapsulated serotypes of H. influenzae are now the cause of the majority of invasive H. influenzae infectons, including bacteraemic CAP. NTHi have long been recognised as an important cause of lower respiratory tract infecton, including pneumonia, in adults, especially those with underlying diseases. The role of NTHi as a cause of non-bacteraemic CAP in children is less clear. In this review the evidence for the role of NTHi and capsulated strains of H. influenzae will be examined.

Polymicrobial community-acquired pneumonia: An emerging entity

Polymicrobial aetiology in community-acquired pneumonia (CAP) is more common than previously recognized. This growing new entity can influence inflammation, host immunity and disease outcomes in CAP patients. However, the true incidence is complicated to determine and probably underestimated due mainly to many cases going undetected, particularly in the outpatient setting, as the diagnostic yield is restricted by the sensitivity of currently available microbiologic tests and the ability to get certain types of clinical specimens. The observed rate of polymicrobial cases may also lead to new antibiotic therapy considerations. In this review, we discuss the pathogenesis, microbial interactions in pneumonia, epidemiology, biomarkers and antibiotic therapy for polymicrobial CAP.

Diagnostic accuracy of C-reactive protein and procalcitonin in suspected community-acquired pneumonia adults visiting emergency department and having a systematic thoracic CT scan

Introduction

Community-acquired pneumonia (CAP) requires prompt treatment, but its diagnosis is complex. Improvement of bacterial CAP diagnosis by biomarkers has been evaluated using chest X-ray infiltrate as the CAP gold standard, producing conflicting results. We analyzed the diagnostic accuracy of biomarkers in suspected CAP adults visiting emergency departments for whom CAP diagnosis was established by an adjudication committee which founded its judgment on a systematic multidetector thoracic CT scan.

Methods

In an ancillary study of a multi-center prospective study evaluating the impact of systematic thoracic CT scan on CAP diagnosis, sensitivity and specificity of C-reactive protein (CRP) and procalcitonin (PCT) were evaluated. Systematic nasopharyngeal multiplex respiratory virus PCR was performed at inclusion. An adjudication committee classified CAP diagnostic probability on a 4-level Likert scale, based on all available data.

Results

Two hundred patients with suspected CAP were analyzed. The adjudication committee classified 98 patients (49.0 %) as definite CAP, 8 (4.0 %) as probable, 23 (11.5 %) as possible and excluded in 71 (35.5 %, including 29 patients with pulmonary infiltrates on chest X-ray). Among patients with radiological pulmonary infiltrate, 23 % were finally classified as excluded. Viruses were identified by PCR in 29 % of patients classified as definite. Area under the curve was 0.787 [95 % confidence interval (95 % CI), 0.717 to 0.857] for CRP and 0.655 (95 % CI, 0.570 to 0.739) for PCT to detect definite CAP. CRP threshold at 50 mg/L resulted in a positive predictive value of 0.76 and a negative predictive value of 0.75. No PCT cut-off resulted in satisfactory positive or negative predictive values. CRP and PCT accuracy was not improved by exclusion of the 25 (25.5 %) definite viral CAP cases.

Conclusions

For patients with suspected CAP visiting emergency departments, diagnostic accuracy of CRP and PCT are insufficient to confirm the CAP diagnosis established using a gold standard that includes thoracic CT scan. Diagnostic accuracy of these biomarkers is also insufficient to distinguish bacterial CAP from viral CAP.

Trial registration

ClinicalTrials.gov registry NCT01574066 (February 7, 2012)

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-1083-6) contains supplementary material, which is available to authorized users.

Serum level of C-reactive protein is not a parameter to determine the difference between viral and atypical bacterial infections

C-reactive protein (CRP) is an acute-phase reactant that increases in the circulation in response to a variety of inflammatory stimuli. Elevated levels in serum during several infectious diseases have been reported. In this study, a highly sensitive CRP enzyme immunoassay was used to evaluate serum CRP values in patients with viral and atypical bacterial infections. Patients (n = 139) with different viral or atypical bacterial infections (systemic or respiratory) and healthy controls (n = 40) were tested for circulating CRP values. High levels of IgM antibodies against several viruses: Dengue virus (n = 36), Cytomegalovirus (n = 9), Epstein Barr virus (n = 17), Parvovirus B19 (n = 26), Herpes simplex 1 and 2 virus (n = 3) and Influenza A and B (n = 8) and against atypical bacteria: Legionella pneumophila (n = 15), Mycoplasma pneumoniae (n = 21) and Coxiella burnetii (n = 4) were found. High values of CRP in infected patients compared with controls (P < 0.001) were found; however, no significant differences between viral and atypical bacterial infections were found. Low levels of CRP in respiratory and Coxiella burnetii infections compared with exanthematic viral and other atypical bacterial infections were found. This study suggests that CRP values are useful to define viral and atypical bacterial infections compared with normal values, but, it is not useful to define type of infection.

A nanobody-based electrochemiluminescent immunosensor for sensitive detection of human procalcitonin

The development of a nanobody-based electrochemiluminescent immunosensor for procalcitonin quantification is described. A highly specific and enhanced sensitivity of target detection was achieved by CdTe quantum dot encapsulated silica nanoparticle-assisted signal amplification.

Procalcitonin, a valuable biomarker assisting clinical decision-making in the management of community-acquired pneumonia

BACKGROUND AND AIM

Community-acquired pneumonia (CAP) is a leading cause of mortality, morbidity and hospital admission, which places strain on our healthcare system. Procalcitonin (PCT) is a biomarker of bacterial infection which may help gauge the severity and prognosis of patients with CAP. In addition to clinical predictors, PCT may assist in decisions pertaining to timing of discharge from hospital and the discontinuation of antibiotics. This study aimed to determine the predictive role of PCT measurement in reducing hospital admissions, length of stay (LOS) and antibiotic (AB) usage in patients with CAP.

METHODS

A prospective, single-blinded, externally controlled study of consenting adult patients admitted with CAP. PCT levels were obtained on day 1 and day 3 (when indicated). Investigator-evaluated clinical parameters, together with results of PCT levels, determined the timing of oral AB switch and discharge from hospital. This process was compared against standard practice, but was not actually implemented, for the purpose of this study.

RESULTS

Sixty patients were included in the study. The mean age was 66.5 ± 21.2 years (56.3% male). The average Pneumonia Severity Index was 93 ± 39 (class IV) and the median CURB-65 was 2. The mean LOS for the standard practice cohort was 5.3 ± 4.6 days versus calculated LOS using the PCT guidance pathway of 3.7 ± 2.8 days. (P = 0.00006).

CONCLUSIONS

Our study supports the hypothesis that by incorporation of PCT levels, hospital admission and LOS in patients with CAP can be reduced. A randomised prospective clinical trial is planned in an attempt to help confirm these findings.

Inflammatory response in mixed viral-bacterial community-acquired pneumonia

Background

The role of mixed pneumonia (virus + bacteria) in community-acquired pneumonia (CAP) has been described in recent years. However, it is not known whether the systemic inflammatory profile is different compared to monomicrobial CAP. We wanted to investigate this profile of mixed viral-bacterial infection and to compare it to monomicrobial bacterial or viral CAP.

Methods

We measured baseline serum procalcitonin (PCT), C reactive protein (CRP), and white blood cell (WBC) count in 171 patients with CAP with definite etiology admitted to a tertiary hospital: 59 (34.5%) bacterial, 66 (39.%) viral and 46 (27%) mixed (viral-bacterial).

Results

Serum PCT levels were higher in mixed and bacterial CAP compared to viral CAP. CRP levels were higher in mixed CAP compared to the other groups. CRP was independently associated with mixed CAP. CRP levels below 26 mg/dL were indicative of an etiology other than mixed in 83% of cases, but the positive predictive value was 45%. PCT levels over 2.10 ng/mL had a positive predictive value for bacterial-involved CAP versus viral CAP of 78%, but the negative predictive value was 48%.

Conclusions

Mixed CAP has a different inflammatory pattern compared to bacterial or viral CAP. High CRP levels may be useful for clinicians to suspect mixed CAP.

Procalcitonin for diagnosis of bacterial pneumonia in critically ill patients during 2009 H1N1 influenza pandemic: a prospective cohort study, systematic review and individual patient data meta-analysis

Introduction

Procalcitonin (PCT) is helpful for diagnosing bacterial infections. The diagnostic utility of PCT has not been examined thoroughly in critically ill patients with suspected H1N1 influenza.

Methods

Clinical characteristics and PCT were prospectively assessed in 46 patients with pneumonia admitted to medical ICUs during the 2009 and 2010 influenza seasons. An individual patient data meta-analysis was performed by combining our data with data from five other studies on the diagnostic utility of PCT in ICU patients with suspected 2009 pandemic influenza A(H1N1) virus infection identified by performing a systematic literature search.

Results

PCT levels, measured within 24 hours of ICU admission, were significantly elevated in patients with bacterial pneumonia (isolated or coinfection with H1N1; n = 77) (median = 6.2 μg/L, interquartile range (IQR) = 0.9 to 20) than in patients with isolated H1N1 influenza pneumonia (n = 84; median = 0.56 μg/L, IQR = 0.18 to 3.33). The area under the curve of the receiver operating characteristic curve of PCT was 0.72 (95% confidence interval (CI) = 0.64 to 0.80; P < 0.0001) for diagnosis of bacterial pneumonia, but increased to 0.76 (95% CI = 0.68 to 0.85; P < 0.0001) when patients with hospital-acquired pneumonia and immune-compromising disorders were excluded. PCT at a cut-off of 0.5 μg/L had a sensitivity (95% CI) and a negative predictive value of 80.5% (69.9 to 88.7) and 73.2% (59.7 to 84.2) for diagnosis of bacterial pneumonia, respectively, which increased to 85.5% (73.3 to 93.5) and 82.2% (68.0 to 92.0) in patients without hospital acquired pneumonia or immune-compromising disorder.

Conclusions

In critically ill patients with pneumonia during the influenza season, PCT is a reasonably accurate marker for detection of bacterial pneumonia, particularly in patients with community-acquired disease and without immune-compromising disorders, but it might not be sufficient as a stand-alone marker for withholding antibiotic treatment.

Diagnosis of pneumococcal pneumonia: current pitfalls and the way forward

Streptococcus pneumoniae is the most common cause of community-acquired pneumonia. However, it can also asymptomatically colonize the upper respiratory tract. Because of the need to distinguish between S. pneumoniae that is simply colonizing the upper respiratory tract and S. pneumoniae that is causing pneumonia, accurate diagnosis of pneumococcal pneumonia is a challenging issue that still needs to be solved. Sputum Gram stains and culture are the first diagnostic step for identifying pneumococcal pneumonia and provide information on antibiotic susceptibility. However, these conventional methods are relatively slow and insensitive and show limited specificity. In the past decade, new diagnostic tools have been developed, particularly antigen (teichoic acid and capsular polysaccharides) and nucleic acid (ply, lytA, and Spn9802) detection assays. Use of the pneumococcal antigen detection methods along with biomarkers (C-reactive protein and procalcitonin) may enhance the specificity of diagnosis for pneumococcal pneumonia. This article provides an overview of current methods of diagnosing pneumococcal pneumonia and discusses new and future test methods that may provide the way forward for improving its diagnosis.

Serum procalcitonin is a valuable diagnostic marker in acute exacerbation of interstitial pneumonia

BACKGROUND AND OBJECTIVE

Acute exacerbation (AE) of interstitial pneumonia (IP) is defined as a life-threatening deterioration of IP without identifiable cause. We evaluated the diagnostic and prognostic role of serum procalcitonin (PCT) in AE-IP.

METHODS

Twenty consecutive patients admitted for AE-IP between May 2010 and April 2012 were evaluated. Controls consisted of 13 consecutively admitted patients with acute respiratory distress syndrome (ARDS) due to bacterial pneumonia (BP) and 24 with bacterial pneumonia with stable IP ('BP with IP'). Serum PCT was measured at baseline, at days 2, 4 and 8 in patients with AE-IP, and at baseline in controls.

RESULTS

Serum PCT levels in AE-IP were significantly lower than in BP-ARDS (mean ± standard deviation, 0.62 ± 1.30 vs 30.14 ± 22.76 ng/mL; P < 0.0001) or 'BP with IP' (mean ± standard deviation, 0.62 ± 1.30 vs 8.31 ± 14.83 ng/mL; P < 0.05). Thus, serum PCT discriminated well between AE-IP and BP-ARDS, or 'BP with IP' (area under the curve 0.99 and 0.85, respectively). However, there were no significant differences in serum PCT between 30-day survivors or non-survivors. Serum PCT tended to be reduced in both patient groups.

CONCLUSIONS

Serum PCT is a useful marker for discriminating between AE-IP and BP. However, serum PCT is not useful as a prognostic marker for survival.

Pancreatic stone protein predicts positive sputum bacteriology in exacerbations of COPD

BACKGROUND

Pancreatic stone protein/regenerating protein (PSP/reg) serum levels are supposed to be increased in bacterial inflammation. PSP/reg levels also might be useful, therefore, as a predictor of bacterial infection in COPD.

METHODS

Two hundred consecutive patients presenting to the ED due to acute exacerbation of COPD were prospectively assessed. Patients were evaluated based on clinical, laboratory, and lung functional parameters at admission (exacerbation) and after short-term follow-up (14-21 days). PSP/reg serum values were measured by a newly developed enzyme-linked immunosorbent assay.

RESULTS

PSP/reg levels were elevated in subjects with COPD exacerbation (23.8 ng/mL; 95% CI, 17.1-32.7) when compared with those with stable disease (19.1 ng/mL; 95% CI, 14.1-30.4; P 5 .03) and healthy control subjects (14.0 ng/mL; 95% CI , 12.0-19.0; P , .01). Higher PSP/reg values were observed in exacerbations with positive sputum bacteriology compared with those with negative sputum bacteriology (26.1 ng/mL [95% CI, 19.2-38.1] vs 20.8 ng/mL [95% CI , 15.6-27.2]; P , .01). Multivariate regression analysis revealed PSP/reg level as an independent predictor of positive sputum bacteriology. A combination of a PSP/reg cutoff value of . 33.9 ng/mL and presence of discolored sputum had a specificity of 97% to identify patients with pathogenic bacteria on sputum culture. In contrast, PSP/reg levels , 18.4 ng/mL and nonpurulent sputum ruled out positive bacterial sputum culture (sensitivity, 92%). In survival analysis, high PSP/reg levels at hospital admission were associated with increased 2-year mortality.

CONCLUSIONS

Serum PSP/reg level might represent a promising new biomarker to identify bacterial etiology of COPD exacerbation.

Biomarkers: what is their benefit in the identification of infection, severity assessment, and management of community-acquired pneumonia?

Biomarkers have been proposed as tools that can guide the management of patients with community-acquired pneumonia, providing information that supplements the usually available clinical data. Among the available biomarkers, procalcitonin has been studied extensively and seems promising for several purposes. The use of biomarkers needs further study, to validate their utility in daily practice, especially given the limitations of the current tools for identifying the need for antibiotic therapy in patients with influenza and secondary bacterial pneumonia, in patients with aspiration syndromes, and in those infected with atypical pathogens.

Procalcitonin predicts response to beta-lactam treatment in hospitalized children with community-acquired pneumonia

Background

Antibiotic treatment of community-acquired pneumonia (CAP) in children remains mostly empirical because clinical and paraclinical findings poorly discriminate the principal causes of CAP. Fast response to beta-lactam treatment can be considered a proxy of pneumococcal aetiology. We aimed to identify the best biological predictor of response to beta-lactam therapy in children hospitalized for CAP.

Methods

A retrospective, single-centre cohort study included all consecutive patients 1 month to 16 years old hospitalized in a teaching hospital in Paris, France, because of CAP empirically treated with a beta-lactam alone from 2003 to 2010. Uni- and multivariate analyses were used to study the ability of routine biological parameters available in the Emergency Department to predict a favourable response to beta-lactam (defined as apyrexia within 48 hours of treatment onset).

Results

Among the 125 included patients, 85% (106) showed a favourable response to beta-lactam. In multivariate logistic regression, we found procalcitonin (PCT) the only independent predictor of apyrexia (p = 0.008). The adjusted odds ratio for the decadic logarithm of PCT was 4.3 (95% CI 1.5–12.7). At ≥3 ng/mL, PCT had 55.7% sensitivity (45.7–65.3), 78.9% specificity (54.4–93.9), 93.7% positive predictive value (84.5–98.2), 24.2% negative predictive value (14.2–36.7), 2.64 positive likelihood ratio (1.09–6.42) and 0.56 negative likelihood ratio (0.41–0.77). In the 4 children with a PCT level ≥3 ng/mL and who showed no response to beta-lactam treatment, secondary pleural effusion had developed in 3, and viral co-infection was documented in 1.

Conclusions

PCT is the best independent biologic predictor of favourable response to beta-lactam therapy in children hospitalized for CAP. Thus, a high PCT level is highly suggestive of pneumococcal aetiology. However, a 3-ng/mL cut-off does not seem compatible with daily medical practice, and additional research is needed to further define the role of PCT in managing CAP in children.

Plasma C-reactive protein levels are associated with mortality in elderly with acute lung injury

PURPOSE

The plasma C-reactive protein (CRP) level is considered to be a predictor of severity in both hospital- and community-acquired pneumonias, whereas recent reports have shown that higher CRP levels lead to better outcomes in patients with acute lung injury (ALI). To explain this discrepancy, we evaluated the relationship among plasma CRP levels, etiology, affectors of CRP production, and mortality in patients with ALI.

MATERIALS AND METHODS

This was a case-control study of 76 consecutive patients with ALI. The plasma CRP levels had been measured in all of the patients within 1 hour of visiting an emergency department. The associations between the plasma CRP levels and 60-day mortality were analyzed after adjusting for the causes of ALI, disease severity, the patients' age, use of corticosteroids, and presence of hepatic failure.

RESULTS

The CRP levels and patients' ages were strongly related to the mortality (adjusted hazard ratio, 1.005 [P = .007] and 1.059 [P = .011], respectively), whereas the etiology of ALI did not affect the mortality (adjusted hazard ratio, 0.789 [P = .530]) in the Cox proportional hazard models.

CONCLUSIONS

The plasma CRP level may be a predictor of mortality in elderly patients with ALI.

[Aetiology and diagnosis of community acquired pneumonia and its complicated forms]

Community Acquired Pneumonia (CAP) is a common childhood disease, involving several paediatric subspecialties in its diagnosis and treatment. This has prompted the Spanish Society of Paediatric Pulmonology (SENP) and the Spanish Society of Paediatric Infectious Diseases (SEIP) to prepare a consensus document on the diagnosis of CAP, assessing the practical aspects by means of evidence-based medicine. It discusses the aetiology and epidemiology, with the current changes and the validity of certain laboratory tests, such as acute phase reactants, microbiological and imaging techniques, guiding the paediatricians in the real value of these tests.

Community-acquired pneumonia: an unfinished battle

Community-acquired pneumonia remains a common illness with substantial morbidity and mortality. Current management challenges focus on identifying the likely etiologic pathogens based on an assessment of host risk factors, while attempting to make a specific etiologic diagnosis, which is often not possible. Therapy is necessarily empiric and focuses on pneumococcus and atypical pathogens for all patients, with consideration of other pathogens based on specific patient risk factors. It is important to understand the expected response to effective therapy, and to identify and manage clinical failure at the earliest possible time point. Prevention is focused on smoking cessation and vaccination against pneumococcus and influenza.

Modern Management of Community-Acquired Pneumonia: Is It Cost-Effective and are Outcomes Acceptable?

Community-acquired pneumonia (CAP) is the most important cause of death from infectious diseases in the developed world and is associated with a high economic burden. Researchers have therefore sought ways to improve CAP outcomes while reducing costs. In this review, we highlight the current evidence supporting modern approaches to CAP management, including the use of severity indices to safely increase the proportion of patients treated at home, the use of procalcitonin to decrease antibiotic use, early intravenous to oral switch of antibiotic therapy, streamlining antimicrobials, and approaches to shorten antibiotic treatment duration. Although promising evidence exists for these modern strategies, there is still a considerable lack of high-quality evidence proving noninferiority of clinical outcomes and cost-effectiveness.

Interpreting assays for the detection of Streptococcus pneumoniae

Streptococcus pneumoniae is both an aggressive pathogen and a normal part of the human respiratory microbiome. Clinicians and microbiologists have struggled to develop tests that can identify pneumococcal respiratory infection and accurately distinguish colonization from invasive disease. Molecular methods hold the promise of an improved ability to rapidly detect microorganisms in respiratory secretions and to make an accurate diagnosis; however, interpretation of diagnostic testing for S. pneumoniae remains problematic. Molecular assays, such as those targeting the pneumolysin gene, may cross-react with other streptococcal species, confounding detection and quantification. Assays that target the autolysin gene appear to be more specific. Even when accurately identified, however, the significance of S. pneumoniae DNA detected in clinical samples is difficult to determine. Here we will discuss the challenges faced in the interpretation of molecular testing for S. pneumoniae, and some strategies that might be used to improve our ability to diagnose pneumococcal respiratory infection.

[Favorable outcome of acute respiratory failure caused by H1N1 virus infection in critical patients]

OBJECTIVE

To describe clinical features, treatment, complications, and outcomes in cases of acute respiratory distress syndrome (ARDS) caused by H1N1 virus infection treated in an anesthesia department's recovery unit.

MATERIALS AND METHODS

Patients were those admitted to our recovery unit with H1N1 virus infection confirmed by reverse transcription polymerase chain reaction, nasopharyngeal swabs, and/or bronchial aspirates.

RESULTS

From August to December 2009, we admitted 8 patients (mean age, 43 [range 24-46] years) to the recovery unit. Six were men, three were of Roma origin, and 50% had concomitant diseases. Mean (SD) time from symptom onset to admittance to the recovery unit was 3.25 (1.6) days. Four had received broad-spectrum antibiotics during the last month. Six had primary viral pneumonia, 1 had secondary bacterial pneumonia and 1 had exacerbated chronic obstructive pulmonary disease. Three had bacterial coinfection, and 4 developed multiple organ dysfunction syndrome and ARDS, requiring mechanical ventilation (5.75 [3.10] days) and vasopressors (4.25 [3.40] days). The mean ratio of PaO2 to the inspired oxygen fraction at admittance was 93.8 (31.0) and the mean positive end-expiratory pressure applied was 14.5 (4.2) cm H2O. Oseltamivir was administered (150 mg/12 h) with a mean delay of 3.88 (1.64) days. Additional inhaled zanamivir was administered on day 7 to a patient with a positive viral culture. Antibiotics were prescribed following the guidelines of the American Thoracic Society and Infectious Diseases Society of America for community-acquired pneumonia (50% of the cases) and healthcare-associated pneumonia (50%). Seven subjects received 1 mg x kg(-1) x day(-1) of methylprednisolone. Patients with mechanical ventilation required continuous insulin infusion (maximum daily dosage, 87 [50.3] IU) to maintain blood glucose levels between 80 and 150 mg x dL(-1). Patients under mechanical ventilation achieved a negative net fluid balance. All patients survived and were discharged from the recovery unit in 7.38 (4.83) days (range, 2-16 days) and subsequently discharged home in 13.25 (7.74) days (range, 6-27 days). All were alive 60 days after discharge.

CONCLUSION

In this series of critically ill patients with H1N1 virus infection that was initially life-threatening, all responded favorably to conventional treatment and could be discharged.

Design of clinical trials of antibacterial agents for community-acquired bacterial pneumonia

Standards for the conduct of clinical trials of antibacterial agents for community-acquired bacterial pneumonia (CABP) have changed dramatically in recent years. A draft guidance from the US FDA on the conduct of such trials was issued in March 2009. However, the guidance has already faced substantial criticism during the open public comment period, resulting in uncertainty regarding the appropriate design of such studies from a regulatory perspective. Controversies regarding the magnitude of the treatment effect associated with antibacterial therapy versus placebo/no therapy, the appropriate timing, nature and noninferiority margin for the primary efficacy end point, and other clinical and statistical issues have complicated efforts to reach consensus on appropriate trial design of antibacterial therapy for CABP. It is critical that studies of new drugs for CABP are designed to ensure that they are feasible to conduct and that their results are scientifically valid, statistically rigorous and clinically meaningful. Based on 3 years of active dialog between clinical, statistical, and regulatory experts, this article proposes an approach to enable a balance of clinical trial feasibility with appropriate scientific, statistical and clinical rigor.

Management of community-acquired pneumonia: a review and update

Community-acquired pneumonia (CAP) is a leading cause of morbidity and mortality worldwide, affecting approximately 5.6 million patients annually in the USA, where the annual cost exceeds US$12 billion. Optimal management should be based on knowledge of the most likely etiologic pathogens for each patient, based on an assessment of specific risk factors. It is also essential to assess severity of illness, to determine the appropriate site of care, and to order appropriate diagnostic testing. New developments in CAP management have focused on recognizing newly identified pathogens, such as methicillin-resistant Staphylococcus aureus and novel H1N1 influenza, understanding when to utilize new microbiological diagnostic techniques, and how to use biomarkers to direct the appropriate utilization of antibiotics and to define the duration of therapy. This paper reviews recent advances in our knowledge about the diagnosis and optimal management of CAP.

Procalcitonin vs C-reactive protein as predictive markers of response to antibiotic therapy in acute exacerbations of COPD

BACKGROUND

Rational prescription of antibiotics in acute exacerbations of COPD (AECOPD) requires predictive markers. We aimed to analyze whether markers of systemic inflammation can predict response to antibiotics in AECOPD.

METHODS

We used data from 243 exacerbations out of 205 patients from a placebo-controlled trial on doxycycline in addition to systemic corticosteroids for AECOPD. Clinical and microbiologic response, serum C-reactive protein (CRP) level (cutoffs 5 and 50 mg/L), and serum procalcitonin level (PCT) (cutoffs 0.1 and 0.25 μg) were assessed.

RESULTS

Potential bacterial pathogens were identified in the majority of exacerbations (58%). We found a modest positive correlation between PCT and CRP (r = 0.46, P < .001). The majority of patients (75%) had low PCT levels, with mostly elevated CRP levels. Although CRP levels were higher in the presence of bacteria (median, 33.0 mg/L [interquartile range, 9.75-88.25] vs 17 mg/L [interquartile range, 5.0-61.0] [P = .004]), PCT levels were similar. PCT and CRP performed similarly as markers of clinical success, and we found a clinical success rate of 90% in patients with CRP ≤ 5 mg/L. A significant effect of doxycycline was observed in patients with a PCT level < .1 μg/L (treatment effect, 18.4%; P = .003). A gradually increasing treatment effect of antibiotics (6%, 10%, and 18%), although not significant, was found for patients with CRP values of ≤ 5, 6-50, and > 50 mg/L, respectively.

CONCLUSIONS

Contrary to the current literature, this study suggests that patients with low PCT values do benefit from antibiotics. CRP might be a more valuable marker in these patients.

Procalcitonin and C-reactive protein in severe 2009 H1N1 influenza infection

PURPOSE

To examine whether, in an adult intensive care unit (ICU), procalcitonin or C-reactive protein (CRP) levels discriminated between 2009 H1N1 influenza infection and community-acquired pneumonia of bacterial origin.

METHODS

A retrospective observational study performed at an Australian hospital over a 4-month winter period during the 2009 H1N1 influenza pandemic. Levels on admission of procalcitonin and CRP were compared between patients admitted to the ICU with community-acquired pneumonia of bacterial and 2009 H1N1 origin.

RESULTS

Compared to those with bacterial or mixed infection (n = 9), patients with 2009 H1N1 infection (n = 16) were significantly more likely to have bilateral chest X-ray infiltrates, lower APACHE scores, more prolonged lengths of stay in ICU and lower white cell count, procalcitonin and CRP levels. Using a cutoff of >0.8 ng/ml, the sensitivity and specificity of procalcitonin for detection of patients with bacterial/mixed infection were 100 and 62%, respectively. A CRP cutoff of >200 mg/l best identified patients with bacterial/mixed infection (sensitivity 100%, specificity 87.5%). In combination, procalcitonin levels >0.8 ng/ml and CRP >200 mg/l had optimal sensitivity (100%), specificity (94%), negative predictive value (100%) and positive predictive value (90%). Receiver-operating characteristic curve analysis suggested the diagnostic accuracy of procalcitonin may be inferior to CRP in this setting.

CONCLUSIONS

Procalcitonin measurement potentially assists in the discrimination between severe lower respiratory tract infections of bacterial and 2009 H1N1 origin, although less effectively than CRP. Low values, particularly when combined with low CRP levels, suggested bacterial infection, alone or in combination with influenza, was unlikely.

Clinical potential of C-reactive protein and procalcitonin serum concentrations to guide differential diagnosis and clinical management of pneumococcal and Legionella pneumonia

We retrospectively analyzed the records of 61 hospitalized patients with community-acquired pneumonia (CAP) caused by Streptococcus pneumoniae or Legionella pneumophila. We found that serum procalcitonin and sodium concentrations were significantly lower, and ferritin levels were significantly higher, in patients infected with L. pneumophila than in those infected with S. pneumoniae. The ratio of C-reactive protein to procalcitonin significantly distinguished between the groups. High procalcitonin levels were associated with an adverse clinical course.

Procalcitonin as a prognostic factor in severe acute exacerbation of chronic obstructive pulmonary disease

BACKGROUND AND OBJECTIVE

Little is known about the value of procalcitonin in predicting mortality in patients with an exacerbation of COPD. This study evaluated the clinical and biological predictors of intensive care unit (ICU) mortality in patients with a severe acute exacerbation of COPD.

METHODS

A prospective observational cohort study was conducted of consecutive patients with severe acute exacerbation of COPD requiring intubation and mechanical ventilation. At ICU admission, data were collected on the patients' clinical condition, blood leukocyte count, C-reactive protein and procalcitonin. Cox proportional hazards model was used to determine the risk factors for ICU mortality.

RESULTS

One hundred and sixteen patients were included in this study. Mean age was 67 years. The mean simplified acute physiology score was 43. Sixty-five per cent of study patients had chronic respiratory insufficiency. Bacteria were cultured at levels considered significant in 36% of study patients. Logistic organ dysfunction score (hazard ratio (95% CI) = 1.19 (1.03-1.37), P = 0.013), rapidly fatal underlying disease (3.33 (1.40-7.87), P = 0.003) and procalcitonin level (1.01 (1-1.03), P = 0.018) were independently associated with increased risk for ICU mortality. Non-invasive mechanical ventilation use before intubation was independently associated with reduced risk for ICU mortality (0.34 (0.14-0.84), P = 0.020).

CONCLUSIONS

In patients with severe acute exacerbation of COPD requiring intubation and mechanical ventilation, logistic organ dysfunction score, rapidly fatal underlying disease and procalcitonin are independently associated with increased risk for ICU mortality. Non-invasive mechanical ventilation use before intubation was independently associated with reduced risk for ICU mortality.

Clinical end points of therapy for patients with mild community-acquired pneumonia

Approximately 80% of patients with community-acquired pneumonia receive treatment as outpatients. The question is what are valid, reproducible, and quantifiable clinical end points that can be used in prospective clinical trials of the safety and efficacy of antibacterials. Patient-reported outcomes and measurements of time to end point are reasonable methods that, according to the limited data available, appear to work in clinical trials of therapy for mild-to-moderate community-acquired pneumonia among outpatients.