Procalcitonin in children admitted to hospital with community acquired pneumonia

Community-acquired pneumonia in children: current challenges and future directions

Pneumonia is a commonly encountered illness and the leading cause of death in children under 5 years of age. Our current management strategies remain less than optimal in part because we do not have adequate tools to determine etiology, classify patients and predict their outcomes. Studies in the last decade have demonstrated that viruses are commonly detected in children with pneumonia, but on many occasions this is not sufficient to establish a clear etiologic diagnosis since bacterial coinfection cannot be excluded. Gene expression profile analysis provides a comprehensive assessment of the host response to infection. Preliminary data suggest that transcriptional profile analysis and measurement of Molecular Distance to Health (MDTH) scores allows more precise patient classification than current diagnostic techniques and laboratory markers. Application of this tool to the evaluation of children with pneumonia may enhance our clinical decision making process and ultimately improve patient outcomes.

Population-based incidence of community-acquired pneumonia hospitalization in Hong Kong children younger than 5 years before universal conjugate pneumococcal immunization

OBJECTIVES

We sought to document the incidence of pediatric hospitalization for bacterial pneumonia before universal childhood conjugate pneumococcal vaccination using two different methods of diagnosis.

METHODS

By following the World Health Organization (WHO) chest radiography (CXR) protocol, two radiologists independently read the CXRs of a cohort of systematically recruited children younger than 5 years. The children had acute respiratory infections and were admitted to one of two hospitals that care for 72.5% of all pediatric admissions on Hong Kong Island. Medical records were reviewed for clinical manifestation and to identify bacterial pneumonia diagnosed by pediatricians.

RESULTS

In children younger than 5 years, the incidences of bacterial pneumonia, as diagnosed by pediatricians and by the WHO CXR standard, were 775.7 per 100,000 population [95% confidence interval (CI, 591.8-998.3)] and 439.5 per 100,000 population (95% CI, 304.6-614.5), respectively. The study period was from 2002 to 2004.

CONCLUSION

This study provided a reliable baseline estimate of the hospitalization burden of pneumococcal pneumonia in Hong Kong children before the advent of universal conjugate pneumococcal vaccination.

Update on procalcitonin measurements

Procalcitonin (PCT) is used as a biomarker for the diagnosis of sepsis, severe sepsis and septic shock. At the same time, PCT has also been used to guide antibiotic therapy. This review outlines the main indications for PCT measurement and points out possible pitfalls. The classic indications for PCT measurement are: (i) confirmation or exclusion of diagnosis of sepsis, severe sepsis, or septic shock, (ii) severity assessment and follow up of systemic inflammation mainly induced by microbial infection, and (iii) individual, patient adapted guide of antibiotic therapy and focus treatment. Using serially monitored PCT levels, the duration and need of antibiotic therapy can be better adapted to the individual requirements of the patient. This individualized approach has been evaluated in various studies, and it is recommended to be a part of an antibiotic stewardship program.

Procalcitonin and C-reactive protein in urinary tract infection diagnosis

BACKGROUND

Urinary infections are a common type of pediatric disease, and their treatment and prognosis are closely correlated with infection location. Common clinical manifestations and laboratory tests are insufficient to differentiate between acute pyelonephritis and lower urinary tract infection. This study was conducted to explore a diagnostic method for upper and lower urinary tract infection differentiation.

METHODS

The diagnostic values of procalcitonin (PCT) and C-reactive protein (CRP) were analyzed using the receiver operating characteristic curve method for upper and lower urinary tract infection differentiation. PCT was determined using chemiluminescent immunoassay.

RESULTS

The PCT and CRP values in children with acute pyelonephritis were significantly higher than those in children with lower urinary tract infection (3.90 ± 3.51 ng/ml and 68.17 ± 39.42 mg/l vs. 0.48 ± 0.39 ng/ml and 21.39 ± 14.92 mg/l). The PCT values were correlated with the degree of renal involvement, whereas the CRP values failed to show such a significant correlation. PCT had a sensitivity of 90.47% and a specificity of 88% in predicting nephropathia, whereas CRP had sensitivity of 85.71% and a specificity of 48%.

CONCLUSIONS

Both PCT and CRP can be used for upper and lower urinary tract infection differentiation, but PCT has higher sensitivity and specificity in predicting pyelonephritis than CRP. PCT showed better results than CRP. PCT values were also correlated with the degree of renal involvement.

Utility of inflammatory markers in predicting the aetiology of pneumonia in children

We aimed to investigate the diagnostic value of applying cut-off levels of inflammatory markers and to develop a prediction model for differentiation between bacterial and viral infections in paediatric community-acquired pneumonia based on C-reactive protein (CRP), neutrophil, and white cell counts (WCC). Amongst 401 children, those with bacterial pneumonia were older than those with viral pneumonia (P<0.001). Compared to viral, bacterial infections had a higher median CRP level (P<0.001), whereas WCC and neutrophil count were not different. Bacterial infections were associated with higher CRP >80 mg/L than viral infections (P=0.001), but levels <20 mg/L were not discriminatory (P=0.254). Receiver operating characteristic curve of the model for differentiating bacterial from viral pneumonia based on age, CRP, and neutrophil count produced area under the curve of 0.894 with 75.7% sensitivity and 89.4% specificity. This aetiological discriminant prediction model is a potentially useful tool in clinical management and epidemiological studies of paediatric pneumonia.

Role of biomarkers in sepsis care

Sepsis is one of the leading causes of mortality and morbidity, even with the current availability of extended-spectrum antibiotics and advanced medical care. Biomarkers offer a tool in facilitating early diagnosis, in identifying patient populations at high risk of complications, and in monitoring progression of the disease, which are critical assessments for appropriate therapy and improvement in patient outcomes. Several biomarkers are already available for clinical use in sepsis; however, their effectiveness in many instances is limited by the lack of specificity and sensitivity to characterize the presence of an infection and the complexity of the inflammatory and immune processes and to stratify patients into homogenous groups for specific treatments. Current advances in molecular techniques have provided new tools facilitating the discovery of novel biomarkers, which can vary from metabolites and chemical products present in body fluids to genes and proteins in circulating blood cells. The purpose of this review was to examine the current status of sepsis biomarkers, with special emphasis on emerging markers, which are undergoing validation and may transition into clinical practice for their informative value in diagnosis, prognosis, or response to therapy. We will also discuss the new concept of combination biomarkers and biomarker risk models, their existing challenges, and their potential use in the daily management of patients with sepsis.

Elevated inflammatory markers combined with positive pneumococcal urinary antigen are a good predictor of pneumococcal community-acquired pneumonia in children

BACKGROUND

Our objective was to evaluate procalcitonin (PCT) and C-reactive protein (CRP) as predictors of a pneumococcal etiology in community-acquired pneumonia (CAP) in hospitalized children.

METHODS

Children requiring hospitalization for CAP were prospectively enrolled. The following indices were determined: antibodies against pneumococcal surface proteins (anti-PLY, pneumococcal histidine triad D, pneumococcal histidine triad E, LytB and pneumococcal choline-binding protein A), viral serology, nasopharyngeal cultures and polymerase chain reaction for 13 respiratory viruses, blood pneumococcal polymerase chain reaction, pneumococcal urinary antigen, PCT and CRP. Presumed pneumococcal CAP (P-CAP) was defined as a positive blood culture or polymerase chain reaction for Streptococcus pneumoniae or as a pneumococcal surface protein seroresponse (≥2-fold increase).

RESULTS

Seventy-five patients were included from which 37 (49%) met the criteria of P-CAP. Elevated PCT and CRP values were strongly associated with P-CAP with odds ratios of 23 (95% confidence interval: 5-117) for PCT and 19 (95% confidence interval: 5-75) for CRP in multivariate analysis. The sensitivity was 94.4% for PCT (cutoff: 1.5 ng/mL) and 91.9% for CRP (cutoff: 100 mg/L). A value≤0.5 ng/mL of PCT ruled out P-CAP in >90% of cases (negative likelihood ratio: 0.08). Conversely, a PCT value≥1.5 ng/mL associated with a positive pneumococcal urinary antigen had a diagnostic probability for P-CAP of almost 80% (positive likelihood ratio: 4.59).

CONCLUSIONS

PCT and CRP are reliable predictors of P-CAP. Low cutoff values of PCT allow identification of children at low risk of P-CAP. The association of elevated PCT or CRP with a positive pneumococcal urinary antigen is a strong predictor of P-CAP.

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.

Field testing the utility of procalcitonin and the acute infantile observation score in febrile infants 6 to 36 months old presenting to the pediatric emergency department with no obvious focus of infection

BACKGROUND

Serious bacterial illness (SBI) presents a diagnostic challenge in febrile infants. History, clinical signs, and laboratory information combined with experiential knowledge affects decisions to admit and treat.

AIM

To assess the utility of serum procalcitonin and the Acute Infantile Observation Score (AIOS) performed at emergency department presentation in predicting (a) confirmed serious bacterial illness and (b) illness severity.

METHODS

Sensitivity, specificity, and likelihood ratios were calculated for C-reactive protein, white cell count, serum procalcitonin, and AIOS.

RESULTS

Forty-six infants were recruited. Seven had a diagnosis of SBI, 28 were moderately ill with length of stay >24 hours, and 12 were severely ill with length of stay >96 hours. The positive likelihood ratios for confirmed SBI were C-reactive protein = 5.3, procalcitonin = 0.43, white cell count = 1.9, and AIOS = 1.5.

CONCLUSION

Procalcitonin and the AIOS do not modify the diagnostic uncertainty of the ED physician assessing the febrile infant with respect to admission or antibiotic treatment above standard laboratory investigations.

Procalcitonin as a diagnostic marker in differentiating parapneumonic effusion from tuberculous pleurisy or malignant effusion

OBJECTIVES

Differential diagnosis of exudative pleural effusions can be difficult, despite the use of several biomarkers. Serum procalcitonin (s-PCT) is a well-known biomarker for systemic bacterial infections. However, the usefulness of pleural fluid procalcitonin (pf-PCT) in clinical practice has not been established. This study evaluated the usefulness of PCT measurements in differentiating parapneumonic effusion (PPE) from tuberculous (TB) pleurisy or malignant effusion.

DESIGN AND METHODS

Ninety eight adult patients diagnosed with exudative pleural effusion were enrolled and allocated into the PPE group (n=32), TB pleurisy group (n=40), or malignant effusion group (n=26). Both s-PCT and pf-PCT concentrations were measured at admission using an immunoluminometric assay.

RESULTS

Both s-PCT and pf-PCT were significantly increased in the PPE group compared with the TB pleurisy or malignant effusion groups (p<0.001). The optimal cut-off value for s-PCT in the diagnosis of PPE was 0.18 ng/mL (sensitivity 83.3%, specificity 81.0%). The pf-PCT cut-off value was 0.16 ng/mL (sensitivity 81.5%, specificity 72.1%). Serum PCT exhibited better diagnostic accuracy than pf-PCT, with areas under the receiver operating characteristic curves of 0.842 for s-PCT and 0.784 for pf-PCT (p=0.015). In addition, s-PCT and pf-PCT showed better diagnostic accuracy than serum C-reactive protein (p=0.005 and p=0.023, respectively).

CONCLUSIONS

Measurement of s-PCT and pf-PCT is useful in differentiating PPE from TB pleurisy and malignant effusion. Both s-PCT and pf-PCT may be useful biomarkers in the differential diagnosis of exudative pleural effusions.

Procalcitonin as a biomarker of acute lower respiratory tract infections

BACKGROUND

Procalcitonin (PCT) has emerged as a promising 'acute phase' biomarker used for diagnosis of acute bacterial infections of the respiratory tract. The introduction of new sensitive PCT assays has facilitated implementation of a new clinical approach to reduce antibiotic use in acute lower respiratory tract infections (LRTIs), without compromising patient safety.

OBJECTIVE

Current state of knowledge on the clinical usefulness of serum PCT measurements for the evaluation of acute LRTIs is presented herein, together with basic information on available rapid diagnostic tests for PCT measurement.

METHODS

During the literature search the emphasis was on PCT use as a diagnostic, monitoring and prognostic tool for acute LRTIs. The acute LRTIs have been defined as acute bronchitis, acute exacerbations of chronic obstructive pulmonary disease or asthma, and pneumonia. Original studies involving patients with these conditions have been considered, and recent articles documenting interventional trials on PCT use for guidance of antimicrobial treatment in LRTIs have been reviewed in particular.

RESULTS/CONCLUSION

When measured with sensitive and rapid assays, PCT has proved to be a good biomarker for acute bacterial LRTIs, which enables an early diagnosis, facilitates therapeutic decisions, and can inform clinicians about the course of disease and prognosis. PCT can become a particularly suitable tool for implementation in an emergency and acute medical care setting.

Procalcitonin in pediatrics

Over the past two decades, the body of literature on the clinical usefulness of procalcitonin (PCT) in adults has grown rapidly. Although this approach has led to increased insight, it has also prompted debate regarding its potential use in diagnosis and management of severe infection. Clinicians, however, are less familiar with the use of PCT in pediatric populations. In this review, we examine PCT as a marker of severe clinical pediatric conditions including its role in systemic inflammation, infection, and sepsis.

Comparison of clinical features and outcomes of hospitalized adult patients with novel influenza A (H1N1) pneumonia and other pneumonia

OBJECTIVES

A novel swine-origin influenza A (H1N1) virus caused worldwide outbreaks starting in April 2009. The aim of this study was to evaluate the clinical characteristics and outcomes of pandemic 2009 H1N1 pneumonia by comparing to community-acquired pneumonia (CAP) of other origin.

METHODS

The authors conducted a prospective cohort study of consecutive adult (over 15 years old) patients with suspected CAP requiring admission to a tertiary university-affiliated hospital during the second wave of pandemic 2009 H1N1 influenza. Based on the results of real-time reverse transcriptase-polymerase chain reaction (RT-PCR) analysis, the staff completed a standard assessment form and managed the patients according to a uniform protocol. Clinical characteristics, as well as laboratory and radiologic findings, were collected and compared between pandemic 2009 H1N1 pneumonia and CAP of other origin. The primary outcome was in-hospital mortality and secondary outcomes were duration of hospitalization, duration of intensive care unit (ICU) stay, and requirement of mechanical ventilation.

RESULTS

A total of 135 patients with suspected CAP were included in the study. Of these, 59 patients were RT-PCR positive for H1N1 virus, and 76 patients were RT-PCR negative. Patients with H1N1 pneumonia were significantly younger than those with CAP of other origin (46.0 years vs. 68.0 years, p < 0.01) and more frequently had nonspecific symptoms (p < 0.01), initial leukopenia (8.5% vs. 0.0%, p = 0.01), lymphopenia (45.8% vs. 26.3%, p = 0.02), low values of C-reactive protein (CRP; 5.2 mg/dL vs. 13.4 mg/dL, p = 0.02), bilateral abnormalities (57.7% vs. 29.7%, p < 0.01) on chest radiography, ground glass opacities (43.9% vs. 12.8%, p < 0.01) on chest computed tomography, and low values of pneumonia severity index (PSI) score (56.0 vs. 91.0, p < 0.01) than those with CAP of other origin. However, there were no significant differences in infection severity, clinical outcome, length of ICU stay, requirement for mechanical ventilation, and mortality between the two groups.

CONCLUSIONS

This study shows that clinical characteristics and outcomes of 2009 H1N1 pneumonia are comparable to those of CAP of other origin. However, some characteristics, including younger age, nonspecific symptoms (including headache, leukopenia, and fatigue), lymphopenia, lower initial CRP and PSI score, and radiologic findings (including bilateral abnormalities and ground glass opacities), may help clinicians to diagnostically differentiate between H1N1 pneumonia and CAP of other origin before the result of RT-PCR are obtained.

Utility of Procalcitonin (PCT) and Mid regional pro-Adrenomedullin (MR-proADM) in risk stratification of critically ill febrile patients in Emergency Department (ED). A comparison with APACHE II score

BACKGROUND

The aim of our study was to evaluate the prognostic value of MR-proADM and PCT levels in febrile patients in the ED in comparison with a disease severity index score, the APACHE II score. We also evaluated the ability of MR-proADM and PCT to predict hospitalization.

METHODS

This was an observational, multicentric study. We enrolled 128 patients referred to the ED with high fever and a suspicion of severe infection such as sepsis, lower respiratory tract infections, urinary tract infections, gastrointestinal infections, soft tissue infections, central nervous system infections, or osteomyelitis. The APACHE II score was calculated for each patient.

RESULTS

MR-proADM median values in controls were 0.5 nmol/l as compared with 0.85 nmol/l in patients (P < 0.0001), while PCT values in controls were 0.06 ng/ml versus 0.56 ng/ml in patients (P < 0.0001). In all patients there was a statistically significant stepwise increase in MR-proADM levels in accordance with PCT values (P < 0.0001). MR-proADM and PCT levels were significantly increased in accordance with the Apache II quartiles (P < 0.0001 and P = 0.0012 respectively).In the respiratory infections, urinary infections, and sepsis-septic shock groups we found a correlation between the Apache II and MR-proADM respectively and MR-proADM and PCT respectively. We evaluated the ability of MR-proADM and PCT to predict hospitalization in patients admitted to our emergency departments complaining of fever. MR-proADM alone had an AUC of 0.694, while PCT alone had an AUC of 0.763. The combined use of PCT and MR-proADM instead showed an AUC of 0.79.

CONCLUSIONS

The present study highlights the way in which MR-proADM and PCT may be helpful to the febrile patient's care in the ED. Our data support the prognostic role of MR-proADM and PCT in that setting, as demonstrated by the correlation with the APACHE II score. The combined use of the two biomarkers can predict a subsequent hospitalization of febrile patients. The rational use of these two molecules could lead to several advantages, such as faster diagnosis, more accurate risk stratification, and optimization of the treatment, with consequent benefit to the patient and considerably reduced costs.

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.

Procalcitonin-guided antibiotic treatment of respiratory tract infections in a primary care setting: are we there yet?

Clinical signs of infection do not allow for correct identification of bacterial and viral aetiology in acute respiratory infections. A valid tool to assist the clinician in identifying patients who will benefit from antibiotic therapy, as well as patients with a potentially serious infection, could greatly improve patient care and limit excessive antibiotic prescriptions. Procalcitonin is a new marker of suspected bacterial infection that has shown promise in guiding antibiotic therapy in acute respiratory tract infections in hospitals without compromising patient safety. Procalcitonin concentrations in primary care are low and can be used primarily to rule out serious infection. However, procalcitonin measurement should not be used as the sole basis for clinical decisions; clinical skills are prerequisites for the correct use of this new tool in practice. At present there is no point-of-care test for procalcitonin with acceptable precision, severely hampering its application in primary care. This article reviews the physiology of procalcitonin, describes the assays available for its measurement, evaluates the present evidence from primary care on its use to identify correctly patients who are likely to benefit from antibiotic treatment and to rule out serious infections, and comments on further research to determine a future role for procalcitonin in primary care.

Diagnostic and prognostic value of procalcitonin in community-acquired pneumonia

INTRODUCTION

The value of measuring procalcitonin (PCT) in patients with community-acquired pneumonia (CAP) is unclear. The aim of this study was to determine the value of PCT as a marker for microbial etiology and a predictor of outcome in CAP patients.

METHODS

A single-center observational study was conducted with CAP patients. On admission, their leukocyte count, serum C-reactive protein level, and serum PCT level were determined, and microbiological tests were performed. Patients were classified into 4 groups according to the A-DROP scoring system, which assesses the severity of CAP.

RESULTS

A total of 102 patients were enrolled. The pathogen was identified in 60 patients, and 31 patients had streptococcal pneumonia. The PCT levels were significantly higher in those patients with pneumococcal pneumonia than in those patients with other bacterial pneumonias (P < 0.0001). Multivariate regression analysis revealed that high PCT levels were associated with a pneumococcal etiology [odds ratio, 1.68; 95% confidence interval (CI): 1.02-2.81; P = 0.04] after adjustment for disease severity and demographic factors. The PCT levels were correlated with the A-DROP score (r = 0.49; P < 0.0001). The area under the curve for predicting mortality was highest for the A-DROP score (0.97; 95% CI: 0.92-0.99), followed by the area under the curve for PCT (0.82; 95% CI: 0.74-0.89) and C-reactive protein (0.77; 95% CI: 0.67-0.84).

CONCLUSIONS

High PCT levels indicate that pneumococcal pneumonia and PCT levels depend on the severity of pneumonia. PCT measurements may provide important diagnostic and prognostic information for patients with CAP.

Serum procalcitonin is not an early marker of pulmonary exacerbation in children with cystic fibrosis

Serum procalcitonin (PCT) has been proposed as a marker to identify bacterial infection in children. For optimal management of cystic fibrosis (CF) patients, early recognition of pulmonary exacerbations is necessary, but sensitive biomarkers to do so are lacking. Our study was done to establish baseline values for PCT in children with CF and to compare these to values at onset of a pulmonary exacerbation. Serum PCT values were determined in CF children during an outpatient clinic visit and at onset of treatment with intravenous (IV) antibiotics for a pulmonary exacerbation. Serum PCT was measured using a quantitative immunoassay (BRAHMS Kryptor PCTsensitive, Henningsdorf, Germany). In 92 outpatients (mean age 10.0 years, SD 4.8 years; mean forced expiratory volume in 1 s 91%, SD 18; 9 chronically colonized with Pseudomonas aeruginosa), mean baseline PCT was 0.05 ng/ml (SD 0.07). Mean PCT on admission for IV treatment of pulmonary exacerbation was 0.07 ng/ml (SD 0.06) (n = 22) and not different from the baseline value. PCT values were markedly higher in two CF patients with an acute nonrespiratory infection (central venous catheter-associated bloodstream infection, acute gastroenteritis), demonstrating that they can mount a PCT response.

CONCLUSION

PCT values in CF children are not different from values reported in healthy children. In CF children, PCT values do not rise significantly at the onset of a respiratory exacerbation and thus hold no promise as an early marker to identify a pulmonary exacerbation.

The management of community-acquired pneumonia in infants and children older than 3 months of age: clinical practice guidelines by the Pediatric Infectious Diseases Society and the Infectious Diseases Society of America

Evidenced-based guidelines for management of infants and children with community-acquired pneumonia (CAP) were prepared by an expert panel comprising clinicians and investigators representing community pediatrics, public health, and the pediatric specialties of critical care, emergency medicine, hospital medicine, infectious diseases, pulmonology, and surgery. These guidelines are intended for use by primary care and subspecialty providers responsible for the management of otherwise healthy infants and children with CAP in both outpatient and inpatient settings. Site-of-care management, diagnosis, antimicrobial and adjunctive surgical therapy, and prevention are discussed. Areas that warrant future investigations are also highlighted.

Procalcitonin measurements for guiding antibiotic treatment in pediatric pneumonia

In order to evaluate the use of an algorithm based on a procalcitonin (PCT) cut-off value as a means of guiding antibiotic therapy, 319 hospitalised children with uncomplicated community-acquired pneumonia (CAP) were randomised 1:1 to be treated on the basis of the algorithm or in accordance with standard guidelines. The children in the PCT group did not receive antibiotics if their PCT level upon admission was <0.25 ng/mL, and those receiving antibiotics from the time of admission were treated until their PCT level was ≥ 0.25 ng/mL. The final analysis was based on 155 patients in the PCT group and 155 in the control group. In comparison with the controls, the PCT group received significantly fewer antibiotic prescriptions (85.8% vs 100%; p < 0.05), were exposed to antibiotics for a shorter time (5.37 vs 10.96 days; p < 0.05), and experienced fewer antibiotic-related adverse events (3.9% vs 25.2%; p < 0.05), regardless of CAP severity. There was no significant between-group difference in recurrence of respiratory symptoms and new antibiotic prescription in the month following enrollment. The results of this first prospective study using a PCT cut-off value to guide antibiotic therapy for pediatric CAP showed that this approach can significantly reduce antibiotic use and antibiotic-related adverse events in children with uncomplicated disease. However, because the study included mainly children with mild to moderate CAP and the risk of the use of the algorithm-based approach was not validated in a relevant number of severe cases, further studies are needed before it can be used in routine clinical practice.

Biomarkers in the critically ill patient: procalcitonin

Infection and/or sepsis biomarkers should help to make the diagnosis and thus initiate therapy earlier, help to differentiate between infectious and sterile inflammation, allow the use of more-specific antimicrobials, shorten the time of antimicrobial use, and ideally identify distinct phenotypes that may benefit from specific adjunctive sepsis therapies. Procalcitonin (PCT) was proposed as a sepsis and infection marker more than 15 years ago. Meanwhile, PCT has been evaluated in various clinical settings. In this review the present use of PCT on the ICU and in critically ill patients is summarized, included it's role for diagnosis of severe sepsis and septic shock and antibiotic stewardship with PCT.

Bronconeumopatías agudas del niño

Las infecciones infantiles afectan con frecuencia al aparato respiratorio inferior. Las clasificaciones convencionales, basadas en el tipo de afección anatómica, radiológica y etiopatogénica, permiten definir entidades clínicas (bronquitis, bronquiolitis, neumopatía); sin embargo, la evaluación de la gravedad del proceso es lo más útil para decidir el tipo y la rapidez del tratamiento. Aunque la etiología viral es la más frecuente, la estrategia fundamental para reducir la morbilidad e incluso la mortalidad de las infecciones respiratorias bajas se basa en el tratamiento adecuado de las neumonías bacterianas. Ante la ausencia de especificidad, es indispensable, cuando esté indicado, recurrir a una antibioticoterapia inicial probabilística que incluya el neumococo. En el niño, las muestras no suelen proceder del parénquima pulmonar y, además, la recogida de las secreciones bronquiales durante los primeros años de vida no es de buena calidad. Al contrario de lo que ocurre con los virus, el examen bacteriológico de las secreciones de las vías respiratorias altas es poco útil, porque los niños suelen ser portadores de gérmenes que pueden causar neumopatías. Los datos clínicos y radiológicos sólo pueden sugerir el diagnóstico. El desarrollo de técnicas que detectan antígenos microbianos o la búsqueda de material genético por biología molecular han permitido mejorar de manera significativa la identificación del patógeno responsable y la elección del tratamiento adecuado. Algunos grupos particulares de pacientes pueden padecer una afección respiratoria por agentes infecciosos inusuales o, incluso, oportunistas. Una proporción importante de la afectación respiratoria del adulto puede atribuirse a las agresiones pulmonares sufridas durante su infancia. La aplicación de vacunas, en especial, la antigripal y la antineumocócica, es fundamental para la prevención de estas afecciones respiratorias.

[Pneumococci isolated from vaccinated children with pneumonia]

Among 76 children fully vaccinated with 7-valent conjugate vaccine and subsequently hospitalized from 2006 to 2009 for community-acquired pneumonia, isolated or with empyema or pleuritis, 10 had confirmed pneumococcal infections. All pneumococci isolated with blood or pleural culture were non vaccine serotypes (1, 5, 7F, and 19A). The proportion of pneumococcal pneumonias was similar to that in two series from the same hospital before the vaccine era. These data show that the 13-valent conjugate vaccine could be useful in prevention of community-acquired pneumonia and that bacteriologic survey of community-acquired pneumonia remains necessary.

Role of procalcitonin and C-reactive protein in differentiation of mixed bacterial infection from 2009 H1N1 viral pneumonia

Please cite this paper as: Ahn et al. (2011) Role of procalcitonin and C‐reactive protein in differentiation of mixed bacterial infection from 2009 H1N1 viral pneumonia. Influenza and Other Respiratory Viruses 5(6), 398–403.

Background  Mixed bacterial infection is an important contributor to morbidity and mortality during influenza pandemics. We evaluated procalcitonin (PCT) and C‐reactive protein (CRP) in differentiating pneumonia caused by mixed bacterial and 2009 H1N1 influenza infection from 2009 H1N1 influenza infection alone.

Methods  Data were collected retrospectively over a 7‐month period during the 2009 H1N1 influenza pandemic. Patients visiting emergency department and diagnosed as community‐acquired pneumonia caused by 2009 H1N1 infection were included (n = 60).

Results  Mixed bacterial and viral infection pneumonia (n = 16) had significantly higher PCT and CRP levels than pneumonia caused by 2009 H1N1 influenza alone (n = 44, P = 0·019, 0·022 respectively). The sensitivity and specificity for detection of mixed bacterial infection pneumonia was 56% and 84% for PCT > 1·5 ng/ml, and 69% and 63% for CRP > 10 mg/dl. Using PCT and CRP in combination, the sensitivity and specificity were 50% and 93%, respectively.

Conclusion  Procalcitonin and CRP alone and their combination had a moderate ability to detect pneumonia of mixed bacterial infection during the 2009 H1N1 pandemic. Considering high specificity, combination of low CRP and PCT result may suggest that pneumonia is unlikely to be caused by mixed bacterial infection.

Multinational, observational study of procalcitonin in ICU patients with pneumonia requiring mechanical ventilation: a multicenter observational study

Introduction

The intent of this study was to determine whether serum procalcitonin (PCT) levels are associated with prognosis, measured as organ dysfunctions and 28-day mortality, in patients with severe pneumonia.

Methods

This was a multicenter, observational study of critically ill adult patients with pneumonia requiring mechanical ventilation conducted in 10 academic hospitals in Canada, the United States, and Central Europe. PCT was measured daily for 14 days using an immuno-luminometric assay.

Results

We included 175 patients, 57 with community acquired pneumonia (CAP), 61 with ventilator associated pneumonia (VAP) and 57 with hospital acquired pneumonia (HAP). Initial PCT levels were higher in CAP than VAP patients (median (interquartile range: IQR); 2.4 (0.95 to 15.8) vs. 0.7 (0.3 to 2.15), ng/ml, P < 0.001) but not significantly different to HAP (2.2 (0.4 to 8.0) ng/ml). The 28-day ICU mortality rate for all patients was 18.3% with a median ICU length of stay of 16 days (range 1 to 142 days). PCT levels were higher in non-survivors than in survivors. Initial and maximum PCT levels correlated with maximum Sequential Organ Failure Assessment (SOFA) score r² = 0.50 (95% CI: 0.38 to 0.61) and r² = 0.57 (0.46 to 0.66), respectively. Receiver operating curve (ROC) analysis on discrimination of 28-day mortality showed areas under the curve (AUC) of 0.74, 0.70, and 0.69 for maximum PCT, initial PCT, and Acute Physiology and Chronic Health Evaluation (APACHE) II score, respectively. The optimal cut-off to predict mortality for initial PCT was 1.1 ng/ml (odds ratio: OD 7.0 (95% CI 2.6 to 25.2)) and that for maximum PCT was 7.8 ng/ml (odds ratio 5.7 (95% CI 2.5 to 13.1)).

Conclusions

PCT is associated with the severity of illness in patients with severe pneumonia and appears to be a prognostic marker of morbidity and mortality comparable to the APACHE II score.

A systematic review on the diagnosis of pediatric bacterial pneumonia: when gold is bronze

Background

In developing countries, pneumonia is one of the leading causes of death in children under five years of age and hence timely and accurate diagnosis is critical. In North America, pneumonia is also a common source of childhood morbidity and occasionally mortality. Clinicians traditionally have used the chest radiograph as the gold standard in the diagnosis of pneumonia, but they are becoming increasingly aware that it is not ideal. Numerous studies have shown that chest radiography findings lack precision in defining the etiology of childhood pneumonia. There is no single test that reliably distinguishes bacterial from non-bacterial causes. These factors have resulted in clinicians historically using a combination of physical signs and chest radiographs as a ‘gold standard’, though this combination of tests has been shown to be imperfect for diagnosis and assigning treatment. The objectives of this systematic review are to: 1) identify and categorize studies that have used single or multiple tests as a gold standard for assessing accuracy of other tests, and 2) given the ‘gold standard’ used, determine the accuracy of these other tests for diagnosing childhood bacterial pneumonia.

Methods and Findings

Search strategies were developed using a combination of subject headings and keywords adapted for 18 electronic bibliographic databases from inception to May 2008. Published studies were included if they: 1) included children one month to 18 years of age, 2) provided sufficient data regarding diagnostic accuracy to construct a 2×2 table, and 3) assessed the accuracy of one or more index tests as compared with other test(s) used as a ‘gold standard’. The literature search revealed 5,989 references of which 256 were screened for inclusion, resulting in 25 studies that satisfied all inclusion criteria. The studies examined a range of bacterium types and assessed the accuracy of several combinations of diagnostic tests. Eleven different gold standards were studied in the 25 included studies. Criterion validity was calculated for fourteen different index tests using eleven different gold standards. The most common gold standard utilized was blood culture tests used in six studies. Fourteen different tests were measured as index tests. PCT was the most common measured in five studies each with a different gold standard.

Conclusions

We have found that studies assessing the diagnostic accuracy of clinical, radiological, and laboratory tests for bacterial childhood pneumonia have used a heterogeneous group of gold standards, and found, at least in part because of this, that index tests have widely different accuracies. These findings highlight the need for identifying a widely accepted gold standard for diagnosis of bacterial pneumonia in children.

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.

Validation and development of a clinical prediction rule in clinically suspected community-acquired pneumonia

OBJECTIVES

To develop a mathematical model to predict the probability of having community-acquired pneumonia and to evaluate an already developed prediction rule that has not been validated in a clinical scenario.

METHODS

Children who presented with fever and had presumptive clinical diagnosis of pneumonia were evaluated in 4 institutions of different complexity during 1 year. The variables assessed were sex, age, respiratory rate, days with fever, maximum body temperature, presence of tachypnea, cough, chest pain, intercostal retraction, nasal flaring, abdominal pain, vomiting, grunting, rales, decreased breath sounds, wheezing, fatigue, loss of appetite, loss of sleep, and season of the year. The chest radiographs were photographed and then interpreted by 2 pediatric radiologists.

RESULTS

A total of 257 children were evaluated: 179 (69%) had clinical and radiological diagnosis of community-acquired pneumonia, and 78 (30%) had no radiological confirmation. A total of 96 photographs were recorded, and in 64 of the cases, there was agreement in the diagnosis between the evaluating pediatrician and the radiologists (kappa index = 0.68).With the calculated probabilities, it was possible to build a receiving operating characteristic curve and, based on the estimated coefficients we calculated, a value associated to the probability of having pneumonia.

CONCLUSIONS

We developed a model including 5 variables of high level of sensitivity for the diagnosis of pneumonia. To use it, it would be useful to apply the appropriate software. In addition, we validated a clinical prediction rule of 4 variables that proved to have 93.8% sensitivity to diagnose pneumonia in children with a fever and localized rales, or decreased breath sounds, or tachypnea, or any combination of these 4 variables.

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 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.

Is procalcitonin better than C-reactive protein for early diagnosis of bacterial pneumonia in children?

Early diagnosis of bacterial pneumonia plays a pivotal role in the management. We evaluated the diagnostic accuracy of procalcitonin (PCT) as compared with C-reactive protein (CRP) for the early diagnosis of bacterial pneumonia in children. In total, 92 children consisting of 46 patients of bacterial pneumonia were admitted in the Military hospital, Rawalpindi, Pakistan and equal number of controls were included. Patient's investigations were carried out at admission. PCT and CRP were analyzed on Vidas analyzer and Immulite 1000, respectively. Out of 46 pneumonia patients, 28 were male and 18 female, with a median age of 4 years. PCT levels were significantly high median (range) of 2.69 ng/ml (0.30-13.00) vs. 0.45 ng/ml (0.10-2.00) in controls. Serum CRP levels were moderately elevated with median (range) 6.5 mg/l (0.30-60) vs. 0.30 mg/l (0.30-5.0) in controls. The area under receiver characteristic curves for PCT and CRP were 0.89 (95% CI=0.83-0.96) and 0.79 (95% CI=0.70-0.88), respectively. In total, 38 patients were diagnosed to have bacterial pneumonia with PCT (sensitivity 83% at cutoff > or = 1 ng/ml) and 26 children with CRP (sensitivity 57% at cutoff > or = 6 mg/L). PCT has better diagnostic accuracy than CRP and can be utilized for early diagnosis of bacterial pneumonia in children.

Procalcitonin as a marker of severe bacterial infection in children in the emergency department

Procalcitonin, the prohormone of calcitonin, is a relatively new and innovative marker of bacterial infection that has multiple potential applications in the pediatric emergency department. In healthy individuals, circulating levels of procalcitonin are generally very low (<0.05 ng/mL), but in the setting of severe bacterial infection and sepsis, levels can increase by hundreds to thousands of fold within 4 to 6 hours. Although the exact physiologic function of procalcitonin has not been determined, the consistent response and rapid rise of this protein in the setting of severe bacterial infection make procalcitonin a very useful biomarker for invasive bacterial disease. In Europe, serum procalcitonin measurements are frequently used in the diagnosis and the management of patients in a variety of clinical settings. To date, the use of procalcitonin has been limited in the United States, but this valuable biomarker has many potential applications in both the pediatric emergency department and the intensive care unit. The intent of this article is to review the history of procalcitonin, describe the kinetics of the molecule in response to bacterial infection, describe the laboratory methods available for measuring procalcitonin, examine the main causes of procalcitonin elevation, and evaluate the potential applications of procalcitonin measurements in pediatric patients.

Role of C-reactive protein and procalcitonin in differentiation of tuberculosis from bacterial community acquired pneumonia

BACKGROUND/AIMS

We investigated the utility of serum C-reactive protein (CRP) and procalcitonin (PCT) for differentiating pulmonary tuberculosis (TB) from bacterial community-acquired pneumonia (CAP) in South Korea, a country with an intermediate TB burden.

METHODS

We conducted a prospective study, enrolling 87 participants with suspected CAP in a community-based referral hospital. A clinical assessment was performed before treatment, and serum CRP and PCT were measured. The test results were compared to the final diagnoses.

RESULTS

Of the 87 patients, 57 had bacterial CAP and 30 had pulmonary TB. The median CRP concentration was 14.58 mg/dL (range, 0.30 to 36.61) in patients with bacterial CAP and 5.27 mg/dL (range, 0.24 to 13.22) in those with pulmonary TB (p<0.001). The median PCT level was 0.514 ng/mL (range, 0.01 to 27.75) with bacterial CAP and 0.029 ng/mL (range, 0.01 to 0.87) with pulmonary TB (p<0.001). No difference was detected in the discriminative values of CRP and PCT (p=0.733).

CONCLUSIONS

The concentrations of CRP and PCT differed significantly in patients with pulmonary TB and bacterial CAP. The high sensitivity and negative predictive value for differentiating pulmonary TB from bacterial CAP suggest a supplementary role of CRP and PCT in the diagnostic exclusion of pulmonary TB from bacterial CAP in areas with an intermediate prevalence of pulmonary TB.

Is serum procalcitonin a reliable diagnostic marker in children with acute respiratory tract infections? A retrospective analysis

INTRODUCTION

Acute respiratory tract infections (ARI) in children are often treated with antibiotics even without evidence of bacterial infection. Serum procalcitonin (PCT) is elevated in bacterial but not in viral infections.

PATIENTS AND METHODS

We performed a retrospective analysis of children in the PID-ARI.net study on respiratory infections to address the question of whether plasma PCT could potentially distinguish between bacterial infections requiring antibiotic therapy and viral ARI. We analysed data on 327 children who had been included in the German PID-ARI.net study and in whom nasopharyngeal aspirates had been analysed with a 19-valent multiplex reverse transcription-polymerase chain reaction-enzyme-linked immunosorbent assay for viral and atypical bacterial pathogens. Serum PCT was determined using a quantitative immunoassay (BRAHMS Kryptor PCTsensitive, Henningsdorf, Germany). We then focussed specifically on those children who were treated with antibiotics and therefore had been suspected of having bacterial infection but who had a serum PCT level lower than 0.1 ng/ml.

RESULTS

Out of 327 children, 132 had serum PCT levels below 0.1 ng/ml. Of these 132, 38 children had been treated with antibiotics. After exclusion of 26 patients (with critical illnesses, antibiotics on admission or for reasons other than ARI), 12 children remained for further evaluation. Of these 12 children, four had atypical pneumonia; four others had positive virus testing, and, in the last four, the aetiology of ARI remained unknown; evidence of bacterial infection could not be detected in any.

CONCLUSIONS

Taken the results of this retrospective analysis, serum PCT values below 0.1 ng/ml might be a marker to identify children with acute respiratory tract infection in whom antibiotic treatment could be withheld. However, only a prospective intervention trial will prove the general safety of this limit.

Inflammatory parameters predict etiologic patterns but do not allow for individual prediction of etiology in patients with CAP: results from the German competence network CAPNETZ

Background

Aim of this study was to evaluate the correlation of inflammatory markers procalcitonin (PCT), C-reactive protein (CRP) and leukocyte count (WBC) with microbiological etiology of CAP.

Methods

We enrolled 1337 patients (62 ± 18 y, 45% f) with proven CAP. Extensive microbiological workup was performed. In all patients PCT, CRP, WBC and CRB-65 score were determined. Patients were classified according to microbial diagnosis and CRB-65 score.

Results

In patients with typical bacterial CAP, levels of PCT, CRP and WBC were significantly higher compared to CAP of atypical or viral etiology. There were no significant differences in PCT, CRP and WBC in patients with atypical or viral etiology of CAP. In contrast to CRP and WBC, PCT markedly increased with severity of CAP as measured by CRB-65 score (p < 0.0001). In ROC analysis for discrimination of patients with CRB-65 scores > 1, AUC for PCT was 0.69 (95% CI 0.66 to 0.71), which was higher compared to CRP and WBC (p < 0.0001). CRB-65, PCT, CRP and WBC were higher (p < 0.0001) in hospitalised patients in comparison to outpatients.

Conclusion

PCT, CRP and WBC are highest in typical bacterial etiology in CAP but do not allow individual prediction of etiology. In contrast to CRP and WBC, PCT is useful in severity assessment of CAP.

Efficacy of serum procalcitonin in evaluating severity of community-acquired pneumonia in childhood

Microbe-specific diagnosis of community-acquired pneumonia (CAP) in childhood is difficult in clinical practice. Chest radiographs and non-specific inflammatory markers have been used to separate presumably bacterial from viral infection but the results have been inconsistent. The aim of the present study was to evaluate the usefulness of procalcitonin (PCT) in assessing the severity as well as the bacterial or viral aetiology of CAP. Serum PCT was measured by an immunoluminometric assay in 100 patients with CAP; 26 were treated as inpatients and 74 as outpatients. The pulmonary infiltrate was considered to be alveolar in 62 and interstitial in 38 cases, according to the radiological diagnosis. The bacterial and viral aetiology of pneumonia was studied by an extensive serological test panel. No differences were found in PCT concentrations between the 4 aetiological (pneumococcal, atypical bacterial, viral, unknown) and the 3 age (< 2, 2-4 and > or = 5 y) groups. Serum PCT was >0.5 ng/ml in 69%, >1.0 ng/ml in 54% and >2.0 ng/ml in 47% of all patients. PCT was higher in patients that were admitted than as outpatients (medians 17.81 vs 0.72 ng/ml, respectively, p<0.01) and higher in alveolar than in interstitial pneumonia (medians 9.43 vs 0.53 ng/ml, respectively, p<0.01). In conclusion, serum PCT values were found to be related to the severity of CAP in children even though they were not capable, at any level of serum concentration, to differentiate between bacterial and viral aetiology.

Serum and pleural fluid procalcitonin in predicting bacterial infection in patients with parapneumonic effusion

This study evaluated the value of procalcitonin (PCT) levels in pleural effusion to differentiate the etiology of parapneumonic effusion (PPE). Forty-one consecutive PPE patients were enrolled and were divided into bacterial and non-bacterial PPE. Blood and pleural effusion samples were collected for PCT measurement on admission and analyzed for diagnostic evaluation. PCT of pleural fluid was significantly increased in the bacterial PPE group (0.24 ng/mL) compared to the non-bacterial PPE group (0.09 ng/mL), but there was no significant difference for serum PCT. A PCT concentration of pleural fluid >0.174 ng/mL (best cut-off value) was considered positive for a diagnosis of bacterial PPE (sensitivity, 80%; specificity, 76%; AUC, 0.84). Pleural effusion PCT in the bacterial PPE is significantly different from those of the non-bacterial PPE and control groups, so the diagnostic use of PCT still warrants further investigation.

Differentiation of bacterial and viral community-acquired pneumonia in children

BACKGROUND

Microbe-specific diagnosis of pediatric community-acquired pneumonia (CAP) and the distinction between typical-bacterial, atypical-bacterial and viral cases are difficult. The aim of the present study was to evaluate the role of four serum non-specific inflammatory markers and their combinations, supplemented by chest radiological findings, in the screening of bacterial etiology of pediatric CAP.

METHODS

Serum procalcitonin (PCT), serum C-reactive protein (CRP), blood erythrocyte sedimentation rate (ESR) and white blood cell (WBC) counts were determined in 101 children with CAP, all confirmed on chest radiograph. Evidence of etiology was achieved in 68 patients (67%) mainly using a serologic test panel including 15 pathogens.

RESULTS

For the combination of CRP > 100 mg/L, WBC count > 15 x 10(9)/L, PCT > 1.0 ng/mL and ESR > 65 mm/h, the likelihood ratio for a positive test result (LR+) was 2.7 in the distinction between pneumococcal and viral CAP and 3.9 between atypical and viral CAP. If there was a higher value in one of these four parameters (CRP > 200 mg/L, WBC count > 22 x 10(9)/L, PCT > 18 ng/mL or ESR > 90 mm/h) LR+ changed to >or=3.4, which means a significant increase from pre-test to post-test disease probability. An alveolar radiological infiltration was associated with higher values in non-specific inflammatory markers when compared with interstitial infiltrates, but there were no significant associations between radiological and etiological findings.

CONCLUSIONS

CRP, WBC count, PCT and ESR or their combinations have a limited role in screening between bacterial and viral pediatric CAP. If all or most of these markers are elevated, bacterial etiology is highly probable, but low values do not rule out bacterial etiology.

Etiology of community-acquired pneumonia in hospitalized children based on WHO clinical guidelines

Community-acquired pneumonia (CAP) is a major cause of death in developing countries and of morbidity in developed countries. The objective of the study was to define the causative agents among children hospitalized for CAP defined by WHO guidelines and to correlate etiology with clinical severity and surrogate markers. Investigations included an extensive etiological workup. A potential causative agent was detected in 86% of the 99 enrolled patients, with evidence of bacterial (53%), viral (67%), and mixed (33%) infections. Streptococcus pneumoniae was accounted for in 46% of CAP. Dehydration was the only clinical sign associated with bacterial pneumonia. CRP and PCT were significantly higher in bacterial infections. Increasing the number of diagnostic tests identifies potential causes of CAP in up to 86% of children, indicating a high prevalence of viruses and frequent co-infections. The high proportion of pneumococcal infections re-emphasizes the importance of pneumococcal immunization.