Influenza virus and rhinovirus-related otitis media: potential for antiviral intervention

Occurrence of acute otitis and sinusitis in patients hospitalized for influenza

Introduction

Acute otitis and sinusitis are common complications in patients with influenza and are responsible for increased hospitalization rates.

Methods

A five-year retrospective study (2018-2023) was conducted including all patients hospitalized for influenza (etiologic diagnosis by RT-PCR) to identify the incidence and characteristics of cases complicated with otitis and/or sinusitis. Cases associated with other viral co-infections were excluded from the analysis.

Results

We identified a cumulative rate of 20.6% (324 cases) of acute otitis (AO) and acute sinusitis (AS) among patients with influenza. Of these, 62.3% had AO, 28.1% AS, and 9.6% concomitant AO and AS. Cases of AO were predominant in the pediatric population (97.0%), while cases of AS were more common in adults (56.1%). Influenza A viruses were identified in 67.2% of patients. The infection with influenza B viruses increased the risk of acute congestive otitis media 2.1-fold (p=0.020), and influenza A viruses increased the risk of acute maxillary sinusitis 2.7-fold (p=0.029). Late presentation to the hospital, with a median of 4 days from the onset of influenza symptoms, was identified as a factor in the occurrence of AO and AS.

Conclusions

The risk of AO and AS is increased in patients with influenza, especially in the pediatric population and in late hospital presentations. These findings highlight the importance of proper monitoring and management of patients with influenza to prevent the development of complications, as well as the need to better understand the mechanisms whereby influenza viruses contribute to these secondary conditions.

Toxic inner ear lesion following otitis media with effusion: a comparative CT-study regarding the morphology of the inner ear

Viral infections of the upper respiratory airways can lead to a delayed viral otitis media (VOM) caused by a diffusion of viruses/virus particles through the round window membrane and resulting in sensorineural hearing loss. The treatment of choice is immediate paracentesis, evacuation of all fluids from the middle ear cavity, and haemorrheological infusions. However, in some cases, persistent symptoms may be an indication for a surgical approach using mastoidectomy. In high-resolution computed tomography, an extended small-sized pneumatisation of the mastoid cells with complete shading was found in these non-responsive cases. Therefore, a direct means of inner ear affliction through weak parts of the labyrinthine bone may be hypothesised. Patients suffering from a toxic inner ear lesion (TIEL) following a common cold, treated over a 10-year period in a Tertiary Care Centre (N = 52, 57 ears), were identified and the morphological characteristics of the temporal bones of affected patients were examined by means of high-resolution computed tomography (hrCT). The findings were compared with a matched control group of 64 normal ears (CONT). Measurements included the grade of pneumatisation, distances within the temporal bones and Hounsfield units (HU) at defined anatomical structures. In the TIEL group, we found a small-sized pneumatisation in 79.4 % and a medium-sized pneumatisation in 10.9 %, thus differing from the CONT group and the literature data. Thickness of the bone wall of the lateral semicircular canal (LSC) and distances within the aditus ad antrum were significantly reduced in the TIEL group. HU's were markedly lower in the TIEL group at the precochlea, the LSC, and dorsolateral to the promentia of the LSC. There was a correlation between the HU's at the prominentia of the LSC and the hearing loss (p = 0.002). Persisting interosseous globuli, as described in 1897 by Paul Manasse, form an osseochondral network within the otic capsule and may be responsible for a direct means of toxic inner ear infection. The CT-morphometric results support this thesis. In the group of these patients (TIEL) a CT-scan and in non-responders to conservative treatment a surgical approach by mastoidectomy is recommended.

The human rhinovirus: human-pathological impact, mechanisms of antirhinoviral agents, and strategies for their discovery

As the major etiological agent of the common cold, human rhinoviruses (HRV) cause millions of lost working and school days annually. Moreover, clinical studies proved an association between harmless upper respiratory tract infections and more severe diseases e.g. sinusitis, asthma, and chronic obstructive pulmonary disease. Both the medicinal and socio-economic impact of HRV infections and the lack of antiviral drugs substantiate the need for intensive antiviral research. A common structural feature of the approximately 100 HRV serotypes is the icosahedrally shaped capsid formed by 60 identical copies of viral capsid proteins VP1-4. The capsid protects the single-stranded, positive sense RNA genome of about 7,400 bases in length. Both structural as well as nonstructural proteins produced during the viral life cycle have been identified as potential targets for blocking viral replication at the step of attachment, entry, uncoating, RNA and protein synthesis by synthetic or natural compounds. Moreover, interferon and phytoceuticals were shown to protect host cells. Most of the known inhibitors of HRV replication were discovered as a result of empirical or semi-empirical screening in cell culture. Structure-activity relationship studies are used for hit optimization and lead structure discovery. The increasing structural insight and molecular understanding of viral proteins on the one hand and the advent of innovative computer-assisted technologies on the other hand have facilitated a rationalized access for the discovery of small chemical entities with antirhinoviral (anti-HRV) activity. This review will (i) summarize existing structural knowledge about HRV, (ii) focus on mechanisms of anti-HRV agents from synthetic and natural origin, and (iii) demonstrate strategies for efficient lead structure discovery.

Immunopathogenesis of polymicrobial otitis media

OM, or inflammation of the middle ear, is a highly prevalent infection in children worldwide. OM is a multifactorial disease with multiple risk factors, including preceding or concurrent viral URT infection. Hence, OM is also a polymicrobial disease. The mechanisms by which viruses predispose to bacterial OM are replete; however, all are predicated on the general principle of compromise of primary host airway defenses. Thus, despite an as-yet incomplete understanding of the molecular mechanisms involved in bacterial superinfection of a virus-compromised respiratory tract, the URT viruses are known to induce histopathology of airway mucosal epithelium, up-regulate expression of eukaryotic receptors used for bacterial adherence, alter the biochemical and rheological properties of airway mucus, and affect innate and acquired host immune functions, among others. Although discussed here in the context of OM, during preceding or concurrent viral infection of the human respiratory tract, viral impairment of airway defenses and the resulting predisposition to subsequent bacterial coinfection are also known to be operational in the mid and lower airway as well.

Chinchilla as a robust, reproducible and polymicrobial model of otitis media and its prevention

There is compelling evidence that many infectious diseases of humans are caused by more than one microorganism. Multiple diverse in vitro systems have been used to study these complex diseases, and although the data generated have contributed greatly to our understanding of diseases of mixed microbial etiology, having rigorous, reproducible and relevant animal models of human diseases are essential for the development of novel methods to treat or prevent them. All animal models have inherent limitations; however, they also have important advantages over in vitro methods, including the presence of organized organ systems and an intact immune system, which promote our ability to characterize the pathogenesis of, and the immune response to, sequential or coinfecting microorganisms. For the highly prevalent pediatric disease otitis media, or middle-ear infection, the chinchilla (Chinchilla lanigera) has served as a gold-standard rodent host system in which to study this multifactorial and polymicrobial disease.

Temporal relationships between colds, upper respiratory viruses detected by polymerase chain reaction, and otitis media in young children followed through a typical cold season

INTRODUCTION

Otitis media is a frequent complication of a viral upper respiratory tract infection, and the reported co-incidence of those diseases increases with assay sensitivity and sampling density. We determined the incidence of otitis-media complications in young children when referenced to cold-like illnesses and to concurrent virus recovery from the nasopharynx.

METHODS

A total of 60 children from 24 families were followed from October 2003 through April 30, 2004, by daily parental recording of illness signs, weekly pneumatic otoscopic examinations, and periodic polymerase chain reaction assay of collected nasal fluids for common viruses.

RESULTS

One hundred ninety-nine cold-like illnesses were observed, but a sample for virus assay was not collected concurrent with 71 episodes. Of the remainder, 73% of cold-like illnesses were temporally related to recovery of 1 or a combination of the assayed viruses, with rhinovirus predominating. For non-cold-like illness periods, 54 (18%) of 297 assays were positive for virus, and the virus frequency distribution was similar to that for cold-like illnesses. There were 93 diagnosed otitis-media episodes; 65 (70%) of these occurred during a cold-like illness. For the 79 otitis-media episodes with available nasal samples, 61 (77%) were associated with a positive virus result. In this population, the otitis-media complication rate for a cold-like illness was 33%.

CONCLUSIONS

A cold-like illness was not a prerequisite for polymerase chain reaction detection of viruses in the nose and nasopharynx of young children. Viral detection by polymerase chain reaction in the absence of a cold-like illness is associated with complications in some subjects. Otitis media is a complication of viral infection both with and without concurrent cold-like illnesses, thus downwardly biasing coincidence estimates that use cold-based illnesses as the denominator.

Use of diagnostic algorithms and new technologies to study the incidence and prevalence of viral upper respiratory tract infections and their complications in high risk populations

PURPOSE OF REVIEW

Most studies on the natural history of viral upper respiratory tract infections and their complications rely for ascertainment on self-assessed cold/flu illness or the identification of presumed complications. The criteria for cold/flu definition, however, are variable within and between individuals and illness is not prerequisite for a viral upper respiratory tract infection. These factors bias estimates of the incidence and prevalence of viral upper respiratory tract infections and their complications. Here we review new methodologies that can be adapted for use in future studies to refine those estimates.

RECENT FINDINGS

We present a theoretical basis for standardized assignment of cold/flu episodes using a minimal algorithm template that operates on a structured set of symptoms/signs. We emphasize the greater accuracy of information derived from longitudinal studies that incorporate identification algorithms and assay of nasal secretions for causal virus by polymerase chain reaction and for proinflammatory chemicals to confirm nasal inflammation.

SUMMARY

The methodologies and sampling strategies that we describe hold promise for better characterizing the incidence of complications for symptomatic and asymptomatic expressions of a viral upper respiratory tract infection caused by specific viruses. These data can then be used to estimate the efficacy and efficiency in a specified target population of prophylactic or intercurrent treatments to prevent the complications.

Inhibition of rhinovirus replication in vitro and in vivo by acid-buffered saline

Human rhinoviruses (HRVs) are quite sensitive to low pH. To determine whether this characteristic might be a therapeutic target, we evaluated the sensitivity of HRV to low-pH buffers in vitro and in vivo. Our findings confirm that low pH inhibited replication of most HRVs and reduced the replication of influenza virus. Preliminary experiments verified that the surface pH of the human nasopharynx could be transiently lowered to pH ∼4.0 by topical administration of citrate/phosphate (CP) buffers, which was well tolerated. In a pilot experimental colds study, intranasal administration of CP buffer, compared with normal saline, reduced viral shedding by 1 log unit (10³ vs. 10⁴ 50%tissue culture infective dose/mL; P < .01), although respiratory symptoms were not significantly reduced. These findings demonstrate that low-pH buffers have antiviral activity in vivo and suggest that a larger clinical trial is warranted to determine whether this approach could reduce rates of viral transmission.

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.

Presence of specific viruses in the middle ear fluids and respiratory secretions of young children with acute otitis media

The purpose of the study was to investigate the presence of different viruses in middle ear fluids and nasopharyngeal aspirates in young children with acute otitis media. Two cohorts of children (N = 329 and 611) were followed from 2 to 24 months of age in Finland in two prospective studies (Finnish Otitis Media Cohort Study and Finnish Otitis Media Vaccine Trial). During the study period, nasopharyngeal and middle ear fluid specimens for each acute otitis media event were examined for eight (Cohort Study) or ten (Vaccine Trial) common respiratory viruses; adenoviruses, influenza viruses A and B, parainfluenza viruses 1, 2, and 3, respiratory syncytial virus (RSV), enteroviruses, parechoviruses, and rhinoviruses. Picornaviruses (rhinoviruses, enteroviruses, and parechoviruses) were determined by reverse transcription PCR while antigen detection was used for the other viruses. A virus was present in either nasopharyngeal or middle ear specimen in 54% of events in the first cohort and in 67% of events in the second. Rhinoviruses formed the most common virus group detected (41–32%), followed by enteroviruses (25%, sought in the second cohort only) and respiratory syncytial virus (RSV) (10%). All the other viruses represented jointly 8–10% of the events. In conclusion, using the methods described in this study, a specific virus infection was diagnosed in two thirds of all acute otitis media events in young children. Picornavirus RNA was detected in association with more than a half of all acute otitis media events. The use of PCR‐based methods for the other respiratory viruses might have increased further the overall virus detection rate in acute otitis media. J. Med. Virol. 72:241–248, 2004. © 2004 Wiley‐Liss, Inc.

Antigenic as well as nonantigenic stimuli induce similar middle ear responses in the rat

OBJECTIVES/HYPOTHESIS

The observation that during otitis media many different types of micro-organisms have been cultured from effusions indicate that, once present in the middle ear cavity, most types of micro-organisms are able to trigger an inflammatory reaction leading to otitis media. The present study was designed to determine the middle ear response after injection of different substances into the middle ear cavity.

STUDY DESIGN

To determine whether and to what extent an inflammatory response of the middle ear depends on the entering agent, the response in the tympanic cavity was studied by otomicroscopy and histological examination after inoculation of various substances.

METHODS

Lewis rats were inoculated in transtympanic fashion either with live or heat-killed bacteria (pathogenic and nonpathogenic), Keyhole limpet hemocyanin, active charcoal, or saline. The mucosal response of the challenged middle ears was studied histologically.

RESULTS

Irrespective of the inoculated substance, no essential differences in the mucosal response were found. The intensity of the inflammatory response was greater when live bacteria were inoculated.

CONCLUSIONS

The present study demonstrates that any substance reaching the middle ear cavity is likely to induce otitis media. These observations emphasize the role of the eustachian tube as "porte d'entrée" in the pathogenesis of this disorder. Determination of specific aspects of the eustachian tube involved in protection or in facilitating bacterial translocation will be important for the understanding of the pathogenesis of otitis media and the subsequent development of new therapeutic strategies. In addition, elucidation of bacterial factors involved in the process of colonization and translocation will be of equal importance.

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.

Nasal swab versus nasopharyngeal aspirate for isolation of respiratory viruses

To determine the usefulness of nasal swabs as a simple method for detection of respiratory viruses, we compared nasal swabs and nasopharyngeal aspirates obtained at the same time from the opposite nostrils of 230 children with upper respiratory infection. The sensitivity of nasal swabs was comparable to that of nasopharyngeal aspirates for the detection of all major respiratory viruses except respiratory syncytial virus.

Influenza vaccination for healthy children

Influenza virus infections cause vaccine-preventable but uncontrolled epidemic disease in the United States. Population dynamics dictate that the burden of disease will increase dramatically over the next 20 years if new strategies are not implemented. New weapons for the diagnosis, treatment and prevention of influenza are now available and should be implemented immediately. The impact of disease in children has been largely overlooked. Control measures should be focused on the prevention of disease in children, who have the highest annual attack rates. The new live attenuated nasal spray influenza vaccine is particularly effective in healthy children who would benefit most from universal immunization.