Pneumolysin polymerase chain reaction for diagnosis of pneumococcal pneumonia and empyema in children

Effect of Prehospital Antibiotic Therapy on Clinical Outcome and Pathogen Detection in Children With Parapneumonic Pleural Effusion/Pleural Empyema

BACKGROUND

Parapneumonic pleural effusion and pleural empyema (PPE/PE) are complications of community-acquired pneumonia. The objective of this study was to analyze prehospital antibiotic therapy (PH-ABT) of children with PPE/PE and investigate its effects on clinical outcome and pathogen detection.

METHODS

Prospective nationwide active surveillance in Germany between October 2010 and June 2018. Children and adolescents <18 years of age with pneumonia-associated PE or PPE requiring drainage or with persistence of PPE/PE >7 days were included.

RESULTS

A total of 1724 children with PPE/PE were reported, of whom 556 children (32.3% of 1719 with available data) received PH-ABT. Children with PH-ABT had a shorter median hospital length of stay (15 vs. 18 days, P < 0.001), a longer time from onset of symptoms until hospital discharge (25 vs. 23 days, P = 0.002), a lower rate of intensive care unit admission (58.3% vs. 64.4%, P = 0.015) and fewer infectious complications (5.9% vs. 10.0%; P = 0.005). Bacterial pathogens in blood or pleural fluid culture were detected in 597 (34.5%) of 1513 children. Positive culture results were less frequent in children with than without PH-ABT (81/466 [17.4%] vs. 299/1005 [29.8%]; P < 0.001), whereas detection rates in pleural fluid samples by polymerase chain reaction were similar (91/181 [50.3%] vs. 220/398 [55.3%]; P = 0.263).

CONCLUSIONS

In children with PPE/PE, PH-ABT significantly reduced the overall rate of bacterial pathogen detection by culture, but not by polymerase chain reaction. PH-ABT was associated with a lower rate of infectious complications but did not affect the overall duration of disease. We therefore speculate that the duration of PPE/PE is mainly a consequence of an infection-induced inflammatory process, which can only partially be influenced by antibiotic treatment.

Pleural effusion with negative culture: a challenge for pneumococcal diagnosis in children

BACKGROUND

Pneumococcal parapneumonic effusion seems to be increasing in children in the postvaccine era and is frequently associated with negative culture. Due to the low yield of culture, culture-independent tools are evaluated.

METHODS

Culture-negative pleural fluid specimens from 38 children with parapneumonic effusion were examined for pneumococcal lytA by quantitative polymerase chain reaction (qPCR) and soluble antigen (C-polysaccharide) using an immunochromatographic test (BinaxNow Streptococcus pneumoniae).

RESULTS

In 81% (30/37) and 63% (24/38) of the specimens, a positive result was obtained by qPCR and antigen detection, respectively. Most mismatches were observed in specimens with low quantities of pneumococcal DNA and a negative antigen test.

CONCLUSIONS

Our results suggest an imperfect relationship between the 2 described methods. The immunochromatographic assay is a simple diagnostic tool, which can be used when resources are limited, and even after antibiotic use, but negative results may require confirmation through a more sensitive test, such as qPCR.

Evaluation of phenotypic and molecular methods for identification of Streptococcus pneumoniae

AIM

The objective of this study is to compare various Streptococcus pneumoniae identification methods.

MATERIALS & METHODS

In total, 1371 putative S. pneumoniae isolates were tested with three phenotypic methods and a molecular-based method targeting a virulence factor (CpsA). We assessed the sensitivity and the specificity of each method and widely used S. pneumoniae identification algorithm.

RESULTS

None of the methods or the identification algorithm used separately was able to correctly identify all S. pneumoniae isolates. Furthermore, a high rate of optochin resistance was found.

CONCLUSIONS

We demonstrated the failure of the current S. pneumoniae identification methods and optochin susceptibility-based algorithm. In addition, the high rate of optochin resistance might justify the necessity of a close monitoring of optochin susceptibility.

The role of latex agglutination test for the etiological diagnosis of pleural effusion in children and adolescents

INTRODUCTION

The etiological diagnosis of pleural effusion is a difficult task because the diagnostic tools can only establish a definitive etiological diagnosis in at most 76% of cases.

OBJECTIVES

To verify the diagnostic accuracy of the latex agglutination test (LAT) for the etiological diagnosis of pleural effusions caused by Streptococcus pneumoniae and Haemophilus influenzae type b.

METHODS

After thoracocentesis, paired fresh samples of pleural fluid from 418 children and adolescents were included in this investigation. They were tested blindly and simultaneously through counterimmunoelectrophoresis (CIE) and LAT for both bacteria. Sensitivity, specificity, predictive values and likelihood ratios (LR) were calculated taking CIE as a reference standard.

RESULTS

The sensitivity and specificity of LAT was 100% (95% confidence interval, 94.4%-100%) and 83.3% (95% confidence interval, 79.0%-87.0%), respectively, whereas the positive (calculated from Bayes' theorem) and negative predictive values were, respectively, lower than 1% and 100% (95% confidence interval, 98.8%-100%). Positive and negative LR were 6.0 (95% confidence interval, 4.7-7.6) and zero, respectively.

CONCLUSIONS

Our results suggest that LAT is a useful tool for the etiological diagnosis of pleural effusion. It is a reliable, rapid, simple to perform and shows an excellent yield in our studied population, helping to prescribe appropriate antibiotics for this clinical condition.

Clinical presentation of invasive pneumococcal disease in Spain in the era of heptavalent conjugate vaccine

BACKGROUND

The aim of this study was to analyze the rate of incidence, clinical presentation, serotype, and clonal distribution of invasive pneumococcal disease (IPD) in the era of heptavalent pneumococcal conjugate vaccine (PCV7) in Barcelona, Spain.

METHODS

This was a prospective study comprising all children <5 years with IPD who were managed in 2 tertiary-care, pediatric hospitals between January 2007 and December 2009. IPD was defined as the presence of clinical findings of infection together with isolation or detection of DNA of Streptococcus pneumoniae in a sterile fluid sample.

RESULTS

In this study, 319 patients (53.3% male), mean age 29.6 months, were included. Comparing rates in 2007 and 2009 (76.2 and 109.9 episodes/100,000 population, respectively), an increase of 44% (95% confidence interval, 10%-89%) was observed. The main clinical presentation was pneumonia (254 episodes, 79.6%), followed by meningitis (29, 9.1%), and bacteremia (25, 7.8%).The diagnosis was made by positive culture in 123 (38.6%) patients and in 196 (61.4%) by real-time polymerase chain reaction. Serotype study was performed in 300 episodes, and 273 (91%) were non-PCV7 serotypes. The most frequent serotypes were 1 (20.7%), 19A (15.7%), and 3 (12.3%). A minimal inhibitory concentration ≥0.12 μg/mL to penicillin was detected in 34.4% of isolates. Sequence type 306 expressing serotype 1 was the most frequent clonal type detected (20.3% of studied strains).

CONCLUSIONS

IPD continues to increase in Barcelona, and the rate is higher than previously reported as a result of low sensitivity of bacterial culture. Non-PCV7 serotypes were responsible for 91% of episodes and pneumonia was the main clinical presentation.

Broad-range bacterial polymerase chain reaction in the microbiologic diagnosis of complicated pneumonia

BACKGROUND

A bacterial cause is not frequently identified in children with pneumonia complicated by parapneumonic effusion (ie, complicated pneumonia).

OBJECTIVES

To determine the frequency of positive blood and pleural fluid cultures in children with complicated pneumonia and to determine whether broad-range 16S rRNA polymerase chain reaction (PCR) improves identification of a microbiologic cause.

METHODS

This prospective cohort study included children 1-18 years of age hospitalized with complicated pneumonia.

RESULTS

Pleural fluid drainage was performed in 64 (51.6%) of 124 children with complicated pneumonia. A microbiologic cause was identified in 11 of 64 patients (17.2%; 95% confidence interval [CI]: 8.9%-28.7%). Bacteria were isolated from pleural fluid culture in 6 of 64 patients (9.4 %; 95% CI: 3.5%-19.3%) undergoing pleural drainage; the causative bacteria were Staphylococcus aureus (n = 5) and Streptococcus pneumoniae (n = 1). Blood culture identified a bacterial cause in 3 of 44 cases (6.8%; 95% CI: 1.4%-18.7%) undergoing pleural fluid drainage; S. pneumoniae (n = 1), Haemophilus influenzae (n = 1), and S. aureus (n = 1) were isolated. Only 3 of the 19 pleural fluid samples (15.8%; 95% CI: 3.4%-39.6%) analyzed with 16S rRNA PCR were positive. S. pneumoniae was the only organism detected in all three samples; two of these three had negative pleural fluid cultures and absence of bacteria on Gram stain. S. aureus was isolated from pleural fluid culture in one patient with a negative 16S rRNA PCR test.

CONCLUSIONS

Causative bacteria were infrequently identified in children with complicated pneumonia. Broad-range 16S rRNA PCR only modestly improved the microbiologic yield over conventional culture methods.

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.

Bacterial causes of empyema in children, Australia, 2007-2009

An increase in the incidence of empyema worldwide could be related to invasive pneumococcal disease caused by emergent nonvaccine replacement serotypes. To determine bacterial pathogens and pneumococcal serotypes that cause empyema in children in Australia, we conducted a 2-year study of 174 children with empyema. Blood and pleural fluid samples were cultured, and pleural fluid was tested by PCR. Thirty-two (21.0%) of 152 blood and 53 (33.1%) of 160 pleural fluid cultures were positive for bacteria; Streptococcus pneumoniae was the most common organism identified. PCR identified S. pneumoniae in 74 (51.7%) and other bacteria in 19 (13.1%) of 145 pleural fluid specimens. Of 53 samples in which S. pneumoniae serotypes were identified, 2 (3.8%) had vaccine-related and 51 (96.2%) had nonvaccine serotypes; 19A (n = 20; 36.4%), 3 (n = 18; 32.7%), and 1 (n = 8; 14.5%) were the most common. High proportions of nonvaccine serotypes suggest the need to broaden vaccine coverage.

Interpreting assays for the detection of Streptococcus pneumoniae

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

Molecular analysis improves pathogen identification and epidemiologic study of pediatric parapneumonic empyema

BACKGROUND

Parapneumonic empyema (PPE) is an increasingly common complication of bacterial pneumonia. Epidemiologic study is complicated by the low frequency of positive cultures. We sought to describe the epidemiology of PPE in children using molecular analysis of pleural fluid.

METHODS

We performed molecular testing for bacterial pathogens using archived pleural fluid from children hospitalized in 2009 with PPE. Real-time polymerase chain reaction (PCR) to detect Streptococcus pneumoniae, Staphylococcus aureus (including methicillin-resistant), Streptococcus pyogenes, Haemophilus influenzae, and Mycoplasma pneumoniae as well as PCR-based serotyping of S. pneumoniae was performed. Demographic, laboratory, and microbiologic data were abstracted.

RESULTS

Pleural fluid specimens from 63 children were available for PCR. By culture, a pathogen was isolated from blood and/or pleural fluid in 22 (35%) patients, with S. pneumoniae in 15 (24%), S. pyogenes in 3 (5%), and methicillin-resistant Staphylococcus aureus in 4 (6%). By PCR, a pathogen was detected in 53 (84%), including S. pneumoniae in 45 (71%). Compared with culture, PCR testing significantly increased detection of any pathogen (35% vs. 84%; P < 0.001) and of S. pneumoniae (24% vs. 71%; P < 0.001). Serotype 7F was the most common pneumococcal serotype detected. Comparison of culture-negative to culture-positive disease showed differences in both the pathogen profile and clinical outcomes.

CONCLUSIONS

Molecular analysis of pleural fluid more than doubled the detection of pathogens causing PPE. S. pneumoniae was the most common cause of both culture-positive and culture-negative PPE, although serotype distribution and outcomes differed.

A bedside assay to detect streptococcus pneumoniae in children with empyema

BACKGROUND

Empyema is a complication of pneumonia, commonly caused by Streptococcus pneumoniae.

AIMS

To validate the utility of an immunochromatographic test for the detection of S. pneumoniae antigen in the pleural fluid of children with empyema.

METHODS

Empyema patients had blood and pleural fluid cultured, and polymerase chain reaction (PCR) to detect the S. pneumoniae autolysin gene, lytA, in pleural fluid. Pleural fluid was tested using the Binax NOW S. pneumoniae antigen detection assay and compared with lytA PCR results and/or culture in blood or pleural fluid.

RESULTS

S. pneumoniae was detected by PCR in pleural fluid of 68 of 137 (49.6%) patients, by culture in 11 of 135 (8.1%) pleural specimens and 16 of 120 (13.3%) blood specimens. Pleural fluid Binax NOW testing from 130 patients demonstrated a sensitivity of 83.8% and specificity of 93.5% (positive predictive value of 93.4% and negative predictive value of 84.1%).

CONCLUSIONS

In pediatric empyema, high predictive values of pleural fluid Binax NOW S. pneumoniae antigen test suggest that this test may help rationalize antibiotic choice in these patients.

recA-based PCR assay for accurate differentiation of Streptococcus pneumoniae from other viridans streptococci

Proper identification of Streptococcus pneumoniae by conventional methods remains problematic. The discriminatory power of the 16S rRNA gene, which can be considered the "gold standard" for molecular identification, is too low to differentiate S. pneumoniae from closely related species such as Streptococcus pseudopneumoniae, Streptococcus mitis, and Streptococcus oralis in the routine clinical laboratory. A 313-bp part of recA was selected on the basis of variability within the S. mitis group, showing <95.8% interspecies homology. In addition, 6 signature nucleotides specific for S. pneumoniae were identified within the 313-bp recA fragment. We show that recA analysis is a useful tool for proper identification to species level within the S. mitis group, in particular, for pneumococci.

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.

PCR using blood for diagnosis of invasive pneumococcal disease: systematic review and meta-analysis

The use of molecular-based methods for the diagnosis of bacterial infections in blood is appealing, but they have not yet passed the threshold for clinical practice. A systematic review of prospective and case-control studies assessing the diagnostic utility of PCR directly with blood samples for the diagnosis of invasive pneumococcal disease (IPD) was performed. A broad search was conducted to identify published and unpublished studies. Two reviewers independently extracted the data. Summary estimates for sensitivity and specificity with 95% confidence intervals (CIs) were calculated by using the hierarchical summary receiver operating characteristic method. The effects of sample processing, PCR type, the gene-specific primer, study design, the participants' age, and the source of infection on the diagnostic odds ratios were assessed through meta-regression. Twenty-nine studies published between 1993 and 2009 were included. By using pneumococcal bacteremia for case definition and healthy people or patients with bacteremia caused by other bacteria as controls (22 studies), the summary estimates for sensitivity and specificity were 57.1% (95% CI, 45.7 to 67.8%) and 98.6% (95% CI, 96.4 to 99.5%), respectively. When the controls were patients suspected of having IPD without pneumococcal bacteremia (26 studies), the respective values were 66.4% (95% CI, 55.9 to 75.6%) and 87.8% (95% CI, 79.5 to 93.1%). With lower degrees of proof for IPD (any culture or serology result and the clinical impression), the sensitivity of PCR decreased and the specificity increased. All analyses were highly heterogeneous. The use of nested PCR and being a child were associated with low specificity, while the use of a cohort study design was associated with a low sensitivity. The lack of an appropriate reference standard might have caused underestimation of the performance of the PCR. Currently available methods for PCR with blood samples for the diagnosis of IPD lack the sensitivity and specificity necessary for clinical practice.

Novel approaches to the identification of Streptococcus pneumoniae as the cause of community-acquired pneumonia

Current diagnostic tests lack sensitivity for the identification of the bacterial etiology of pneumonia. Attempts during the past 2 decades to improve sensitivity of detection of bacterial constituents in blood by use of antibody-antigen complexes and polymerase chain reaction have been disappointing. Recent data using pneumococcal conjugate vaccines as probes suggest that increased levels of both C-reactive protein and procalcitonin may be useful adjuncts to chest radiographs in the selection of patients with presumed bacterial pneumonia for inclusion in clinical trials. Among pneumococcal diagnostics currently under investigation, quantitative real-time polymerase chain reaction of respiratory secretions, as well as urinary antigen detection and pneumococcal surface adhesin A serological analysis for adults, are candidates for use in future clinical trials of antibiotics.

Five-fold increase in pediatric parapneumonic empyema since introduction of pneumococcal conjugate vaccine

A retrospective review of medical records for all pediatric parapneumonic empyema (PPE) patients admitted to our hospital from 1996 to 2006 revealed that PPE increased 5-fold in the post-heptavalent pneumococcal conjugate vaccine (PCV7) period (2001-2005) relative to the pre-PCV7 period (1996-2000), from 13 cases to 65. Most of this increase was associated with culture-negative empyema, which accounted for 61% of all post-2000 cases; 19% was culture-positive pneumococcal empyema. Our analysis indicates that non-PCV7 serotypes became more prevalent at our institution after introduction of the vaccine.

Molecular detection methods and serotyping performed directly on clinical samples improve diagnostic sensitivity and reveal increased incidence of invasive disease by Streptococcus pneumoniae in Italian children

The aims of this study were to evaluate the incidence of invasive pneumococcal disease (IPD) in Italian children and perform serotyping by PCR-based assays directly on clinical samples. A 1-year paediatric (0-14 years) population-based surveillance study was designed to evaluate the incidence of IPD in the province of Florence, Italy, by cultural and molecular methods. Among 92 children (80 with pneumonia, 8 with meningitis/sepsis, 4 with arthritis), 4 cases of IPD were diagnosed both by culture and real-time PCR and 18 cases exclusively by molecular methods. The sensitivity of molecular methods was significantly higher than that of cultural methods (Cohen's kappa 0.41; McNemar P=0.000008). The incidence of IPD in children below 2 years of age was 11.5/100,000 and 51.8/100,000 by cultural and molecular methods, respectively. Pneumococcal serotyping by multiplex sequential PCR was obtained in 19/22 samples. Real-time PCR and multiplex sequential PCR can be used directly on biological samples, improving the ability to diagnose IPD. The incidence of IPD appears 5-10 times higher by PCR than by cultural methods.

Detection of 11 common viral and bacterial pathogens causing community-acquired pneumonia or sepsis in asymptomatic patients by using a multiplex reverse transcription-PCR assay with manual (enzyme hybridization) or automated (electronic microarray) detection

Community-acquired pneumonia (CAP) and sepsis are important causes of morbidity and mortality. We describe the development of two molecular assays for the detection of 11 common viral and bacterial agents of CAP and sepsis: influenza virus A, influenza virus B, respiratory syncytial virus A (RSV A), RSV B, Mycoplasma pneumoniae, Chlamydophila pneumoniae, Legionella pneumophila, Legionella micdadei, Bordetella pertussis, Staphylococcus aureus, and Streptococcus pneumoniae. Further, we report the prevalence of carriage of these pathogens in respiratory, skin, and serum specimens from 243 asymptomatic children and adults. The detection of pathogens was done using both a manual enzyme hybridization assay and an automated electronic microarray following reverse transcription and PCR amplification. The analytical sensitivities ranged between 0.01 and 100 50% tissue culture infective doses, cells, or CFU per ml for both detection methods. Analytical specificity testing demonstrated no significant cross-reactivity among 19 other common respiratory organisms. One hundred spiked "surrogate" clinical specimens were all correctly identified with 100% specificity (95% confidence interval, 100%). Overall, 28 (21.7%) of 129 nasopharyngeal specimens, 11 of 100 skin specimens, and 2 of 100 serum specimens from asymptomatic subjects tested positive for one or more pathogens, with S. pneumoniae and S. aureus giving 89% of the positive results. Our data suggest that asymptomatic carriage makes the use of molecular assays problematic for the detection of S. pneumoniae or S. aureus in upper respiratory tract secretions; however, the specimens tested showed virtually no carriage of the other nine viral and bacterial pathogens, and the detection of these pathogens should not be a significant diagnostic problem. In addition, slightly less sensitive molecular assays may have better correlation with clinical disease in the case of CAP.

Survey of childhood empyema in Asia: implications for detecting the unmeasured burden of culture-negative bacterial disease

Background

Parapneumonic empyema continues to be a disease of significant morbidity and mortality among children despite recent advances in medical management. To date, only a limited number of studies have assessed the burden of empyema in Asia.

Methods

We surveyed medical records of four representative large pediatric hospitals in China, Korea, Taiwan and Vietnam using ICD-10 diagnostic codes to identify children <16 years of age hospitalized with empyema or pleural effusion from 1995 to 2005. We also accessed microbiology records of cultured empyema and pleural effusion specimens to describe the trends in the epidemiology and microbiology of empyema.

Results

During the study period, we identified 1,379 children diagnosed with empyema or pleural effusion (China, n = 461; Korea, n = 134; Taiwan, n = 119; Vietnam, n = 665). Diagnoses of pleural effusion (n = 1,074) were 3.5 times more common than of empyema (n = 305), although the relative proportions of empyema and pleural effusion noted in hospital records varied widely between the four sites, most likely because of marked differences in coding practices. Although pleural effusions were reported more often than empyema, children with empyema were more likely to have a cultured pathogen. In addition, we found that median age and gender distribution of children with these conditions were similar across the four countries. Among 1,379 empyema and pleural effusion specimens, 401 (29%) were culture positive. Staphylococcus aureus (n = 126) was the most common organism isolated, followed by Streptococcus pneumoniae (n = 83), Pseudomonas aeruginosa (n = 37) and Klebsiella (n = 35) and Acinetobacter species (n = 34).

Conclusion

The age and gender distribution of empyema and pleural effusion in children in these countries are similar to the US and Western Europe. S. pneumoniae was the second leading bacterial cause of empyema and pleural effusion among Asian children. The high proportion of culture-negative specimens among patients with pleural effusion or empyema suggests that culture may not be a sufficiently sensitive diagnostic method to determine etiology in the majority of cases. Future prospective studies in different countries would benefit from standardized case definitions and coding practices for empyema. In addition, more sensitive diagnostic methods would improve detection of pathogens and could result in better prevention, treatment and outcomes of this severe 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.

Development of parapneumonic empyema in children

AIM

The aim of the study was to find clinical predictors for parapneumonic empyema in children.

METHODS

Thirty-seven children treated for parapneumonic empyema at the Department of Pediatrics, Turku University Hospital, were retrospectively evaluated. Two distinct comparison groups of children with uncomplicated community-acquired pneumonia with alveolar consolidation (n = 37 in both groups) were included. Clinical and laboratory data on admission as well as fever kinetics and inflammatory markers during hospitalization were analyzed.

RESULTS

In a multivariate analysis, a history of prolonged fever, tachypnoea and pain on abdominal palpation on admission were the most significant clinical predictors for empyema. On admission, serum C-reactive protein levels were higher among children with empyema than among those with uncomplicated pneumonia (means, 234 mg/L vs. 178 mg/L; p = 0.037). During hospitalization, prolonged fever and persistence of high serum C-reactive protein levels were associated with empyema. At the initial evaluation, pleural fluid was not reported in 35% of children with empyema.

CONCLUSIONS

Early recognition of developing empyema is challenging. Children with pneumonia presenting with prolonged fever, tachypnoea, pain on abdominal palpation and high serum C-reactive protein levels are at risk for parapneumonic empyema.

Microbiological aspects of bacterial lower respiratory tract illness in children: typical pathogens

Whilst childhood immunization programmes have had an impact on the spectrum of pneumonic diseases seen in children, bacteria remain an important cause of lower respiratory tract infection (LRTI), particularly in younger and debilitated children. Because of the difficulty in obtaining lower respiratory tract specimens in children, specific diagnosis has often been difficult, although advances in diagnostic techniques have provided a much greater range of tools for the clinician. The challenge is to understand the application and limitation of these tests in the diagnosis of LRTI. This review examines the microbiological and diagnostic issues around Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenzae, Moraxella catarrhalis, Neisseria meningitidis and enteric Gram negative pathogens.

[Epidemiology and clinical characteristics of childhood parapneumonic empyemas]

Several studies have reported an increasing incidence of childhood parapneumonic empyemas in various countries.

AIM OF THE STUDY

The aim of our study was to estimate the annual incidence of complicated community-acquired pneumonias in children during a 9-year period in a French area and to describe the epidemiological and clinical characteristics of these complications.

POPULATION AND METHODS

We have listed the children from 28 days to 15 years old, hospitalized in the 2 children hospitals of the Isere district for a community-acquired pneumonia complicated with a pleural empyema or a pulmonary abscess from 1995 to 2003.

RESULTS

During the study period, 90 children were hospitalized for a complicated pneumonia including 83 pleural empyemas and 7 isolated lung abscess. The average number of cases was 4 per year from 1995 to 1998 then increased since 1999 to reach 34 cases in 2003, according to a linear model (P<0,001). The incidence of the complicated pneumonia, plotted to the paediatric population of the area has gone up from 0.5 per 100000 to 13 per 100000 children between 1995 and 2003.

CONCLUSION

The incidence of the complicated pneumonias in children increased since 1999 in a French area. Additional investigations are necessary to identify the causes of this increase.

Bacteriology of complicated parapneumonic effusions

PURPOSE OF REVIEW

The bacteriology of complicated parapneumonic effusions has changed in recent decades, but the causative organisms often remain obscure in up to 40% of cases. Recently, new molecular methods have become available which might help clinical management and improve our understanding of this condition. In this review, we will consider the current bacteriological spectrum of pleural infection and look at some of the new molecular methods.

RECENT FINDINGS

Hospital-acquired pleural infection exhibits a different bacteriology than pleural infection originating in the community. It carries a significantly higher mortality and requires different antibiotics at presentation. Streptococcal and anaerobic infections have low associated mortalities whereas staphylococcal, enterobacterial and mixed aerobic infections carry a worse prognosis. The yield of causative organisms can be significantly increased by the use of bacterial nucleic acid amplification and this may have a role in routine clinical practice in the near future.

SUMMARY

The bacteriology of pleural infection has changed markedly in recent years. Mortality is highest with hospital-acquired pleural infection and infections caused by staphylococci, Enterobacteriacae and mixed aerobes. New molecular microbiological methods substantially increase bacterial yield in pleural fluid.

Molecular diagnostic methods in pneumonia

PURPOSE OF REVIEW

Molecular techniques offer the promise of improving diagnosis of lower respiratory tract infections. This review focuses on currently used molecular diagnostic techniques for various types of pneumonia and highlights potential future applications of this technology.

RECENT FINDINGS

Lower respiratory tract infections result in a high degree of morbidity and mortality, but a definitive microbiologic diagnosis is often not obtained by traditional culture or serologic methods. In addition, culture of certain organisms may be difficult or require extended periods of time. Molecular techniques have the potential to improve diagnostic yield and decrease time to pathogen identification. These techniques are also helpful in the determination of drug sensitivity and the understanding of transmission and outbreaks. Most currently used techniques employ some variation of the polymerase chain reaction. Limitations include high costs, the need for specialized equipment, and problems with false-positive and -negative results.

SUMMARY

Molecular diagnosis of pneumonia has the potential to improve identification of pathogens in patients with suspected lower respiratory tract infection. Limitations of molecular techniques currently prevent their widespread use, but future developments will likely lead to inclusion of these tests in routine diagnostic evaluations.