Assessment of a rapid urinary antigen detection by an immunochromatographic test for diagnosis of pneumococcal infection in children

A case report of disseminated Streptococcus pneumoniae infection complicated by infective endocarditis, septic arthritis and epidural abscess in an immunocompetent patient

Streptococcus pneumoniae is a highly virulent, vaccine-preventable pathogen which can cause disease on a spectrum from benign to fatal. Apart from pneumonia, it commonly causes septicaemia and meningitis. This case report describes an unusual range of complications in a 53-year-old Caucasian female presenting to a regional hospital, without any risk known factors for severe disease (such as extremes of age, immunodeficiency or co-morbidities). Progressing from an episode of otitis media, her condition rapidly progressed to mastoid sinusitis, septic arthritis, infective endocarditis, epidural abscesses and multiple subcutaneous abscesses. Following quick identification of S. pneumoniae from a positive blood culture, the patient was treated with high-dose benzylpenicillin and ceftriaxone and aggressive source control by surgery, enabling a good clinical recovery.

Etiology and the challenge of diagnostic testing of community-acquired pneumonia in children and adolescents

Background

Pneumonia is the leading cause of mortality in pediatric population. The etiology of pneumonia in this population is variable and changes according to age and disease severity and where the study is conducted. Our aim was to determine the etiology of community-acquired pneumonia (CAP) in children aged 1 month to 17 years admitted to 13 Colombian hospitals.

Methods

Prospective cohort study. Hospitalized children with radiologically confirmed CAP and ≤ 15 days of symptoms were included and followed together with a control group. Induced sputum (IS) was submitted for stains and cultures for pyogenic bacteria and Mycobacterium tuberculosis, and multiplex PCR (mPCR) for bacteria and viruses; urinary antigens for pneumococcus and Legionella pneumophila; nasopharyngeal swabs for viruses, and paired serology for atypical bacteria and viruses. Additional cultures were taken at the discretion of primary care pediatricians.

Results

Among 525 children with CAP, 71.6% had non-severe pneumonia; 24.8% severe and 3.6% very severe pneumonia, and no fatal cases. At least one microorganism was identified in 84% of children and 61% were of mixed etiology; 72% had at least one respiratory virus, 28% pyogenic bacteria and 21% atypical bacteria. Respiratory syncytial virus, Parainfluenza, Rhinovirus, Influenza, Mycoplasma pneumoniae, Adenovirus and Streptococcus pneumoniae were the most common etiologies of CAP. Respiratory syncytial virus was more frequent in children under 2 years and in severe pneumonia. Tuberculosis was diagnosed in 2.3% of children. IS was the most useful specimen to identify the etiology (33.6%), and blood cultures were positive in 3.6%. The concordance between all available diagnostic tests was low. A high percentage of healthy children were colonized by S. pneumoniae and Haemophilus influenzae, or were infected by Parainfluenza, Rhinovirus, Influenza and Adenovirus.

Conclusions

Respiratory viruses are the most frequent etiology of CAP in children and adolescents, in particular in those under 5 years. This study shows the challenges in making an etiologic diagnosis of CAP in pediatric population because of the poor concordance between tests and the high percentage of multiple microorganisms in healthy children. IS is useful for CAP diagnosis in pediatric population.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-022-03235-z.

Seeking diagnostic and prognostic biomarkers for childhood bacterial pneumonia in sub-Saharan Africa: study protocol for an observational study

INTRODUCTION

Clinically diagnosed pneumonia in children is a leading cause of paediatric hospitalisation and mortality. The aetiology is usually bacterial or viral, but malaria can cause a syndrome indistinguishable from clinical pneumonia. There is no method with high sensitivity to detect a bacterial infection in these patients and, as result, antibiotics are frequently overprescribed. Conversely, unrecognised concomitant bacterial infection in patients with malarial infections occur with omission of antibiotic therapy from patients with bacterial infections. Previously, we identified two combinations of blood proteins with 96% sensitivity and 86% specificity for detecting bacterial disease. The current project aimed to validate and improve these combinations by evaluating additional biomarkers in paediatric patients with clinical pneumonia. Our goal was to describe combinations of a limited number of proteins with high sensitivity and specificity for bacterial infection to be incorporated in future point-of-care tests. Furthermore, we seek to explore signatures to prognosticate clinical pneumonia.

METHODS AND ANALYSIS

Patients (n=900) aged 2-59 months presenting with clinical pneumonia at two Gambian hospitals will be enrolled and classified according to criteria for definitive bacterial aetiology (based on microbiological tests and chest radiographs). We will measure proteins at admission using Luminex-based immunoassays in 90 children with definitive and 160 with probable bacterial aetiology, and 160 children classified according to the prognosis of their disease. Previously identified diagnostic signatures will be assessed through accuracy measures. Moreover, we will seek new diagnostic and prognostic signatures through machine learning methods, including support vector machine, penalised regression and classification trees.

ETHICS AND DISSEMINATION

Ethics approval has been obtained from the Gambia Government/Medical Research Council Unit The Gambia Joint Ethics Committee (protocol 1616) and the institutional review board of Boston University Medical Centre (STUDY00000958). Study results will be disseminated to the staff of the study hospitals, in scientific seminars and meetings, and in publications.

TRIAL REGISTRATION NUMBER

H-38462.

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

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

Identifying pneumococci in parapneumonic pleural effusion: Is there a role for culture-independent methods?

OBJECTIVE

To evaluate culture-independent procedures (immunochromatography and quantitative polymerase chain reaction [qPCR]) in the detection and susceptibility of Streptococcus pneumoniae directly from culture-negative pleural fluid (PF) in children.

METHOD

Detection of S. pneumoniae in PF of children with parapneumonic effusion and/or empyema by using two culture-independent methods: an immunochromatographic membrane test (IMT) which identifies the pneumococcal C antigen, and a real-time PCR test to detect pneumococcal genes lytA and pbp2b, a marker of susceptibility of β-lactam agents, in PF samples.

RESULTS

We tested 36 PF specimens and recorded the previous use of antimicrobials. In the final analysis, 34 samples were included. IMT and qPCR presented positive results in 23 (67.6%) and 24 (70.6%) of the samples, respectively, showing a moderate agreement (k = 0.518) between the two methods. From the 36 children included, 34 (94.4%) had antibiotic data available by the time when PFs were collected. Thirty-four (100%) children had been given treatment before PF sampling, with 33 (97%) receiving β-lactam antibiotics administered empirically. Of the 24 lytA real-time positive samples, 21 (87.5%) were also positive for pbp2b, a marker of β-lactam susceptibility.

CONCLUSION

The reduced sensitivity of culture for pneumococcal detection can be improved through the addition of IMT and qPCR analysis. The utility of qPCR combining detection of lytA and a marker of β-lactam susceptibility should be explored further.

Microbiological Diagnosis of Respiratory Illness

A wide variety of microorganisms are potential respiratory pathogens, and the spectrum of known pathogens for each respiratory infection syndrome has not changed markers over recent years. Detection of likely etiologic agents of respiratory infections can help direct management and can also play an important role in disease surveillance. For this purpose, we are still reliant on many traditional diagnostic tools that have been used for decades in order to determine the microbial etiology of respiratory infections. However, these tools have been increasingly supplemented by newer methods, particular molecular diagnostic techniques, which have enabled the more rapid detection of many pathogens that were previously difficult to detect. These advances have particularly lead to improvements in the ability to detect respiratory viruses and also other microorganisms that do not normally colonize the respiratory tract. Recognition of the existence of the lung microbiome has challenged the traditional views of pneumonia pathogenesis and may provide the opportunity for new diagnostic tools that are focused on more than just detection of specific known pathogens. Continued liaison between clinicians and laboratory staff is vital in order to facilitate the most cost-effective use of laboratory diagnostics.

Detection of Pneumococcal DNA in Blood by Polymerase Chain Reaction for Diagnosing Pneumococcal Pneumonia in Young Children From Low- and Middle-Income Countries

BACKGROUND.

We investigated the performance of polymerase chain reaction (PCR) on blood in the diagnosis of pneumococcal pneumonia among children from 7 low- and middle-income countries.

METHODS.

We tested blood by PCR for the pneumococcal autolysin gene in children aged 1-59 months in the Pneumonia Etiology Research for Child Health (PERCH) study. Children had World Health Organization-defined severe or very severe pneumonia or were age-frequency-matched community controls. Additionally, we tested blood from general pediatric admissions in Kilifi, Kenya, a PERCH site. The proportion PCR-positive was compared among cases with microbiologically confirmed pneumococcal pneumonia (MCPP), cases without a confirmed bacterial infection (nonconfirmed), cases confirmed for nonpneumococcal bacteria, and controls.

RESULTS.

In PERCH, 7.3% (n = 291/3995) of cases and 5.5% (n = 273/4987) of controls were blood pneumococcal PCR-positive (P < .001), compared with 64.3% (n = 36/56) of MCPP cases and 6.3% (n = 243/3832) of nonconfirmed cases (P < .001). Blood pneumococcal PCR positivity was higher in children from the 5 African countries (5.5%-11.5% among cases and 5.3%-10.2% among controls) than from the 2 Asian countries (1.3% and 1.0% among cases and 0.8% and 0.8% among controls). Among Kilifi general pediatric admissions, 3.9% (n = 274/6968) were PCR-positive, including 61.7% (n = 37/60) of those with positive blood cultures for pneumococcus.

DISCUSSION.

The utility of pneumococcal PCR on blood for diagnosing childhood pneumococcal pneumonia in the 7 low- and middle-income countries studied is limited by poor specificity and by poor sensitivity among MCPP cases.

Transcriptional Categorization of the Etiology of Pneumonia Syndrome in Pediatric Patients in Malaria-Endemic Areas

Background

Pediatric acute respiratory distress in tropical settings is very common. Bacterial pneumonia is a major contributor to morbidity and mortality rates and requires adequate diagnosis for correct treatment. A rapid test that could identify bacterial (vs other) infections would have great clinical utility.

Methods and Results

We performed RNA (RNA-seq) sequencing and analyzed the transcriptomes of 68 pediatric patients with well-characterized clinical phenotype to identify transcriptional features associated with each disease class. We refined the features to predictive models (support vector machine, elastic net) and validated those models in an independent test set of 37 patients (80%-85% accuracy).

Conclusions

We have identified sets of genes that are differentially expressed in pediatric patients with pneumonia syndrome attributable to different infections and requiring different therapeutic interventions. Findings of this study demonstrate that human transcription signatures in infected patients recapitulate the underlying biology and provide models for predicting a bacterial diagnosis to inform treatment.

Evaluation of chest radiography, lytA real-time PCR, and other routine tests for diagnosis of community-acquired pneumonia and estimation of possible attributable fraction of pneumococcus in northern Togo

Streptococcus pneumoniae (Spn) is a leading cause of community-acquired pneumonia (CAP), yet existing diagnostic tools remain inadequate. We aimed to evaluate laboratory and radiological methods for detecting pneumococcal aetiology in CAP patients and to estimate Spn prevalence in this group. All-aged patients hospitalized with clinically defined CAP in northern Togo were enrolled during 2010–2013. Latent class analysis pooled results of semi-automated blood culture (SABC), whole blood lytA real-time polymerase chain reaction (rt-PCR), serum C-reactive protein (CRP), and chest radiography (CXR) and categorized patients as likely pneumococcal or non-pneumococcal CAP. We enrolled 1684 patients; 1501 had results for all tests. CXR, SABC, lytA rt-PCR and CRP >71·2 mg/l had sensitivities of 94% [95% confidence interval (CI) 87–100], 13% (95% CI 10–16), 17% (95% CI 14–21) and 78% (95% CI 75–80), and specificities of 88% (95% CI 84–93), 100% (95% CI 99–100), 97% (95% CI 96–99) and 77% (95% CI 75–79), respectively. Pneumococcal attributable proportion was 34% (95% CI 32–37), increasing with age and in men. We estimated that Spn caused one third of CAP. Whole blood lytA rt-PCR was more sensitive than SABC; both had low sensitivity and high specificity. Conversely CXR was highly sensitive and reasonably specific; it could be a useful tool for epidemiological studies aiming to define Spn pneumonia incidence across all ages.

Responses to Bacteria, Virus, and Malaria Distinguish the Etiology of Pediatric Clinical Pneumonia

RATIONALE

Plasma-detectable biomarkers that rapidly and accurately diagnose bacterial infections in children with suspected pneumonia could reduce the morbidity of respiratory disease and decrease the unnecessary use of antibiotic therapy.

OBJECTIVES

Using 56 markers measured in a multiplexed immunoassay, we sought to identify proteins and protein combinations that could discriminate bacterial from viral or malarial diagnoses.

METHODS

We selected 80 patients with clinically diagnosed pneumonia (as defined by the World Health Organization) who also met criteria for bacterial, viral, or malarial infection based on clinical, radiographic, and laboratory results. Ten healthy community control subjects were enrolled to assess marker reliability. Patients were subdivided into two sets: one for identifying potential markers and another for validating them.

MEASUREMENTS AND MAIN RESULTS

Three proteins (haptoglobin, tumor necrosis factor receptor 2 or IL-10, and tissue inhibitor of metalloproteinases 1) were identified that, when combined through a classification tree signature, accurately classified patients into bacterial, malarial, and viral etiologies and misclassified only one patient with bacterial pneumonia from the validation set. The overall sensitivity and specificity of this signature for the bacterial diagnosis were 96 and 86%, respectively. Alternative combinations of markers with comparable accuracy were selected by support vector machine and regression models and included haptoglobin, IL-10, and creatine kinase-MB.

CONCLUSIONS

Combinations of plasma proteins accurately identified children with a respiratory syndrome who were likely to have bacterial infections and who would benefit from antibiotic therapy. When used in conjunction with malaria diagnostic tests, they may improve diagnostic specificity and simplify treatment decisions for clinicians.

Finnish guidelines for the treatment of community-acquired pneumonia and pertussis in children

Evidence-based guidelines are needed to harmonise and improve the diagnostics and treatment of children's lower respiratory tract infections. Following a professional literature search, an interdisciplinary working group evaluated and graded the available evidence and constructed guidelines for the treatment of community-acquired pneumonia and pertussis.

CONCLUSION

The clinical guidelines state that chest radiography is not needed if the child is diagnosed with pneumonia and treated at home. Complications should be considered if there is no improvement after antimicrobial therapy and a paroxysmal cough can indicate pertussis, which is life-threatening in unvaccinated infants and can lead to respiratory failure.

Invasive pneumococcal diseases in children and adolescents--a single centre experience

Background

S. pneumoniae is a major cause of meningitis, pneumonia and sepsis in children. In 2006 universal pneumococcal vaccination was recommended in Germany for all children up to their second birthday. We have compared the prevalence and outcome of IPD at a single hospital before and after the introduction of vaccination.

Findings

55 cases of IPD were identified over an 11 year period. Almost half of the patients were younger than 2 years of age. Most of the children were affected by pneumonia. The second highest incidence seen was for meningitis and sepsis. 17 patients exhibited additional complications. Significant pre-existing and predisposing disorders, such as IRAK 4 defect, ALPS or SLE were identified in 4 patients. Complete recovery was seen in 78% of affected children; 11% had a fatal outcome and 11% suffered from long term complications. Only 31% overall had been vaccinated. The most common serotype was 14. Serotypes not covered by any of the current vaccines were also found. Antibiotic treatment commenced with cephalosporins in over 90%.

Conclusion

Frequency of IPD in our hospital did not decrease after initiation of the pneumococcal vaccination. This might be due to vaccinations not being administered satisfactorily as well as to poor education about the need of the vaccination. Pre-existing diseases must be monitored and treated accordingly and rare deficiencies taken into account when IPD takes a foudroyant course. In addition, antibiotic stewardship has been initiated at this hospital centre as a consequence of the high cephalosporin use detected in this study.

Diagnosis of pneumococcal pneumonia: current pitfalls and the way forward

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

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.

Childhood pneumonia in developing countries

Pneumonia is a widespread and common infectious lung disease that causes inflammation, which can lead to reduced oxygenation, shortness of breath, and death. An estimated nearly 1.2 million children younger than 5 years died in 2011 from pneumonia. Most of these deaths occured in developing countries where access to care is limited and interventions that have improved care in developed countries are scarce. Despite substantial increases in our understanding of the clinical syndrome of pneumonia and its aetiologies, its accurate diagnosis is challenging when clinical indicators are relied on, and improves only modestly with addition of laboratory, microbiological, or radiographical tests. Prevention programmes and treatment guidelines have led to impressive reductions in disease, but children remain at risk of misdiagnosis and inadequate treatment. Research to address challenges in the aetiological diagnosis of pneumonia and widespread implementation of treatment interventions beyond vaccines and antibiotics are necessary to mitigate the burden of pneumonia and improve child survival.

Pneumococcal diagnosis and serotypes in childhood community-acquired pneumonia

The 7-valent pneumococcal conjugate vaccine (PCV7) was introduced routinely in the UK from September 2006 and replaced by PCV13 in 2010. In a prospective study from 2009 to 2011 of 160 children aged ≤16 years with radiologically confirmed pneumonia, likely pneumococcal infections were identified in 26%. Detection of pneumococci was improved with polymerase chain reaction compared to culture (21.6% versus 6% of children tested, P = 0.0004). Where serotyping was possible, all (n = 23) were non-PCV7 but PCV13 serotypes; 1 (43.5%), 3 (21.7%), 7A/F, and 19A (17.4% each).

Microbiological diagnosis of community-acquired respiratory tract infections by nucleic acid detection

BACKGROUND

Microbiological diagnostic procedures have changed significantly over the last decade. Initially the implementation of the polymerase chain reaction (PCR) resulted in improved detection tests for microbes that were difficult or even impossible to detect by conventional methods such as culture and serology, especially in community-acquired respiratory tract infections (CA-RTI). A further improvement was the development of real-time PCR, which allows end point detection and quantification, and many diagnostic laboratories have now implemented this powerful method.

OBJECTIVE

At present, new performant and convenient molecular tests have emerged targeting in parallel many viruses and bacteria responsible for lower and/or upper respiratory tract infections. The range of test formats and microbial agents detected is evolving very quickly and the added value of these new tests needs to be studied in terms of better use of antibiotics, better patient management, duration of hospitalization and overall costs.

CONCLUSIONS

Molecular tools for a better microbial documentation of CA-RTI are now available. Controlled studies are now required to address the relevance issue of these new methods, such as, for example, the role of some newly detected respiratory viruses or of the microbial DNA load in a particular patient at a particular time. The future challenge for molecular diagnosis will be to become easy to handle, highly efficient and cost-effective, delivering rapid results with a direct impact on clinical management.

Rapid diagnosis of invasive pneumococcal disease in pediatric population

The aim of this study was to evaluate the Binax NOW immunochromatographic pneumococcal antigen test for the identification of Streptococcus pneumoniae in pleural and cerebrospinal fluids from children with suspected invasive pneumococcal disease. The results were compared with those obtained by PCR. Binax NOW was applied to these samples as recommended by the manufacturer for urine and cerebrospinal samples. Detection of pneumococcal DNA was performed by real-time PCR assay targeting the autolysin gene (lytA). Of the 199 samples analyzed, 131 were positive by both Binax NOW and lytA PCR, and 36 samples were negative by both techniques. Using the real-time PCR as a comparative method to the Binax for the detection of S. pneumoniae, the sensitivity and specificity of Binax NOW was 88% and 72.5%, respectively. Of the 145 positive samples analyzed by Binax NOW, 119 showed intense coloring of the sample line and 26 showed weak intensity. Conventional culture is the most common method in clinical settings, but Binax NOW is an easier and faster test for identifying S. pneumoniae in pleural and cerebrospinal fluids from children with suspected invasive pneumococcal disease.

A literature review and survey of childhood pneumonia etiology studies: 2000-2010

The Pneumonia Etiology Research for Child Health (PERCH) project is the largest multicountry etiology study of childhood pneumonia since the Board on Science and Technology in International Development studies of the 1980s. However, it is not the only recent or ongoing pneumonia etiology study, and even with seven sites, it cannot capture all epidemiologic settings in the developing world. Funding providers, researchers and policymakers rely on the best available evidence to strategically plan programs, new research directions and interventions. We aimed to describe the current landscape of recent pneumonia etiology studies in children under 5 years of age in the developed and developing world, as ascertained by a literature review of relevant studies with data since the year 2000 and a survey of researchers in the field of childhood pneumonia. We collected information on the study population, study design, case definitions, laboratory samples and methods and identified pathogens. A literature review identified 88 studies with child pneumonia etiology results. As of June 2010, our survey of researchers identified an additional 65 ongoing and recently completed child pneumonia etiology studies. This demonstrates the broad existing context into which the PERCH study must be placed. However, the landscape analysis also reveals a multiplicity of case definitions, levels of clinician involvement, facility types, specimen collection, and laboratory techniques. It reinforces the need for the standardization of methods and analyses for present and future pneumonia etiology studies in order to optimize their cumulative potential to accurately describe the microbial causes of childhood pneumonia.

Diagnosis of pneumococcal empyema using immunochromatographic test on pleural fluid and serotype distribution in Korean children

To evaluate the diagnostic value of immunochromatographic test (ICT) on pleural fluid in diagnosing pneumococcal empyema in children and to determine pneumococcal serotypes, 62 exudative parapneumonic effusions from Korean children were tested with culture, ICT for S. pneumoniae, pneumococcal autolysin polymerase chain reaction (PCR), and subsequent sequencing. Of the 62 patients, culture was positive in 3 patients only (4.8%). Pneumococci were identified in 13 samples (21.0%) by sequencing-confirmed PCR and ICT, respectively. When pneumococcal empyema was defined by either positive culture or sequence confirmation, the sensitivity of ICT was 76.9% (10/13) and the specificity of ICT was 93.9%. Eight of 10 patients with positive ICT and culture-negative results had a history of prior antibiotics use, whereas none of the culture-proven cases had. Serotypes of PCR-positive samples were determined by multiplex PCR assays. Multiplex PCR detected serotypes 19A (6), 1 (1), 14 (1), 34 (1), and untypable (4). ICT on pleural fluid is a relatively sensitive and highly specific method for diagnosis of pneumococcal empyema, especially in children given prior antibiotics.

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.

Pleural antigen assay in the diagnosis of pediatric pneumococcal empyema

PURPOSE

The purpose of the study was to assess the diagnostic value of rapid pneumococcal antigen detection (PAD) in pleural fluid samples of children with empyema.

MATERIAL AND METHODS

We performed a prospective evaluation in a pediatric intensive care unit of a tertiary university hospital of children aged 1 month to 14 years admitted with empyema. Standard cultures (conventional microbiological culture [CMC]), PAD by immunochromatographic testing (Binax NOW Streptococcus pneumoniae; Binax, Portland, ME), and/or real-time polymerase chain reactions (RTPs) on pleural samples were performed in all included patients.

RESULTS

Fifty-five cases with a mean (SD) age of 6.5 (6.1) years were enrolled. Streptococcus pneumoniae was identified in 28 cases (51%): by CMC in 15 cases and by RTP in a further 13 cases. Using CMC and/or RTP as the criterion standard, PAD showed a sensitivity of 96% (95% confidence interval, 86%-100%), a specificity of 100% (75%-100%), a positive predictive value of 100% (98%-100%), and a Youden index of 0.96 (0.88-1.04).

CONCLUSIONS

Pneumococcal antigen detection in pleural fluid specimens from children provides a rapid, simple, sensitive, and reliable method of diagnosis for pneumococcal empyema at bedside.

Pneumococcal DNA is not detectable in the blood of healthy carrier children by real-time PCR targeting the lytA gene

The diagnosis of invasive pneumococcal disease (IPD) is currently based on culture methods, which lack sensitivity, especially after antibiotic therapy. Molecular methods have improved sensitivity and do not require viable bacteria; however, their use is complicated by reports of low specificity with some assays. The present study investigated the specificity of a real-time PCR targeting lytA for the detection of IPD. A group of 147 healthy children, aged 6 months to 16 years (mean 6.4 years, median 4.9 years, interquartile range 6.4 years), who were in hospital for routine examinations, were tested for pneumococcal carrier status and for the presence of detectable pneumococcal DNA in their blood by real-time PCR targeting the pneumococcal lytA gene. In addition, 35 culture-positive biological samples were analysed. Urine was examined for the presence of pneumococcal DNA and C-polysaccharide antigen. Carriage was detected in 77 of the 147 subjects (52.4 %); however, regardless of carrier status, none of the subjects had a positive result from blood. Analysis of the culture-positive biological samples yielded positive results in 100 % (15/15) of cerebrospinal fluid samples and 95 % (19/20) of blood samples. All urine samples from healthy carriers were negative for DNA, whilst antigenuria was detected in 44/77 carriers (57.1 %). In conclusion, real-time PCR is both sensitive and specific and can be a useful tool in the routine diagnosis of IPD. Its sensitivity, which surpasses that of other methods for this purpose, does not come at the cost of reduced specificity.

Usefulness of pneumococcal antigen detection in pleural effusion for the rapid diagnosis of infection by Streptococcus pneumoniae

Pleural effusion is increasingly reported in children. Standard culture of blood or pleural fluid is frequently negative and molecular diagnosis by polymerase chain reaction is not available in all hospitals. The Binax NOW Streptococcus pneumoniae Antigen test (Binax, Portland, USA) is a rapid immunochromatographic test (ICT) for the detection of the C polysaccharide antigen. We evaluated the Binax NOW test on the pleural fluid of 73 children hospitalized with pleural effusion over a period of 4 years. In our sample, the sensitivity and specificity of ICT were high (88% and 71%, respectively), with a positive predictive value of 96%. Detection of the pneumococcal antigen in pleural fluid by ICT is easy and quick, and enables us to identify the pneumococcal origin of the effusion, thus, making the treatment of complicated pneumonia suitably and early.

Pneumococcal pneumonia: potential for diagnosis through a urinary metabolic profile

Pneumonia, an infection of the lower respiratory tract, is caused by any of a number of different microbial organisms including bacteria, viruses, fungi, and parasites. Community-acquired pneumonia (CAP) causes a significant number of deaths worldwide, and is the sixth leading cause of death in the United States. However, the pathogen(s) responsible for CAP can be difficult to identify, often leading to delays in appropriate antimicrobial therapies. In the present study, we use nuclear magnetic resonance spectroscopy to quantitatively measure the profile of metabolites excreted in the urine of patients with pneumonia caused by Streptococcus pneumoniae and other microbes. We found that the urinary metabolomic profile for pneumococcal pneumonia was significantly different from the profiles for viral and other bacterial forms of pneumonia. These data demonstrate that urinary metabolomic profiles may be useful for the effective diagnosis of CAP.

Comparison of the effect of antibiotic treatment on the possibility of diagnosing invasive pneumococcal disease by culture or molecular methods: a prospective, observational study of children and adolescents with proven pneumococcal infection

BACKGROUND

Detection of Streptococcus pneumoniae in culture specimens in invasive pneumococcal disease (IPD) may be hampered by antibiotic treatment administered before hospital admission. Realtime polymerase chain reaction (RT-PCR) assays do not require viable bacteria and are therefore less influenced by antimicrobial therapy. It is not known how long results of culture or molecular tests remain positive after antibiotic therapy is begun.

OBJECTIVE

The goal of the current study was to assess, in a pediatric population with a diagnosis of IPD confirmed by laboratory tests (culture and/or RT-PCR assay), the relationship between use of antibiotic therapy before hospital admission and the result of diagnostic methods (culture or molecular techniques) after admission.

METHODS

This prospective, observational study was conducted from April 2006 through March 2009. All children and adolescents aged 0 to 16 years, admitted to the hospital with a diagnosis of IPD confirmed by culture and/or molecular methods, were included in the study. Previous antibiotic treatment (drug, duration of therapy) was recorded. Primers and probes designed from the pneumococcal autolysin gene (lytA) were used in an RT-PCR assay for detection of S pneumoniae. Antibiotic tolerability, permanent sequelae (after a 6-month follow-up), and deaths were recorded.

RESULTS

Eighty-three patients (50 males, 33 females; 80 white, 3 Asian; mean age, 4.6 years; median age, 4.0 years; age range, 10 days-16 years) were included in the study. Fifty-four patients presented with pneumonia, 26 with meningitis/sepsis (meningitis, 19; sepsis, 7), and 3 with arthritis. Results of RT-PCR assays were positive in all 83 patients (100.0%), and 28 of the 83 patients (33.7%) also had culture-positive findings. Forty-two of the 83 patients (50.6%) had received antibiotic treatment before hospital admission, and 41 (49.4%) had not received antibiotics. Results of cultures were positive in 9 of the 42 patients with IPD (21.4%) who had received antibiotic treatment and in 19 of the 41 patients with IPD (46.3%) who had not received antibiotics (odds ratio, 3.2; 95% CI, 1.1-9.3; P = 0.03). Molecular methods appeared more sensitive than culture in any type of disease studied but particularly in patients with pneumonia, in whom the difference was statistically significant (P = 0.043). The mean length of antibiotic therapy was 1.4 days (median, 1 day; SD, 0.53 day; range, 1-2 days) for culture-confirmed cases and 4.5 days (median, 4 days; SD, 3.08 days; range, 1-15 days) for cases confirmed by RT-PCR assay (P = 0.002). No adverse reactions to the antibiotics used during home or hospital treatment were found. Two patients with meningitis suffered permanent, severe neurologic sequelae, and 1 girl died of sepsis 3 days after hospital admission. No permanent sequelae were recorded in patients with pneumonia or arthritis.

CONCLUSION

In these children and adolescents with IPD, the molecular methods used appeared to be more sensitive than culture in any IPD patient, with a higher statistical significance in patients previously treated with antibiotics and in patients with pneumonia.

Early diagnosis of lower respiratory tract infections (point-of-care tests)

PURPOSE OF REVIEW

Respiratory tract infections are a common reason for prescribing antibiotics, although not all of these infections require such therapy. Rapid diagnosis of etiology using point-of-care tests is a potentially useful way of reducing prescriptions of both unnecessary and unnecessarily broad-spectrum antibiotics. This can also lead to the facilitation of appropriate infection control measures to prevent spread of respiratory viruses within institutions.

RECENT FINDINGS

Point-of-care tests are available for diagnosing influenza, respiratory syncytial virus, Streptococcus pneumoniae, and Legionella infections using easily obtainable specimens. Their main benefit is that results can be obtained in about 15 min with reasonable accuracy. In many situations, however, it is still important to confirm diagnosis with more accurate but slower tests such as bacterial cultures with antibacterial susceptibility testing or viral polymerase chain reaction testing.

SUMMARY

Although the sensitivities of many of the rapid diagnostic tests are moderate, when used at the time of initial consultation, they have the potential to reduce costs, length of stay, secondary spread of respiratory viruses, and inappropriate antibiotic prescribing.

[Why are pediatric empyemas on the increase in Spain?]

There is a widespread perception among Spanish pediatricians that the incidence of empyema has significantly increased in the last few years, even though the objective information available is limited, and there is no specific active epidemiological surveillance system for this condition. In the present article, we review the situation of empyema in Spain, and discuss the main hypotheses put forward in the international literature to explain this increase, as well as the limitations of the sources available. Despite the scarcity of information, we draw the following conclusions: 1) the incidence of pediatric empyema is increasing in Spain, both generally and when caused by pneumococcus in particular; 2) the reason for this increase remains unknown, and to date no firm link has been established between this phenomenon and the heptavalent conjugate pneumococcal vaccine; and 3) this situation justifies the establishment of prospective systems for the surveillance and control of empyema and, once again, highlights the importance of developing active surveillance systems for pneumococcal disease.

Medical microbiology: laboratory diagnosis of invasive pneumococcal disease

The laboratory diagnosis of invasive pneumococcal disease (IPD) continues to rely on culture-based methods that have been used for many decades. The most significant recent developments have occurred with antigen detection assays, whereas the role of nucleic acid amplification tests has yet to be fully clarified. Despite developments in laboratory diagnostics, a microbiological diagnosis is still not made in most cases of IPD, particularly for pneumococcal pneumonia. The limitations of existing diagnostic tests impact the ability to obtain accurate IPD burden data and to assess the effectiveness of control measures, such as vaccination, in addition to the ability to diagnose IPD in individual patients. There is an urgent need for improved diagnostic tests for pneumococcal disease--especially tests that are suitable for use in underresourced countries.

Performance of a pneumolysin enzyme-linked immunosorbent assay for diagnosis of pneumococcal infections

A pneumolysin-specific enzyme-linked immunosorbent assay (PLY-ELISA) for the detection of pneumolysin in urine was developed and evaluated in comparison with the commercially available Binax Now Streptococcus pneumoniae test (Binax, Portland, ME) for the diagnosis of pneumococcal infections. Assay sensitivity was evaluated using urine from 108 patients with culture-confirmed pneumococcal infections. In adults, the sensitivity and specificity of the PLY-ELISA were 56.6% and 92.2%, respectively. In children with nasopharyngeal pneumococcal carriage, PLY-ELISA and Binax Now S. pneumoniae test sensitivities were 62.5% and 87.5%, respectively, while specificities were 94.4% and 27.8%, respectively. In children with nonnasopharyngeal pneumococcal carriage, PLY-ELISA and Binax Now S. pneumoniae test sensitivities were 68.7% and 93.7%, respectively, and test specificities were 94.1% and 41.2%, respectively. The persistence of pneumolysin in urine of pneumococcal pneumonia patients decreased significantly after 4 to 6 days of treatment. Our data suggest that combining the high specificity of the PLY-ELISA with the high sensitivity of the Binax Now S. pneumoniae test would enable pneumococcal infections to be accurately diagnosed in children.

Point‐of‐care testing for community‐acquired pneumonia: do we have all the answers?

Point-of-care tests (POCTs) are available for rapid, "bedside" diagnosis of some causes of community-acquired pneumonia. POCTs complement other laboratory investigations for pneumonia. Although their sensitivity and specificity are improving, they are generally less sensitive than nucleic acid amplification and culture techniques. Questions remain as to the most cost-effective use of POCTs in clinical practice. To ensure their maximum value for both individual patients and the public health system, POCTs are probably best used as part of laboratory-designed algorithms for investigating pneumonia. POCTs are a valuable tool for surveillance, for rapid investigation of outbreaks, and for use in laboratories with limited diagnostic facilities.