Determination of avidity of IgG against protein antigens from Streptococcus pneumoniae: assay development and preliminary application in clinical settings.

The measurement of antibody levels is a common test for the diagnosis of Streptococcus pneumoniae infection in research. However, the quality of antibody response, reflected by avidity, has not been adequately evaluated. We aimed to evaluate the role of avidity of IgG against eight pneumococcal proteins in etiologic diagnosis. Eight pneumococcal proteins (Ply, CbpA, PspA1 and 2, PcpA, PhtD, StkP-C, and PcsB-N) were used to develop a multiplex bead-based avidity immunoassay. The assay was tested for effects of the chaotropic agent, multiplexing, and repeatability. The developed assay was applied to paired samples from children with or without pneumococcal disease (n = 38 for each group), determined by either serology, polymerase chain reaction (PCR), or blood culture. We found a good correlation between singleplex and multiplex assays, with r ≥ 0.94.The assay was reproducible, with mean inter-assay variation ≤ 9% and intra-assay variation < 6%. Children with pneumococcal disease had lower median avidity indexes in the acute phase of disease for PspA1 and 2 (p = 0.042), PcpA (p = 0.002), PhtD (p = 0.014), and StkP-C (p < 0.001). When the use of IgG avidity as a diagnostic tool for pneumococcal infection was evaluated, the highest discriminative power was found for StkP-C, followed by PcpA (area under the curve [95% confidence interval, CI]: 0.868 [0.759-0.977] and 0.743 [0.607-879], respectively). The developed assay was robust and had no deleterious influence from multiplexing. Children with pneumococcal disease had lower median avidity against five pneumococcal proteins in the acute phase of disease compared to children without disease.

Detection of antibody responses against Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis proteins in children with community-acquired pneumonia: effects of combining pneumococcal antigens, pre-existing antibody levels, sampling interval, age, and duration of illness.

We evaluated the effects of combining different numbers of pneumococcal antigens, pre-existing antibody levels, sampling interval, age, and duration of illness on the detection of IgG responses against eight Streptococcus pneumoniae proteins, three Haemophilus influenzae proteins, and five Moraxella catarrhalis proteins in 690 children aged <5 years with pneumonia. Serological tests were performed on acute and convalescent serum samples with a multiplexed bead-based immunoassay. The median sampling interval was 19 days, the median age was 26.7 months, and the median duration of illness was 5 days. The rate of antibody responses was 15.4 % for at least one pneumococcal antigen, 5.8 % for H. influenzae, and 2.3 % for M. catarrhalis. The rate of antibody responses against each pneumococcal antigen varied from 3.5 to 7.1 %. By multivariate analysis, pre-existing antibody levels showed a negative association with the detection of antibody responses against pneumococcal and H. influenzae antigens; the sampling interval was positively associated with the detection of antibody responses against pneumococcal and H. influenzae antigens. A sampling interval of 3 weeks was the optimal cut-off for the detection of antibody responses against pneumococcal and H. influenzae proteins. Duration of illness was negatively associated with antibody responses against PspA. Age did not influence antibody responses against the investigated antigens. In conclusion, serological assays using combinations of different pneumococcal proteins detect a higher rate of antibody responses against S. pneumoniae compared to assays using a single pneumococcal protein. Pre-existing antibody levels and sampling interval influence the detection of antibody responses against pneumococcal and H. influenzae proteins. These factors should be considered when determining pneumonia etiology by serological methods in children.

Prevalence and risk factors for wheezing in Salvador, Brazil: a population-based study.

BACKGROUND: Wheezing is one of the most frequent causes of visit to emergency rooms among children. However, data on wheezing burden are mostly provided at healthcare setting, and particularly only for infants. AIMS: We sought to estimate the prevalence of wheezing in children under 4 years and to assess potential risk factors in the community. DESIGN: This was a cross-sectional analysis of a population-based cohort study. METHODS: The sample comprised children aged <4 years living in Salvador, Brazil. Data were collected via home visits when the parents/guardians were interviewed. Data were recorded on standardized forms. RESULTS: Of 1534 children, mean age was 21 ± 14 months (minimum 3 days; maximum 47 months; 6% <2 months); 780 (51%) were males and 501 [33%; 95% confidence interval (95% CI): 30-35%] reported wheezing in the last 12 months. Among wheezers, 321 (64%) had occasional wheezing. Overall, 180 (12%; 95% CI: 10-14%) had recurrent wheezing and 157 (10%; 95% CI: 9-12%) had asthma. For children in the first, second, third and fourth year of life wheezing was reported in 23, 41, 34 and 37%, respectively. Mother atopic-related disease was independently associated with recurrent wheezing (AdjPR[95% CI]: 1.54 [1.12-2.11]) and asthma (AdjPR[95% CI]: 1.54 [1.10-2.16]). Smoker at home (AdjPR[95% CI]: 1.34 [1.07-1.67]) and low birth weight (AdjPR[95%CI]: 1.38 [1.05-1.81]) were independently associated with occasional wheezing. CONCLUSIONS: One-third of under 4 years reported wheezing; history of mother's atopic-related disease was an independent risk factor for recurrent wheezing and asthma; smoker at home and low birth weight were independent risk factors for occasional wheezing.

Differences in evolution of children with non-severe acute lower respiratory tract infection with and without radiographically diagnosed pneumonia.

OBJECTIVE: To identify differences in the evolution of children with non-severe acute lower respiratory tract infection between those with and without radiographically diagnosed pneumonia. DESIGN: Prospective cohort study. SETTING: A public university pediatric hospital in Salvador, Northeast Brazil. PATIENTS: Children aged 2-59 months. METHODS: By active surveillance, the pneumonia cases were prospectively identified in a 2-year period. Each case was followed-up for changes in various clinical symptoms and signs. Demographic, clinical and radiographic data were recorded in standardized forms. Exclusion was due to antibiotic use in the previous 48 hours, signs of severe disease, refusal to give informed consent, underlying chronic illness, hospitalization in the previous 7 days or amoxicillin allergy. Chest X-ray (CXR) was later read by at least 2 independent pediatric radiologists. MAIN OUTCOME MEASURES: Radiographic diagnosed pneumonia based on agreed detection of pulmonary infiltrate or pleural effusion in 2 assessments. RESULTS: A total of 382 patients receiving amoxicillin were studied, of whom, 372 (97.4%) had concordant radiographic diagnosis which was pneumonia (52%), normal CXR (41%) and others (7%). By multivariate analysis, age (OR=1.03; 95% CI: 1.02-1.05), disease > 5 days (OR = 1.04; 95% CI: 1.001-1.08), reduced pulmonary expansion (OR = 3.3; 95% CI: 1.4-8.0), absence of wheezing (OR = 0.5; 95% CI: 0.3-0.9), crackles on admission (OR = 2.0; 95% CI: 1.2-3.5), inability to drink on day 1 (OR = 4.2; 95% CI: 1.05-17.3), consolidation percussion sign (OR = 7.0; 95% CI: 1.5-32.3), tachypnea (OR = 2.0; 95% CI: 1.09-3.6) and fever (OR = 3.6; 95% CI: 1.4-9.4) on day 2 were independently associated with pneumonia. The highest positive predictive value was at the 2nd day of evolution for tachypnea (71.0%) and fever (81.1%). CONCLUSION: Persistence of fever or tachypnea up to the second day of amoxicillin treatment is predictive of radiographically diagnosed pneumonia among children with non-severe lower respiratory tract diseases.

Characteristics of radiographically diagnosed pneumonia in under-5 children in Salvador, Brazil.

OBJECTIVE: To assess the association of demographic and clinical aspects with radiographically diagnosed pneumonia. DESIGN: By active surveillance, the admitted pneumonia cases by the pediatrician on duty were identified in a 2 year period. Demographic, clinical and radiographic data were registered into standardized forms. SETTING: A public university pediatric hospital in Salvador, Northeast Brazil. PATIENTS: Children <5 years-old. MAIN OUTCOME MEASURES: Radiographically diagnosed pneumonia based on detection of pulmonary infiltrate/ consolidation. RESULTS: 301 cases had the chest X-ray evaluated by a pediatric radiologist blinded to clinical information, among whom pulmonary infiltrate and consolidation were described in 161 (54%) and 119 (40%), respectively. Chest X-ray was read normal for 140 cases. Overall, the median age was 17 months (mean 20±14, range 12 days-59 months). Pulmonary infiltrate was less frequently described among patients aged under 1 year (41.3% vs 59.9%, P=0.002, OR [95% CI] = 0.47 [0.29-0.76]) and hyperinflation was significantly more frequent in this age group (27.9% vs 4.1%, P<0.001, OR [95% CI] = 9.14 [4.0-20.9]). By multiple logistic regression, fever on admission was independently associated with pulmonary infiltrate (OR [95% CI] = 1.68 [1.03-2.73]) or consolidation (1.79 [1.10-2.92]), wheezing was independently associated with absence of pulmonary infiltrate (0.53 [0.33-0.86]) or of consolidation (0.53 [0.33-0.87]). The positive likelihood ratio of fever on examination for pulmonary infiltrate and consolidation was 1.49 (95% CI:1.11-1.98) and 1.49 (95% CI: 1.14-1.94), respectively. CONCLUSION: Presence of fever enhanced 2.5 times the chance of children hospitalized with lower respiratory tract disease to have radiographically diagnosed pneumonia.

Radiographic findings among children hospitalized with severe community-acquired pneumonia.

BACKGROUND: Community-acquired pneumonia (CAP) is a leading cause of childhood death. There are few published reports of radiographic findings among children with severe CAP. OBJECTIVE: To describe chest X-ray (CXR) findings and assess association between these radiographic findings and pneumococcal isolation in children with severe CAP. METHODS: A prospective, multicenter, observational study was conducted in 12 centers in Argentina, Brazil, and the Dominican Republic. Children aged 3-59 months, hospitalized with severe pneumonia, were included. On admission, blood and pleural effusion cultures were performed. Streptococcus pneumoniae was identified according to standard procedures in the respective national reference laboratory. Chest X-rays were taken on admission and read before the culture results were reported. RESULTS: Out of 2,536 enrolled patients, 283 (11.2%) had S. pneumoniae isolated, in 181 cases (7.1%) from blood. The follow radiographic patterns were observed: alveolar infiltrate (75.2%), pleural effusion (15.6%), and interstitial infiltrate (9.2%). Overall, pleural effusion was associated with pneumococcal isolation and pneumococcal bacteremia (P < 0.001). Infiltrates were unilateral (78.7%) or bilateral (21.3%), right-sided (76%) or left-sided (24%), in the lower lobe (53.6%) or the upper lobe (46.4%). Multivariate analysis including patients with affection of only one lobe showed that upper lobe affection and pleural effusion were associated with pneumococcal isolation (OR 1.8, 95% CI, 1.3-2.7; OR 11.0, 95% CI, 4.6-26.8, respectively) and with pneumococcal bacteremia (OR 1.7, 95% CI, 1.2-2.6; OR 3.1, 95% CI, 1.2-8.0, respectively). CONCLUSIONS: Three-quarters of the patients studied had alveolar infiltrates. Upper lobe compromising and pleural effusion were associated with pneumococcal invasive disease.

Additional markers to refine the World Health Organization algorithm for diagnosis of pneumonia.

INTRODUCTION: WHO guidelines for primary care of children with tachypnea indicate that all should receive antibiotics for presumed pneumonia. These guidelines have led to excessive antibiotic use. OBJECTIVE: To examine the value of history of previous respiratory distress, chest indrawing and fever, and response to bronchodilator(BD) to refine these guidelines. DESIGN: Prospective study. SETTING: Urban tertiary care hospital. SUBJECTS: Children, between the ages of 6 and 59 months, presenting with cough and tachypnea. METHODS: 182 children were enrolled. Each child had a chest X-ray that was read by two blinded, independent radiologists. Discordance between the two radiologists led to excluding 17 patients. The remaining 165 children were examined for fever and/or chest indrawing, and if they had a history of previous respiratory distress, challenge with a BD. The association of persistent tachypnea after BD and presence of pulmonary infiltrates was recorded. RESULTS: The median age was 22 months (mean 25.1 +- 14.5 mo) and 75.8% were aged greater than 1 year. There were 58.8% males. Previous respiratory distress occurred in 65.0% and 79.2% of children aged less than 1 year and 1 year, respectively. Pneumonia was radiologically diagnosed in 26/165 (15.8%). 2/40 (5 %) of children without a history of previous respiratory distress had pneumonia diagnosed. Of 125 children with history of previous respiratory distress, pneumonia was identified in 24 (19.2 %). Persistence of tachypnea after BD was associated with pulmonary infiltrate in 14/24 (58.3%), whereas, tachypnea persisted in 32/101 (31.7%) children without pulmonary infiltrates (P = 0.02). The negative predictive value of resolution of tachypnea was 87.3% (95% CI 77.5 93.4). BD non-response was most useful in children without fever and/or with chest indrawing to indicate pneumonia as the cause of the tachypnea. CONCLUSION: This study indicates that by adding the simple procedures of a history of previous respiratory distress, recording of fever and chest indrawing, and observing the response to bronchodilators, pneumonia can be reliably identified in children presenting with tachypnea and cough. It is probable that this approach to management of children with cough and tachypnea could reduce unnecessary use of antibiotics.

Evaluation of the degree of tachypnea for hospitalizing children with pneumonia.

This was a hospital based prospective study to determine the cut-off respiratory rates which can identify children (age < or =14.5 yr) with sever pneumonia with chest indrawing and to evaluate the validity of the cutoff respiratory rate so obtained in identifying sever pneumonia requiring hospitalization. All children diagnosed with pneumonia (radiologically proven) between September 1997 and October 1999 were enrolled. Of 1,665 cases, 54.7% were males; the median age was 1.8 yr (range 8 days-14.5 yr, mean 2.8 +/- 2.7 yr). Frequency of hospitalization, tachypnea and chest indrawing were 29.9%, 58.9% and 42.7%. In hospitalized children, cutoff respiratory rate > or =57, > or =48, and > or =36 were found to identify sever pneumonia requiring hospitalization in the age groups 2-11 mo, 12-59 mo and > or =5 yr, respectively.

Etiology of childhood community acquired pneumonia and its implications for vaccination.

Pneumonia is an important cause of morbidity and mortality among children throughout the world. Vaccines are available for some organisms, but they are underutilized and/or still in development. To evaluate the potential impact of vaccines, we review studies in which the etiology of childhood community-acquired pneumonia was recorded. In North America and Europe (9 studies), the etiology of pneumonia was established in 62% of studied children (range 43%-88%) by use of noninvasive specific methods for microbiologic diagnosis. The most often identified agents were S. pneumoniae (22%), respiratory syncytial virus (RSV) (20%), Haemophilus influenzae (7%), and Mycoplasma pneumoniae (15%). In Africa and South America (8 studies), bacteria were recovered from 56% (range 32%-68%) of severely ill children studied by lung aspirate. The most often isolated bacteria were Streptococcus pneumoniae (33%) and Haemophilus influenzae (21%). A high percentage of H. influenzae strains were not serotype b. Throughout the world, children requiring hospitalization were most likely to have infection caused by pneumococcus, H. influenzae or RSV. Out patients also had Mycoplasma pneumoniae. Countries in Africa and Asia recorded 2 to 10 times more children with pneumonia (7 to 40/100 annually) than in the USA. Widespread use of pneumococcal and H. influenzae type b conjugate vaccines could reduce the frequency of childhood pneumonia by one-third. Further reduction will require development of non-type b H. influenzae, RSV and M. pneumoniae vaccines. This could result in a > 50% reduction of pneumonia in children. This goal should be sought and achieved as soon as possible.

Community acquired pneumonia among pediatric outpatients in Salvador, Northeast Brazil, with emphasis on the role of pneumococcus.

Pneumonia is one of the leading causes of hospitalization and death among children in developing countries, and mortality due to pneumonia has been associated with S. pneumoniae infection. This investigation was designed to describe the antimicrobial susceptibility and serotype patterns of pneumococcal strains recovered from the blood of children with community-acquired pneumonia (CAP) and to assess the clinical findings of pneumococcal bacteremic patients with pneumonia. In a 26 month prospective study, blood cultures were obtained as often as possible from children (<16 years of age) diagnosed with CAP in two emergency rooms. Antimicrobial drug susceptibility tests and serotyping were performed when pneumococcus was identified. We studied 3,431 cases and cultured blood samples from 65.5% of those. Pneumococcus was recovered from 0.8% of the blood samples. The differences in age, somnolence, wheezing and hospitalization among children with and without pneumococcal bacteremia were statistically significant. Pneumococcal bacteremia was age-related (mean 1.63 +/- 1.55; median 0.92) and associated with somnolence and hospitalization among children with CAP. One strain was recovered from pleural fluid. Penicillin resistance was detected in 21.0% (4/19) of the strains at an intermediate level, whereas 63.0% of the strains were resistant to trimethoprim-sulfamethoxazole. The most common serotypes were 14 and 6B, and these serotypes included the resistant strains. Eight of our 18 isolates from blood were of types included in the heptavalent conjugate pneumococcal vaccine, recently licensed in the USA.

Normal cerebrospinal fluid values in full-term gestation and premature neonates.

Results of cerebrospinal fluid (CSF) examinations from 77 high-risk neonates were reviewed. The mean CSF white cells (WBC) count was 4.5 cell/mm3, being two standard deviations above the mean 11.7 cells/mm3 in the full-term gestation neonate group; in the premature neonate one, the mean CSF WBC count was 5.1 cells/mm3, being two standard deviations above the mean 16.7 cell/mm3. PMNs (polymorphonuclear leukocytes) were present in less than 40% of those children, being the mean PMN percentage 4.2% and 0.6%, the mean ANC (absolute neutrophil count) was 0.3/mm3 and 0.06/mm3, in full-term gestation neonate group and premature neonate one, respectively. The mean CSF protein concentration is significantly greater in those premature neonates (101.2 mg/dl) compared with that in term neonates (77.6 mg/dl). The average glucose was just the same in both groups (67 mg/dl). All of these values were from patients who underwent nontraumatic cisternal puncture, with no red blood cells (RBC/mm3 = 0). Traumatic puncture, even up to 500 RBC/mm3, interfered on CSF parameters.

[Etiology of bacterial meningitis in a cohort from Salvador, Bahia]. / Etiologia de meningites bacterianas em uma amostra da população de Salvador-Bahia.

Bacterial meningitis remains a very important disease world-wide, mainly during childhood. In order to describe the etiology of bacterial meningitis among some children in Salvador, Bahia-Brazil, we retrospectively reviewed 7000 cerebrospinal fluid exams, performed within the period of September 1988 up to August 1995, at the CSF Laboratory, José Silveira Foundation; 892(12.7%) exams met the inclusion criteria; patients less than 16 years of age and clinical meningitis diagnosis. Among 139 cases of bacterial meningitis, H. influenzae type b (Hib) was the most frequent cause (26.0%), all of the cases in children under 5 years. We have been questioning whether the declining Hib disease trend since 1992 has been associated with the use of Hib conjugate vaccines among those children.

HTLV-I associated tropical spastic paraparesis: cerebral spinal fluid evolutive aspects in 128 cases

Com o objetivo de verificar se existe mudanças na intensidade da resposta inflamatória do líquido cefalorraqueano (LCR) no curso da paraparesia espastica tropical (PET) associada ao HTLV-1 foram estudados retrospectivamente os exames de LCR de 128 pacientes com PET. Os resultados indicam que embora alteraçöes inflamatórias possam persistir por período superior a 10 anos, existe tendência a diminuiçäo de sua intensidade ou mesmo de normalizaçäo após o segundo ano de evoluçäo da doença