Etiology of community-acquired pneumonia in 254 hospitalized children

Mixed microbial aetiology of community-acquired pneumonia in children

Seven paediatric studies on community-acquired pneumonia with serological methods for both viruses and bacteria have been published, allowing the evaluation of concomitant multiple etiological findings. In these studies, dual viral infection has been present in 0-14%, dual bacterial infection likewise in 0-14%, and mixed viral-bacterial infection in 3-30% of the pneumonia cases. The results confirm former clinical observations that respiratory viruses often pave the way for airway-colonising bacteria. The measured frequency of multiple infections has been dependent on the available test panel, mainly on the tests used for pneumococcal aetiology. Mixed viral-bacterial infections have been especially common in young children under 2 years of age, reflecting the high frequency of respiratory syncytial virus infections and their tendency to induce bacterial co-infections. No microbe-specific viral-bacterial associations have been demonstrated. The clinical implications of mixed viral-bacterial infections, compared with viral infections alone or bacterial infections alone, have so far remained unresolved. Current guidelines recommend antibiotic therapy for all community-acquired pneumonia cases in children.

Clinical and economic outcomes of pneumonia in children: a longitudinal observational study in an Italian paediatric hospital

RATIONALE, AIMS AND OBJECTIVES

Antibiotic prescription for acute lower respiratory infections (ALRI) in hospitalized children can have a major impact on cure and costs. We performed a longitudinal study to explore the appropriateness of prescriptions, the predictors of therapeutic patterns, and the main outcomes: readmission, length of stay (LOS) and costs.

METHODS

Ninety-nine children who were inpatients of a paediatric hospital receiving antibiotic treatment for community acquired ALRI were consecutively enrolled. To calculate the costs of pneumonia treatment, we collected data on clinical presentation and resources consumption. We used multiple regression analysis to identify predictors of LOS and choice of therapy, and one-way ANOVA to evaluate cost differences among treatment groups.

RESULTS

Parenteral antibiotics were administered in 64.6% of cases, whereas 35.4% received oral antibiotic therapy by itself (OAT). Switch therapy (SWT) was performed in 43.4% of cases. The most frequently prescribed antibiotic for parenteral therapy was ceftriaxone (58.3%), and for oral therapy cefprozil (58.1%). The median LOS was 3 days and the cure rate 99% (95%CI: 97-100%). SWT and OAT were significantly associated with a shorter LOS. The clinical variables were not significantly associated with SWT or OAT. The average costs per patient in the management of pneumonia were Euro 1435. SWT or OAT were associated with significant lower costs: Euro 1487 per patient (95%CI: 1395-1580) and Euro 1335 per patient (95%CI: 1233-1437), respectively.

CONCLUSIONS

The hospital management of paediatric pneumonia was more influenced by the early discharge policy than by clinical variables without under-cure.

Current state of pneumococcal vaccines

Streptococcus pneumoniae is a leading cause of bacterial pneumonia, meningitis, and acute otitis media in children and adults worldwide. According to World Health Organization estimates, at least 1 million children under 5 years of age die each year from pneumococcal pneumonia. The emergence of resistant strains necessitates the development of an effective vaccine with a large serotype coverage. The 11 most common serotypes cause 72-83% of all serious pneumococcal diseases worldwide. Currently marketed 23-valent pneumococcal polysaccharide vaccine provides large serotype coverage and offers a less expensive option. However, it is efficacious only in adults but not in infants. Conjugate vaccines offer a solution by generating immunological memory already at early age. A recently licensed 7-valent conjugate vaccine is immunogenic and efficacious in infants. Its serotype coverage might be sufficient in Europe and North America, but not in Africa, Asia and Oceania. A need exists to develop pneumococcal vaccines with lower cost and larger serotype coverage. Several 11-valent pneumococcal conjugate vaccines are being evaluated in phase I-III trials. This study reviews the current state of pneumococcal problem and pneumococcal vaccines in clinical use.

Management of community-acquired pediatric pneumonia in an era of increasing antibiotic resistance and conjugate vaccines

The antibiotic management of infants and children with pneumonia is based on the clinician's assessment of the most likely infecting pathogens, the susceptibilities of the infecting pathogens and the seriousness of the illness. The bacterial etiology of pneumonia changed significantly following the universal use of protein-conjugated vaccines for Haemophilus influenzae type b. Similar significant changes are likely to occur with universal use of protein-conjugated vaccines for Streptococcus pneumoniae, requiring the clinician to alter assumptions of the risk of invasive bacterial infection in the child who presents with pneumonia. New strategies are likely to require fewer ancillary tests (e.g. white blood cell count, C-reactive protein and blood culture) and suggest a decreased need for empiric antibiotic therapy. Although the majority of lower respiratory tract infections in children have a viral etiology and are not amenable to antibiotic therapy, for the seriously ill child who is thought to be likely to have pneumonia caused by a bacterial pathogen, recent changes in the susceptibility patterns of both common organisms such as S. pneumoniae and more unusual pulmonary pathogens such as Staphylococcus aureus have forced changes in the selection of both empiric and definitive antibiotic therapy. Third generation cephalosporins ceftriaxone and cefotaxime appear to be effective therapy for pneumonia caused by virtually all current isolates of S. pneumoniae. In contrast antibiotic regimens for life-threatening pulmonary infections in which Staphylococcus aureus is a suspected pathogen should include vancomycin.

Differentiation of bacterial and viral pneumonia in children

BACKGROUND

A study was undertaken to investigate the differential diagnostic role of chest radiographic findings, total white blood cell count (WBC), erythrocyte sedimentation rate (ESR), and serum C reactive protein (CRP) in children with community acquired pneumonia of varying aetiology.

METHODS

The study population consisted of 254 consecutive children admitted to hospital with community acquired pneumonia diagnosed between 1993 and 1995. WBC, ESR, and CRP levels were determined on admission. Seventeen infective agents (10 viruses and seven bacteria) were searched for. Chest radiographs were retrospectively and separately reviewed by three paediatric radiologists.

RESULTS

A potential causative agent was found in 215 (85%) of the 254 cases. Bacterial infection was found in 71% of 137 children with alveolar infiltrates on the chest radiograph, while 72% of the 134 cases with a bacterial pneumonia had alveolar infiltrates. Half of the 77 children with solely interstitial infiltrates on the chest radiograph had evidence of bacterial infection. The proportion of patients with increased WBC or ESR did not differ between bacterial and viral pneumonias, but differences in the CRP levels of >40 mg/l, >80 mg/l, and >120 mg/l were significant although the sensitivity for detecting bacterial pneumonia was too low for use in clinical practice.

CONCLUSIONS

Most children with alveolar pneumonia, especially those with lobar infiltrates, have laboratory evidence of a bacterial infection. Interstitial infiltrates are seen in both viral and bacterial pneumonias.

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

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

Effects of socioeconomic status on presentation with acute lower respiratory tract disease in children in Salvador, Northeast Brazil

Two different socioeconomic groups of children with pneumonia were studied, and their clinical and demographic aspects were evaluated. The diagnosis of pneumonia was based on findings of cough and tachypnea, or on crackles on auscultation or on radiologically confirmed infiltrate. This was a prospective cross-sectional study conducted at the Professor Hosannah de Oliveira Pediatric Center, which cares for children of lower socioeconomic status (PHOPC), and at one private hospital which cares for children from middle to high socioeconomic status (Aliança Hospital, AH). Demographics and clinical differences were assessed by the Pearson chi-square test or Fisher's exact test as appropriate; means of continuous variables were compared by Mann-Whitney U-test. In a 26-month period, 3,431 cases were recruited. The 2,476 cases identified at the PHOPC were younger than the 955 identified at AH (2.2 +/- 2.3 vs. 4.5 +/- 3.1 years, P < 0.0001) and had higher scores for severity (3.5 +/- 1.5 vs. 2.7 +/- 1.7, P < 0.0001), duration of hospitalization (days) (10.9 +/- 12.1 vs. 6.2 +/- 7, P < 0.0001), frequency of tobacco smoker in the household (48% vs. 31%, P < 0.0001), cardiopathy (15.3% vs. 5.9%, P = 0.003), fever (44.4% vs. 36.3%, P = 0.0001), tachypnea (67.6% vs. 32.3%, P < 0.0001), crackles (69.5% vs. 64.9%, P = 0.02), somnolence (19.9% vs. 10.4%, P < 0.0001), malnutrition (13.7% vs. 5%, P < 0.0001), hospitalization rate (27.4% vs. 22.5%, P = 0.003), and death (0.9% vs. 0.1%, P = 0.009). However, other features were more frequent among AH cases: parent's university level of education (38.2% vs. 1.0%, P < 0.0001), underlying chronic illness (40.6% vs. 28.5%, P < 0.0001), asthma (62.7% vs. 50.8%, P = 0.01), rhinitis (9.2% vs. 0.4%, P < 0.0001), previous use of antibiotics (34.3% vs. 27.1%, P = 0.001), and wheezing (53.1% vs. 42.2%, P < 0.0001). Children of lower socioeconomic status have more serious lower respiratory tract disease, whereas children with pneumonia of middle to high socioeconomic status have more allergic diseases (rhinitis, asthma) and wheezing.

Etiological diagnosis of childhood pneumonia by use of transthoracic needle aspiration and modern microbiological methods

Childhood pneumonia is usually treated without determining its etiology. The causative organism can be isolated from specimens of blood, empyema fluid, or lung aspirate, but this is rarely done. The potential of transthoracic needle aspiration for identification of causative agents was tested with use of modern microbiological methods. Aspiration was performed for 34 children who had radiological signs compatible with community-acquired pneumonia and had alveolar consolidation. In addition to bacterial and viral cultures and viral antigen detection, nucleic acid detection for common respiratory pathogens was performed on aspirate specimens. Aspiration disclosed the etiology in 20 (59%) of 34 cases overall and in 18 (69%) of 26 patients from whom a representative specimen was obtained. Aspiration's advantages are high microbiological yield and a relatively low risk of a clinically significant adverse event. Aspiration should be used if identification of the causative agent outweighs the modest risk of the procedure.

An epidemiological investigation of a sustained high rate of pediatric parapneumonic empyema: risk factors and microbiological associations

We investigated the increasing incidence of pediatric empyema during the 1990s at Primary Children's Medical Center in Salt Lake City. Of 540 children hospitalized with community-acquired bacterial pneumonia (CAP) who were discharged from 1 July 1993 through 1 July 1999, 153 (28.3%) had empyema. The annual population incidence of empyema increased during the study period from 1 to 5 cases per 100,000 population aged <19 years. Streptococcus pneumoniae was identified as the most common cause of CAP with or without empyema; serotype 1 accounted for 50% of the cases of pneumococcal empyema. Patients with empyema were more likely to be >3 years old, to have > or =7 days of fever, to have varicella, and to have received antibiotics and ibuprofen before admission to the hospital, compared with patients without empyema (P<.0001 for each factor). The increasing incidence of empyema was associated with infection due to S. pneumoniae serotype 1, outpatient treatment with certain antibiotics, ibuprofen use, and varicella.

Diagnosis of Streptococcus pneumoniae lower respiratory infection in hospitalized children by culture, polymerase chain reaction, serological testing, and urinary antigen detection

A prospective study of 154 consecutive high-risk hospitalized children with lower respiratory infections was conducted to determine the clinical utility of a pneumolysin-based polymerase chain reaction (PCR) assay compared with blood and pleural fluid cultures and serological and urinary antigen tests to determine the incidence of Streptococcus pneumoniae. Whole blood, buffy coat, or plasma samples from 67 children (44%) tested positive by PCR. Sensitivity was 100% among 11 promptly tested culture-confirmed children and specificity was 95% among control subjects. Age, prior oral antibiotic therapy, and pneumococcal nasopharyngeal colonization did not influence PCR results, whereas several surrogates of disease severity were associated with positive tests. Although serological and urinary antigen tests had comparable sensitivity, specificity varied among infected children, and statistical agreement among all assays was limited. These findings support the use of PCR tests to evaluate the protective efficacy of pneumococcal conjugate vaccines and to identify promptly children with pretreated or nonbacteremic pneumococcal lower respiratory infections.

Laboratory diagnosis of community-acquired lower respiratory tract infection

This article has focused on the evaluation of outpatients with lower respiratory illness. In large part, the need for microbiological work-up is host-dependent. Healthy patients usually do well, and laboratory data are often unnecessary. The abnormal host requires a different approach and, in general, the more compromised the host, the more aggressive the laboratory evaluation. A renal transplant patient with respiratory symptoms often follows the dictum that "common things happen commonly;" however, the clinician needs that extra level of assurance in this case. Some transplant patients may have respiratory illness caused by strongyloidiasis. Cystic fibrosis is another example of the need for a more comprehensive laboratory evaluation. Specialized selective media and additional susceptibility studies may be needed to evaluate isolates associated with exacerbation of symptoms in these patients. The clinical laboratory should be forewarned of any materials coming from invasive diagnostic techniques, so they can prepare and offer useful advice regarding specimens, transport, and follow-up. Microbiological laboratories are often most knowledgeable regarding what type of testing is appropriate. Direct communication with the laboratory is essential to assure the best patient care.

Clinical profile of serologically diagnosed pneumococcal pneumonia

OBJECTIVE

To describe the characteristics of serologically diagnosed pneumococcal pneumonia and compare them with those of respiratory syncytial virus (RSV) pneumonia and bacteremic pneumococcal pneumonia.

METHODS

IgG antibodies to pneumococcal pneumolysin and C-polysaccharide as well as immune complexes containing IgG antibodies to pneumolysin and C-polysaccharide were measured from acute and convalescent sera of 254 children with community-acquired pneumonia. Evidence of pneumococcal infection was found in 93 children. Clinical and laboratory data were retrospectively collected from the records of 38 children with sole (all tests for 16 other microbes negative) pneumococcal pneumonia and compared with 26 sole RSV-induced pneumonia from the present series and with the data of our 85 bacteremic pneumococcal pneumonia cases reported earlier.

RESULTS

Serologically diagnosed sole pneumococcal pneumonia clinically overlapped with RSV pneumonia, but RSV pneumonia was more often associated with tachypnea (45% vs. 17%, P < 0.05) and low white blood cell counts (means, 12.0 x 109/l vs. 20.8 x 109/l; P < 0.001) as well as low serum C-reactive protein levels (means, 28 mg/l vs. 137 mg/l; P < 0.001). Alveolar infiltrates were found in 15% of chest radiographs of children with RSV pneumonia compared with 76% of those in children with sole pneumococcal pneumonia (P < 0.001). Patients with bacteremic pneumonia more often appeared ill (79% vs. 50%, P < 0.001) and more often had typical pneumococcal pneumonia with high fever, leukocytosis and lobar infiltrates in their chest radiographs (70% vs. 34%, P < 0.05) than those with serologically diagnosed pneumococcal pneumonia.

CONCLUSIONS

Serologically detected pneumococcal pneumonia differs significantly from RSV pneumonia in laboratory and chest radiography findings, but the clinical signs and symptoms overlap considerably. Bacteremic pneumococcal pneumonia is a more severe illness than the serologically diagnosed one.

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.

Reappraisal of lung tap: review of an old method for better etiologic diagnosis of childhood pneumonia

Identification of the etiology of childhood pneumonia is difficult, even in the cases that most likely have bacterial origins. A positive blood culture result is diagnostic but rare (< 10% of cases), and other noninvasive microbiological methods are nonspecific or are at least shadowed by interpretation problems. However, lung tap (or aspiration), a method developed a century ago, warrants reappraisal, especially since the prevalence of pneumococcal resistance to penicillin is increasing. An analysis of 59 studies that were published in 6 languages led us to conclude that (1) bacterial etiology is disclosed in approximately 50% of cases (virological tests were rarely done); (2) lung tap is safer than is generally considered; (3) potential pneumothorax is mostly symptomless and resolves spontaneously without impairing recovery; and (4) in comparison with routine diagnostic tools, lung tap offers so many advantages that it warrants reconsideration at centers where personnel have experience in handling potential pneumothorax.

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.

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.

Diagnosis and management of pneumonia in children

BACKGROUND

This paper describes challenges in etiologic diagnosis and treatment of childhood community-acquired pneumonia and the means of addressing some of them.

MICROBIOLOGICAL DIAGNOSIS

From about one-third to two-thirds of cases of pneumonia can be attributed to a specific etiology depending on which culture, antigen detection and specialized serologic techniques, some of which are unavailable to clinicians, are used. Results of studies in which microbiologic causes have been sought confirm the importance of Streptococcus pneumoniae as the primary bacterial cause of pneumonia in infants and children. Viral etiologies become less prevalent and mycoplasmal and chlamydial infections become more prevalent with increasing age.

EMPIRIC TREATMENT

Because definitive information about causative pathogens is seldom available, treatment of pneumonia is most often empiric. Antibiotic therapy can be withheld in mildly ill, ambulatory patients in whom viral infection is likely. Most guidelines suggest initial treatment with orally administered amoxicillin or amoxicillin/clavulanate or with intravenous cefuroxime when patients require hospitalization. In May, 2000, the Centers for Disease Control-convened Drug-Resistant S. pneumoniae Therapeutic Working Group identified oral beta-lactams including cefuroxime axetil, amoxicillin and amoxicillin/clavulanate as appropriate options for first line therapy of community-acquired pneumonia in ambulatory adults and children.

CONCLUSIONS

New diagnostic techniques such as pneumococcal serologies and polymerase chain reaction testing have improved the ability to determine the microbiologic etiology of childhood pneumonia. Because these tests are not generally available, empiric treatment is necessary. Efforts to identify new intervention strategies, diagnostic tools, therapies and vaccines will be helpful in managing this disease.

Serum procalcitonin, C-reactive protein and interleukin-6 for distinguishing bacterial and viral pneumonia in children

OBJECTIVE

Serum procalcitonin (PCT), C-reactive protein (CRP) and interleukin-6 (IL-6) concentrations were measured in 126 children hospitalized for community-acquired, radiologically confirmed pneumonia to assess whether these host response values could be used to distinguish bacterial from viral pneumonia.

METHODS

The samples for PCT, CRP and IL-6 measurements were obtained on admission or the first day of hospitalization. The etiology of pneumonia was studied with an extensive panel of methods that detected 6 bacteria and 11 viruses.

RESULTS

In all, 54% had evidence of bacterial pneumonia, and 32% had evidence of sole viral pneumonia. In 14% of the cases the etiology could not be determined. Children with bacterial pneumonia had significantly higher PCT (median 2.09 ng/ml vs. 0.56 ng/ml, P = 0.019) and CRP concentrations (96 mg/l vs. 54 mg/l, P = 0.008) than those with sole viral etiology. However, the values markedly overlapped. No significant difference in IL-6 concentrations was seen between the two patient groups. Using PCT > or = 2.0 ng/ml, CRP > or = 150 mg/l or IL-6 > or = 40 pg/ml, the specificity was > or =80% for bacterial pneumonia. The sensitivities with these cutoff values were 50% for PCT, 31% for CRP and 34% for IL-6.

CONCLUSIONS

The results indicate that the measurement of serum PCT, CRP and IL-6 has little value in the differentiation of bacterial and viral pneumonia in children. However, in some patients with very high serum PCT, CRP or IL-6 values, bacterial pneumonia is probable.