Analysis of cells obtained by bronchial lavage of infants with respiratory syncytial virus infection

To study the cellular infiltrate that occurs within the airways of infants with respiratory syncytial virus bronchiolitis, samples of airways secretions were obtained by bronchial lavage from the lower respiratory tract of infants ventilated for this condition and from the upper airway of non-intubated infants with this disorder using nasopharyngeal aspirates. Cytospin samples were prepared so that differential cell counts could be performed on the cells obtained and alkaline phosphatase-antialkaline phosphatase immunocytochemical analysis of lymphocyte subsets was carried out using a panel of monoclonal antibodies, which included anti-CD3, anti-CD4, anti-CD8, anti-CD19, and anti-TcR gamma delta. Results from the lower and upper airways were similar. Large numbers of inflammatory cells were obtained, of which neutrophils accounted for a median of 93% in the upper airway and 76% in the lower airway. The numbers of CD8 positive cells detected were small and consistently less than CD4 positive cells, median CD4:CD8 ratios being 22.5:1 and 15:1 for the lower and upper airways. CD19 positive cells were rarely observed and no gamma delta positive lymphocytes were detected. These results indicate that neutrophils probably play a major part in causing symptoms in these infants. They do not support the concept that excessive lymphocyte mediated cytotoxic activity is principally responsible for the pathology in respiratory syncytial virus bronchiolitis.     

Leucocyte populations in respiratory syncytial virus-induced bronchiolitis

OBJECTIVES: To enumerate the cellular composition of the airways in infants with acute bronchiolitis. METHODOLOGY: Cells were obtained by airway lavage from the upper and lower airway and the peripheral blood of infants with respiratory syncytial virus (RSV)+ bronchiolitis, RSV- bronchiolitis and age-matched controls. RESULTS: Neutrophils are the predominant cells present in the upper and lower airway. Neutrophils are present at a higher number/unit volume in the airway than in the peripheral blood. CONCLUSIONS: Neutrophils, being the dominant cellular infiltrate into the airway, are likely to contribute to the pathophysiology of bronchiolitis. Therapies targeted at limiting neutrophil influx or neutrophil-mediated damage in the airway may have a therapeutic role.     

The release of leukotrienes in the respiratory tract during infection with respiratory syncytial virus: role in obstructive airway disease

Samples of nasopharyngeal secretions from a group of 73 infants with bronchiolitis or upper respiratory illness alone during infection with respiratory syncytial virus were analyzed for leukotriene C4 (LTC4) content using a reverse-phase high-pressure liquid chromatography assay with confirmation by radioimmunoassay. Titers of respiratory syncytial virus (RSV)-specific IgE in nasopharyngeal secretion (NPS) specimens were determined using an enzyme-linked immunosorbent assay. The highest concentrations of LTC4 were found in the first 3 to 8 days after the onset of illness, and LTC4 was detectable in progressively lower concentrations in samples obtained up to 28 days after the onset of illness. LTC4 was detected in samples of NPS obtained in the acute phase of illness from 67% of infants with bronchiolitis due to RSV and in 33% of samples of NPS obtained during the same interval from infants with upper respiratory illness alone (p less than 0.025). Concentrations of LTC4 in children with bronchiolitis were 5-fold higher (1271 pg/ml) than the mean concentration of LTC4 in children with upper respiratory illness (224 pg/ml, p less than 0.02). LTC4 was detected in 83% of the children developing an RSV-IgE response and in 24% of subjects not developing an RSV-IgE response (p less than 0.001). Quantities of LTC4 measured in NPS were directly correlated with the magnitude of the RSV-IgE response in secretions (r = 0.33, p less than 0.02). These studies lend support to previous investigations suggesting that severe bronchiolitis due to RSV results from IgE-mediated hypersensitivity reactions to viral antigens, with release of chemical mediators of airway obstruction.(ABSTRACT TRUNCATED AT 250 WORDS)     

Peripheral blood T and B lymphocyte subpopulations in infants with acute respiratory syncytial virus brochiolitis

Most data concerning immunopathogenetic mechanisms involved in respiratory syncytial virus (RSV) infection are derived from animal studies. In infants with RSV bronchiolitis the target organ i. e. the airway is hard to explore. We looked for specific alterations in peripheral blood lymphocyte subpopulations in infants hospitalized for RSV bronchiolitis. Flow cytometric analysis with a large panel of monoclonals was performed on peripheral blood lymphocytes in thirty-two infants (mean age: 4. 9 months) admitted for RSV bronchiolitis. Data collected on admission were compared with age-matched control values and also with results obtained at the end of the first week of hospitalization. Differences between age-groups (older or younger than 4 months) and between clinical subgroups (clinical severity score more or less than 6) were looked for. In the group of infants as a whole, regardless of age and clinical score the number of CD4+ cells on admission was significantly elevated compared to normal values for age (p < 0.001) including a high fraction of the naive suppressor-inducer subpopulation (CD4+/CD45RA+) and a low fraction of the reciprocal memory helper-inducer subpopulation (CD4+/CD29+). Within the CD8+ cell population the number of T cells with cytotoxic activity (CD8+/S6F1+) was significantly elevated (p < 0.001) as were other types of cytotoxic cells. A significant decrease (p < 0.0001) in the proportion of the precursor/suppressor-effector subpopulation (CD8+/S6F1-) was seen. Absolute numbers and percentages of CD 19+ B cells were significantly elevated (p < 0.001) with a significant increase in the CD5+ subfraction (p < 0.001) as well as in the CD 10+ subfraction (p < 0.001). In the older age group immunophenotypic cytotoxicity was more pronounced with increased clinical score. During recovery the CD45RA+: CD29+ ratio tended to normalize within the CD4+ T cells. Within the B lymphocyte subsets significant increase in the CD19+/ CD5+ fraction (p < 0.5) was seen. We conclude that there are significant changes in the number of peripheral blood lymphocyte subsets in infants with RSV bronchiolitis as compared to age-related controls. We hope that present data could be useful in further exploration of RSV immunology in humans. A possible link between RSV bronchiolitis and the subsequent development of atopy is mentioned.     

Tryptase and IgE concentrations in the respiratory tract of infants with acute bronchiolitis.

It has been proposed that a specific IgE response contributes to the immunopathology of acute respiratory syncytial virus (RSV) bronchiolitis but previous work has been difficult to replicate. Indirect evidence that might support this contention was sought by measuring total IgE concentrations in bronchoalveolar lavage (BAL) samples obtained from intubated infants and by attempting to detect mRNA for IgE in cells obtained from both the upper and lower respiratory tract. Evidence of significant mast cell activation was sought by measuring tryptase concentrations in BAL fluid and serum. Detectable concentrations of IgE were found in two of seven BAL samples obtained more than five days after intubation and mRNA for IgE was demonstrated in three of six BAL samples and three of six samples obtained from the upper respiratory tract. Tryptase was detectable in 11 of 12 BAL samples with the two highest values detected on day 1. These values were raised compared with control samples but were not such to suggest that mast cell degranulation is the major contributor to the inflammatory process. These results suggest that IgE may be produced in the airways of infants in response to RSV infection. The relationships between IgE production, RSV infection, and symptoms of acute bronchiolitis remain obscure.     

Neutrophil-mediated inflammation in respiratory syncytial viral bronchiolitis

BACKGROUND: The involvement of neutrophil-mediated inflammation may play an important role in the pathogenesis of acute respiratory syncytial virus bronchiolitis. However, no measurable marker is sensitive enough to assess neutrophil-mediated inflammation in the airways. Released neutrophil elastase (NE) in intraluminal airways has been reported to induce pulmonary inflammation. The aim of this study was to determine whether the amount of urinary trypsin inhibitor (UTI) in serum, a degenerate induced by NE, reflects the degree of airway inflammation in children with respiratory syncytial viral (RSV) bronchiolitis and whether the severity of inflammation is evaluated. The pre-alpha-/inter-alpha-trypsin inhibitor is assumed to be precursors of the UTI. When NE degrades these inhibitors, UTI is liberated. METHODS: Serum UTI concentrations in infants admitted with RSV bronchiolitis, other viral infections, bacterial pneumonia and control subjects were measured by means of one-step sandwich-type enzyme immunoassay. RESULTS: Serum UTI concentrations in 25 patients on admission were significantly higher than the 15 infantile control values (mean +/- SEM, 22.126 +/- 2.317 and 6.701 +/- 0.719 U/mL, respectively; P < 0.0001). The elevated levels returned to baseline values with improvement in the respiratory symptoms. Higher levels of serum UTI with RSV infection were consistently associated with clinical symptoms and artificial ventilation. Serum NE concentrations of patients were elevated in some patients but not significantly different from controls in the patients who showed only upper respiratory symptoms with RSV infections. CONCLUSION: The findings strongly suggested that neutrophil-mediated events are involved in the pathogenesis of RSV bronchiolitis, and the monitoring of UTI concentrations might be useful for evaluating the neutrophil-mediated airway inflammation.     

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??Objective To determine the relationship between clinical features of bronchiolitis in children under 2 years old and lymphocyte subsets ratio. Methods Two hundred and sixty-eight hospitalized children in Children Hospital of Soochow University from January 2014 to September 2015 were enrolled in this study. Peripheral blood was collected and cellular immunity was detected by flow cytometry. Pathogens were tested and patients’ clinical data was collected. Results Bronchiolitis infants were identified in 11.84% of 2264 patients in corresponding period. Prevalence rate of pathogen was 57.84%??whose sequence was??from high to low?? respiratory syncytial virus??RSV??21.27%????mycoplasma pneumoniae??MP??16.42%????Haemophilus influenzae??10.07%????Streptococcus pneumoniae??8.96%??. CD3+??CD3+CD8+ ratio of the children with bronchiolitis and without wheezing patients was lower than healthy control group. The CD4+/CD8+ ratio was the highest in bronchiolitis group??which was the lowest in healthy control group. The CD3- CD19+ ratio was higher in bronchiolitis and no-wheezing group than in healthy control group??P??0.05??. Conclusion Lymphocyte subsets disorder in brochiolitis children was samilar to that in asthma patients. Children between 6 months and 1 year old were more likely to develop bronchiolitis than the other two groups. Bronchiolitis infants may have high expression tendency of B lymphocyte??especially those with allergic symptoms. RSV is still the most common pathogen in bronchiolitis.     

2岁以下毛细支气管炎患儿临床特征与淋巴细胞亚群比值关系

目的 探究2岁以下毛细支气管炎患儿临床特征与淋巴细胞亚群比值关系。方法 以2014年1月至2015年9月在苏州大学附属儿童医院呼吸科住院诊断为毛细支气管炎的268例患儿为研究对象,入院后24 h内取静脉血进行流式检测淋巴细胞亚群比值,同时进行多病原检测,并收集其他临床资料与同龄非喘息肺炎患儿淋巴细胞亚群进行比较。结果 毛细支气管炎患儿占同期2岁以下住院病例的11.84%。病原阳性检出率57.84%,病原阳性检出排序为呼吸道合胞病毒（21.27%）、肺炎支原体（16.42%）、流感嗜血杆菌（10.07%）、肺炎链球菌（8.96%）。毛细支气管炎组和非喘息肺炎组CD3+、CD3+CD8+比值均低于正常对照组;毛细支气管炎组CD4+/CD8+比值最高,正常对照组最低,毛细支气管炎与非喘息肺炎组CD3-CD19+比值均高于正常对照组（P＜0.05）。结论 毛细支气管炎患儿存在与哮喘相似的淋巴细胞亚群失衡。6个月至1岁儿童更易发生毛细支气管炎。毛细支气管炎特别是过敏体质患儿可能存在B细胞表达水平增强倾向。呼吸道合胞病毒仍是毛细支气管炎最主要病原体。     

Association of cytokine responses with disease severity in infants with respiratory syncytial virus infection

Aim: To explore the relationship between cytokine responses and severity of respiratory syncytial virus (RSV) infection in infants. Methods: Intracellular interleukin-4 (IL-4) and interferon- γ (IFN- γ) expression in peripheral blood CD3 + and CD8 + lymphocytes was measured by four-colour flow cytometry. Serum IL-12, IL-4 and IFN- γ levels were also determined by enzyme-linked immunosorbent assay. Results: The frequency of IL-4 and IFN- γ expression in CD3 + CD8 - cells was the same in RSV-infected, non-RSV-infected and control infants and in those with RSV bronchiolitis or RSV pneumonia, indicating that no Th2 predominance exists in the acute phase of RSV infection and RSV bronchiolitis. Furthermore, RSV-infected infants had a more frequent IFN- γ expression in CD3 + CD8 + cells than controls, and they also showed a much lower serum IL-4/ IFN- γ ratio because of decreased IL-4 and elevated IFN- γ, the latter being most prominent in RSV bronchiolitis. The serum IL-12 level in RSV-infected infants was the same as in control infants, while those with non-RSV infections had a much higher level. Serum IL-12, IFN- γ and frequency of IFN- γ expression in CD3 + CD8 + cells in mild RSV infection were much higher than in controls, while no difference existed between severe cases and controls.

Conclusion: Type 2 cytokine predominance was not found in the acute phase of RSV infection and RSV bronchiolitis, but both were accompanied by enhanced production of IFN- γ and a much higher serum IFN- γ level than in healthy controls, especially in those with RSV bronchiolitis, suggesting a role in causing airway obstruction. IFN- γ and IL-12 may also play a protective role in RSV infections by diminishing viral replication, and high levels of IL-12 and IFN- γ may be associated with lessening of the severity of infection.     

Bronchoalveolar lavage cellularity in infants with severe respiratory syncytial virus bronchiolitis.

Aim: To examine over time, the cellular response within the lungs of infants ventilated with respiratory syncytial virus (RSV) bronchiolitis and to compare this response in infants born at term with those born preterm. METHODS: Non-bronchoscopic bronchoalveolar lavage (BAL) samples were taken from 47 infants (24 born at term and 23 born preterm) who were ventilated for RSV positive bronchiolitis and 10 control infants. BAL cellularity and differential cell counts were calculated using standard techniques. RESULTS: Total cellularity in BAL over the first four days of ventilation in infants with RSV bronchiolitis was greater in term infants (median 2.2 (IQR 4.27) x 10(6) cells/ml) compared with preterm infants (0.58 (1.28) x 10(6) cells/ml). The magnitude of the cellular response in preterm infants with bronchiolitis was similar to that in the control group measured on day 1 (0.62 (0.77) x 10(6) cells/ml). BAL cellularity decreased progressively from the time of intubation in term infants, but remained relatively constant in preterm infants up to seven days after intubation. CONCLUSIONS: There are differences in the magnitude and type of pulmonary cellular response in term and preterm infants ventilated with RSV bronchiolitis. The cellular response in term infants with bronchiolitis differs from that in a control group of infants. These differences may reflect variations in cellular recruitment in the lung and/or variations in airway calibre.     

Bronchoalveolar lavage cellularity in infants with severe respiratory syncytial virus bronchiolitis

Aim: To examine over time, the cellular response within the lungs of infants ventilated with respiratory syncytial virus (RSV) bronchiolitis and to compare this response in infants born at term with those born preterm. Methods: Non-bronchoscopic bronchoalveolar lavage (BAL) samples were taken from 47 infants (24 born at term and 23 born preterm) who were ventilated for RSV positive bronchiolitis and 10 control infants. BAL cellularity and differential cell counts were calculated using standard techniques. Results: Total cellularity in BAL over the first four days of ventilation in infants with RSV bronchiolitis was greater in term infants (median 2.2 (IQR 4.27) x 10⁶ cells/ml) compared with preterm infants (0.58 (1.28) x 10⁶ cells/ml). The magnitude of the cellular response in preterm infants with bronchiolitis was similar to that in the control group measured on day 1 (0.62 (0.77) x 10⁶ cells/ml). BAL cellularity decreased progressively from the time of intubation in term infants, but remained relatively constant in preterm infants up to seven days after intubation. Conclusions: There are differences in the magnitude and type of pulmonary cellular response in term and preterm infants ventilated with RSV bronchiolitis. The cellular response in term infants with bronchiolitis differs from that in a control group of infants. These differences may reflect variations in cellular recruitment in the lung and/or variations in airway calibre.     

Nebulization of drugs in a nasal CPAP system

Aerosolized drugs have been used in infants for the treatment of respiratory distress syndrome and bronchopulmonary dysplasia (beta-agonists, steroids and surfactant) and bronchiolitis due to respiratory syncytial virus (epinephrine and ribavirin). Controlled clinical trials have, however, produced conflicting results, probably due in part to problems with the transportation of the aerosol from the nebulizer to the bronchioli. We have modified a nasal continuous positive airway pressure (CPAP) system permitting an aerosol to flow through a canal to the nasal prongs and into the airways of the infant. It has been used successfully for the administration of epinephrine, salbutamol, budesonide, acetylcysteine, natural surfactant and ribavirin to sick infants. The modified nasal CPAP system is a simple, safe, cost-efficient and baby-friendly system for respiratory support and drug treatment, which can be used in future trials of aerosolized drugs.     

Latent sensitisation to respiratory syncytial virus during acute bronchiolitis and lung function after recovery.

To determine whether latent sensitivity to respiratory syncytial virus antigen(s) occurs after infection, 27 infants with acute bronchiolitis were studied and compared with 15 hospital controls. Blood was collected for whole blood challenge, and histamine release was measured by a high performance liquid chromatography technique with fluorometric detection. There was a significantly greater histamine release to respiratory syncytial virus antigen(s) in those with bronchiolitis than in controls, expressed either in amount (median 154 nmol/l compared with 104 nmol/l) or percentage release (median 20% compared with 3%). There was a significant difference between index and control groups in terms of individual histamine responses. These findings strongly suggest that infants develop latent sensitivity to respiratory syncytial virus antigen(s) during the course of acute bronchiolitis. Serial lung function tests were performed in 15 infants. All infants had abnormalities of lung function at some stage, but the small numbers of subjects precluded comparison between ''sensitised'' and ''non-sensitised'' infants. Further study is indicated to define the relation of latent sensitisation and subsequent bronchial hyper-responsiveness after respiratory syncytial virus infection in infants.     

Plasma surfactant protein-B is elevated in infants with respiratory syncytial virus-induced bronchiolitis

Respiratory syncytial virus (RSV) is the most frequent cause of bronchiolitis. However the pathophysiology of bronchiolitis is unclear. Leukocytes, especially neutrophils, may play an important role in the pathogenesis of bronchiolitis. Whereas we have previously shown that neutrophils augment epithelial leakage and detachment in RSV infection in vitro, it is unknown whether epithelial damage occurs in vivo in infants with RSV bronchiolitis. We hypothesized that respiratory epithelial damage occurs in infants with RSV bronchiolitis and that surfactant proteins leak into the circulation. The plasma concentrations of surfactant protein-A and surfactant protein-B in infants with RSV bronchiolitis were measured by ELISA. Plasma immunoreactive surfactant protein-B in infants with RSV bronchiolitis was markedly higher than that in matching controls. Our study suggests that alveolocapillary permeability is increased in infants with RSV bronchiolitis in vivo and that surfactant protein-B may be a sensitive marker for lung injury in such infants.     

呼吸道合胞病毒毛细支气管炎患儿T细胞亚群检测的临床价值

目的：呼吸道合胞病毒(RSV)感染所致的毛细支气管炎日后发展为哮喘的机率很高,由于哮喘患儿机体存在明显的免疫功能紊乱,而RSV毛细支气管炎在这方面的研究不多,为此该研究探讨毛细支气管炎患儿T细胞亚群的变化及其临床意义。方法：采用流式细胞术对21例RSV毛细支气管炎患儿及20例正常儿童T细胞亚群进行检测。结果：RSV毛细支气管炎组与对照组外周血T细胞亚群CD4,CD8差异无显著性(P>0.05),CD4/CD8比值RSV毛细支气管炎组高于对照组,差异有显著性(P<0.05)。结论：RSV毛细支气管炎患儿存在与哮喘相似的T细胞亚群变化相关的免疫功能紊乱,提示两者在发病机制上存在一定的联系。     

Bronchoalveolar lavage cellular composition in acute asthma and acute bronchiolitis

OBJECTIVE: To compare cellular inflammation in the airways between acute bronchiolitis and asthma. STUDY DESIGN: Using a bronchoalveolar lavage with flexible bronchoscopy procedure, we investigated the cellular constituents of BAL fluid in children with acute exacerbation of asthma (n = 18) and infants with acute bronchiolitis caused by respiratory syncytial virus (n = 20). These results were compared with those of healthy control subjects (n = 14). RESULTS: Total lavage fluid recovered was similar in all groups. The total cell numbers were highest in the bronchiolitis group. The BAL cellular profile in the asthma group was characterized by a higher median (interquartile range) ratio of eosinophils (2.4% [1.6%-9.5%]; P <.01) than in the bronchiolitis group (0% [0%-0%]) or the control group (0% [0%-0%]). Neutrophil ratio was higher in the bronchiolitis group (40.0% [26.5%-50.0%]; P <.01), with no difference found between the asthma group (3.3% [2.0%-7.9%]) and the control group (2.0% [0.8%-5.5%]). CONCLUSIONS: Asthma and acute bronchiolitis are characterized by an elevated cellular percentage of eosinophils and neutrophils, respectively, in bronchoalveolar lavage fluid.     

Eosinophil cationic protein in nasopharyngeal secretions and serum of infants infected with respiratory syncytial virus

Eosinophil cationic protein (ECP) was assayed in nasopharyngeal secretion (NPS) and serum from 42 infants, hospitalized with acute lower respiratory infection, in El Salvador and the results analyzed in relation to etiology of the infection. ECP concentrations were high in NPS, at an average 50 times higher than those found in serum. Exceedingly high levels of ECP (> 1000 μg/L) were found more frequently in wheezing than in non-wheezing children (30% vs 7%) and, accordingly, were more commonly found in children hospitalized with bronchiolitis than in those with pneumonia. Excessive levels were significantly more common in girls than in boys. Of the 42 cases, 28 were found to be caused by respiratory syncytial virus (RSV) subgroup A, and 3 by RSV-B, by means of detection of RSV antigen in nasopharyngeal cells. ECP serum levels were moderately elevated during the acute phase of the respiratory infection and increased slightly but significantly, in cases with RSV antigen-positive bronchiolitis, but not in those with pneumonia. The ECP levels in NPS from patients in Sweden who, by antigen detection in NPS cells, were diagnosed as either RSV or para-influenza 3 infection or none of these, were similar. These results indicate that elevation of ECP in NPS is associated with acute lower respiratory infection in general, but particularly pronounced in cases of bronchiolitis. Elevation of ECP is not an exclusive consequence of RSV infection, but may occur to an equal extent in infections caused by other agents. Girls generally seem to be less prone than boys to developing airway obstruction and may, therefore, acquire severe bronchiolitis only when large amounts of inflammatory mediators, such as ECP, accumulate in the airways.     

Interleukin-16 in tracheal aspirate fluids of newborn infants

BACKGROUND: It is currently unknown if interleukin (IL)-16 exists in the lungs of ventilated infants, and because the predominant cells in the airways of infants with CLD are CD4+ macrophages, we hypothesized that IL-16 plays a role as a pro-inflammatory mediator in lung inflammation. AIMS: To examine if IL-16, a chemoattractant for CD4+ cells, is detectable in airway secretions of ventilated newborns. Its presence may be associated with lung inflammatory responses. STUDY DESIGN: Cohort cross-sectional study. SUBJECTS: Thirty-four mechanically ventilated newborn infants. MAIN OUTCOME MEASURES: Tracheal fluid (TF) specimens collected during the first month of life were examined for cell differentials determined from cytospin slides and supernatant was analyzed by ELISA for IL-16. RESULTS: Eighty-three cross-sectional tracheal fluid (TF) specimens were analyzed. Eleven of the 27 preterm but none of the 7 term infants developed chronic lung disease (CLD). IL-16, ranging from 203 to 42,073 pg/ml, was detected in 16 of the 46 specimens obtained from CLD infants, 1 of the 30 specimens from 16 non-CLD preterm and 2 of the 7 specimens from 7 term infants (p<0.001). Leukocyte counts (median 16.6 vs. 2.0 x 10(-9)/l, p<0.0001) and percentage neutrophils (median 93% vs. 73%, p<0.001) were higher in IL-16 positive specimens. CONCLUSION: IL-16 is detectable within the airway secretions of ventilated newborn infants and its presence is associated with a neutrophilic infiltration. Further studies are required to investigate its role in chronic inflammation in CLD.     

Incidence and predisposing factors for severe disease in previously healthy term infants experiencing their first episode of bronchiolitis

Aim: To determine the incidence and predisposing factors for severe bronchiolitis in previously healthy term infants <12 months of age experiencing their first episode of bronchiolitis. Methods: Epidemiological, clinical and virological data were prospectively collected. Severity was assessed by the need for ventilatory support. Results: Of the 310 infants enrolled, 16 (5.1%) presented with severe bronchiolitis requiring ventilatory support (11 since admission). Compared with infants with less severe bronchiolitis, infants with severe disease presented with lower birth weight, gestational age, postnatal weight and postnatal age, and were more likely to be born by cesarian section. C‐reactive protein positive results (>0.8 mg/dL) and pulmonary consolidation on chest X‐ray were more common among infants with severe disease. Severity was independently associated with younger age on admission <30 days, respiratory syncytial virus (RSV) infection and lymphocyte counts <3200/μL. No significant differences were found between epidemiologic variables. Conclusions: Severe bronchiolitis is uncommon in previously healthy term infants <12 months of age and when present develops soon after disease onset. Severity is predicted by young age and RSV carriage, whereas epidemiologic variables seem less likely to intervene.     

Concurrent serious bacterial infections in 2396 infants and children hospitalized with respiratory syncytial virus lower respiratory tract infections

BACKGROUND: At Driscoll Children's Hospital (Corpus Christi, Tex), we observed that most infants and children hospitalized for treatment of respiratory syncytial virus (RSV) bronchiolitis and/or pneumonia received broad-spectrum intravenous antibiotics despite having typical RSV signs and symptoms and positive RSV-rapid-antigen tests on admission. Physicians were concerned about the possibility of concurrent serious bacterial infections, especially in infants younger than 3 months and in those with infiltrates present on the chest x-ray films. OBJECTIVE: To report the frequency of concurrent serious bacterial infections in infants and children hospitalized for treatment of RSV lower respiratory tract infections. METHODS: The medical records of 2396 infants and children admitted to Driscoll Children's Hospital with RSV bronchiolitis and/or pneumonia during 7 RSV seasons from July 1, 1991, through June 30, 1998, were reviewed. RESULTS: There were positive cultures obtained from initial sepsis/meningitis workups on admission in 39 infants and children (1.6%). Of these, 12 (31%) were positive blood cultures and 27 (69%) were positive urine cultures. There were no positive cerebrospinal fluid cultures. All of the positive blood cultures contained either Staphylococcus epidermidis, Staphylococcus warneri, or Bacillus species, which are common contaminants. None of the patients received a standard 10-day course of intravenous antibiotic therapy. All of the positive urine cultures were typical urinary tract pathogens. All of the patients were treated. CONCLUSIONS: Concurrent serious bacterial infections are rare in infants and children hospitalized with RSV lower respiratory tract infections and the empiric use of broad-spectrum intravenous antibiotics is unnecessary in children with typical signs and symptoms of RSV bronchiolitis.