Respiratory syncytial virus-enriched globulin for the prevention of acute otitis media in high risk children

Approaches to the Prevention and Treatment of Respiratory Syncytial Virus Infection in Children: Rationale and Progress to Date

Respiratory syncytial virus (RSV) is the most common cause of lower respiratory tract infection (LRTI) in children, and is associated with long-term pulmonary sequelae for up to 30 years after infection. The mainstay of RSV management is supportive therapy such as supplemental oxygen. Palivizumab (Synagis™-AstraZeneca), a monoclonal antibody targeting the RSV F protein site II, has been licensed for the prevention of RSV in high-risk groups since 1998. There has been recent promising progress in preventative strategies that include vaccines and long-acting, high-potency monoclonal antibodies. Nirsevimab (Beyfortus™-AstraZeneca/Sanofi), a monoclonal antibody with an extended half-life, has recently been registered in the European Union and granted licensure by the US Food and Drug Administration. Furthermore, a pre-fusion sub-unit protein vaccine has been granted licensure for pregnant women, aimed at protecting their young infants, following established safety and efficacy in clinical trials (Abrysvo™-Pfizer). Also, multiple novel antiviral therapeutic options are in early phase clinical trials. The next few years have the potential to change the landscape of LRTI through improvements in the prevention and management of RSV LRTI. Here, we discuss these new approaches, current research, and clinical trials in novel therapeutics, monoclonal antibodies, and vaccines against RSV infection in infants and children.

Respiratory Syncytial Virus-associated Acute Otitis Media in Infants and Children

Despite recent declines in the incidence of acute otitis media (AOM), more than 5 million cases and 5-6 million primary AOM visits still occur in young children in the United States, resulting in $4.4 billion direct medical costs annually. Our aims in this review are to describe the role of respiratory syncytial virus (RSV) in the etiology of AOM, discuss the prospect of prevention of RSV-associated AOM through immunization, and suggest future research strategies to assess the impact of immunization on RSV-associated AOM.

Characterization of circulating RSV strains among subjects in the OUTSMART-RSV surveillance program during the 2016-17 winter viral season in the United States

Background

Respiratory syncytial virus (RSV) is an established cause of serious lower respiratory disease in infants, elderly and high-risk populations. The OUTSMART surveillance program aims to characterize patient populations and currently circulating RSV strains, and monitor temporal and geographic evolution of RSV F and G proteins in the U.S.

Methods

The OUTSMART 2016–17 study collected RSV-positive samples from 25 RSVAlert^® laboratories from 4 U.S. regions and Puerto Rico during November 2016 through March 2017. Frequencies of A and B subtypes and genotypes were determined for several demographic and geographic variables. To gauge the representativeness of the OUTSMART patients, results were compared to discharge data from the NEDS and NIS databases.

Results

A total of 1,041 RSV-positive samples with associated demographic data were obtained and the RSV F gene and second variable region of the G gene were sequenced. The majority of samples (76.0%) came from children under 2 years old: <1 year (48.4%), 1–2 years (27.6%). The OUTSMART patient sample was similar to NEDS and NIS for age, gender, and geographic location. Both OUTSMART and national RSV cases peaked in January. Of OUTSMART samples, 45.3% were subtype A, 53.7% were subtype B and 1.0% were mixed A and B. The percentage of RSV B cases increased with increasing age. Hospitalization (length of hospital stay, LOS, >24 hrs) occurred in 29.0% of patients of which 52.0% had RSV B. Outpatients (LOS <24 hrs) were 64.4% of total of which 73.3% were diagnosed in the ER and discharged, while only 6% were diagnosed in other outpatient settings.

Conclusions

The OUTSMART 2016–17 study was representative of the U.S. RSV experience. Geographic and temporal information from the RSV surveillance program will be used to establish a molecular baseline of RSV F and G sequence variability and to help inform development of novel agents for RSV prophylaxis and treatment.

RI-002, an intravenous immunoglobulin containing high titer neutralizing antibody to RSV and other respiratory viruses for use in primary immunodeficiency disease and other immune compromised populations

INTRODUCTION

Novel immune globulin (IG) products (RI-002, RI-001) have been designed to provide protection against respiratory syncytial virus (RSV) mediated respiratory illness while at the same time meeting the manufacturing requirements established by FDA for antibody supplementation in immunocompromised subjects. Areas covered: This review covers the manufacture and development of both RI-001 and RI-002, including the selection of plasma donors for IG preparation with high-titers of anti-RSV antibody, in vitro, and preclinical data in the cotton rat model S. hispidus, and clinical trials including Phase II and compassionate use studies of RI-001 and a multi-center, pivotal Phase III study of RI-002 in PIDD patients. Expert commentary: The data demonstrate that RI-002 is efficacious in the prevention and treatment of RSV in preclinical normal and immune suppressed animal models and is safe and efficacious in the treatment of patients with various forms of primary immunodeficiency disease (PIDD). This product offers potential advantages over other available IG's for prophylaxis in immunocompromised patients requiring polyclonal immunoglobulin supplementation because of its unique antibody composition. In addition to its enhanced neutralizing anti-RSV activity and its polyclonal IG composition, there is preclinical data to support the use of RI-002 for humoral protection against other respiratory pathogens.

Efficacy, Safety, and Pharmacokinetics of a New 10 % Liquid Intravenous Immunoglobulin Containing High Titer Neutralizing Antibody to RSV and Other Respiratory Viruses in Subjects with Primary Immunodeficiency Disease

PURPOSE

Immune globulins for IgG supplementation have been produced for over 35 years with essentially no differentiating features regarding their specific antibody composition. Furthermore, the compositions of plasma donor pools used for IG manufacturing are not standardized. While all immune globulin products meet the specifications set by the US FDA for antibodies to pathogens like measles and polio, they have variable levels of antibodies to other important viruses and infectious pathogens, particularly respiratory syncytial virus (RSV).

METHODS

An IVIG was developed that satisfies the requirements for treating patients with primary immune deficiency disease (PIDD) and also has standardized elevated levels of RSV neutralizing antibodies (RI-002). Plasma donors who have naturally occurring high circulating levels of neutralizing anti-RSV antibody were selected as the source for manufacturing IVIG to treat patients with PIDD to prevent serious bacterial infections. While the introduction of the monoclonal antibody Palivizumab has had a dramatic impact in diminishing the burden of RSV disease in the pediatric population, it does not meet the standards for replacing the deficient immune compartments of patients with PIDD.

RESULTS

Fifty-nine patients with PIDD at 9 different sites across the US were enrolled in this study and received regular infusions of RI-002 over the course of 1 year.

CONCLUSIONS

There were zero serious bacterial infections, thus meeting the primary endpoint for this trial. The secondary endpoints including days missed from work due to infection, unscheduled visits to the physician, and days of hospitalization due to infection compared favorably to published reports of other IVIG products.

Co-infections with respiratory viruses in dogs with bacterial pneumonia

Background

Bacterial pneumonia (BP) is an inflammation of the lower airways and lung parenchyma secondary to bacterial infection. The pathogenesis of BP in dogs is complex and the role of canine respiratory viruses has not been fully evaluated.

Objectives

The aim of this study was to investigate the occurrence of viral co‐infections in dogs with BP and to assess demographic or clinical variables as well as disease severity associated with viral co‐infections.

Animals

Twenty household dogs with BP caused by opportunistic bacteria and 13 dogs with chronic (>30 days) tracheobronchitis caused by Bordetella bronchiseptica (BBTB).

Methods

Prospective cross‐sectional observational study. Diagnosis was confirmed by clinical and laboratory findings, diagnostic imaging, and cytologic and microbiologic analysis of bronchoalveolar lavage or transtracheal wash fluid. Canine parainfluenza virus (CPIV), canine adenovirus, canine herpes virus, canine influenzavirus, canine distemper virus, canine respiratory coronavirus (CRCoV) and canine pneumovirus, as well as B. bronchiseptica and Mycoplasma spp. were analyzed in respiratory samples using PCR assays.

Results

CPIV was detected in 7/20 and CRCoV in 1/20 dogs with BP. Respiratory viruses were not detected in dogs with BBTB. There were no significant differences in clinical variables between BP dogs with and without a viral co‐infection.

Conclusion and Clinical Importance

Respiratory viruses were found frequently in dogs with BP and may therefore play an important role in the etiology and pathogenesis of BP. Clinical variables and disease severity did not differ between BP dogs with and without viral co‐infection.

Differential impact of respiratory syncytial virus and parainfluenza virus on the frequency of acute otitis media is explained by lower adaptive and innate immune responses in otitis-prone children

BACKGROUND

Acute otitis media (AOM) is a leading cause of bacterial pediatric infections associated with viral upper respiratory infections (URIs). We examined the differential impact of respiratory syncytial virus (RSV) and parainfluenza virus URIs on the frequency of AOM caused by Streptococcus pneumoniae (Spn) and nontypeable Haemophilus influenzae (NTHi) in stringently defined otitis-prone (sOP) and non-otitis-prone (NOP) children as a potential mechanism to explain increased susceptibility to AOM.

METHODS

Peripheral blood and nasal washes were obtained from sOP and NOP children (n = 309). Colonization events and antiviral responses consisting of total specific immunoglobulin G (IgG) responses, neutralizing antibody responses, and T-cell responses were determined. Isolated neutrophils were infected with varying multiplicities of infection of both viruses, and opsonophagocytosis potential was measured.

RESULTS

A significant increase was found in frequency of AOM events caused by Spn and NTHi, with a concurrent RSV infection in sOP children. These results correlated with diminished total RSV-specific IgG, higher viral nasal burdens, and lower IgG neutralizing capacity. The sOP children had diminished T-cell responses to RSV that correlated with lower Toll-like receptor 3/7 transcript and decreased expression of HLA-DR on antigen-presenting cells. RSV interfered with the Spn phagocytic capacity of neutrophils in a dose-dependent manner. Parainfluenza virus infections did not differentially affect AOM events in sOP and NOP children.

CONCLUSIONS

Lower innate and adaptive immune responses to RSV in sOP children may slow the kinetics of viral clearance from the nasopharynx and allow for viral interference with antibacterial immune responses, thus contributing to increased frequency of AOMs.

Adherence to Immunoprophylaxis Regimens for Respiratory Syncytial Virus Infection in Insured and Medicaid Populations

BACKGROUND

Immunoprophylaxis is the only pharmaceutical intervention for mitigating respiratory syncytial virus (RSV) infection. Patient level data on adherence to American Academy of Pediatrics (AAP) immunoprophylaxis recommendations are limited. This study characterizes adherence to AAP guidelines in privately insured and Medicaid populations.

METHODS

We performed a retrospective birth cohort study of 211 174 privately insured children in Northern California; and 458 837 publicly insured children in Tennessee born between January 1, 1996 and December 31, 2008. Adherence to the AAP guideline was defined for eligible infants as the number of doses of RSV immunoprophylaxis administered over the number recommended for 4 mutually exclusive eligibility groups: chronic lung disease, prematurity <29 weeks, prematurity <32 weeks, and other eligibility.

RESULTS

We identified 3456 California (Kaiser Permanente Northern California [KPNC]) and 12 251 Tennessee (Tennessee Medicaid [TennCare]) infants meeting AAP eligibility criteria. Immunoprophylaxis administration increased over the study period, from 15% for all eligible groups in 1998 to 54% in 2007. Adherence was highest among babies with chronic lung disease (KPNC 67% and TennCare 55%). Nonadherence (0% adherence) was greatest among infants of African American mothers (adjusted odds ratio [AOR] = 1.32; 95% confidence interval [CI] = .98-1.78); those with mothers with less than a high school education (AOR = 1.58; CI = 1.09-2.30) in KPNC; and in infants of Hispanic mothers in TennCare (AOR = 1.65; CI = 1.24-2.20). In KPNC, 0.11% of ineligible term infants and 5% of ineligible premature infants received immunoprophylaxis; the corresponding proportions in TennCare were 1% and 11%.

CONCLUSIONS

Overall adherence with AAP guidelines has increased over time. Considerable overuse and underuse of immunoprophylaxis are evident with identifiable risk groups to target for improvement.

Seasonality of acute otitis media and the role of respiratory viral activity in children

BACKGROUND

Acute otitis media (AOM) occurs as a complication of viral upper respiratory tract infections in young children. AOM and respiratory viruses both display seasonal variation. Our objective was to examine the temporal association between circulating respiratory viruses and the occurrence of pediatric ambulatory care visits for AOM.

METHODS

This retrospective study included 9 seasons of respiratory viral activity (2002 to 2010) in Utah. We used Intermountain Healthcare electronic medical records to assess community respiratory viral activity via laboratory-based active surveillance and to identify children <18 years with outpatient visits and International Classification of Diseases, Ninth Revision codes for AOM. We assessed the strength of the association between AOM and individual respiratory viruses using interrupted time series analyses.

RESULTS

During the study period, 96,418 respiratory viral tests were performed; 46,460 (48%) were positive. The most commonly identified viruses were respiratory syncytial virus (22%), rhinovirus (8%), influenza (8%), parainfluenza (4%), human metapneumovirus (3%) and adenovirus (3%). AOM was diagnosed during 271,268 ambulatory visits. There were significant associations between peak activity of respiratory syncytial virus, human metapneumovirus, influenza A and office visits for AOM. Adenovirus, parainfluenza and rhinovirus were not associated with visits for AOM.

CONCLUSIONS

Seasonal respiratory syncytial virus, human metapneumovirus and influenza activity were temporally associated with increased diagnoses of AOM among children. These findings support the role of individual respiratory viruses in the development AOM. These data also underscore the potential for respiratory viral vaccines to reduce the burden of AOM.

Detection of respiratory viruses in nasopharyngeal secretions and middle ear fluid from children with acute otitis media

CONCLUSIONS

Our results suggest that various respiratory viruses contribute to the pathogenesis of acute otitis media (AOM).

OBJECTIVE

AOM is one of the most common complications of viral upper respiratory tract infections in children. Recently, the importance of respiratory viruses has been stressed as causative agents of AOM.

SUBJECTS AND METHODS

A total of 1092 children < or =10 years old (average age 1.38 years) diagnosed as having AOM between 2002 and 2004 were studied. Bacterial and viral cultures of both nasopharyngeal secretions (NPS) and middle ear fluid (MEF) were performed for all 1092 children. Body temperature, changes of the tympanic membrane, and the number of days from the onset of illness were analyzed.

RESULTS

Respiratory viruses were detected in 360 of 1092 NPS specimens, including 157 isolates of respiratory syncytial virus and 88 of influenza virus. Among 1092 MEF specimens, 102 were virus-positive, including 43 for respiratory syncytial virus and 29 for influenza virus. In 75 children, respiratory viruses were only detected in MEF. The viral detection rate was higher in children with fever at an early stage of their illness. The tympanic membrane changes associated with viral infection tended to be less severe, while changes were more severe in cases with bacterial infection, especially co-infection with bacteria and viruses.

Respiratory viruses other than influenza virus: impact and therapeutic advances

Though several antivirals have been developed and marketed to treat influenza virus infections, the development of antiviral agents with clinical activity against other respiratory viruses has been more problematic. Here we review the epidemiology of respiratory viral infections in immunocompetent and immunocompromised hosts, examine the evidence surrounding the currently available antivirals for respiratory viral infections other than influenza, highlight those that are in the pipeline, and discuss the hurdles for development of such agents.

WITHDRAWN: Immunoglobulin for preventing respiratory syncytial virus infection

BACKGROUND

Respiratory Syncytial virus, the most important cause of lower respiratory tract infections in infants and young children in industrialized countries, is associated with increased morbidity in premature infants with or without bronchopulmonary dysplasia as well as those with congenital heart disease. Because of observations that lower rates of disease occur immediately after birth, presumably due to vertical transmission of maternal antibody, and animal studies where protection from pneumonia was observed through administration of immune globulin, the efficacy of passive prophylaxis in premature infants has been studied.

OBJECTIVES

This meta-analysis was performed to assess the effects of polyclonal respiratory syncytial virus hyperimmune globulin or monoclonal antibody in preventing RSV hospitalization, receipt of intensive care, mechanical ventilation, and mortality in those with underlying prematurity, bronchopulmonary dysplasia, or congenital heart disease.

SEARCH STRATEGY

We searched the Cochrane Acute Respiratory Infections trials register and MEDLINE in March, 1999. In addition, abstracts on these topics were sought from the Pediatric Academies Meetings and the Intersciences Conference on Antimicrobial Agents and Chemotherapy for the years 1994 to 1997, inclusive.

SELECTION CRITERIA

Randomized, controlled trials of prevention of RSV using immune globulin, respiratory syncytial virus immune globulin, or monoclonal RSV antibody in children with prematurity, bronchopulmonary dysplasia or congenital heart disease.

DATA COLLECTION AND ANALYSIS

Two authors independently abstracted data and assessed study quality. Only incidences could be pooled because data for durations was summarized in a manner that did not allow combining results across the studies.

MAIN RESULTS

Four studies with a total of 2598 subjects were included in the main analysis. All were randomized controlled trials. Two trials were not blinded. Three studies examined RSV hyperimmune globulin and one examined monoclonal RSV antibody. A study of a different monoclonal RSV antibody could not be included because it has not been presented or published. The pooled Peto Odds Ratios favoring prophylaxis were 0.48 (95% CI 0.37, 0.64), 0.47 (0.29, 0.77), and 0.99 (0.48, 2.07) for incidence of hospitalization, incidence of ICU admission, and incidence of mechanical ventilation, respectively. The numbers needed to prevent one hospitalization and one ICU admission are 17 and 50 respectively.

AUTHORS' CONCLUSIONS

RSVIG is effective in preventing RSV hospitalizations and admission to the intensive care unit, but not in preventing mechanical ventilation. There was a non-significant trend towards a higher mortality in children given RSVIG.

Acute otitis media and respiratory viruses

The present study was performed to elucidate the clinical outcome, and etiology of acute otitis media (AOM) in children based on virologic and bacteriologic tests. The study group consisted of 120 children aged 6 to 144 months with AOM. Middle ear fluid (MEF) was tested for viral pathogens by reverse transcriptase polymerase chain reaction (RT-PCR) and for bacteria by gram-staining and culture. Clinical response was assessed on day 2 to 4, 11 to 13, 26 to 28. Respiratory viruses were isolated in 39 patients (32.5%). Respiratory syncytial virus (RSV) (46.5%) was the most common virus identified in MEF samples, followed by human rhinovirus (HRV) (25.6%), human coronavirus (HCV) (11.6%), influenza (IV) type A (9.3%), adenovirus type sub type A (AV) (4%), and parainfluenza (PIV) type -3 (2%) by RT-PCR. In total 69 bacterial species were isolated from 65 (54.8%) of 120 patients. Streptococcus pneumoniae (S. pneumoniae) was the most frequently isolated bacteria. Viral RNA was detected in 31 (56.3%) of 55 bacteria-negative specimens and in 8 (12.3%) of 65 bacteria-positive MEF samples. No significant differences were found between children representing viral infection alone, combined viral and bacterial infection, bacterial infection alone, and neither viral nor bacterial infection, regarding clinical cure, relapse and reinfection rates. A significantly higher rate of secretory otitis media (SOM) was observed in alone or combined RSV infection with S. pneumonia or Haemophilus influenzae (H. influenzae) than in other viruses infection. Conclusion. This study provides information about etiologic agents and diagnosis of AOM in Turkish children. The findings highlight the importance of common respiratory viruses and bacterial pathogens, particularly RSV, HRV, S. pneumoniae and H. influenzae, in predisposing to and causing AOM in children.

Role of respiratory syncytial virus in acute otitis media: implications for vaccine development

We summarize herein the results of various virologic studies of acute otitis media (AOM) conducted at our site over a 10-year period. Among 566 children with AOM, respiratory syncytial virus (RSV) was the most common virus identified in either middle ear fluid or nasal wash; it was found in 16% of all children and 38% of virus-positive children. Seventy-one percent of the children with RSV were 1 year of age or older, which was significantly older than all other viruses combined (P=0.045). RSV infection was associated with the common bacterial pathogens causing AOM. Past efforts to develop vaccines for RSV have emphasized prevention of lower respiratory tract infection in infants, which is a more serious problem but less common than AOM. Our results suggest that RSV vaccines that work only against infection in older children may have value in preventing AOM, the most common pediatric disease.

Evolving role of leukotrienes in the pathogenesis of viral infections, including otitis media

Otitis media (OM) is one of the most common childhood disorders and has been associated with an alarming rise in prevalence. Because medical therapy with antibiotics, antihistamines, decongestants, and corticosteroids has no demonstrable efficacy in the treatment of OM, the mainstay of treatment is surgical intervention. Although effective, surgical treatment is quite expensive and exposes patients to the risks associated with general anesthesia. Results of recent studies suggest that locally produced leukotrienes may play a role in the pathogenesis of OM. As such, a potential candidate for treatment of OM is the leukotriene receptor antagonist, montelukast, which has been approved by the US Food and Drug Administration for the treatment of asthma and/or allergic rhinitis. If proven effective, this drug's safety/convenience profiles and indication for children as young as 6 months of age would make it suitable for treatment of OM, and perhaps even prophylaxis of OM in at-risk populations.

A high prevalence of new onset otitis media during parent diagnosed common colds

INTRODUCTION

Past studies suggest that the majority of new otitis media (OM) diagnoses is a complication of a colds/flu. A prospective format was used to determine the coincidence of otitis media and parent diagnosed cold/flu episodes in young children followed over a typical cold/flu season.

METHODS

Eighteen families with children aged 1-8 years were followed from October 1 to April 30 using parent-completed daily diaries focused on cold/flu signs and weekly examinations using pneumatic otoscopy for diagnosis of the presence/absence of otitis media.

RESULTS

Overall, 108 cold episodes were documented in 36 enrolled children with 20 colds (19%) occurring during a pre-existing OM episode and 40 colds (37%) complicated by a new OM episode. Conversely, there were 82 new OM episodes, 40 (49%) were associated with a cold in the individual child and 18 (22%) with a concurrent cold in a family member. The median duration of the OM episodes was approximately 2 weeks but this was longer for OM episodes where earache was reported.

CONCLUSION

The results confirm past observation relating new OM episodes to a concurrent cold/flu but show these episodes to usually be of short duration. Two sources of potential bias were identified for point prevalence study formats: the presence of a pre-existing OM for a new onset cold/flu and the possibility of subclinical colds in patients with new OM episodes. These biases reinforce the need for longitudinal study formats to address this important relationship.

The therapeutic potential of monoclonal antibodies against respiratory syncytial virus

Attempts to develop a vaccine against respiratory syncytial virus (RSV), the major cause of lower respiratory tract disease in infants and young children, have been unsuccessful. Passive immunisation with antibody to RSV has been found to be an effective alternative method for prophylaxis. The product currently in use for RSV passive immunisation, a preparation of purified human IgG containing virus-neutralising activity, requires monthly iv. infusions. Monoclonal antibodies (mAbs) are currently under development as an alternative means of treatment that would require lower doses. The first such mAb was recently approved for RSV prophylaxis in the USA. The mucosal delivery of antibodies is also effective and a mAb nose drop treatment for immunoprophylaxis is under development. The potential of passive immunisation for the treatment of existing RSV infections is not clear. Antibody treatment following infection clearly suppresses viral replication but it may not reduce disease once inflammatory processes have been initiated.

Chinchilla and murine models of upper respiratory tract infections with respiratory syncytial virus

Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections in infants and the elderly. While the primary infection is the most serious, reinfection of the upper airway throughout life is the rule. Although relatively little is known about either RSV infection of the upper respiratory tract or host mucosal immunity to RSV, recent literature suggests that RSV is the predominant viral pathogen predisposing to bacterial otitis media (OM). Herein, we describe mouse and chinchilla models of RSV infection of the nasopharynx and Eustachian tube. Both rodent hosts were susceptible to RSV infection of the upper airway following intranasal challenge; however, the chinchilla proved to be more permissive than the mouse. The chinchilla model will likely be extremely useful to test the role of RSV in bacterial OM and the efficacy of RSV vaccine candidates designed to provide mucosal and cytotoxic T-lymphocyte immunity. Ultimately, we hope to investigate the relative ability of these candidates to potentially protect against viral predisposal to bacterial OM.

The novel parainfluenza virus hemagglutinin-neuraminidase inhibitor BCX 2798 prevents lethal synergism between a paramyxovirus and Streptococcus pneumoniae

An association exists between respiratory viruses and bacterial infections. Prevention or treatment of the preceding viral infection is a logical goal for reducing this important cause of morbidity and mortality. The ability of the novel, selective parainfluenza virus hemagglutinin-neuraminidase inhibitor BCX 2798 to prevent the synergism between a paramyxovirus and Streptococcus pneumoniae was examined in this study. A model of secondary bacterial pneumonia after infection with a recombinant Sendai virus whose hemagglutinin-neuraminidase gene was replaced with that of human parainfluenza virus type 1 [rSV(hHN)] was established in mice. Challenge of mice with a sublethal dose of S. pneumoniae 7 days after a sublethal infection with rSV(hHN) (synergistic group) caused 100% mortality. Bacterial infection preceding viral infection had no effect on survival. The mean bacterial titers in the synergistic group were significantly higher than in mice infected with bacteria only. The virus titers were similar in mice infected with rSV(hHN) alone and in dually infected mice. Intranasal administration of BCX 2798 at 10 mg/kg per day to the synergistic group of mice starting 4 h before virus infection protected 80% of animals from death. This effect was accompanied by a significant reduction in lung viral and bacterial titers. Treatment of mice 24 h after the rSV(hHN) infection showed no protection against synergistic lethality. Together, our results indicate that parainfluenza viruses can prime for secondary bacterial infections. Prophylaxis of parainfluenza virus infections with antivirals might be an effective strategy for prevention of secondary bacterial complications in humans.

Respiratory viruses predisposing to bacterial infections: role of neuraminidase

BACKGROUND AND METHODS

Viral-bacterial coinfections in humans are well-documented. Viral infections often lead to bacterial superinfections. In vitro and animal models for influenza, as well as molecular microbiology study of viruses and bacteria, provide an understanding of the mechanisms that explain how respiratory viruses and bacteria combine to cause disease. This article focuses on viral and bacterial combinations, particularly synergism between influenza and Streptococcus pneumoniae.

RESULTS

Potential mechanisms for synergism between viruses and bacteria include: virus destruction of respiratory epithelium may increase bacterial adhesion; virus-induced immunosuppression may cause bacterial superinfections; and inflammatory response to viral infection may up-regulate expression of molecules that bacteria utilize as receptors. Influenza and parainfluenza viruses possess neuraminidase (NA) activity, which appears to increase bacterial adherence after viral preincubation. Experimental studies demonstrate that viral NA exposes pneumococcal receptors on host cells by removing terminal sialic acids. Other studies show that inhibition of viral NA activity reduces adherence and invasion of S. pneumoniae, independently of effects on viral replication. Clinical studies reveal that influenza vaccination reduces the incidence of secondary bacterial respiratory tract infections.

CONCLUSIONS

Detection of viral factors (e.g. high NA activity) that increase the likely potential of epidemic/pandemic influenza strains for causing morbidity and mortality from secondary bacterial infections provides new possibilities for intervention. Additional study is needed to identify the mechanisms for the development of bacterial complications after infections with respiratory syncytial virus and other important respiratory viruses that lack NA activity. Prevention of bacterial superinfection is likely to depend on effective antiviral measures.

Revised indications for the use of palivizumab and respiratory syncytial virus immune globulin intravenous for the prevention of respiratory syncytial virus infections

Palivizumab and Respiratory Syncytial Virus Immune Globulin Intravenous (RSV-IGIV) are licensed by the Food and Drug Administration for use in preventing severe respiratory syncytial virus (RSV) infections in high-risk infants, children younger than 24 months with chronic lung disease (formerly called bronchopulmonary dysplasia), and certain preterm infants. This report summarizes the clinical trial information on which the guidance in the accompanying policy statement for administering RSV prophylaxis to certain children with a history of preterm birth, chronic lung disease, or congenital heart disease is based. On the basis of results of a recently completed clinical trial, palivizumab is appropriate for infants and young children with hemodynamically significant congenital heart disease. RSV-IGIV should not be used in children with hemodynamically significant heart disease. Palivizumab is preferred for most high-risk infants and children because of ease of intramuscular administration. Monthly administration of palivizumab during the RSV season results in a 45% to 55% decrease in the rate of hospitalization attributable to RSV. Because of the large number of infants born after 32 to 35 weeks' gestation and because of the high cost, immunoprophylaxis should be considered for this category of preterm infants only if 2 or more risk factors are present.

Prevention of otitis media caused by viral upper respiratory tract infection: vaccines, antivirals, and other approaches

Otitis media (OM) imposes significant morbidity on the pediatric age group and a large financial burden on the general population. Because standard medical treatments are not highly efficacious in resolving the accompanying middle ear (ME) inflammation, a goal of current research is OM prevention. Past studies show that new episodes of OM are usually a complication of viral upper respiratory infection (vURI), and therefore, a rational approach to achieving that goal is to develop intervention strategies that target vURI-associated OM. However, past experiences with antibiotics show that, in the absence of well-defined treatment protocols that maximize expected efficacy, the adoption of prophylactic or active treatments for OM can have negative consequences for the patient and for the general population. In this review, we discuss the hypothesized mechanisms by which a vURI is translated into an acute OM episode and describe different strategies for aborting that process. Limitations to deployment of each strategy are outlined.

Importance of respiratory viruses in acute otitis media

Acute otitis media is usually considered a simple bacterial infection that is treated with antibiotics. However, ample evidence derived from studies ranging from animal experiments to extensive clinical trials supports a crucial role for respiratory viruses in the etiology and pathogenesis of acute otitis media. Viral infection of the upper respiratory mucosa initiates the whole cascade of events that finally leads to the development of acute otitis media as a complication. The pathogenesis of acute otitis media involves a complex interplay between viruses, bacteria, and the host's inflammatory response. In a substantial number of children, viruses can be found in the middle-ear fluid either alone or together with bacteria, and recent studies indicate that at least some viruses actively invade the middle ear. Viruses appear to enhance the inflammatory process in the middle ear, and they may significantly impair the resolution of otitis media. Prevention of the predisposing viral infection by vaccination against the major viruses would probably be the most effective way to prevent acute otitis media. Alternatively, early treatment of the viral infection with specific antiviral agents would also be effective in reducing the occurrence of acute otitis media.

Viral otitis media

Acute otitis media (AOM) and viral upper respiratory tract infections (URIs) represent the two most common diseases affecting the human population, and account for substantial patient morbidity and health care costs. Epidemiologic and experimental studies suggest that URIs play a causal role in the pathogenesis of AOM. Specifically, viruses can either invade the middle ear (ME) space and invoke an inflammatory response that culminates in ME effusion formation and consequent symptoms, or URIs might cause eustachian-tube dysfunction, resulting in negative ME pressures and subsequent ME effusion (hydrops ex vacuo theory). The events responsible for the inflammatory response of the human ME following viral exposure have not been well characterized. Although many prophylactic and therapeutic interventions have been evaluated for the treatment of AOM, the information on virus-specific interventions is sparse. In this article, the epidemiology, pathogenesis, diagnosis, and management of viral otitis media are reviewed.

Parental emotional and time costs predict compliance with respiratory syncytial virus prophylaxis

BACKGROUND

Two agents are effective in preventing respiratory syncytial virus (RSV) hospitalization in premature infants: RSV immune globulin (RSV-IG) and palivizumab. RSV-IG is associated with greater parental emotional and time costs, which may account for the more limited adherence to recommended monthly treatment with this agent.

OBJECTIVES

To compare the emotional distress and time costs associated with RSV-IG and palivizumab treatments and to determine the influence of these costs on treatment adherence.

METHODS

We surveyed parents of 82 infants who received RSV-IG (90% of eligible) and parents of 61 infants who received palivizumab (87% of eligible) at Arkansas Children's Hospital by telephone. We measured infant distress during treatment, parental distress, parental time costs, and adherence with recommended monthly prophylaxis.

RESULTS

Half of parents of RSV-IG recipients witnessed their infant in distress during infusion, over half (61%) were upset by observing the needle stick, and 22% observed infusion in the scalp. Fewer than 5% of parents of palivizumab recipients observed their infant in distress or were themselves distressed during treatment. A quarter of parents took time off from work for RSV-IG or palivizumab treatment. RSV-IG recipients completed 62% of recommended monthly treatments compared with 86% completed by palivizumab recipients. Increased parental distress and time costs largely accounted for the reduction in adherence to monthly treatment among RSV-IG recipients.

CONCLUSIONS

The emotional and time costs of RSV-IG treatment far exceed those of palivizumab and predict substantial differences in treatment adherence between the 2 agents. The impact of hidden costs on treatment adherence should be included in economic evaluations of medical procedures.

Medical and surgical management of otitis media in children

OM, though frequent and seemingly simple to evaluate and manage, remains a treatment challenge. Increasingly sophisticated clinical trials assessing OM medical treatment efficacy and outcome have demonstrated that many treatment regimens that were commonly used a decade ago are no longer recommended. Surgical therapy for OM, though remaining the same, has come under intense scrutiny from several angles but still plays a central role for this disease. Given the multiple facets of OM, its frequency, and its potential to cause short- and long-term morbidity in children, the next decade is sure to bring further treatment innovations.

Nasal and otologic effects of experimental respiratory syncytial virus infection in adults

PURPOSE

Upper respiratory tract viral infections continue to cause substantial patient morbidity and complications including sinusitis, otitis media, and pneumonia. This study was conducted to more clearly define the extent and frequency of nasal and otologic effects of respiratory syncytial virus infection in healthy adult volunteers.

MATERIALS AND METHODS

Thirty-two healthy, susceptible adult volunteers were cloistered for a 9-day period. During this time, subjects underwent nasal inoculation with respiratory syncytial virus. Monitoring included daily self-assessment of general health, as well as nasal and otologic symptoms. Objective measurements of nasal and otologic function included expelled nasal secretion weight, saccharin-dye mucociliary clearance, sonotubometry, tympanometry, and physical examination. A nasal lavage was done each morning, and fluids were submitted for viral detection. Twenty-one days after viral inoculation, all subjects had convalescent blood samples drawn for assay of virus-specific antibody titres.

RESULTS

Eighteen subjects (56%) became infected with the challenge as determined by either viral shedding (47%) or antigen detection (41%) from the nose or a 4-fold rise in virus-specific antibody titer (34%). Infected subjects more frequently reported adverse nasal (congestion, rhinorrhea) and general symptoms (fever, malaise, illness). By day 6, only 46% of infected subjects had normal middle ear pressure (> -100 mm H2O). Nasal secretion also increased substantially after infection. No patterned changes in mucociliary clearance or sonotubometry occurred, and no subjects developed otitis media.

CONCLUSIONS

Nasal inoculation of healthy, susceptible adult volunteers with respiratory syncytial virus results in detectable infection in only about half of the subjects challenged. Infected subjects experience substantial symptoms and signs of a viral upper respiratory tract illness. As in our previous studies using rhinovirus and influenza A virus, respiratory syncytial virus disrupted the maintenance of normal middle ear pressures. These findings provide further support for the relationship between viral upper respiratory tract infections and otitis media.

Maternal vaccines

Acute lower respiratory illness (LRI) is the leading cause of disease worldwide as measured by disability-adjusted life years. New strategies are necessary to decrease the disease burden that is largely borne by infants. Respiratory syncytial virus is the most important cause of LRI in infants. Lower respiratory illness can be prevented by endowing infants with high levels of neutralizing antibodies from mothers whose antibodies are boosted during pregnancy with a potent subunit vaccine. Another important cause of infant mortality is group B streptococcus sepsis in the neonatal period; maternal immunization with a group B conjugate vaccine could prevent this devastating infection.

Vaccine prevention of acute otitis media

The incidence of acute otitis media (AOM) in infants and young children has increased dramatically in recent years in the United States. AOM often follows upper respiratory tract infections due to pathogens such as respiratory syncytial virus (RSV), influenza virus, and parainfluenza virus (PIV). These viruses cause eustachian tube dysfunction that is critical to the pathogenesis of AOM. Vaccines against these viruses would likely reduce the incidence of AOM. In three previous studies, influenza virus vaccines reduced the incidence of AOM by 30% to 36%. Vaccines to prevent infections with RSV and PIV type 3 are undergoing clinical testing at this time. Streptococcus pneumoniae, nontypeable Haemophilus influenzae (NTHi), and Moraxella catarrhalis are the three most common AOM pathogens. Heptavalent pneumococcal conjugate vaccine is effective in preventing invasive disease and AOM caused by serotypes contained in the vaccine. Vaccine candidates for NTHi and M. catarrhalis are under development.

Recent advances in the management and prophylaxis of respiratory syncytial virus infection

Respiratory syncytial virus (RSV) infection is an important cause of morbidity, particularly in prematurely born infants who have had chronic lung disease. Current therapy is essentially supportive. Overall, the results of randomized trials do not support the use of bronchodilators, corticosteroids or Ribavirin. Nitric oxide and exogenous surfactant may improve the respiratory status of those infants who require ventilatory support. Nosocomial infection can be reduced by appropriate handwashing. There is no safe and effective vaccine for use in infants. Immunoprophylaxis reduces hospitalization and requirement for intensive care. Palivizumab, a humanized monoclonal antibody, is preferred to RSV immune globulin as the immunoprophylactic agent. Immunoprophylaxis should be reserved for infants at highest risk of severe respiratory syncytial virus infection, if this strategy is to be used most cost-effectively.

Passive immunization for the prevention of otitis media

The safety and protective efficacy of exogenously-administered immunoglobulin for the prevention of otitis media has been demonstrated in the clinical trials of the human-derived polyclonal immune globulin used to prevent Haemophilus influenzae type b disease and respiratory syncytial virus infection in high risk neonates and young children. However, this form of therapy is expensive, difficult to administer due to the requirements of slow intravenous infusion or relatively large volumes given intramuscularly, and associated with side effects related to the volume and nature of the immunoglobulin preparation. In contrast, RSV-specific monoclonal antibody has not been as successful as human-derived immunoglobulin in preventing otitis media in high risk infants. The administration of monoclonal-antibody for the prevention of otitis media will be difficult, potentially due to the need for antibody to multiple epitopes of the viral and bacterial pathogens which could be targets. The use of maternal antibody to provide passive immunity to young infants at a time when they are most vulnerable to severe sequelae of infection can also be considered. We have studied maternal immunization using either a 23-valent pneumococcal polysaccharide vaccine or a conjugate H. influenzae type b (Hib) vaccine. Significant levels of maternally-derived Hib or pneumococcal antibody were transferred from the mother to the infant at the time of birth and persisting, for some antigens, through 2 months of age. The use of maternal immunization to prevent otitis media and other respiratory complications remains to be studied, but results of these small clinical trials indicate further clinical investigation is warranted.

Respiratory syncytial virus vaccines for otitis media

RSV is a high priority for vaccine development because of its propensity to cause pneumonia and bronchiolitis in the infant and young child. Since RSV infection is likely to be a substantial contributor to otitis media, a vaccine could also decrease rates of this disease. No vaccine has yet been developed but it is hoped that the availability of an RSV infectious clone will make it possible to develop a live virus vaccine for the infant and young child. Subunit RSV vaccines are being developed for previously infected persons, i.e. in older children at high risk for RSV disease and the elderly. An effective RSV vaccine for the infant and young child could markedly decrease otitis media disease.

Passive immunity in prevention and treatment of infectious diseases

Antibodies have been used for over a century in the prevention and treatment of infectious disease. They are used most commonly for the prevention of measles, hepatitis A, hepatitis B, tetanus, varicella, rabies, and vaccinia. Although their use in the treatment of bacterial infection has largely been supplanted by antibiotics, antibodies remain a critical component of the treatment of diptheria, tetanus, and botulism. High-dose intravenous immunoglobulin can be used to treat certain viral infections in immunocompromised patients (e.g., cytomegalovirus, parvovirus B19, and enterovirus infections). Antibodies may also be of value in toxic shock syndrome, Ebola virus, and refractory staphylococcal infections. Palivizumab, the first monoclonal antibody licensed (in 1998) for an infectious disease, can prevent respiratory syncytial virus infection in high-risk infants. The development and use of additional monoclonal antibodies to key epitopes of microbial pathogens may further define protective humoral responses and lead to new approaches for the prevention and treatment of infectious diseases.

Passive immunity in prevention and treatment of infectious diseases

Antibodies have been used for over a century in the prevention and treatment of infectious disease. They are used most commonly for the prevention of measles, hepatitis A, hepatitis B, tetanus, varicella, rabies, and vaccinia. Although their use in the treatment of bacterial infection has largely been supplanted by antibiotics, antibodies remain a critical component of the treatment of diptheria, tetanus, and botulism. High-dose intravenous immunoglobulin can be used to treat certain viral infections in immunocompromised patients (e.g., cytomegalovirus, parvovirus B19, and enterovirus infections). Antibodies may also be of value in toxic shock syndrome, Ebola virus, and refractory staphylococcal infections. Palivizumab, the first monoclonal antibody licensed (in 1998) for an infectious disease, can prevent respiratory syncytial virus infection in high-risk infants. The development and use of additional monoclonal antibodies to key epitopes of microbial pathogens may further define protective humoral responses and lead to new approaches for the prevention and treatment of infectious diseases.

Influenza A virus infection of human middle ear cells in vitro

HYPOTHESIS

Human-derived normal middle ear mucosal cells can be harvested and cultured and will support influenza A virus (INF A) infection.

STUDY DESIGN

Protocols for the collection and in vitro culture of middle ear mucosal cells were developed and used to investigate the effects of INF A infection as it relates to the pathogenesis of otitis media.

MATERIALS AND METHODS

Middle ear mucosa was harvested during surgeries that opened the normal middle ear. Middle ear mucosal cells were plated and grown in collagen-coated dishes. Cells were characterized before and after INF A exposure using phase-contrast and immunofluorescence microscopy as well as reverse transcriptase-polymerase chain reaction (RT-PCR) for cytokeratin 18 gene expression and INF A.

RESULTS

Primary cultures of human middle ear epithelial cells were established. Prolonged growth of middle ear cells yielded a second cell type that failed to stain for cytokeratin on immunofluorescence but continued to produce positive RT-PCR results on cytokeratin 18 analysis. After INF A exposure, cytological changes and immunofluorescence staining showed cellular infection. RT-PCR analysis using INF A-specific primers showed positive results for up to 72 hours after viral exposure.

CONCLUSIONS

Primary cultures of human middle ear mucosal cells have been established. Two distinctly different cell culture systems have been developed: 1) middle ear epithelial cells and 2) either dedifferentiated epithelial cells or fibroblasts. Exposure of both cell types to INF A demonstrates that each can support cellular infection and viral replication. These models should be useful for studies of the pathogenesis of virus-mediated otitis media.

Does immune serum globulin confer protection against skin diseases?

BACKGROUND

Following a case of serologically proven hepatitis A in a food-handling worker serving several military bases in the same vicinity, the entire military population was vaccinated with immune serum globulin (ISG).

OBJECTIVE

To evaluate the effectiveness of ISG in preventing skin disease.

METHODS

The data for this study were drawn from the military archives of the Medical Corps. The population of the bases was followed for a period of 3 months after immunization. Rates of selected skin diseases were compared with those of a nearby base during the same period, and with those in the population of the same bases a year earlier.

RESULTS

The rates of several skin diseases (bacterial skin infections, dermatitis and eczema, fungal infections, acne, warts, nail disorders, and nonspecific skin diseases) among the vaccinated population were significantly lower when compared to the historical control group and to the contemporary control group of the nearby base.

CONCLUSIONS

ISG provides a protecting effect for skin diseases, especially those of infectious origin.

Management of otitis media: 2000 and beyond

BACKGROUND

In the next few years what will alter our modes of diagnosis, choice of therapies and strategies for prevention of acute otitis media (AOM)? These issues, as well as whether antibiotic resistance will continue to threaten the efficacy of currently available antimicrobial agents, whether industry and academia will be able to respond to bacterial resistance with effective new antimicrobial drugs and whether the pneumococcal conjugate vaccine will substantially reduce the incidence of AOM provide a basis for discussing the problems and possible solutions related to AOM. ANTIMICROBIAL DRUGS: Bacteria and viruses will continue to find ways to survive the activity of currently available antimicrobial drugs. Among the new antibacterial drugs under consideration are ketolides, oxazolodinones and quinolones. Guidelines stress limiting usage of antimicrobial agents to diseases that are likely caused by bacterial pathogens. Antiviral drugs are now available against influenza virus and respiratory syncytial virus infections.

DIAGNOSIS

Tympanometry and/or acoustic reflectometry are adjunctive techniques for assisting in the diagnosis of middle ear effusion in children whose otoscopic examination is ambiguous. Laser myringotomy has been used in several hundred children; however, there are no published studies of randomized trials. NEW VACCINES: Investigators have evaluated the safety and efficacy of a heptavalent pneumococcal polysaccharide vaccine conjugated with CRM197 (a diphtheria toxin mutant). The results showed a reduction in the overall burden of severe and recurrent AOM. Respiratory syncytial virus is the viral pathogen most frequently associated with AOM. For this reason safe and effective viral vaccines are needed to complement the efficacy of bacterial vaccines for prevention of AOM.

CONCLUSIONS

Parents influence decisions by pediatricians to use antimicrobial agents and should be informed about the appropriate usage of antibiotics. Educators and public health officials must find techniques to distinguish WebSites that provide information of value from those that are not credible. Of paramount importance is the development of techniques to increase the accuracy of clinical and microbiologic diagnosis. Finally there is a need for studies of appropriate scientific design that can assess the efficacy and safety of alternative therapies.

Prophylaxis for respiratory syncytial virus with respiratory syncytial virus-immunoglobulin intravenous among preterm infants of thirty-two weeks gestation and less: reduction in incidence, severity of illness and cost

OBJECTIVE

To determine the impact of respiratory syncytial virus (RSV) prophylaxis among preterm infants of < or =32 weeks gestation by comparing the severity of illness and cost of RSV-related care during the two winter seasons before (1994 to 1995, 1995 to 1996) with the two seasons after initiation of prophylaxis (1996 to 1997, 1997 to 1998).

METHODS

Preterm infants of < or =32 weeks gestation at risk for hospitalization with RSV infection were identified retrospectively from the infants hospitalized in our neonatal units. Infants were included if they (1) were born 6 months before or during four winter seasons (1994 to 1998), (2) were discharged from the neonatal unit and (3) had remained in the university outpatient clinic system during at least the first winter of life. Preterm infants of < or =32 weeks gestation hospitalized with RSV were identified from our RSV database (which includes cost of hospitalization, duration of hospital stay, pediatric intensive care unit stay and intubation). Infants receiving prophylaxis were identified prospectively.

RESULTS

The incidence of hospitalization with RSV was significantly lower among the cohort of infants born after initiation of prophylaxis: 8.7% (17 of 195) vs. 22% (35 of 159), P = 0.00049 by two tailed Fisher's exact test. Among the cohort of infants born after initiation of prophylaxis (n = 195), 100 infants received prophylaxis. The gestational and chronologic ages of the prophylaxis-treated infants were significantly lower than those of the non-prophylaxis-treated infants (n = 95). The prophylaxis-treated infants also were more likely to have bronchopulmonary dysplasia. Only 1 (1%) of the prophylaxis-treated infants required hospitalization for RSV. Comparison of the cohort of infants born before initiation of prophylaxis to the cohort born after initiation of prophylaxis (includes prophylaxis-treated and non-prophylaxis-treated infants) revealed a significant reduction in severity of illness and cost. The length of stay in the cohort born before initiation of prophylaxis was reduced 83.8%: 373.6 days per 100 infants at risk vs. 60.5 (P = 0.00055). The length of stay in the pediatric intensive care unit was reduced 92.7%: 218.2 days per 100 infants at risk vs. 15.9 (P = 0.00029). The duration of intubation was reduced 95.6%: 187.4 days per 100 infants at risk vs. 8.2 (P = 0.00024). The dollars spent for RSV-related care (hospitalizations and prophylaxis) per 100 infants at risk for RSV was reduced 65% in the cohort of infants born after prophylaxis: $670,590 per 100 infants at risk vs. $234,596 (P = 0.00056). This reduction remained significant (64.9%) if the cost of ribavirin (drug and administration fees) was excluded from the cost of hospitalization.

CONCLUSIONS

These data reveal that RSV prophylaxis significantly reduced the incidence of RSV hospitalizations and severity of illness as well as the cost of RSV-related care among these infants.