Procalcitonin in children admitted to hospital with community acquired pneumonia

Procalcitonin in young febrile infants for the detection of serious bacterial infections

OBJECTIVES

The objectives of the study were (1) to study the test performance of procalcitonin for identifying serious bacterial infections in febrile infants <or=90 days of age without an identifiable bacterial source and (2) to determine an optimal cutoff value to identify infants at low risk for serious bacterial infections.

METHODS

A prospective observational study was performed with febrile infants <or=90 days of age presenting to an urban, pediatric, emergency department. Serum procalcitonin levels were measured by using an automated high-sensitivity assay. An optimal procalcitonin cutoff value was selected to maximize sensitivity and negative predictive value for the detection of serious bacterial infections. Infants were classified as having definite, possible, or no serious bacterial infections.

RESULTS

A total of 234 infants (median age: 51 days) were studied. Thirty infants (12.8%) had definite serious bacterial infections (bacteremia: n = 4; bacteremia with urinary tract infections: n = 2; urinary tract infections: n = 24), and 12 infants (5.1%) had possible serious bacterial infections (pneumonia: n = 5; urinary tract infections: n = 7). Mean procalcitonin levels for definite serious bacterial infections (2.21 +/- 3.9 ng/mL) and definite plus possible serious bacterial infections (2.48 +/- 4.6 ng/mL) were significantly higher than that for no serious bacterial infection (0.38 +/- 1.0 ng/mL). The area under the receiver operating characteristic curve was 0.82 for definite serious bacterial infections and 0.76 for definite and possible serious bacterial infections. For identifying definite and possible serious bacterial infections, a cutoff value of 0.12 ng/mL had sensitivity of 95.2%, specificity of 25.5%, negative predictive value of 96.1%, and negative likelihood ratio of 0.19; all cases of bacteremia were identified accurately with this cutoff value.

CONCLUSIONS

Procalcitonin has favorable test characteristics for detecting serious bacterial infections in young febrile infants. Procalcitonin measurements performed especially well in detecting the most serious occult infections.

Procalcitonin as a diagnostic aid in diabetic foot infections

The diagnosis of diabetic foot infection (DFI) is usually a challenge to the clinician. Procalcitonin (PCT), a 116-amino acid propeptide of calcitonin, is a new marker of bacterial infections and sepsis. We evaluated the serum value of PCT as a marker of bacterial infection in diabetic patients with foot ulcers. Forty-nine diabetic patients with foot ulcers were consecutively enrolled into the study. DFI was diagnosed clinically by the presence of purulent secretions or at least two of the symptoms of inflammation including redness, warmth, swelling, and pain. According to these criteria, DFI was determined in 27 patients (DFI group) and not detected in 22 patients (NDFI group). The blood samples were taken for biochemical analysis on admission. PCT, white blood cell count (WBC) and erythrocyte sedimentation rate (ESR), but not C-reactive protein (CRP), was found significantly higher in DFI group compared with NDFI group. The best cut-off value, sensitivity and specificity were 0.08 ng/ml, 77% and 100% for PCT, 32.1 mg/dl, 29% and 100% for CRP, 8.6 10(9)/L, 70% and 72% for WBC and 40.5 mm/h, 77% and 77% for ESR, respectively. The area under the receiver operating characteristic curve for infection identification was greatest for PCT (0.859; p < 0.001), followed by WBC (0.785; p = 0.001), ESR (0.752; p = 0.003), and finally CRP (0.625; p = 0.137). These results suggest that PCT may be a useful diagnostic marker for DFI. Additional research is needed to better define the role of PCT in DFI.

The burden of respiratory viral disease in hospitalized children in Paris

A virus was identified in 464 out of 1,212 patients, 8 days to 16 years of age, who were admitted to the hospital in Paris during a 3 year period. Respiratory syncytial virus (RSV) was found in 428 patients, 74% were younger than 6 months with bronchiolitis, and 6% were older than 2 years. RSV was the first virus isolated in all patients and in those with pneumonia or asthma. The low number of admissions due to parainfluenzae viruses is characteristic of this area compared to other countries.

Serum procalcitonin measurement as diagnostic and prognostic marker in febrile adult patients presenting to the emergency department

Introduction

Identification of bacterial infections is crucial if treatment is to be initiated early and antibiotics used rationally. The primary objective of this study was to test the efficiency of procalcitonin (PCT) in identifying bacterial/parasitic episodes among febrile adult patients presenting to an emergency department. Secondary objectives were to identify clinical or biological variables associated with either bacterial/parasitic infection or critical illness.

Methods

This was a prospective, single centre, non-interventional study, conducted in the adult emergency department of an academic tertiary care hospital. We included patients with body temperature of 38.5°C or greater. A serum sample for measurement of PCT was collected in the emergency room. Patients were followed up until day 30. After reviewing the medical files, two independent experts, who were blind to the PCT results, classified each of the patients as having a bacterial/parasitic infection, viral infection, or another diagnosis.

Results

Among 243 patients included in the study, 167 had bacterial/parasitic infections, 35 had viral infections and 41 had other diagnoses. The PCT assay, with a 0.2 μg/l cutoff value, had a sensitivity of 0.77 and a specificity of 0.59 in diagnosing bacterial/parasitic infection. Of the patients with PCT 5 μg/l or greater, 51% had critical illness (death or intensive care unit admission) as compared with 13% of patients with lower PCT values.

Conclusion

Bearing in mind the limitations of an observational study design, the judgements of the emergency department physicians were reasonably accurate in determining the pretest probability of bacterial/parasitic infection. PCT may provide additional, valuable information on the aetiology and prognosis of infection in the emergency department.

The utility of serum C-reactive protein in differentiating bacterial from nonbacterial pneumonia in children: a meta-analysis of 1230 children

BACKGROUND

Differentiating bacterial from nonbacterial community-acquired pneumonia in children is difficult. Although several studies have evaluated serum concentrations of C-reactive protein (CRP) as a predictor of bacterial pneumonia in this patient population, the utility of this test remains unclear.

OBJECTIVE

The purpose of this meta-analysis was to quantitatively define the utility of serum CRP as a predictor of bacterial pneumonia in acutely ill children.

METHODS

Multiple databases were searched, bibliographies reviewed, and 2 authorities in the field were queried. Studies were included if: (1) the patient population was between 1 month and 18 years of age; (2) CRP was quantified in all subjects as part of the initial evaluation of a suspected, infectious, pulmonary process; (3) a cutoff serum CRP concentration between 30 and 60 mg/dL was used to distinguish nonbacterial from bacterial pneumonia; (4) some criteria were applied to differentiate bacterial from nonbacterial or viral pneumonia; (5) all patients were acutely ill; and (6) a chest radiograph was obtained as part of the initial evaluation. The quality of each included study was determined across 4 metrics: diagnostic criteria; study design; exclusion of chronically ill or human immunodeficiency virus infected subjects; and exclusion of patients who recently received antibiotics. Data was extracted from each article; the primary outcome measure was the odds ratio of patients with bacterial or mixed etiology pneumonia and serum CRP concentrations exceeding 30-60 mg/L. Heterogeneity among the studies was determined by Cochran's Q statistic; the methods of both Mantel and Haenszel, and DerSimonian and Laird were used to combine the study results.

RESULTS

Eight studies fulfilled inclusion criteria. Combining all of the studies demonstrated a pooled study population of 1230 patients with the incidence of bacterial infection of 41%. Children with bacterial pneumonia were significantly more likely to have serum CRP concentrations exceeding 35-60 mg/L than children with nonbacterial infections (odds ratio = 2.58, 95% confidence interval = 1.20-5.55). Sensitivity analysis demonstrated that this difference was robust. There was significant heterogeneity among the 8 studies (Q = 37.7, P < 0.001, I2 = 81.4) that remained throughout the sensitivity analysis.

CONCLUSIONS

In children with pneumonia, serum CRP concentrations exceeding 40-60 mg/L weakly predict a bacterial etiology.

[Respiratory syncytial virus in hospitalized children. A 3-year study]

OBJECTIVE

To assess the prevalence of respiratory syncytial virus (RSV) and other important respiratory viruses in children hospitalized in a pediatric hospital in Paris (France) during a 3-year period (2001 to 2004).

PATIENTS AND METHODS

The study included all patients aged 8 days to 16 years admitted from the community through emergency department with bronchiolitis, pneumonia, upper respiratory tract infection, asthma or acute isolated fever and who had nasopharyngeal samples taken for viral identification by immunofluorescence (RSV, influenza, para-influenza, and adenoviruses).

RESULTS

A virus was found in 464 of 1208 patients with samples taken. RSV was identified in 375 patients, 74% of them younger than 6 months and diagnosed with bronchiolitis. RSV was isolated more often than any other virus, overall and for all diagnoses except "isolated fever," for which influenza was more frequent. In patients aged 24 months or older, influenza and RSV were identified at the same frequency. Overall, influenza virus was found in 53 patients, adenoviruses in 24 and para-influenza viruses in 11.

CONCLUSION

RSV was the respiratory virus isolated most often, even in older children, during this 3-year study. The relative rarity of hospitalizations due to para-influenza viruses is characteristic of this area, compared with some other countries.

Procalcitonin for the clinical laboratory: a review

Procalcitonin measurement has been claimed as a helpful marker in bacterial infection and sepsis. It has obtained FDA approval and is now widely marketed in the United States and Europe. This review summarises the current assays available, the evidence for its use and possible future applications of the assay.

Value of serum procalcitonin, neopterin, and C-reactive protein in differentiating bacterial from viral etiologies in patients presenting with lower respiratory tract infections

The values of procalcitonin (PCT), neopterin, and C-reactive protein (CRP) alone and in combination to differentiate bacterial from viral etiology in patients with lower respiratory tract infections (LRTIs) were evaluated. Sera obtained on the day of hospitalization for LRTI from 139 patients with confirmed bacterial etiology and 128 patients with viral etiology were examined. A further 146 sera from healthy Chinese subjects with no infection were included as controls. The area under the receiver operating characteristic (ROC) curve (area under curve [AUC]) for distinguishing bacterial from viral infections was 0.838 for CRP and 0.770 for PCT (P < 0.05). The AUC for distinguishing viral from bacterial infections was 0.832 for neopterin (P < 0.05). When the markers were used in combination, AUC of ROC (CRP/neopterin) was 0.857, whereas (CRP x PCT)/neopterin was 0.856. Combination of 2 or all 3 of the biomarkers may improve the discriminatory power in delineating bacterial versus viral etiology in LRTI.

Effective treatment strategies for paediatric community-acquired pneumonia

Pneumonia is the leading cause of death in children under 5 years of age worldwide and a cause of morbidity in a considerable number of children. A number of studies have sought to identify the ideal choice of antibiotics, route of administration and optimum duration of treatment based on the most likely aetiological agents. Emerging bacterial resistance to antibiotics is also an important consideration in treatment. However, inconsistent clinical and radiological definitions of pneumonia make comparison between studies difficult. There is also a lack of well designed adequately powered randomised controlled trials. This review describes the difficulties encountered in diagnosing community-acquired pneumonia, aetiology, treatment strategies with recommendations and highlights areas for further research.

Diagnostic and prognostic accuracy of clinical and laboratory parameters in community-acquired pneumonia

Background

Community-acquired pneumonia (CAP) is the most frequent infection-related cause of death. The reference standard to diagnose CAP is a new infiltrate on chest radiograph in the presence of recently acquired respiratory signs and symptoms. This study aims to evaluate the diagnostic and prognostic accuracy of clinical signs and symptoms and laboratory biomarkers for CAP.

Methods

545 patients with suspected lower respiratory tract infection, admitted to the emergency department of a university hospital were included in a pre-planned post-hoc analysis of two controlled intervention trials. Baseline assessment included history, clinical examination, radiography and measurements of procalcitonin (PCT), highly sensitive C-reactive protein (hsCRP) and leukocyte count.

Results

Of the 545 patients, 373 had CAP, 132 other respiratory tract infections, and 40 other final diagnoses. The AUC of a clinical model including standard clinical signs and symptoms (i.e. fever, cough, sputum production, abnormal chest auscultation and dyspnea) to diagnose CAP was 0.79 [95% CI, 0.75–0.83]. This AUC was significantly improved by including PCT and hsCRP (0.92 [0.89–0.94]; p < 0.001). PCT had a higher diagnostic accuracy (AUC, 0.88 [0.84–0.93]) in differentiating CAP from other diagnoses, as compared to hsCRP (AUC, 0.76 [0.69–0.83]; p < 0.001) and total leukocyte count (AUC, 0.69 [0.62–0.77]; p < 0.001). To predict bacteremia, PCT had a higher AUC (0.85 [0.80–0.91]) as compared to hsCRP (p = 0.01), leukocyte count (p = 0.002) and elevated body temperature (p < 0.001). PCT, in contrast to hsCRP and leukocyte count, increased with increasing severity of CAP, as assessed by the pneumonia severity index (p < 0.001).

Conclusion

PCT, and to a lesser degree hsCRP, improve the accuracy of currently recommended approaches for the diagnosis of CAP, thereby complementing clinical signs and symptoms. PCT is useful in the severity assessment of CAP.

[Different diagnosis of children with viral or bacterial bronchopneumonia infection]

Community-acquired bronchopneumonia is very common in children and responsible for a great morbidity. It can be revealed by bronchiolitis, due to viral infection, bronchitis (80% due to viruses), and pneumonia potentially much more severe due to bacteria (60%), viruses (40%) or both causes (20%). Being unable to exclude a bacterial origin in pneumonia leads physicians to prescribe systematically antibiotics.

[Procalcitonin measurement in adult clinical practice]

PURPOSE

The availability of a sensitive, specific and prognostic marker of bacterial infection is a major issue. More than ten years after the first publication assessing the usefulness of serum procalcitonin dosage (PCT), its exact place in the diagnostic process remained to be defined. The purpose of this review is to point out the indications of PCT measurement in clinical practice in the adult population.

RELEVANT DATA

PCT is an early, sensitive but above all specific marker of severe bacterial/parasitic infections. After being studied mostly in critically ill patients, the indications of PCT measurement have been extended to medical and emergency medicine practice, generating cut-off points between 0.2 and 0.6 microg/L. The medical area of application of PCT measurement is varied: discrimination between inflammatory disease and infectious complication or between bacterial/parasitic and viral infection, diagnosis of negative result gram staining meningitis or shock, assessment of antibiotic treatment efficiency. Moreover, PCT measurement provides outcome information in that sepsis-related raised PCT levels seem to be closely related to the magnitude of host systemic inflammatory response to microbial invasion. High PCT levels allow the early identification of patients prone to develop severe sepsis or septic shock.

PROSPECTS

After the first published study reporting the usefulness of PCT as a screening biological tool in emergency medicine, future studies will probably refined the place of PCT in such practice fields: decision about inpatient or outpatient management or antibiotics dispensation. Finally, PCT measurement could help physician in screening which septic patients should benefit from sepsis innovative therapeutics.

Bacterial pneumonia vaccines and childhood pneumonia: are we winning, refining, or redefining?

Bacterial pneumonia is a substantial cause of childhood morbidity and mortality worldwide, but determination of pathogen-specific burden remains a challenge. In less developed settings, the WHO recommended guidelines are useful for initiating care, but are non-specific. Blood culture has low sensitivity, while radiological findings are non-specific and do not discriminate between viral and bacterial causes of pneumonia. In vaccine probe studies, efficacy is dependent on the specificity of the study outcome to detect pneumonia and the impact of the vaccine on the selected outcome, and may underestimate the true burden of bacterial pneumonia. The rising incidence of antibiotic resistance, emerging respiratory pathogens, potential replacement pneumococcal disease following widespread introduction of pneumococcal polysaccharide-protein conjugate vaccine, the limited specificity of chest radiography, and the poor sensitivity of blood culture are substantial obstacles to accurate surveillance. We provide an overview of the diagnostic challenges of bacterial pneumonia and highlight the need for refining the current diagnostic approach to ensure adequate epidemiological surveillance of childhood pneumonia and the success, or otherwise, of any immunisation strategies.

Usefulness of procalcitonin to differentiate typical from atypical community-acquired pneumonia

BACKGROUND

The value of elevated serum procalcitonin concentration for differentiating between typical and atypical community-acquired pneumonia was assessed and compared with other parameters that are usually used in clinical practice.

PATIENTS AND METHODS

Thirty consecutive adult patients with community-acquired bacterial pneumonia admitted to the Department of Infectious Diseases, University Medical Center Ljubljana, Slovenia, were included in this prospective study. Only those patients for whom the etiology of bacterial pneumonia was confirmed participated in the study.

RESULTS

The median serum procalcitonin level in patients with typical pneumonia was 7.64 ng/ml (range 0.26-63.16) and in the group with atypical pneumonia 0.80 ng/ml (range 0.13-34.90). A significant difference between the typical and atypical pneumonia groups was found only for the procalcitonin serum concentration on admission. The standard laboratory markers of bacterial infections, such as C-reactive protein, total leukocyte count and immature polymorphonuclear cells, did not discriminate between typical and atypical etiology. Median procalcitonin levels were significantly higher among patients with bacteremic pneumonia.

CONCLUSIONS

Determination of the procalcitonin level may provide useful additional diagnostic information on the etiology of pneumonia and could have a crucial influence on the initial antimicrobial therapy.

Quantitative analysis of procalcitonin after pediatric cardiothoracic surgery

Procalcitonin appears to be an early and sensitive marker of bacterial infection in a variety of clinical settings. The use of levels of procalcitonin to predict infection in children undergoing cardiac surgery, however, may be complicated by the systemic inflammatory response that normally accompanies cardiopulmonary bypass. The aim of our study was to estimate peri-operative concentrations of procalcitonin in non-infected children undergoing cardiac surgery. Samples of serum for assay of procalcitonin were obtained in 53 patients at baseline, 24, 48, and 72 hours following cardiac surgery. Concentrations were assessed using an immunoluminetric technique. Median concentrations were lowest at baseline at less than 0.5 nanograms per millilitre, increased at 24 hours to 1.8 nanograms per millilitre, maximized at 48 hours at 2.1 nanograms per millilitre, and decreased at 72 hours to 1.3 nanograms per millilitre, but did not return to baseline levels. Ratios of concentrations between 24, 48 and 72 hours after surgery as compared to baseline were 6.15, with 95 percent confidence intervals between 4.60 and 8.23, 6.49, with 95 percent confidence intervals from 4.55 to 9.27, and 4.26, with 95 percent confidence intervals between 2.78 and 6.51, respectively, with a p value less than 0.001. In 8 patients, who had no evidence of infection, concentrations during the period from 24 to 72 hours were well above the median for the group. We conclude that concentrations of procalcitonin in the serum increase significantly in children following cardiac surgery, with a peak at 48 hours, and do not return to baseline within 72 hours of surgery. A proportion of patients, in the absence of infection, had exaggerated elevations post-operatively.

Pre-emptive antibiotic treatment vs 'standard' treatment in patients with elevated serum procalcitonin levels after elective colorectal surgery: a prospective randomised pilot study

BACKGROUND

Procalcitonin (PCT) is regarded as a specific indicator of bacterial infection. Infectious complications in patients after colorectal surgery are a common cause of morbidity and mortality. The aim of this study was to investigate (a) whether PCT could serve as a negative predictive marker for postoperative complications and (b) whether, in patients with elevated PCT levels, a pre-emptive treatment with the third-generation cephalosporin ceftriaxone is superior to an antibiotic treatment starting later on the appearance of clinical signs and symptoms of infection.

PATIENTS AND METHODS

By screening 250 patients with colorectal surgery, we identified 20 patients with PCT serum levels more than 1.5 ng/ml on at least 2 of the first 3 postoperative days. The remaining 230 patients were followed-up for the occurrence of infectious complications. The 20 patients with elevated PCT were included in a prospective randomised pilot study comparing pre-emptive antibiotic treatment with ceftriaxone vs standard treatment.

RESULTS

The negative predictive value of PCT for systemic infectious complications was 98.3%. In patients receiving pre-emptive antibiotic treatment (ceftriaxone), both the incidence and the severity of postoperative systemic infections were significantly lower compared to those in a control group (Pearson's chi(2) test; p=0.001 and p=0.007, respectively). Major differences were also observed with respect to duration of antibiotic treatment and length of hospital stay.

CONCLUSIONS

PCT is an early marker for systemic infectious complications after colorectal surgery with a high negative predictive value. A significant reduction in the rate of postoperative infections in patients with elevated PCT serum concentrations was achieved by means of pre-emptive antibiotic treatment.

Usefulness of procalcitonin levels in community-acquired pneumonia according to the patients outcome research team pneumonia severity index

STUDY OBJECTIVES

To evaluate the usefulness of procalcitonin serum levels as a predictor of etiology and prognosis in adult patients with community-acquired pneumonia (CAP) when they are stratified according to severity.

DESIGN

One-year, population-based, prospective study.

SETTING

University teaching hospital.

PATIENTS

All adult patients who received a diagnosis of CAP throughout the study period.

INTERVENTIONS AND MEASUREMENTS

An extensive noninvasive microbiological workup was performed. In patients who gave informed consent, a blood sample was collected at the time the diagnosis of CAP was established to measure biological markers. Procalcitonin levels were measured by a commercially available monoclonal immunoluminometric assay (limit of detection, 0.1 microg/L). Patients were classified according to microbial diagnosis, Patients Outcome Research Team pneumonia severity index (PSI), and outcome measures, and procalcitonin levels were compared among groups.

RESULTS

Of 240 patients who received a diagnosis of CAP during the study period, procalcitonin concentrations were measured in 185 patients (77.1%). Levels were higher in patients with high-severity risk classes (PSI classes III-V) [p = 0.01] and in those with complications (p = 0.03) or death (p < 0.0001). Among patients classified into PSI low-severity risk classes (classes I-II), levels tended to be higher in those with bacterial etiology (p = 0.08); in this group, a serum procalcitonin level > or = 0.15 microg/L was more frequently found in patients with bacterial pneumonia than in those with nonbacterial pneumonia (p = 0.03). In patients with higher-severity risk classes, no significant differences were observed in procalcitonin levels among etiologic groups, but higher concentrations were associated with development of complications (p = 0.01) and death (p < 0.0001).

CONCLUSIONS

Procalcitonin contribution to the evaluation of CAP varies according to severity. While procalcitonin may have a role to predict the microbial etiology in patients with a low PSI score, in patients classified within high PSI risk classes, it is a prognostic marker rather than a predictor of etiology.

Use of procalcitonin and C-reactive protein to evaluate vaccine efficacy against pneumonia

BACKGROUND

Pneumonia remains the leading cause of death in young children. The poor specificity of chest radiographs (CXRs) to diagnose pneumococcal pneumonia may underestimate the efficacy of pneumococcal conjugate vaccine in preventing pneumococcal pneumonia.

METHODS AND FINDINGS

The efficacy of nine-valent pneumococcal conjugate vaccine among children not infected with HIV (21%; 95% confidence interval, 1%-37%) increased when CXR-confirmed pneumonia was associated with serum C-reactive protein of 120 mg/l (12 mg/dl) or more and procalcitonin of 5.0 ng/ml or more (64%; 95% confidence interval, 23%-83%). Similar results were observed in children infected with HIV.

CONCLUSION

C-reactive protein and procalcitonin improve the specificity of CXR to diagnose pneumococcal pneumonia and may be useful for the future evaluation of the effectiveness of pneumococcal conjugate vaccine in preventing pneumococcal pneumonia.

Pneumonia in children in the developing world: new challenges, new solutions

Pneumonia has been a leading cause of death in both developed and developing countries as long as health indicators have been available. Yet the issues of concern for this syndrome are far from static. Improvements in access to health services have lowered infant mortality rates, benefiting children around the world and lowering the fraction of child deaths caused by pneumonia. However, progress has been interrupted repeatedly by the emergence of new pathogens. Landmark randomized controlled trials have now demonstrated the effectiveness of Haemophilus influenzae type b (Hib) and multivalent pneumococcal conjugate vaccines against childhood pneumonia, as well as meningitis and bacteremic disease. Momentum has gathered to tackle long-standing economic obstacles to expand access to new vaccines and programs for the poorest countries of the world. A pressing challenge for the control of pneumonia in developing countries is to identify better metrics for pneumonia. Surveillance tools are needed that will bridge studies of interventions, establish preventable disease burden, and serve as indicators for monitoring new programs.

Legionella Pneumonia and Serum Procalcitonin

Procalcitonin is a specific marker of severe bacterial infections with systemic inflammation. Quantitative evaluation of serum procalcitonin was performed in 140 patients with Legionella pneumonia. Positive values (>0.5 ng/mL) were found in 57.1% of the subjects. The positive sample rate was higher in early sera (73.9% in the first week) and decreased progressively. Mean values and the positive sample rate (69.8%) were higher in sera collected in the first 2 weeks of disease. Procalcitonin was positive in 86.7% of legionellosis cases confirmed by culture and mean positive values were significantly higher (P < 0.001) than those of culture-negative subjects. We conclude that procalcitonin can represent a useful prognostic marker for severe suspected Legionella pneumonia in the first 2 weeks of disease.

Procalcitonin as an early marker of infection in neonates and children

A child or neonate presenting with fever is a common medical problem. To differentiate between those with a severe bacterial infection and those with a localised bacterial or a viral infection can be a challenge. This review provides an overview of neonatal and paediatric studies that assess the use of procalcitonin as an early marker of bacterial infection. Procalcitonin is an excellent marker for severe, invasive bacterial infection in children. However, the use of procalcitonin in the diagnosis of neonatal bacterial infection is complicated, but if correctly used procalcitonin results in a higher specificity than C-reactive protein. In addition, procalcitonin has been shown to correlate with severity of disease (urinary tract infections and sepsis), and can therefore be used as a prognostic marker. Procalcitonin is therefore a useful additional tool for the diagnosis of bacterial disease in neonates and children.

Serum procalcitonin and C-reactive protein levels as markers of bacterial infection: a systematic review and meta-analysis

A meta-analysis was performed to evaluate the accuracy of determination of procalcitonin (PCT) and C-reactive protein (CRP) levels for the diagnosis of bacterial infection. The analysis included published studies that evaluated these markers for the diagnosis of bacterial infections in hospitalized patients. PCT level was more sensitive (88% [95% confidence interval [CI], 80%-93%] vs. 75% [95% CI, 62%-84%]) and more specific (81% [95% CI, 67%-90%] vs. 67% [95% CI, 56%-77%]) than CRP level for differentiating bacterial from noninfective causes of inflammation. The Q value for PCT markers was higher (0.82 vs. 0.73). The sensitivity for differentiating bacterial from viral infections was also higher for PCT markers (92% [95% CI, 86%-95%] vs. 86% [95% CI, 65%-95%]); the specificities were comparable (73% [95% CI, 42%-91%] vs. 70% [95% CI, 19%-96%]). The Q value was higher for PCT markers (0.89 vs. 0.83). PCT markers also had a higher positive likelihood ratio and lower negative likelihood ratio than did CRP markers in both groups. On the basis of this analysis, the diagnostic accuracy of PCT markers was higher than that of CRP markers among patients hospitalized for suspected bacterial infections.

Procalcitonin in severe acute respiratory syndrome (SARS)

OBJECTIVE AND METHODS

The role of procalcitonin (PCT) in severe acute respiratory syndrome (SARS) has not been highlighted so far. We described retrospectively eight cases of sepsis from pneumonia of various microbiological aetiologies including two due to SARS, compared their PCT concentrations and provided further descriptors of SARS as a viral pneumonia.

RESULTS

Like any viral pneumonia, patients with SARS had low PCT levels in contrast to bacterial or fungal pneumonia.

CONCLUSIONS

In the setting of pneumonia with a finding of low PCT, testing for SARS should be considered, especially if there is a positive travel or contact history. During a SARS epidemic, we also strongly advocate isolating all suspected community acquired pneumonia with a low PCT level.

Mycoplasma pneumoniae and asthma in children

The aim of this prospective study of a population of children (age, 2-15 years) hospitalized for severe asthma was to test them for acute infection due to Mycoplasma pneumoniae and acute infection due to Chlamydia pneumoniae. Of 119 patients with previously diagnosed asthma, acute M. pneumoniae infection was found in 24 (20%) and C. pneumoniae infection was found in 4 (3.4%) of the patients during the current exacerbation. Of 51 patients experiencing their first asthma attack, acute M. pneumoniae infection was proven in 26 (50%) of the patients (P<.01) and C. pneumoniae in 4 (8.3%). In the control group of 152 children with stable asthma or rhinitis, 8 (5.2%) had M. pneumoniae infection (P<.005). Of the 29 patients experiencing their first asthma attack and infected with M. pneumoniae or C. pneumoniae, 18 (62%) had asthma recurrences but only 6 (27%) of the 22 patients who did not have such infections had asthma recurrences (P<.05). M. pneumoniae may play a role in the onset of asthma in predisposed children and could be a trigger for recurrent wheezing.

Procalcitonin and C-reactive protein kinetics in postoperative pediatric cardiac surgical patients

OBJECTIVE

To determine the kinetics of procalcitonin (PCT) and C-reactive protein (CRP) concentration after pediatric cardiac surgery with cardiopulmonary bypass.

DESIGN

Prospective, clinical cohort study.

SETTING

A fifteen-bed tertiary-care pediatric intensive care unit.

PATIENTS

Fourteen pediatric patients admitted for cardiac surgery.

MEASUREMENTS AND MAIN RESULTS

Serum PCT and CRP were measured before cardiopulmonary bypass (CPB); after CPB; and on the first, second, and third days after surgery by means of immunoluminometry and nephelometry, respectively. Reference values for systemic inflammatory response syndrome are 0.5 to 2.0 ng/mL for PCT and <5 mg/L for CRP. Baseline serum PCT and CRP concentrations were 0.24 +/- 0.13 ng/mL and 4.06 +/- 3.60 mg/L (median 25th percentile-75th percentile), respectively. PCT concentrations increased progressively from the end of CPB (0.62 +/- 0.30 ng/mL), peaked at 24 hours postoperatively (POD1) (0.77 +/- 0.49 ng/mL), and began to decrease at 48 hours or POD2 (0.35 +/- 0.21 ng/mL). CRP increased just after CPB (58.82 +/- 42.23 mg/L) and decreased after 72 hours (7.09 +/- 9.81 mg/L).

CONCLUSION

An increment of both PCT and CRP was observed just after CPB. However, PCT values remained within reference values, whereas CRP concentrations increased significantly after CPB until the third day. These preliminary results suggest that PCT was more effective than CRP to monitor patients with SIRS and a favorable outcome.

Pneumonies communautaires et infection grippale

Children without chronic or serious medical conditions are at increased risk for hospitalization during influenza seasons, mainly with respiratory tract infections. But influenza virus infections frequently remain undiagnosed, even in hospitalized patients. We prospectively studied the rate of concomitant and preceding influenza infections in children hospitalized with a community acquired pneumonia (CAP).

POPULATION AND METHODS

All 1-15-year-old children with CAP requiring hospitalization between 1st April 2000 and 2002 had nasopharyngeal aspirate for viruses, immunofluorescence and serologies for respiratory pathogens. The peak of influenza IgG measured by complement fixation (CF) is transient, and a titer of 1/64 or more indicates an acute influenza infection in the preceding weeks. Children with chronic disease were excluded and a control group of patients from outpatient clinic was measured.

RESULTS

Among 33 previously healthy children (age 4.9 years, range 1.2-14 years), 8 had a pneumococcal pneumonia, 10 a pneumonia caused by Mycoplasma pneumoniae (MP), 1 by Chlamydia pneumonia, and 8 of unknown origin. In six patients immunofluorescence was positive: Respiratory Syncitial Virus, 2, Adenovirus, 1 and Influenza A, 3 (including a patient with concomitant MP infection). Thirteen of the 33 children (39.4%) had evidence of a recent influenza A infection with CF ab > or = 1/64: with pneumococcal pneumonia, 5/10 with MP pneumonia, 3/8 with unknown origin pneumonia, 9/13 of these previous influenza infections being clinically inapparent. Only 1/30 children of control group (3.3%) had CF ab > or = 1/64.

CONCLUSION

In this study, influenza infection is the direct cause of CAP of children in 12% of cases. In other children with CAP, 39.4% of patients had an influenza infection in the preceding weeks which leads to secondary infection caused by Streptococcus pneumoniae or by MP or other pathogens.

Procalcitonin, C-reactive protein and leukocyte count in children with lower respiratory tract infection

BACKGROUND

Lower respiratory tract infection is the most common infection leading to unnecessary antibiotic treatment in children. Etiologic diagnosis is not immediately achieved, and the pathogen remains unidentified in a large number of cases. Neither clinical nor laboratory factors allow for a rapid distinction between bacterial and viral etiology. The aim of our study was to evaluate the reliability of procalcitonin (PCT), C-reactive protein (CRP) and leukocyte count in distinguishing pneumococcal, atypical and viral lower respiratory tract infection.

METHODS

PCT, CRP and leukocyte count were measured in children with microbiologically documented diagnoses of lower respiratory tract infection. The results were compared of children with pneumococcal, atypical and viral etiologies.

RESULTS

PCT and CRP showed significant correlation with a bacterial etiology of lower respiratory tract infection. No significance was found for leukocyte count. Using a cutoff point of 2 ng/ml for PCT and 65 mg/l for CRP, the sensitivities and specificities for distinguishing bacterial from viral lower respiratory tract infections were 68.6 and 79.4% for PCT and 79.1 and 67.1% for CRP. The sensitivities and specificities for distinguishing pneumococcal from other etiologies were 90.3 and 74.1% for PCT and 90.3 and 60% for CRP, respectively.

CONCLUSIONS

High PCT and CRP values show a significant correlation with the bacterial etiology of lower respiratory tract infection. PCT and CRP show good sensitivity for distinguishing pneumococcal from other etiologies. PCT shows higher specificity than CRP. PCT and CRP can help make decisions about antibiotic therapy in children with lower respiratory tract infections.

Paediatric community-acquired pneumonia: current concept in pharmacological control

Community-acquired pneumonia (CAP) is one of the most frequent infections in childhood but it is not easy to establish a rational therapeutic approach for a number of reasons, including difficulties in identifying the aetiology, the fact that the most frequent bacterial pathogens become resistant to commonly used antibiotics and the lack of certain information concerning the possible preventive role of conjugate vaccines. This leads paediatricians to treat almost all cases of CAP with antibiotics, often using a combination of different antimicrobial classes. In order to avoid unnecessary antibiotic use and limit the spread of antibiotic resistance, consensus guidelines for the management of CAP in childhood should be developed and used by practitioners in their offices and hospitals.

Serum procalcitonin concentrations in bacterial pneumonia in children: a negative result in primary healthcare settings

A microbe-specific diagnosis in community-acquired pneumonia (CAP) is difficult in children, and studies on nonspecific chest radiographic and host response markers have been inconsistent. Serum procalcitonin (PCT) is a newly recognized, promising marker for differentiating between bacterial and viral infections. Serum PCT was measured by a luminometric assay in 190 children with CAP diagnosed in the primary healthcare setting during a population-based study in a geographically defined population. The pneumococcal, mycoplasma, chlamydia, and viral etiology of infections was studied by an extensive serologic test panel. The median PCT concentrations were 0.47, 0.46, and 0.35 ng/mL in children aged <5 years, 5-9 years, and >/=10 years (P = 0.004). An elevated PCT >1.0 ng/mL was seen in 12.1% and >2.0 ng/mL in only 2.1% of the children. No association was seen between severity (inpatient vs. outpatient care) and etiology of CAP (evidence for pneumococcal, mycoplasma, or chlamydia, vs. viral infection). We conclude that serum PCT measurements have no role in the diagnosis of bacterial CAP in children in primary healthcare settings.

Pathobiochemistry and clinical use of procalcitonin

Induction of the protein procalcitonin during infection and inflammation was first described approximately 10 years ago. A large number of publications, primarily clinical studies, demonstrate the increasing use of procalcitonin in modern clinical practice. However, data on the biological function and origin of procalcitonin is scarce. Findings regarding the possible role and source of procalcitonin in sepsis and infection were recently published, and the pathophysiology of the protein has meanwhile been investigated in various experimental models. Procalcitonin obviously has certain biological functions, and it is also known to be specifically induced. Given the hormonal origin of the mature protein and the inflammation-related functions of its propeptides, some investigators suggest that procalcitonin should be referred to as a "hormokine," although its biological functions should be studied in more detail. This review will survey the data now available in recent publications on the induction, production sources, possible biological functions and clinical uses of procalcitonin.

Procalcitonin as a marker of sepsis

Prompt diagnosis and treatment with appropriate antimicrobial chemotherapy is of paramount importance to reduce morbidity and mortality associated with sepsis. Inflammatory markers currently in use, such as C-reactive protein (CRP) do not reliably differentiate between the systemic inflammatory response and sepsis. Procalcitonin (PCT), a precursor of calcitonin, is a 116 amino acid protein that has been proposed as a marker of disease severity in conditions such as septicaemia, meningitis, pneumonia, urinary tract infection (UTI) and fungal and parasitic infection. In particular, serial measurements are useful in order to monitor response to therapy. Together with good clinical judgement and judicious use of antimicrobial agents, PCT should serve as a valuable adjunct in the diagnosis and management of sepsis.

Mycoplasma pneumoniae and Chlamydia pneumoniae cause lower respiratory tract disease in paediatric patients

New studies suggest that Mycoplasma pneumoniae and Chlamydia pneumoniae play a more significant role as causes of lower respiratory tract infections in childhood than was previously thought. In particular, the incidence of infections caused by these pathogens is high in children aged less than 5 years, the infections themselves seem to be a possible cause of wheezing, and may present a more complicated course when not treated with adequate antimicrobial agents. However, despite the increasing pathogenic significance of M. pneumoniae and C. pneumoniae, progress in fighting them is hampered by the lack of rapid and standardized diagnostic methods. This not only makes it practically impossible for practitioners to make a specific microbiological diagnosis, but has also had an adverse effect on treatment trials and has generated some questionable results. Carefully randomized and controlled trials are clearly needed to examine the effectiveness of different antibiotics against M. pneumoniae or C. pneumoniae and the optimal duration of therapy in various patient populations.

Emerging resistance to antibiotics against respiratory bacteria: impact on therapy of community-acquired pneumonia in children

Perhaps because of its etiologic complexity, community-acquired pneumonia (CAP) in infants and children remains a significant problem worldwide. Over the last few years, difficulties related to CAP treatment in children have greatly increased because of the emergence of resistance to the most widely used antibiotics against some of the bacterial pathogens involved in the development of the disease. There are few data describing the impact of antibiotic resistance on clinical outcomes in CAP, but many experts believe that the clinical impact is limited. We here discuss the prevalence of different etiologic agents in CAP of children, the diagnostic criteria, problems related to antibiotic resistance, therapeutic strategies, and future implications.

Usefulness of procalcitonin as a marker of systemic infection in emergency department patients: a prospective study

We prospectively evaluated serum procalcitonin concentrations in patients who presented to an emergency department (ED) with suspected infectious or inflammatory disease. Of 195 study patients, 68 had final diagnosis of systemic infection, and 24 of those 68 had elevated serum procalcitonin levels (>0.5 ng/mL). The procalcitonin level had a sensitivity of 0.35 and specificity of 0.99 for the diagnosis of systemic infection. In multivariate analysis, the procalcitonin level was the only independent variable associated with this diagnosis; in contrast, the C-reactive protein level was not. All patients with systemic infections who ultimately died had procalcitonin levels of >0.5 ng/mL at admission. Procalcitonin levels were significantly higher in patients who ultimately died of systemic infection than in patients who survived. The optimal procalcitonin threshold for the ED population may be lower than that proposed for critically ill patients. Determination of the procalcitonin level may be useful for screening and prognosis of more-severely ill ED patients.

[Community-acquired pneumonia in children: etiology and treatment]

Due to their very different etiological agents, community-acquired pneumoniae in children frequently require empiric antibiotic therapy in emergency. Streptococcus pneumoniae represents between 15 to 30% of the etiologies and has unspecific diagnostic procedures; as a matter of fact radiological lobar consolidation is seen in less than half of cases, and laboratory data, except for high procalcitonin level, are poorly reliable. Pneumonia due to Mycoplasma pneumoniae is frequent after 2 years of age, reaching 40 to 60% of causes in ambulatory teenagers; it must be treated with macrolides as sequellae are possible. The exact number of viral pneumonia is difficult to establish because of the lack of reliable diagnostic methods. If bacterial superinfections are probably overestimated during acute phase, viral infections may lead to bacterial pneumonia 2 to 4 weeks after the initial episode. Empiric antibiotic treatment must take into account pneumococci and their penicillin-resistant strains. Amoxicillin is the antibiotic of choice, having a higher efficacy on resistant pneumococci than oral cephalosporins. In case of clinical failure of amoxicillin, mycoplasma infection must be considered and patient must receive macrolides. Future epidemiology will be affected by anti-pneumococcal immunisation but difficulties in diagnosis and empiric antibiotic treatment will probably remain. Studies in immunised children are needed to evaluate the importance of pneumococcal infections due to serotypes not included in the vaccine.

Pneumonia due to viral and atypical organisms and their sequelae

Most children presenting with pneumonia in the industrialised world will have a viral or 'atypical' organism. The clinical features of these 'atypical' pneumonias may be indistinguishable from bacterial pneumonia. New diagnostic techniques such as the polymerase chain reaction may help in diagnosis and choice of treatment, where appropriate. The pathological and clinical features of infection with each agent are discussed, together with their sequelae.