The causes of hospital-treated acute lower respiratory tract infection in children

Poly I:C enhances susceptibility to secondary pulmonary infections by gram-positive bacteria

Secondary bacterial pneumonias are a frequent complication of influenza and other respiratory viral infections, but the mechanisms underlying viral-induced susceptibility to bacterial infections are poorly understood. In particular, it is unclear whether the host's response against the viral infection, independent of the injury caused by the virus, results in impairment of antibacterial host defense. Here, we sought to determine whether the induction of an “antiviral” immune state using various viral recognition receptor ligands was sufficient to result in decreased ability to combat common bacterial pathogens of the lung. Using a mouse model, animals were administered polyinosine-polycytidylic acid (poly I:C) or Toll-like 7 ligand (imiquimod or gardiquimod) intranasally, followed by intratracheal challenge with Streptococcus pneumoniae. We found that animals pre-exposed to poly I:C displayed impaired bacterial clearance and increased mortality. Poly I:C-exposed animals also had decreased ability to clear methicillin-resistant Staphylococcus aureus. Furthermore, we showed that activation of Toll-like receptor (TLR)3 and Retinoic acid inducible gene (RIG-I)/Cardif pathways, which recognize viral nucleic acids in the form of dsRNA, both contribute to poly I:C mediated impairment of bacterial clearance. Finally, we determined that poly I:C administration resulted in significant induction of type I interferons (IFNs), whereas the elimination of type I IFN signaling improved clearance and survival following secondary bacterial pneumonia. Collectively, these results indicate that in the lung, poly I:C administration is sufficient to impair pulmonary host defense against clinically important gram-positive bacterial pathogens, which appears to be mediated by type I IFNs.

Procalcitonin predicts response to beta-lactam treatment in hospitalized children with community-acquired pneumonia

Background

Antibiotic treatment of community-acquired pneumonia (CAP) in children remains mostly empirical because clinical and paraclinical findings poorly discriminate the principal causes of CAP. Fast response to beta-lactam treatment can be considered a proxy of pneumococcal aetiology. We aimed to identify the best biological predictor of response to beta-lactam therapy in children hospitalized for CAP.

Methods

A retrospective, single-centre cohort study included all consecutive patients 1 month to 16 years old hospitalized in a teaching hospital in Paris, France, because of CAP empirically treated with a beta-lactam alone from 2003 to 2010. Uni- and multivariate analyses were used to study the ability of routine biological parameters available in the Emergency Department to predict a favourable response to beta-lactam (defined as apyrexia within 48 hours of treatment onset).

Results

Among the 125 included patients, 85% (106) showed a favourable response to beta-lactam. In multivariate logistic regression, we found procalcitonin (PCT) the only independent predictor of apyrexia (p = 0.008). The adjusted odds ratio for the decadic logarithm of PCT was 4.3 (95% CI 1.5–12.7). At ≥3 ng/mL, PCT had 55.7% sensitivity (45.7–65.3), 78.9% specificity (54.4–93.9), 93.7% positive predictive value (84.5–98.2), 24.2% negative predictive value (14.2–36.7), 2.64 positive likelihood ratio (1.09–6.42) and 0.56 negative likelihood ratio (0.41–0.77). In the 4 children with a PCT level ≥3 ng/mL and who showed no response to beta-lactam treatment, secondary pleural effusion had developed in 3, and viral co-infection was documented in 1.

Conclusions

PCT is the best independent biologic predictor of favourable response to beta-lactam therapy in children hospitalized for CAP. Thus, a high PCT level is highly suggestive of pneumococcal aetiology. However, a 3-ng/mL cut-off does not seem compatible with daily medical practice, and additional research is needed to further define the role of PCT in managing CAP in children.

Epidemiological and economic burden of pneumococcal diseases in Canadian children

BACKGROUND

With the arrival of a new conjugate pneumococcal vaccine, it is important to estimate the burden of pneumococcal diseases in Canadian children. The epidemiological data and the economic cost of these diseases are crucial elements in evaluating the relevance of a vaccination program.

METHODS

Using provincial databases, ad hoc surveys and published data, age-specific incidence rates of pneumococcal infections were estimated in a cohort of 340,000 children between six months and nine years of age. The costs of these diseases to the health system and to families were also evaluated using data from Quebec and Manitoba.

RESULTS

Cumulative risks were one in 5000 for pneumococcal meningitis, one in 500 for bacteremia and one in 20 for pneumonia, leading to 16 deaths in the cohort. About 262,000 otitis media episodes and 32,000 cases of myringotomy with ventilation tube insertion were attributable to Streptococcus pneumoniae. Societal costs were estimated at $125 million, of which 32% was borne by the health system and 68% was borne by families. Invasive infections represented only 2% of total costs, while 84% were generated by otitis media.

CONCLUSION

Pneumococcal infections represent a significant burden for Canadian children and society that could be significantly reduced through immunization.

Respiratory syncytial virus infection alters surfactant protein A expression in human pulmonary epithelial cells by reducing translation efficiency

Infection of neonatal lung by respiratory syncytial virus (RSV) is a common cause of respiratory dysfunction. Lung alveolar type II and bronchiolar epithelial (Clara) cells secrete surfactant protein A (SP-A), a collectin that is an important component of the pulmonary innate immune system. SP-A binds to the virus, targeting the infectious agent for clearance by host defense mechanisms. We have previously shown that while the steady-state level of SP-A mRNA increases approximately threefold after RSV infection, steady-state levels of cellular and secreted SP-A protein decrease 40-60% in human type II cells in primary culture, suggesting a mechanism where the virus alters components of the innate immune response in infected cells. In these studies, we find that changes in SP-A mRNA and protein levels in RSV-infected NCI-H441 cells (a bronchiolar epithelial cell line) recapitulate the results in SP-A expression observed in primary lung cells. While SP-A protein is normally ubiquitinated, there is no change in the level of SP-A protein ubiquitination or proteasome activity during RSV infection, suggesting that the reduced levels of SP-A protein are not due to degradation by activated proteasomes. SP-A mRNA is appropriately processed and exported from the nucleus to the cytoplasm during RSV infection. As evidenced by polysome analysis of SP-A mRNA and pulse-chase analysis of newly synthesized SP-A protein, we find a decrease in translational efficiency that is specific for SP-A mRNA. Therefore, the decrease in SP-A protein levels observed after RSV infection of pulmonary bronchiolar epithelial cells results from a mechanism that affects SP-A mRNA translation efficiency.

Effective treatment strategies for paediatric community-acquired pneumonia

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

Viral pneumonia in children

Viral pneumonia causes a heavy burden on our society. In the United States, more than one million cases of pneumonias afflict children under the age of 5 years, costing hundreds of millions of dollars annually. The majority of these infections are caused by a handful of common viruses. Knowledge of the epidemiology of these viruses combined with new rapid diagnostic techniques will provide faster and more, reliable diagnoses in the future. Although the basic clinical epidemiology of these viruses has been carefully investigated over the last 30 years, new molecular techniques are greatly expanding our understanding of these agents and the diseases they cause. Antigenic and genetic variations are being discovered in many viruses previously thought to be homogeneous. The exact roles and the biological significance of these variations are just beginning to be explored, but already evidence of differences in pathogenicity and immunogenicity has been found in many of these substrains. All of this information clearly will impact the development of future vaccines and antiviral drugs. Effective drugs exist for prophylaxis against influenza A and respiratory syncytial virus, and specific therapy exists for influenza A. Ribarivin is approved for use in respiratory synctial virus infections, and it alone or in combination with other agents (eg, IGIV) may be effective in immunocompromised patients, either in preventing the development of pneumonia or in decreasing morbidity and mortality. Many new antiviral agents are being tested and developed, and several are in clinical trials.

Effects of RSV infection on pulmonary surfactant protein SP-A in cultured human type II cells: contrasting consequences on SP-A mRNA and protein

Respiratory syncytial virus (RSV) is the most important cause of serious lower respiratory illness in infants and children. Surfactant proteins A (SP-A) and D (SP-D) play critical roles in lung defense against RSV infections. Alterations in surfactant protein homeostasis in the lung may result from changes in production, metabolism, or uptake of the protein within the lung. We hypothesized that RSV infection of the type II cell, the primary source of surfactant protein, may alter surfactant protein gene expression. Human type II cells grown in primary culture possess lamellar bodies (a type II cell-specific organelle) and the ability to express surfactant protein mRNA. These cells were infected with RSV (by morphology and antibody binding). Surfactant protein mRNA levels determined by quantitative RT-PCR indicated a marked increase in SP-A mRNA levels (3-fold) 24 h after RSV exposure, whereas SP-D mRNA levels were unaffected. In contrast to mRNA levels, total SP-A protein levels (determined by Western blot analysis) were decreased 40% after RSV infection. The percentage of secreted SP-A was 43% of the total SP-A in the RSV-infected cells, whereas the percentage of secreted SP-A was 61% of the total SP-A in the uninfected cells. These changes in SP-A transcript levels and protein secretion in cultured human cells were recapitulated in RSV-infected mouse lung. Our findings suggest that type II cells are potentially important targets of RSV lower respiratory infection and that alterations in surfactant protein gene expression and SP-A protein homeostasis in the lung may arise via direct effects of RSV.

Advances in the diagnosis of respiratory virus infections

Background: Advances have been made in selecting sensitive cell lines for isolation, in early detection of respiratory virus growth in cells by rapid culture assays, in production of monoclonal antibodies to improve many tests such as immunofluorescence detection of virus antigens in nasopharyngeal aspirates, in highly sensitive antigen detections by time-resolved fluoroimmunoassays (TR-FIAs) and biotin-enzyme immunoassays (BIOTH-E), and, finally, in the polymerase chain reaction (PCR) detection of respiratory virus DNA or RNA in clinical specimens. All of these advances have contributed to new or improved possibilities for the diagnosis of respiratory virus infections.

Objectives and study design: This review summarizes our experiences during the last 15 years in the development of diagnostic tests for respiratory virus infections, and in use of these tests in daily diagnostic work and in epidemiological studies.

Results: Immunofluorescence tests based on monoclonal antibodies, all-monoclonal TR-FIAs, and biotin-enzyme immunoassays (EIAs) have about the same sensitivities and specificities. They compare well with the sensitivity of virus culture. PCR followed by liquid-phase hybridization is a sensitive method for detecting adenovirus DNA and enterovirus and rhinovirus RNA in clinical specimens. IgG EIA on paired acute and convalescent phase sera is the most sensitive serological test for respiratory virus infections and is a valuable reference method when evaluating the sensitivity of new diagnostic tests. The IgG avidity test can distinguish primary infections from re-infections at least in respiratory syncytial virus (RSV) infections. IgM antibody assays, on the other hand, had low sensitivities in our studies.

Conclusions: The choice of diagnostic methods for respiratory virus infections depends on the type and location of the laboratory, the number of specimens tested, and the previous experience of the laboratory. Virus culture, whenever possible, should be the basic diagnostic method; the results, including identification of the virus, should be available no more than 24 h later than the results of rapid diagnostic tests. In small laboratories, especially in hospitals where specimen transportation is well organized, immunofluorescence may be the best choice for antigen detection with the provision that an experienced microscopist and a good UV microscope are available. If the laboratory receives a large number of specimens and has previous experience with EIAs, then biotin-EIAs or TR-FIAs may be the most practical techniques. Their advantages include the stability of the antigens in clinical samples since intact, exfoliated epithelial cells are not required, treatment of specimens is practical, testing of large numbers of specimens is possible, and reading the printed test result is less subjective than reading fluorescence microscopy. The larger role of PCR in the diagnosis of respiratory virus infections depends on future developments such as practical methods to extract DNA or RNA and to purify the extracts from nonspecific inhibitors, plus further improvements to minimize cross-contamination. Group-specific detection of enteroviruses and rhinoviruses is an example of the potential for PCR technology. In experienced laboratories. EIA IgG antibody tests should be available. Recombinant antigens may be a useful part of such assays.

Burden of influenza in healthy children and their households

OBJECTIVE

A prospective, multicentre study was conducted to evaluate the burden of laboratory confirmed influenza in healthy children and their household contacts.

METHODS

The patients were enrolled in four emergency departments (EDs) and by five primary care paediatricians (PCPs) in different Italian municipalities 2 days a week between November 1, 2001 and April 30, 2002. The study involved 3771 children less than 14 years of age with no chronic medical conditions who presented with a respiratory tract infection in EDs or PCP outpatient clinics during the study period. Nasopharyngeal swabs were collected for the isolation of influenza viruses and RNA detection. Information was also collected concerning respiratory illnesses and related morbidities among the study children and their household contacts.

RESULTS

Influenza virus was demonstrated in 352 cases (9.3%). In comparison with the influenza negative children, those who were influenza positive had an older mean age, were more often attending day care centres or schools, more frequently experienced fever and croup, received more antipyretics, and had a longer duration of fever and school absence. Furthermore, their parents and siblings had more respiratory illnesses, received more antipyretics and antibiotics, needed more medical visits, missed more work or school days, and needed help at home to care for the ill children for a longer period of time.

CONCLUSIONS

Influenza has a significant clinical and socioeconomic impact on healthy children and their families. Prevention strategies should also focus on healthy children regardless of their age because of their role in disease transmission.

Etiology of community-acquired pneumonia in hospitalized school-age children: evidence for high prevalence of viral infections

BACKGROUND

Community-acquired pneumonia (CAP) in young children is most commonly associated with viral infections; however, the role of viruses in CAP of school-age children is still inconclusive.

METHODS

Seventy-five school-age children hospitalized with CAP were prospectively evaluated for the presence of viral and bacterial pathogens. Nasopharyngeal washes were examined by polymerase chain reaction for viruses and atypical bacteria. Antibody assays to detect bacterial pathogens in acute-phase and convalescent-phase serum samples were also performed.

RESULTS

A viral infection was identified in 65% of cases. Rhinovirus RNA was detected in 45% of patients; infection with another virus occurred in 31%. The most common bacterial pathogen was Mycoplasma pneumoniae, which was diagnosed in 35% of cases. Chlamydia pneumoniae DNA was not detected in any patient; results of serological tests were positive in only 2 patients (3%). Mixed infections were documented in 35% of patients, and the majority were a viral-bacterial combination.

CONCLUSIONS

The high prevalence of viral and mixed viral-bacterial infections supports the notion that the presence of a virus, acting either as a direct or an indirect pathogen, may be the rule rather than the exception in the development of CAP in school-age children requiring hospitalization.

Community-acquired pneumonia in children: issues in optimizing antibacterial treatment

The treatment of community-acquired pneumonia (CAP) in children is empirical, being based on the knowledge of the etiology of CAP at different ages. As a result of currently available methods in everyday clinical practice, a microbe-specific diagnosis is not realistic in the majority of patients. Even the differentiation between viral, 'atypical' bacterial (Mycoplasma pneumoniae or Chlamydia pneumoniae) and 'typical' bacterial (Streptococcus pneumoniae) CAP is often not possible. Moreover, up to one-third of CAP cases seem to be mixed viral-bacterial or dual bacterial infections. Recent serologic studies have confirmed that S. pneumoniae is an important causative agent of CAP at all ages. M. pneumoniae is common from the age of 5 years onwards, and C. pneumoniae is common from the age of 10 years onwards. In addition to age, the etiology and treatment of CAP are dependent on the severity of the disease. Pneumococcal infections are predominant in children treated in hospital, and mycoplasmal infections are predominant in children treated at home.In ambulatory patients with CAP, amoxicillin (or penicillin V [phenoxymethylpenicillin]) is the drug of choice from the age of 4 months to 4 years, and at all ages if S. pneumoniae is the presumptive causative organism. Macrolides, preferably clarithromycin or azithromycin, are the first-line drugs from the age of 5 years onwards. In hospitalized patients who need parenteral therapy for CAP, cefuroxime (or penicillin G [benzylpenicillin]) is the drug of choice. Macrolides should be administered concomitantly if M. pneumoniae or C. pneumoniae infection is suspected. Radiologic findings and C-reactive protein (CRP) levels offer limited help for the selection of antibacterials; alveolar infiltrations and high CRP levels indicate pneumococcal pneumonia, but the lack of these findings does not rule out bacterial CAP. Most guidelines recommend antibacterials for 7-10 days (except azithromycin, which has a recommended treatment duration of 5 days). If no improvement takes place within 2 days, therapy must be reviewed.

Parainfluenza viruses

Human parainfluenza viruses (HPIV) were first discovered in the late 1950s. Over the last decade, considerable knowledge about their molecular structure and function has been accumulated. This has led to significant changes in both the nomenclature and taxonomic relationships of these viruses. HPIV is genetically and antigenically divided into types 1 to 4. Further major subtypes of HPIV-4 (A and B) and subgroups/genotypes of HPIV-1 and HPIV-3 have been described. HPIV-1 to HPIV-3 are major causes of lower respiratory infections in infants, young children, the immunocompromised, the chronically ill, and the elderly. Each subtype can cause somewhat unique clinical diseases in different hosts. HPIV are enveloped and of medium size (150 to 250 nm), and their RNA genome is in the negative sense. These viruses belong to the Paramyxoviridae family, one of the largest and most rapidly growing groups of viruses causing significant human and veterinary disease. HPIV are closely related to recently discovered megamyxoviruses (Hendra and Nipah viruses) and metapneumovirus.

Quantitative detection of Streptococcus pneumoniae in nasopharyngeal secretions by real-time PCR

Streptococcus pneumoniae is an important cause of community-acquired pneumonia. However, in this setting the diagnostic sensitivity of blood cultures is below 30%. Since during such infections changes in the amounts of S. pneumoniae may also occur in the upper respiratory tract, quantification of these bacteria in nasopharnygeal secretions (NPSs) may offer a suitable diagnostic approach. Real-time PCR offers a sensitive, efficient, and routinely reproducible approach to quantification. Using primers and a fluorescent probe specific for the pneumolysin gene, we were able to detect DNA from serial dilutions of S. pneumoniae cells in which the quantities of DNA ranged from the amounts extracted from 1 to 10(6) cells. No difference was noted when the same DNA was mixed with DNA extracted from NPSs shown to be deficient of S. pneumoniae following culture, suggesting that this bacterium can be detected and accurately quantitated in clinical samples. DNAs from Haemophilus influenzae, Moraxella catarrhalis, or alpha-hemolytic streptococci other than S. pneumoniae were not amplified or were only weakly amplified when there were > or =10(6) cells per reaction mixture. When the assay was applied to NPSs from patients with respiratory tract infections, the assay performed with a sensitivity of 100% and a specificity of up to 96% compared to the culture results. The numbers of S. pneumoniae organisms detected by real-time PCR correlated with the numbers detected by semiquantitative cultures. A real-time PCR that targeted the pneumolysin gene provided a sensitive and reliable means for routine rapid detection and quantification of S. pneumoniae present in NPSs. This assay may serve as a tool to study changes in the amounts of S. pneumoniae during lower respiratory tract infections.

Streptococcus pneumoniae and Mycoplasma pneumoniae coinfection in community acquired pneumonia

The characteristics of nine children with community acquired pneumonia with evidence of Streptococcus pneumoniae and Mycoplasma pneumoniae coinfection are described.

Community acquired pneumonia--a prospective UK study

BACKGROUND

There are few data on paediatric community acquired pneumonia (PCAP) in the UK.

AIMS

To investigate the aetiology and most useful diagnostic tests for PCAP in the north east of England.

METHODS

A prospective study of hospital admissions with a diagnosis of PCAP.

RESULTS

A pathogen was isolated from 60% (81/136) of cases, and considered a definite or probable cause of their pneumonia in 51% (70/136). Fifty (37%) had a virus implicated (65% respiratory syncytial virus) and 19 (14%) a bacterium (7% group A streptococcus, 4% Streptococcus pneumoniae), with one mixed infection. Of a subgroup (51 patients) in whom serum antipneumolysin antibody testing was performed, 6% had evidence of pneumococcal infection, and all were under 2 years old. The best diagnostic yield was from paired serology (34%, 31/87), followed by viral immunofluorescence (33%, 32/98).

CONCLUSION

Viral infection accounted for 71% of the cases diagnosed. Group A streptococcus was the most common bacterial infective agent, with a low incidence of both Mycoplasma pneumoniae and S pneumoniae. Pneumococcal pneumonia was the most common bacterial cause of pneumonia in children under 2 years but not in older children. Inflammatory markers and chest x ray features did not differentiate viral from bacterial pneumonia; serology and viral immunofluorescence were the most useful diagnostic tests.

Errors in registered birth weight and its implications for mortality statistics

BACKGROUND

Birth weight mortality statistics are important for examining trends and monitoring the outcomes of neonatal care.

AIM

To determine the effects of errors in the registered birth weight on birth weight specific mortality.

METHODS

All twins born in England and Wales during 1993-95 comprise the denominator population. For those twins that died, the Office for National Statistics (ONS) provided copies of the death certificates. From the information on the death certificates, the registered birth weight was validated and amended using predetermined rules. The neonatal, postneonatal, and infant mortality rates were recalculated.

RESULTS

In 2.5% of cases the registered birth weight was "not stated" and in others there were miscoding errors. Important differences between published and amended birth weight specific mortality rates especially in <500 g and >/=3500 g groups were evident.

CONCLUSIONS

The bias arising from these errors should be taken into account in interpreting mortality rates and their trends.

Rationalised prescribing for community acquired pneumonia: a closed loop audit

AIMS

To audit the management of community acquired pneumonia before and after the introduction of a protocol. To determine the aetiology of pneumonia using routine investigations and polymerase chain reaction (PCR).

METHODS

Retrospective and prospective audit following the introduction of a management protocol. Prospective cases were investigated routinely and with PCR on blood and nasopharyngeal aspirate.

RESULTS

There was a significant increase in rational prescribing following introduction of the protocol with 75% of children receiving intravenous penicillin or erythromycin compared with 26% beforehand. Of 89 children in the prospective group, 51 microbiological diagnoses were achieved in 48 children. Seven children had Streptococcus pneumoniae infection, 14 had Mycoplasma infection, six had pertussis, and one had Chlamydia pneumoniae infection. Twenty three children had a viral cause of which respiratory syncytial virus was commonest.

CONCLUSIONS

Introduction of the protocol led to improved prescribing. PCR increased the diagnostic yield and the results support the management protocol.

Clinical use of cefuroxime in paediatric community-acquired pneumonia

Cefuroxime has been recommended as a component of treatment for community-acquired pneumonia (CAP) in guidelines produced by several groups, including the US and British Thoracic Societies. It is effective in vitro against the major bacterial pathogens in CAP but it needs to be given with an agent that is active against Mycoplasma, Chlamydia or Legionella spp. if the presence of any of these organisms is suspected. Cefuroxime penetrates respiratory tissue effectively after either parenteral or oral administration, and it has a pharmacodynamic profile which suggests that adequate cover can be achieved with oral therapy for respiratory pathogens susceptible to cefuroxime concentrations of 4 mg/L or less. This break-point is applicable to oral monotherapy and to sequential therapy regimens for the treatment of pneumonia. Cefuroxime can be used either orally or parenterally and it is approved in many countries for the treatment of adult pneumonia by either route. The oral form, cefuroxime axetil, has been used extensively in the treatment of children aged over 3 months but its use in paediatric pneumonia has not been reviewed. The present review summarises clinical experience in the treatment of bacterial pneumonia, of varying severity, in children. The data show that children with severe pneumonia, including those with pleural effusion or complications, can be treated with a full course of intravenous cefuroxime therapy, whereas hospitalised children whose pneumonia stabilises rapidly after initial intravenous therapy can change to oral cefuroxime axetil after 24 to 72 hours and may be able to return home. Oral cefuroxime axetil was appropriate for patients with milder pneumonia managed either in hospital or at home.

Prospective study to determine clinical relevance of detection of pneumococcal DNA in sera of children by PCR

We undertook a prospective study to evaluate the accuracy of PCR of serum (aimed at the pneumococcal pneumolysin gene) at detecting pneumococcal infections in infants and children. The assay was positive for all blood and cerebrospinal fluid culture-positive samples and for 38 and 44% of patients with lobar pneumonia and acute otitis media, respectively. It was positive for 17% of healthy controls. There was a marked effect of age on the rate of positivity among healthy controls, with the highest rate (33%) being in 2-year-old children, the age group with the highest rate of nasopharyngeal (NP) carriage; the lowest rate was found among infants <2 months of age (13%) and adults ages 18 to 50 years (0%), age groups with the lowest NP pneumococcal carriage rates. Carriers of pneumococci in the nasopharynges had a higher rate of positivity than noncarriers of pneumococci in the nasopharynges for all groups. Our results suggest that although PCR of serum is a sensitive test for the detection of Streptococcus pneumoniae in sterile fluids, its high rate of positivity for healthy controls, related to NP pneumococcal carriage, might exclude it from being useful in detecting deep-seated pneumococcal infections.

[Epidemiology of community-acquired pneumonia in children. Current data]

Viruses, particularly syncitial respiratory virus, are the main aetiology of community-acquired lower respiratory tract infections in infants, while bacterial agents are more frequently responsible in children older than 3 years. Antimicrobial therapy must take into account the development of reduced susceptibility of penicillin to strains of Streptoccocus pneumoniae and Haemophilus influenzae with beta-lactamase, and high frequency of Mycoplasma pneumoniae and Chlamydia pneumoniae infections. Although the mortality rate has remained low in France, the morbidity appeared to increase in recent years.

Identification of a variant subgroup A strain of respiratory syncytial virus

During epidemiologic surveillance of children with respiratory syncytial virus (RSV) disease in Huntington, W.Va., we identified seven strains of a new variant subgroup A RSV (subgroup A-Var) by their reactions in an enzyme immunoassay with two anti-F monoclonal antibodies (MAbs) specific for two epitopes, F1 and F4, generated against the subgroup B RSV. The prototype strain of subgroup A and all other subgroup A field strains from that epidemiologic year failed to react with these two subgroup B MAbs. Additional enzyme immunoassays with 18 subgroup B anti-F MAbs specific for 14 epitopes showed that subgroup A-Var strains also reacted with a MAb specific for the subgroup B F2 epitope. In a radioimmune precipitation assay, the molecular size of the subgroup A-Var F2 subunit of the fusion (F) protein clearly differed from those of both prototype strains of subgroup A and subgroup B RSV. The molecular size of the F2 subunit of subgroup A-Var (24 kDa) was intermediate between the size of the F2 subunit of subgroup A (25 kDa) and that of subgroup B (23 kDa). However, the molecular sizes of the F1 subunits of both subgroup A and subgroup A-Var were identical (54 kDa) and slightly larger than those of the F1 subunits of both subgroups B1 and B2 (53 kDa). These data suggest that subgroup A-Var may represent a distinct RSV A subgroup, analogous to subgroup B1 and B2 RSV, and it is the first-identified naturally occurring subgroup A RSV with an F protein different from that of the prototype A RSV.

Parenteral-oral switch in the management of paediatric pneumonia

In phase I of a 2-phase study, 56 evaluable children (0.8 to 5 years) with lobar or segmental pneumonia received intravenous or intramuscular ceftriaxone 50 mg/kg/day for 2 days followed by oral cefetamet pivoxil 20 mg/kg/day in 2 divided doses to complete 7 days of treatment. All patients achieved a clinical cure. In phase II, a randomised open multicentre study, 62 children with pneumonia received an identical regimen to phase I (arm A), and 59 children received ceftriaxone 50 mg/kg/day for 1 day followed by 6 days' treatment with cefetamet pivoxil 20 mg/kg/day (arm B). Patients from phase I and arm A were combined giving a total of 118 evaluable patients in arm A. At the end of treatment, 100% of patients in arm A and 96% in arm B achieved a clinical cure; cure was maintained in 99 and 98% of patients, respectively. Two (4%) patients in arm B failed therapy; in both cases, factors other than treatment failure may have accounted for the poor response. 11 and 12% of patients in treatment arms A and B, respectively, experienced adverse events; gastrointestinal events (nausea and/or vomiting) were reported in 9 and 8% of patients, respectively. In conclusion, 1 or 2 days' treatment with parenteral ceftriaxone before switching to oral cefetamet pivoxil was safe and effective in the treatment of childhood pneumonia. Therefore, parenteral-oral switch is a feasible treatment option in the treatment of serious paediatric community-acquired pneumonia.

Aetiology of community-acquired pneumonia in children treated in hospital

Viral and bacterial antigen and antibody assays were prospectively applied to study the microbial aetiology of community-acquired pneumonia in 195 hospitalised children during a surveillance period of 12 months. A viral infection alone was indicated in 37 (19%), a bacterial infection alone in 30 (15%) and a mixed viral-bacterial infection in 32 (16%) patients. Thus, 46% of the 69 patients with viral infection and 52% of the 62 patients with bacterial infection had a mixed viral and bacterial aetiology. Respiratory syncytial virus (RSV) was identified in 52 patients and Streptococcus pneumoniae in 41 patients. The next common agents in order were non-classified Haemophilus influenzae (17 cases), adenoviruses (10 cases) and Chlamydia species (8 cases). The diagnosis of an RSV infection was based on detecting viral antigen in nasopharyngeal secretions in 79% of the cases. Pneumococcal infections were in most cases identified by antibody assays; in 39% they were indicated by demonstrating pneumococcal antigen in acute phase serum. An alveolar infiltrate was present in 53 (27%) and an interstitial infiltrate in 108 (55%) of the 195 patients. The remaining 34 patients had probable pneumonia. C-reactive protein (CRP), erythrocyte sedimentation rate and total white blood cell count were elevated in 25%, 40% and 36% of the patients, respectively. CRP was more often elevated in patients with bacterial infection alone than in those with viral or mixed viral-bacterial infections. No other correlation was seen between the radiological or laboratory findings and serologically identified viral, bacterial or mixed viral-bacterial infections.(ABSTRACT TRUNCATED AT 250 WORDS)

Pneumonia in childhood: etiology and response to antimicrobial therapy

A prospective eight-month study was carried out in 50 children admitted to hospital for radiologically confirmed community-acquired pneumonia. A potential causative agent of infection was identified in 44 (88%) cases. Using virus isolation, virus antigen detection and enzyme immunoassay serology, respiratory virus infection was diagnosed in 30 (60%) patients. Antibody assays for seven bacteria and antigen detection from serum and urine for Streptococcus pneumoniae produced evidence of bacterial infection in 31 (62%) cases. Streptococcus pneumoniae (38%), respiratory syncytial virus (30%) and Mycoplasma pneumoniae (20%) were the most common causative agents. A mixed infection was diagnosed in 25 (50%) episodes. Nine patients failed to respond to antibiotics within 24 h after onset of treatment. Three of them had a pure viral infection, three a mixed viral-bacterial infection, two a Mycoplasma pneumoniae infection mixed with other bacteria and one a pure Mycoplasma pneumoniae infection. All three Mycoplasma pneumoniae infections were initially treated with penicillin.