Seroetiology of acute lower respiratory infections among hospitalized children in Beijing

Clinical symptoms and signs for the diagnosis of Mycoplasma pneumoniae in children and adolescents with community-acquired pneumonia

BACKGROUND

Mycoplasma pneumoniae (M. pneumoniae) is a significant cause of community-acquired pneumonia in children and adolescents. Treatment with macrolide antibiotics is recommended. However, M. pneumoniae is difficult to diagnose based on clinical symptoms and signs. Diagnostic uncertainty can lead to inappropriate antibiotic prescribing, which may worsen clinical prognosis and increase antibiotic resistance.

OBJECTIVES

The objectives of this review are (i) to assess the diagnostic accuracy of symptoms and signs in the clinical recognition of M. pneumoniae in children and adolescents with community-acquired pneumonia; and (ii) to assess the influence of potential sources of heterogeneity on the diagnostic accuracy of symptoms and signs in the clinical recognition of M. pneumoniae.

SEARCH METHODS

We searched MEDLINE (January 1950 to 26 June 2012) and EMBASE (January 1980 to 26 June 2012). We identified additional references by handsearching the reference lists of included articles and snowballing. We searched the reference lists of relevant systematic reviews identified by searching the Medion database, Database of Reviews of Effects 2012, Issue 6 (25 June 2012) and the Cochrane Register of Diagnostic Test Accuracy studies (2 July 2012). Experts in the field reviewed our list of included studies for any obvious omissions.

SELECTION CRITERIA

We included peer-reviewed published studies which prospectively and consecutively recruited children with community-acquired pneumonia from any healthcare setting, confirmed the presence of M. pneumoniae using serology with or without other laboratory methods and reported data on clinical symptoms and signs in sufficient detail to construct 2 x 2 tables.

DATA COLLECTION AND ANALYSIS

One review author scanned titles to exclude obviously irrelevant articles. Two review authors independently scanned the remaining titles and abstracts, reviewed full-text versions of potentially relevant articles, assessed the quality of included articles and extracted data on study characteristics and the following clinical features: cough, wheeze, coryza, crepitations, fever, rhonchi, shortness of breath, chest pain, diarrhea, myalgia and headache.We calculated study-specific values for sensitivity, specificity and positive and negative likelihood ratios with 95% confidence intervals (CIs). We estimated the post-test probability of M. pneumoniae based on the absence or presence of symptoms and signs.We calculated pooled sensitivities, specificities, positive and negative likelihood ratios with 95% CIs for symptoms and signs where data were reported by at least four included studies by fitting a bivariate normal model for the logit transforms of sensitivity and specificity. We explored potential sources of heterogeneity by fitting bivariate models with covariates using multi-level mixed-effects logistic regression. We performed sensitivity analyses excluding data from studies for which we were concerned about the representativeness of the study population and/or the acceptability of the reference standard.

MAIN RESULTS

Our search identified 8299 articles (excluding duplicates). We examined the titles and abstracts of 1125 articles and the full-text versions of 97 articles. We included seven studies in our review, which reported data from 1491 children; all were conducted in hospital settings. Overall, study quality was moderate. In two studies the presence of chest pain more than doubled the probability of M. pneumoniae. Wheeze was 12% more likely to be absent in children with M. pneumoniae (pooled positive likelihood ratio (LR+) 0.76, 95% CI 0.60 to 0.97; pooled negative likelihood ratio (LR-) 1.12, 95% CI 1.02 to 1.23). Our sensitivity analysis showed that the presence of crepitations was associated with M. pneumoniae, but this finding was of borderline statistical significance (pooled LR+ 1.10, 95% CI 0.99 to 1.23; pooled LR- 0.66, 95% CI 0.46 to 0.96).

AUTHORS' CONCLUSIONS

M. pneumoniae cannot be reliably diagnosed in children and adolescents with community-acquired pneumonia based on clinical symptoms and signs. Although the absence of wheeze is a statistically significant diagnostic indicator, it does not have sufficient diagnostic value to guide empirical macrolide treatment. Data from two studies suggest that the presence of chest pain more than doubles the probability of M. pneumoniae. However, further research is needed to substantiate this finding. More high quality large-scale studies in primary care settings are needed to help develop prediction rules based on epidemiological data as well as clinical and baseline patient characteristics.

Radiological findings in 210 paediatric patients with viral pneumonia: a retrospective case study

OBJECTIVE

The objective of this study was to assess the radiological presentations of different types of viral pneumonia in children.

METHODS

Nasopharyngeal swab specimens and bronchial aspirate samples from children with acute respiratory infections were obtained and tested for influenza B, adenovirus, respiratory syncytial virus and parainfluenza (Types 1, 2 and 3) by direct immunofluorescence assay, or for influenza A (Subtype H1N1) by quantitative real-time polymerase chain reaction. The chest radiographs of the 210 confirmed cases of viral pneumonia were analysed retrospectively by two independent radiologists for the identification, characterisation and description of the distribution of imaging abnormalities. The cases were divided into six groups on the basis of confirmed causative viral agent, and radiographic findings were compared, analysed and presented.

RESULTS

The abnormal chest radiograph findings consisted of bilateral patchy areas of consolidation (n=133), interstitial lung disease (n=33), diffuse areas of air space consolidation (n=29) and lobar consolidation (n=15). The abnormalities were distributed bilaterally in 195 cases and observed more frequently in the lower zones than in other regions. The radiological findings varied significantly among the six groups (p=0.0050). Pairwise comparison showed significant difference between influenza A (H1N1) and adenovirus (p=0.0031) only.

CONCLUSION

The predominant radiological finding in paediatric viral pneumonia was bilateral patchy areas of consolidation. The radiological findings differed significantly only between adenovirus and influenza A pneumonia. The diagnosis of the specific causative organism requires laboratory confirmation.

A systematic review and critical evaluation of invasive Haemophilus influenzae type B disease burden studies in Asia from the last decade: lessons learned for invasive bacterial disease surveillance

In Asia, questions regarding the burden of Haemophilus influenzae type b (Hib) disease have delayed decision-making on introduction of Hib vaccine. However, over the past decade many studies have been published regarding Hib disease burden in Asia. We conducted a systematic literature review of all reports of Hib disease burden in Asia between 1998 and 2009, and critically reviewed their methods and data quality. We identified 94 studies from 28 countries in Asia presenting data on Hib disease burden. Of the 94 studies reviewed, 49 (52%) used a case definition consistent with World Health Organization standards, and 47 (50%) described laboratory methodology used. Twenty-seven surveillance studies presented data on incidence of Hib disease, with 8 (30%) accounting for missed cases, 6 (15%) accounting for cases with missed diagnostic tests, and 2 (7%) that considered prior antibiotic use. Of the 21 studies that provided incidence data for Hib meningitis, 10 (48%) used active, prospective, population-based surveillance, and found unadjusted incidence rates of Hib meningitis ranging from a low of 0.98 per 100,000 child-years in children aged less than 5 years in China to a high of 28 per 100,000 child-years in children less than 5 years in Mongolia. Of 49 studies that reported the etiology of bacterial meningitis, 30 (60%) identified Hib as the most common cause. This review highlights the importance of using rigorous methodologies, including standardized surveillance methods and appropriate laboratory diagnostic tests, when conducting studies measuring the burden of invasive bacterial diseases including those caused by Hib. When poorly conducted, studies can underestimate disease burden and lead to inappropriate decisions about vaccine introduction.

Respiratory viruses in pediatric necropsies: an immunohistochemical study

Infections of the respiratory system are responsible for the majority of hospitalizations and deaths in pediatric patients in developing countries. We selected 177 necropsies of pediatric patients who died as a result of serious respiratory infections. The histopathological findings and epidemiological data were reviewed, and lung tissue samples were separated for immunohistochemistry testing. Conventional immunohistochemistry techniques were used to detect viral antigens in formalin-fixed, paraffin-embedded (FF-PE) lung tissue samples using a pool of monoclonal antibodies against respiratory viruses (respiratory syncytial virus, influenza A and B, adenovirus, and parainfluenza 1, 2, and 3 viruses) as primary antibodies. The histopathological findings were classified into bronchopneumonia (BCP) and interstitial pneumonitis (IP) patterns. The immunohistochemistry results were compared with histopathological patterns and epidemiological data. Positive results for viruses were found in 34% and 62.5% of the BCP and IP cases, respectively. Males and infants below 1 year of age were more frequent in the group that had positive results for viruses. Acute enteritis was the main cause of hospitalization and sepsis the most frequent cause of death in this group. A clear seasonal distribution was observed, with the majority of cases occurring in the 2nd and 3rd trimesters (autumn and winter) of each year in the period studied. Immunohistochemistry is an affordable and easy-to-perform method for viral-antigen detection in FF-PE tissue samples. Although BCP is a classic histopathological pattern found in bacterial infections, it is possible that children with serious respiratory infections had concomitant viral and bacterial infections, regardless of their previous immunologic state.

A multiplex PCR-based reverse line blot hybridization (mPCR/RLB) assay for detection of bacterial respiratory pathogens in children with pneumonia

OBJECTIVES

To develop and evaluate a novel method for simultaneous identification of 12 potential bacterial pathogens in children with community-acquired pneumonia.

METHODS

A multiplex PCR-based reverse line blot (mPCR/RLB) assay was developed, to identify 12 respiratory bacterial pathogens, namely Staphylococcus aureus, Streptococcus pneumoniae, Streptococcus pyogenes, Moraxella catarrhalis, Haemophilus influenzae, Haemophilus influenzae type b, Bordetella pertussis, Klebsiella pneumoniae, Legionella pneumophila, Mycobacterium tuberculosis, Chlamydia pneumoniae, Mycoplasma pneumoniae, and single (uniplex) PCRs were used for S. pneumoniae and H. influenzae only. In a preliminary evaluation, we compared the results of mPCR/RLB with those of single (uniplex) PCRs and culture of nasopharyngeal aspirates (NPAs) from 100 children under 5 years, admitted to Beijing Children's Hospital between October 2004 and May 2005, with pneumonia.

RESULTS

Reference strains and clinical isolates of all 12 target species were correctly identified by mPCR/RLB. Potential pathogens were isolated from one blood culture and 26% of respiratory cultures. One or more pathogens were identified in 70% of respiratory specimens--by mPCR/RLB in 63%, uPCR only in another 3%, culture only in 2%, and culture plus uPCR in 2%. The species most commonly identified were S. pneumoniae (54%) and H. influenzae (38%, including type b, 4%). Cultures were not performed for B. pertussis, M. tuberculosis, C. pneumoniae or M. pneumoniae but each was identified by mPCR/RLB in between one and four specimens. Two or more potential pathogens were identified in 35% of specimens. Ten of 14 S. pneumoniae isolates belonged to serotypes represented in the 11-valent pneumococcal conjugate vaccine.

CONCLUSIONS

The mPCR/RLB assay is a sensitive tool for identification of respiratory pathogens, including mixed infections and bacteria requiring special culture methods.

The role of Chlamydia pneumoniae in acute respiratory tract infections in young children in The Gambia, West Africa

BACKGROUND

Little is known about the role of Chlamydia pneumoniae in the aetiology of acute respiratory tract infections (ARI) in children in developing countries.

AIMS

To obtain better information, we studied the presence of C. pneumoniae and its association with clinical signs and symptoms of ARI in children under 5 years of age in The Gambia.

METHODS

C. pneumoniae was sought by polymerase chain reaction in nasopharyngeal secretions and/or lung puncture aspirates from 324 infants under 3 months of age and 325 children between 3 months and 5 years of age with malnutrition, with or without pneumonia, and in control children. Clinical signs and symptoms for ARI and the spectrum of other viral and bacterial organisms were compared between those positive for C. pneumoniae and those negative.

RESULTS

Of 324 young infants, ten (3.1%) showed the presence of C. pneumoniae whereas in the older children 50 of 325 (15%) were positive for C. pneumoniae. There was no significant association between clinical signs and symptoms of ARI and C. pneumoniae positivity in the young infants. Among older infants and children, there was a trend to more frequent lobar alveolar changes in those positive for C. pneumoniae. No bacterial pathogens were found to be significantly associated with C. pneumoniae infection. However, there was an association with measles in the malnutrition group and with RSV in the young infants group.

CONCLUSIONS

In this study, C. pneumoniae was not associated with any particular clinical syndrome. We found no evidence that the organism plays a major role in ARI in young children in developing countries such as The Gambia.

Global reduction of Hib disease: what are the next steps? Proceedings of the meeting Scottsdale, Arizona, September 22-25, 2002

On September 22 to 25, 2002, a group of infectious disease specialists, public health officials, and vaccine experts from 33 countries gathered in Scottsdale, Arizona, to discuss the epidemiology and control of disease caused by Haemophilus influenzae type b (Hib) in the era of Hib conjugate vaccines. This supplement is a synthesis of the major themes and key lessons identified at the meeting. The objectives of the conference were to review the 10-year experience with Hib conjugate vaccines, discuss strategies to reduce Hib disease rates to lowest possible levels in industrialized countries, review impediments to the introduction of Hib vaccine in developing countries, and discuss strategies for disseminating lessons learned from countries using to those not using Hib conjugate vaccines. Over 10 years of international experience with Hib conjugate vaccines has demonstrated that they are safe and effective. Routine use of Hib conjugate vaccine has consistently led to decreases in the incidence of invasive Hib disease of 90% or more across a wide range of epidemiologic situations in industrialized countries. In some countries, the vaccine has caused a near-disappearance of invasive Hib disease through a combination of direct protection and herd immunity. Developing countries that have implemented routine vaccination (eg, The Gambia, Chile) have also had substantial disease reduction. In countries where Hib conjugate vaccine is being used, reducing Hib disease incidence to the lowest possible level will depend on maintaining high vaccine coverage levels, conducting surveillance for Hib disease, and investigating Hib disease cases. The optimal Hib vaccination strategy will depend on many factors, including local epidemiology and programmatic considerations. In countries that are not using Hib conjugate vaccine, information on the local burden of Hib disease will be essential for leaders considering vaccine introduction. Where disease burden is high, a multifaceted approach is urgently needed to evaluate and overcome barriers to vaccine introduction. In areas where Hib disease burden is not well characterized, additional work will be needed to understand the epidemiology of Hib disease and to communicate the value of Hib conjugate vaccine.

Community-acquired pneumonia

Community-acquired pneumonia (CAP) remains an important cause of morbidity and mortality. Streptococcus pneumoniae is the most common pathogen and respiratory syncitial virus the most important viral pathogen in children. The role of urinary antigen testing and PCR for the diagnosis forS. pneumoniae infection has been an important adjunct to clinical examination, showing good sensitivity and specificity. Host-related immune responses play an important role in defining the severity of illness. Other than the use of Activated Protein C and immunization, the clinical use of therapies designed to modulate these abnormal responses remains largely experimental. The 7-valent vaccine represents a major advance in the prevention of invasive pneumococcal disease. The importance of effective triage and the deleterious effects of deviation from protocols are underscored. Continuous positive pressure ventilation and noninvasive mechanical ventilation are available as options for respiratory support in cases of severe CAP and require further evaluation.

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.

Relative frequency of Haemophilus influenzae type b pneumonia in Chinese children as evidenced by serology

OBJECTIVES

It is commonly held that Haemophilus influenzae pneumonia among children in Asia is mostly caused by serotypes other than b (Hib). If so, Hib conjugate vaccines would play little role in the prevention of pneumonia. In two prospective series of children hospitalized for pneumonia in China, the causative agents were searched for with a wide panel of microbiologic assays.

METHODS

In the university hospitals of Beijing and Hefei, 156 consecutive children 3 months of age and older with symptoms and signs of pneumonia were studied. Blood culture, chest radiograph, nasopharyngeal aspirate for viral antigen detection and paired sera for 20 microbiologic assays were taken. Severity was graded, and the course of illness was monitored uniformly.

RESULTS

In Beijing only likely contaminants grew from blood cultures, and in Hefei pathogens were identified in two cases. In combined series evidence for bacterial, mixed and viral etiology was obtained in 30, 7 and 21% of cases, respectively. The dominant bacteria were pneumococcus, Hib, Mycoplasma pneumoniae and Chlamydia pneumoniae, responsible for 13, 10, 8 and 8% of cases, respectively. Most patients were treated with extended spectrum antimicrobials such as piperacillin, cefotaxime or ceftriaxone, alone or in combination. One child died.

CONCLUSIONS

As in most other series from other countries, the leading agent causing childhood pneumonia was pneumococcus but, in line with our previous experience from Beijing, the second most common agent detected was Hib. This observation suggests great potential for pneumococcal and Hib vaccinations in China. Because no evidence supported the need for routine use of extended spectrum antimicrobials, narrower spectrum agents would be safer for patients, would be cheaper for the community and would offer a way to address increasing resistance problems.