Prevalence of respiratory syncytial virus subgroups over six consecutive outbreaks: 1981-1987

Indirect immunofluorescence with strain-specific monoclonal antibodies was used to determine the phenotype of respiratory syncytial virus (RSV) isolates obtained from infants hospitalized in greater Boston over six successive outbreaks from 1981 to 1987. Of 981 isolates, 591 (60%) were classified as subgroup A and 383 (39%) as subgroup B. The prevalence of subgroups varied both between and within yearly outbreaks. In 1983-84 and 1984-85, both subgroups circulated concurrently and in almost equal proportions; in 1981-82, 1982-83, and 1985-86 subgroup A was dominant, accounting for 93% of all RSV isolates; and in 1986-87 subgroup B accounted for 89% of all RSV isolates. In some outbreaks both geographic and temporal clustering of subgroups occurred. No major differences in age, gender, or frequency of nosocomially acquired RSV between infants infected with either subgroup were seen, either overall or between or within yearly outbreaks. An expanded panel of monoclonal antibodies revealed further heterogeneity among subgroup A isolates. Comparison of these results with similar studies from other geographic locations indicated that the pattern of RSV subgroup prevalence is a localized phenomenon.     

Multicenter study of strains of respiratory syncytial virus

Two major groups of respiratory syncytial virus (RSV) strains, A and B, have been identified and their patterns of isolation determined in different communities but not simultaneously in multiple communities. In this study, we tested 483 RSV isolates from 14 university laboratories in the United States and Canada for the 1984/1985 and 1985/1986 RSV seasons; 303 (63%) isolates were group A, 114 (24%) were group B, and 66 (14%) could not be grouped. Isolates were subdivided into six subgroups within group A and three within group B; up to six and often four or more different subgroups were isolated in the same laboratory during the same RSV season. The pattern of group and subgroup isolations varied among laboratories during the same year and between years for the same laboratory. These differences suggest that RSV outbreaks are community, possibly regional, but not national phenomena. The ability to identify group and subgroup differences in isolates is a powerful tool for epidemiologic studies of RSV.     

Clinical characteristics of respiratory syncytial virus (RSV) subgroup infections in Japan.

The subgroup characteristics of 130 strains of respiratory syncytial virus (RSV) isolated in Sapporo during 9 epidemic years 1980-1989 were determined. Monoclonal antibodies raised against the RSV Long strains were used. Subgroup A included 77 (59.2%) isolates and subgroup B 52 (40.0%) strains, while 1 strain was considered to be a variant of a subgroup A strain. The distribution by age of infants and children was different for the 2 subgroups: less than 1 year of age infants with subgroup A infection dominated, greater than 1 year of age subgroup A infections were less common than subgroup B infections. These was no difference in type of illness between the subgroups. Bronchiolitis was the dominant diagnosis in all patients.     

An epidemiological study of respiratory syncytial virus infection in Yokohama, Japan for five years

The epidemiologic features of respiratory syncytial virus (RSV) infection were investigated by detecting the virus in throat swab specimens from patients with acute respiratory symptoms attending the sentinel surveillance clinics in Yokohama City in 5 seasons from July 1998 to June 2003. Throughout the 5 seasons, RSV was found from 181 in 2683 specimens tested (6.7%) by virus isolation in cell culture or genome detection using nested RT-PCR, and this detection rate followed that of influenza virus (infl.v.) (441/2683; 16.4%), while the proportion of RSV isolates in a season fluctuated from 12 to 22% of all causative viruses identified. Analysis of monthly detected number of strains revealed that the peak of RSV isolation was present in December which preceded that of infl.v. by 2 months. Moreover, RSV strains were isolated sporadically during late spring to early autumn (from May to September) when infl.v. was scarcely detected. Among 181 RSV strains, 172 could be subgrouped; 104 were identified as subgroup A, while 68 were B. Subgroup A were detected more frequently throughout the 5 seasons (57%), though the proportion varied seasonally and subgroup B exceeded both in 2000/2001 and 2002/2003 seasons (61% and 70%, respectively). Clinical characteristics of RSV-infected patients were compared with those infected with infl.v. Age distribution of cases revealed that RSV detected predominantly (79%) from lower age groups (less than 5 years) compared to infl. v (41%). As for the proportion of cases showing clinical symptoms of lower respiratory inflammation predominated in RSV-infected irrespective of age groups.     

Genetic diversity and molecular epidemiology of the G protein of subgroups A and B of respiratory syncytial viruses isolated over 9 consecutive epidemics in Korea

To study genetic variation and molecular epidemiology of the G protein of respiratory syncytial virus (RSV), 253 strains from a children's hospital in Korea over 9 consecutive epidemics were analyzed. Restriction analysis of the entire G protein gene demonstrated 24 genotypes among 188 subgroup A and 6 among 65 subgroup B isolates. Two to 4 dominant genotypes of subgroup A cocirculated, and different genotypes predominated in each epidemic. Predominant genotypes were replaced with new genotypes during consecutive epidemics. One of 2 dominant genotypes among subgroup B predominated alternately or concurrently. Phylogenetic analysis revealed that there were multiple lineages, with clustering related to their location and time of isolation among strains from Korea and worldwide. Geographic and temporal distinction have been shown more clearly for subgroup B than subgroup A. These results suggest that the G protein of RSV is continuously evolving, with a distinct pattern presumably due to immune selection in a localized region over time.     

Hospitalization Incidence,Mortality, and Seasonality of Common Respiratory Viruses Over a Period of 15 Years in a Developed Subtropical City

Information on respiratory viruses in subtropical region is limited.Incidence, mortality, and seasonality of influenza (Flu) A/B, respiratory syncytial virus (RSV), adenovirus (ADV), and parainfluenza viruses (PIV) 1/2/3 in hospitalized patients were assessed over a 15-year period (1998–2012) in Hong Kong.Male predominance and laterally transversed J-shaped distribution in age-specific incidence was observed. Incidence of Flu A, RSV, and PIV decreased sharply from infants to toddlers; whereas Flu B and ADV increased slowly. RSV conferred higher fatality than Flu, and was the second killer among hospitalized elderly. ADV and PIV were uncommon, but had the highest fatality. RSV, PIV 2/3 admissions increased over the 15 years, whereas ADV had decreased significantly. A “high season,” mainly contributed by Flu, was observed in late-winter/early-spring (February–March). The “medium season” in spring/summer (April–August) was due to Flu and RSV. The “low season” in late autumn/winter (October–December) was due to PIV and ADV. Seasonality varied between viruses, but predictable distinctive pattern for each virus existed, and temperature was the most important associating meteorological variable.Respiratory viruses exhibit strong sex- and age-predilection, and with predictable seasonality allowing strategic preparedness planning. Hospital-based surveillance is crucial for real-time assessment on severity of new variants.     

Biotyping, serotyping and ribotyping as epidemiological tools in the evaluation of Acinetobacter baumannii dissemination in hospital units, Sorocaba, São Paulo, Brazil

Dissemination of Acinetobacter baumannii strains in different units of a hospital in Sorocaba, S?o Paulo, Brazil was evaluated over a period of two years. By using biotyping, serotyping and ribotyping, 27 distinct clones were differentiated among 76 strains isolated between 1993-94, from clinical specimens of hospitalized patients. Two clones, 2:O4:A (biotype:serotype:ribotype) and 2:O29:A accounted for the majority of strains widely disseminated in the units during 1993. The introduction in the hospital setting, of a new clone, 6:O13:B, at the end of 1993 and its predominance through 1994 is discussed. Among 15 strains isolated from neonates, 6 (40%) belonged to the same clone, 2:O4:A. Interestingly, this clone was almost all recovered in neonatal intensive care unit, nursery and in pediatric unit. All strains were susceptible to imipenem and polymyxcin B. Multiresistant strains (up to 12 antimicrobial agents) accounted for 66.7% and 84.8% of the strains isolated in 1993 and in 1994, respectively.     

Antigenic and genomic diversity within group A respiratory syncytial virus

Antigenic analysis using monoclonal antibodies and genomic analysis using ribonuclease protection was done on 47 isolates of group A respiratory syncytial virus (RSV) recovered from children in St. Louis during four RSV seasons. Antigenic analysis identified four subgroups; of the three that included more than one member, those designated A/2 and A/2V had characteristic ribonuclease protection patterns. A third subgroup, A/4, exhibited more extensive genomic heterogeneity, but all isolates were distinguishable from those in subgroups A/2 and A/2V. Individual RSV epidemic seasons included isolates representing multiple subgroups of group A and multiple intrasubgroup variants, in addition to isolates from group B. Isolates that were indistinguishable by either antigenic or genomic analysis were present in more than one epidemic season. The subgroups may represent parallel evolutionary lineages, whose relevance to RSV immunity and pathogenesis requires further study.     

Correlation between respiratory syncytial virus genotype and severity of illness

Respiratory syncytial virus (RSV) causes seasonal outbreaks of respiratory tract infections, but the viral factors associated with virulence remain unknown. To determine whether RSV genotype correlated with severity of illness, isolates were characterized by phylogenetic analysis of the RSV G gene, and a composite score was used to quantify severity of illness. During the 1998-1999 and 1999-2000 winter seasons, 137 subgroup A and 84 subgroup B isolates were identified. The severity of illness caused by subgroup A isolates did not differ from that caused by subgroup B isolates (P=.086). However, the GA3 clade was associated with significantly greater severity of illness, compared with clades GA2 (P=.004) and GA4 (P=.016). In a subpopulation of patients < or =24 months old who had no known risk factors for severe RSV disease, clade GA3 was again associated with greater severity of illness, compared with clade GA2 (P=.018). Severity of RSV infection is associated with RSV genotype.     

Recombinant human deoxyribonuclease in infants with respiratory syncytial virus bronchiolitis

BACKGROUND: Treatment of hospitalized infants with respiratory syncytial virus (RSV) bronchiolitis is mainly supportive. Bronchodilators and systemic steroids are often used but do not reduce the length of hospital stay. Because hypoxia and airways obstruction develop secondary to viscous mucus in infants with RSV bronchiolitis, and because free DNA is present in RSV mucus, we tested the efficacy of the mucolytic drug recombinant human deoxyribonuclease (rhDNase). METHODS: In a multicenter, randomized, double-blind, controlled clinical trial, 225 oxygen-dependent infants admitted to the hospital for RSV bronchiolitis were randomly assigned to receive 2.5 mg bid of nebulized rhDNase or placebo until discharge. The primary end point was length of hospital stay. Secondary end points were duration of supplemental oxygen, improvement in symptom score, and number of intensive care admissions. RESULTS: There were no significant differences between the groups with regard to the length of hospital stay (p = 0.19) or the duration of supplemental oxygen (p = 0.07). The ratio (rhDNase/placebo) of geometric means of length of stay was 1.12 (95% confidence interval, 0.96 to 1.33); for the duration of supplemental oxygen, the ratio was 1.28 (95% confidence interval, 0.97 to 1.68). There were no significant differences in the rate of improvement of the symptom score or in the number of intensive care admissions. CONCLUSIONS: Administration of rhDNase did not reduce the length of hospital stay or the duration of supplemental oxygen in oxygen-dependent infants with RSV bronchiolitis.     

Concurrent circulation of antigenically distinct strains of respiratory syncytial virus during community outbreaks

Respiratory syncytial virus (RSV) is considered to be of a single serotype. Antigenic variants are detectable both by neutralization and monoclonal antibodies and have been divided into two broad categories, groups 1 and 2. Group 2 isolates have been considered to be uncommon. We used indirect immunofluorescence with strain-specific monoclonal antibodies to study RSV isolates from hospitalized infants in the greater Boston area. Of 223 RSV isolates recovered over a five-month period in 1983-1984, 125 (56%) were group 1, 92 (41%) were group 2, and 6 (3%) were of an intermediate character. Among 181 community-acquired RSV isolates, both temporal and geographic clustering was observed: group 1 isolates were common from January through March and predominated in central Boston; group 2 isolates were found principally in February and were acquired in outlying, particularly northern, areas. Strain-specific differences were not found with respect to sex, age, or clinical findings. An analysis of 82 RSV isolates from the 1981-1982 season showed 75 (91%) group 1 isolates and 7 (9%) group 2 isolates. We conclude that at least two antigenically distinct groups of RSV isolates may circulate concurrently in the community and that the prevalence of group 2 isolates appears greater than previously suspected.     

Retrospective comparison of respiratory syncytial virus and metapneumovirus clinical presentation in hospitalized children

Respiratory syncytial virus (RSV) and Human metapneumovirus (hMPV), members of Pneumoviridae family are common causes of acute respiratory tract infections (ARTI) among children. Study material includes routine nasopharyngeal samples obtained during 8-year period for hMPV and one single season for RSV in children hospitalized for ARTI between 0 and 15 years at the Center Hospitalier Universitaire (CHU) Saint Pierre in Brussels. Positive samples for RSV or hMPV identified by viral culture, lateral flow chromatography test for RSV or direct fluorescent assay for hMPV were selected retrospectively. Characteristics of children hospitalized for RSV or hMPV infections were compared. Children hospitalized for RSV infection were significantly younger and requiring more respiratory support, longer hospital stay and transfers in Pediatric intensive Care Units than those hospitalized for hMPV infection. Pneumonia diagnostic and antibiotics therapies were more significantly associated with hMPV infections. In conclusion, despite their genetic similarities, RSV, and hMPV present epidemiological and clinical differences in pediatric infections. Our results should be confirmed prospectively.     

Human monoclonal Fab fragments derived from a combinatorial library bind to respiratory syncytial virus F glycoprotein and neutralize infectivity.

Respiratory syncytial virus (RSV) is the most important cause, throughout the world, of severe viral lower respiratory tract illness in young children. Antibodies are known to mediate resistance to RSV infection and illness. We have isolated a number of human monoclonal Fab fragments to RSV F glycoprotein from a combinatorial antibody library expressed on the surface of phage. One of these neutralized a wide range of virus isolates, 10 subgroup A and 9 subgroup B isolates, with a titer (60% neutralization) of approximately 0.1-1.0 micrograms/ml. Another Fab neutralized diverse isolates at a concentration somewhat higher. These human Fab fragments show great promise for use in the prophylaxis or therapy of serious RSV lower respiratory tract disease. For intramuscular or intravenous administration, whole antibodies will be required, whereas for aerosol application, F(ab')2 or Fab fragments may suffice.     

Prospective Population-based Study of RSV-related Intermediate Care and Intensive Care Unit Admissions in Switzerland over a 4-Year Period (2001–2005)

Abstract Objectives:   Respiratory syncytial virus (RSV) infections are a leading cause of hospital admissions in small children. A substantial proportion of these patients require medical and nursing care, which can only be provided in intermediate (IMC) or intensive care units (ICU). This article reports on all children aged < 3 years who required admission to IMC and/or ICU between October 1, 2001 and September 30, 2005 in Switzerland. Patients and Methods:   We prospectively collected data on all children aged < 3 years who were admitted to an IMC or ICU for an RSV-related illness. Using a detailed questionnaire, we collected information on risk factors, therapy requirements, length of stay in the IMC/ICU and hospital, and outcome. Results:   Of the 577 cases reported during the study period, 90 were excluded because the patients did not fulfill the inclusion criteria; data were incomplete in another 25 cases (5%). Therefore, a total of 462 verified cases were eligible for analysis. At the time of hospital admission, only 31 patients (11%) were older than 12 months. Since RSV infection was not the main reason for IMC/ICU admission in 52% of these patients, we chose to exclude this subgroup from further analyses. Among the 431 infants aged < 12 months, the majority (77%) were former near term or full term (NT/FT) infants with a gestational age ≥ 35 weeks without additional risk factors who were hospitalized at a median age of 1.5 months. Gestational age (GA) < 32 weeks, moderate to severe bronchopulmonary dysplasia (BPD), and congenital heart disease (CHD) were all associated with a significant risk increase for IMC/ICU admission (relative risk 14, 56, and 10, for GA ≤ 32 weeks, BPD, and CHD, respectively). Compared with NT/FT infants, high-risk infants were hospitalized at an older age (except for infants with CHD), required more invasive and longer respiratory support, and had longer stays in the IMC/ICU and hospital. Conclusions:   In Switzerland, RSV infections lead to the IMC/ICU admission of approximately 1%–2% of each annual birth cohort. Although prematurity, BPD, and CHD are significant risk factors, non-pharmacological preventive strategies should not be restricted to these high-risk patients but also target young NT/FT infants since they constitute 77% of infants requiring IMC/ICU admission.     

A 1-year prospective study of the infectious etiology in patients hospitalized with acute exacerbations of COPD

INTRODUCTION: Infection is a major cause of acute exacerbations of COPD (AECOPDs). We aimed to study the infectious etiology related to AECOPD. METHODS: Patients admitted to an acute care hospital in Hong Kong with an AECOPD were recruited prospectively from May 1, 2004, to April 30, 2005. Sputum samples, nasopharyngeal aspirate (NPA) samples, and paired serology specimens were collected. Spirometry was performed with patients in the stable phase 2 to 3 months after hospital discharge. RESULTS: There were 643 episodes of AECOPD among 373 patients. Their mean age was 75.3 years (SD, 7.9 years) with 307 male patients. The mean FEV(1) was 40.4% predicted (SD, 18.7% predicted), and the mean FEV(1)/FVC ratio was 58.4% (SD, 16.0%). Among sputum samples from the 530 episodes of AECOPD hospital admissions that were saved, 13.0%, 6.0%, and 5.5%, respectively, had positive growth of Haemophilus influenzae, Pseudomonas aeruginosa, and Streptococcus pneumoniae. Among the 505 hospital admissions with patients who had NPA samples saved, 5.7%, 2.3%, 0.8%, and 0.8%, respectively, had influenza A, respiratory syncytial virus (RSV), influenza B, and parainfluenza 3 isolated from viral cultures. Paired serology test results revealed a fourfold rise in viral titers in 5.2%, 2.2%, and 1.4% of patients, respectively, for influenza A, RSV, and influenza B. Very severe airflow obstruction (stable-state spirometry) was associated with a higher chance of a positive sputum culture (FEV(1) >/= 30% predicted, 28.2%; FEV(1) < 30% predicted, 40.4%; p = 0.006). CONCLUSION: H influenzae and influenza A were the most common etiologic agents in patients who were hospitalized with AECOPDs. More severe airflow obstruction was associated with a higher chance of a positive sputum culture finding.     

5岁以下儿童反复喘息发作呼吸道病原分析

目的探讨5岁以下儿童反复喘息发作与呼吸道感染之间的关系。方法 2014年1月1日至2014年12月31日在我科住院治疗的525例5岁以下反复喘息儿童按年龄分三组:A组30天-1岁,B组1-3岁,C组3-5岁。收集急性喘息发作期血清,采用间接免疫荧光法同时检测:腺病毒(ADV)、呼吸道合胞病毒(RSV)、甲型流感病毒(IAV)、乙型流感病毒(IBV)、副流感病毒(PIVs)、嗜肺军团菌Ⅰ型(LP1)、肺炎支原体(MP)、Q热立克次体(COX)、肺炎衣原体(CP)9种呼吸道病原体Ig M抗体。结果呼吸道病原体Ig M检测阳性者233例(阳性率44.38%);MP检测阳性率最高,达24.38%;其次是ADV和RSV,阳性率分别为10.10%和9.90%。不同年龄组喘息儿童病原体检测种类亦不相同。A组以RSV检测阳性率最高,达18.10%,显著高于其他组患儿(P0.01);B组和C组患儿以MP检测阳性率最高,分别为31.15%和25.22%,高于A组(P0.05)。结论儿童喘息反复发作主要与呼吸道感染有关,MP、ADV和RSV是本地区引起5岁以下儿童喘息发作的主要病原体。     

Molecular epidemiology of Escherichia coli bacteremia in liver transplant recipients

F. Bert, B. Huynh, F. Dondero, J.R. Johnson, C. Paugam‐Burtz, F. Durand, J. Belghiti, D. Valla, R. Moreau, M.‐H. Nicolas‐Chanoine. Molecular epidemiology of Escherichia coli bacteremia in liver transplant recipients.
Transpl Infect Dis 2011: 13: 359–365. All rights reserved Abstract: The characteristics of Escherichia coli strains causing bacteremia in profoundly immunosuppressed patients such as transplant recipients are undefined. The phylogenetic group and the virulence genotype of 57 distinct E. coli strains that caused bacteremia in 53 liver transplant recipients were investigated, and the association of these characteristics with host factors and in‐hospital mortality was examined. Phylogenetic groups A, B1, B2, and D accounted for 39%, 10%, 25%, and 26% of the isolates, respectively. The most prevalent virulence genes were fyuA (yersiniabactin system: 70%) and iutA (aerobactin system: 63%), whereas hlyA (alpha‐hemolysin) and cnf1 (cytotoxic necrotizing factor 1) occurred in only 14% and 12% of isolates, respectively. Most virulence genes were significantly more prevalent among group B2 and D isolates, vs. group A and B1 isolates. The overall rate of in‐hospital mortality after E. coli bacteremia was 20%. Predictors of mortality included onset of bacteremia within 30 days of transplantation or during the intensive care unit stay, and non‐urinary source and cutaneous source, but not E. coli phylogenetic group or virulence profile. Compared with historical E. coli bloodstream isolates from non‐transplant patients, those from liver transplant recipients are characterized by a higher prevalence of groups A and B1 isolates and reduced virulence gene content. This finding can be explained by the severely immunocompromised status of the patients and the predominance of abdominal‐source bacteremic episodes. Time of onset and source of bacteremia, not bacterial characteristics, predict mortality.