The role of respiratory syncytial virus and other viral pathogens in acute otitis media

Comprehensive Detection of Respiratory Bacterial and Viral Pathogens in the Middle Ear Fluid and Nasopharynx of Pediatric Patients With Acute Otitis Media

BACKGROUND

Acute otitis media (AOM) is a common ear infection caused by respiratory viruses and bacteria of the nasopharynx. The present study aimed to detect various respiratory viruses and bacteria in middle ear fluid (MEF) and nasopharyngeal aspirates (NPA) using polymerase chain reaction (PCR).

METHODS

We collected MEF and NPA samples from 122 pediatric patients with AOM. Real-time PCR detected 11 types of respiratory viruses (respiratory syncytial virus A/B, parainfluenza virus 1/2/3, human metapneumovirus, influenza virus A/B, adenovirus, human bocavirus and rhino virus) and 7 types of bacteria (Streptococcus pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae, Chlamydia pneumoniae, Streptococcus pyogenes, Legionella pneumophila and Moraxella catarrhalis). MEF specimens were also examined using bacterial culture.

RESULTS

At least 1 respiratory viral or bacterial pathogen was detected in MEF of 120 cases (98%) by viral and bacterial PCR and of 93 cases (76%) by viral PCR and bacterial culture. Respiratory viruses were detected in NPA of 84 cases (69%) and MEF of 67 cases (55%). The most common virus detected in MEF was respiratory syncytial virus (21%), followed by parainfluenza virus (15%). All the viruses present in MEF were also detected in NPA specimens. Bacteria were detected by PCR in MEF of 109 cases (89%); H. influenzae was the most frequently detected (65%).

CONCLUSIONS

In many cases, pediatric AOM was found to constitute a respiratory polymicrobial infection. Multiplex PCR was useful to detect multiple respiratory viruses and bacteria in AOM. To understand intractable AOM, further studies regarding the clinical features of each viral and bacterial coinfection are required.

Viral Upper Respiratory Tract Infections

The upper respiratory system is one of the most common sites of infection for adults, but even more so for children. Several viruses, from variable families, cause upper respiratory infections which, although generally underestimated due to their typically self-limiting nature, underlie enormous healthcare resource utilization and financial burden. Such, otherwise “benign” infections, can have very significant sequelae both in the form of bringing about local complications but also inducing asthma attacks, thus greatly increasing morbidity. Their enormous prevalence also indicates that rigorous research should be undertaken in order to tackle them, in both the prevention and treatment field.

Evaluation of concordance between the microorganisms detected in the nasopharynx and middle ear of children with otitis media

Studies of microorganisms involved in otitis media in children often use a nasopharyngeal sample as a proxy for the middle ear fluid to test for bacteria and viruses. The question is whether such studies provide an accurate estimate of the prevalence of microorganisms involved in otitis media. We performed a systematic review of the literature reporting on the concordance between test results of nasopharyngeal and middle ear fluid samples for the most prevalent microorganisms in children with otitis media. Our findings show that the concordances vary from 68% to 97% per microorganism. For the most prevalent microbes, positive predictive values are around 50%. Most negative predictive values are moderate to high, with a range from 68% up to 97%. These results indicate that test results from nasopharyngeal samples do not always provide an accurate proxy for those of the middle ear fluid. It is important to interpret and use results of such studies carefully.

Virus respiratorio sincitial, metapneumovirus y virus parainfluenza humanos: cuadro clínico y fisiopatología

El VRSh causa la mayor parte de las bronquiolitis del lactante, infecciones respiratorias bajas que provocan trastornos respiratorios obstructivos y sibilancias. Los factores relacionados con las características del paciente (prematuridad, enfermedades asociadas, predisposición genética), con el virus (VRShA, genotipo, etc.) o el ambiente (contaminación, tabaquismo, etc.) son determinantes en la génesis de las bronquiolitis y determinan su gravedad. La mortalidad de la bronquiolitis es del 0,005-0,2% dependiendo de las características del paciente. No se conoce la fisiopatología de la bronquiolitis por VRSh. El papel directo del virus sobre el epitelio, la inmadurez del pulmón del lactante y, como se ha demostrado recientemente, el papel de la reacción inflamatoria, son factores destacados. También es probable que haya mecanismos inmunopatológicos (anticuerpos IgE, respuesta CD4+ Th2, etc.) que intervengan en ciertas bronquiolitis. La inmunidad anti-VRSh nunca llega a ser completa y las reinfecciones son frecuentes en los niños pequeños y las personas de edad avanzada, en quienes la infección por el VRSh representa aproximadamente el 5% de las afecciones respiratorias bajas. Con frecuencia se presentan con un cuadro de neumopatía infecciosa atípica con signos de bronquiolitis. Las infecciones debidas al VPIh3 suelen manifestarse por bronquiolitis, y las infecciones secundarias al VPIh1 y al 2 por laringotraqueítis. No se conoce bien la expresión clínica de las infecciones por VPIh4. El MPVh causa bronquiolitis comparables en todos sus aspectos a las que origina el VRSh.

Immunopathogenesis of polymicrobial otitis media

The synergistic relationship between URT viruses and bacteria in OM pathogenesis is not fully understood, but overall is predicated on viral impairment of airway defenses.

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.

Microbiology of acute otitis media in children with tympanostomy tubes: prevalences of bacteria and viruses

Background. Bacteria are found in 50%–90% of cases of acute otitis media (AOM) with or without otorrhea, and viruses are found in 20%–49% of cases. However, for at least 15% of patients with AOM, the microbiological etiology is never determined. Our aim was to specify the full etiology of acute middle ear infection by using modern microbiological methods concomitantly for bacterial and viral detection.

Methods. The subjects were 79 young children having AOM with new onset (<48 h) of otorrhea through a tympanostomy tube. Middle ear fluid samples were suctioned from the middle ear through the tympanostomy tube. Bacteria were sought by culture and polymerase chain reaction; viruses were analyzed by culture, antigen detection, and polymerase chain reaction.

Results. At least 1 respiratory tract pathogen was noted in 76 children (96%). Bacteria were found in 73 cases (92%), and viruses were found in 55 (70%). In 52 patients (66%), both bacteria and viruses were found. Bacteria typical of AOM were detected in 86% of patients. Picornaviruses accounted for 60% of all viral findings.

Conclusions. In the great majority of children, AOM is a coinfection with bacteria and viruses. The patent tympanostomy tube does not change the spectrum of causative agents in AOM. A microbiological etiology can be established in practically all cases.

Viral upper respiratory tract infections in young children with emphasis on acute otitis media

Viral upper respiratory infection is the most common reason for seeking medical care for children. Recurrent viral respiratory infections and subsequent complications (e.g. acute otitis media (AOM)) are a burden for children, their families and society. Over the past decade, our knowledge on the significance of respiratory viruses has broadened remarkably. Viruses cause large variety of respiratory diseases and cause alone diseases, which previously have been assumed to be bacterial only (e.g. AOM and pneumonia). Methods for detection analysis of respiratory viruses are developing making both the diagnosis and epidemiological investigations of respiratory infections easier. Accurate diagnosis of respiratory infections and awareness of possible viral etiology could reduce the use of antibiotics. Etiologic studies of viral infections are becoming increasingly important, with the emergence of new antiviral drugs and vaccines.

[Infectious and non infectious factors in otitis media and in sinusitis]

Les infections de la sphère ORL sont fréquentes et les otites chez l’enfant, les sinusites de l’adulte sont généralement perçues comme étant d’origine bactérienne ou virale. Cependant de nombreux facteurs non infectieux jouent un rôle non négligeable, mais restent souvent méconnus et d’interprétation difficile : ils conduisent encore trop souvent à des thérapeutiques antibiotiques inutiles. Ainsi dans l’otite, ont été reconnus divers facteurs de risque non infectieux tels que : atteinte mécanique de la trompe d’Eustache, immaturité immunitaire, tabagisme passif, carence martiale etc… susceptibles de favoriser l’infection de l’oreille moyenne, souvent virale dans un 1^er temps, secondairement surinfectée par les espèces bactériennes du rhinopharynx ((pneumocoques, Haemophilus influenzae, Moraxella catarrhalis). Les sinusites sont d’étiologie multifactorielle et, si les mécanismes et les agents des sinusites infectieuses (virus et bactéries) sont bien connus, en revanche de multiples facteurs non infectieux peuvent être identifiés : l’allergie est un facteur fréquent qui favorise les sinusites à répétition ; moins souvent reconnus sont le diabète, le reflux gastro-oesophagien, des facteurs anatomiques, des anomalies de la fonction muco-ciliaire ou l’immunodépression dans le cadre VIH. Des recherches doivent être poursuivies pour approfondir ces mécanismes complexes.

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.

Otitis and respiratory distress episodes following a respiratory syncytial virus infection

OBJECTIVE

To document, over two consecutive respiratory syncytial virus (RSV) seasons, the occurrence of acute otitis media (AOM) and recurrence of respiratory distress in children < 2 years of age hospitalized for respiratory distress.

METHODS

Patients were examined during hospitalization and at 6 weeks and 6 months after discharge. RSV testing was performed on all patients, and hospitalized patients were evaluated daily for the occurrence of AOM.

RESULTS

In total, 347 children were enrolled; 54.8% were RSV positive, and 45.2% were RSV negative. Children were most frequently diagnosed as having bronchiolitis (71.9%) or asthmatic bronchitis (17.9%); other diagnoses included pneumonia, laryngitis, and rhinitis. During hospitalization, AOM was diagnosed in 16.8% of RSV-positive versus 8.3% of RSV-negative children (P < 0.05). Six weeks after discharge, AOM was reported in 10.4% of RSV-positive as compared with 5.8% of RSV-negative patients. Six months later, AOM was reported in 2.9% of the RSV-positive and 7.6% of the RSV-negative patients. A second episode of acute respiratory distress, which either required (9) or did not require (35) hospitalization, occurred in 18.4% of the total population, with similar proportions of RSV-positive and RSV-negative children (17% versus 18.6%).

CONCLUSION

We conclude that RSV appears to be an important contributing factor for the occurrence of AOM in young children hospitalized with respiratory distress. The occurrence of a second episode of acute respiratory distress did not appear to correlate with the previous RSV infection, but longer-term follow-up is required.

Role of respiratory viruses in children with acute otitis media

OBJECTIVE

The role of viral infection in acute otitis media (AOM) has not been fully elucidated. We determined the presence of various respiratory viruses in middle ear fluid (MEF) specimens from children with AOM in order to determine whether viral infection or combined effects of viral and bacterial infection enhance or prolong the inflammation in the middle ear, thus worsening clinical outcome.

METHODS

Multiplex nested reverse transcription-polymerase chain reactions was carried out to detect influenza A and B viruses, respiratory syncytial virus (RSV) types A and B, parainfluenza virus types 1, 2, and 3; rhinovirus; and adenovirus in 93 MEF specimens from 79 children with AOM. And we examined whether viral infection with or without an identifiable bacterial infection affect clinical outcomes in AOM. We considered persistent MEF (fluid accumulation in the middle ear persisting up to 1 month after treatment), early recurrence of AOM (within 1 month after initial improvement), and recurrent AOM (more than three recurrences during 6 months of follow up) as indicators for evaluating clinical outcomes.

RESULTS

One or more respiratory viruses were detected in 39 specimens (42%); a total of 42 viral infections identified (three specimens were infected by two viruses). Of the 42 infections, RSV type A was detected in 29, adenovirus in eight, rhinovirus in three, and influenza virus in two. RSV accounted for 73% of viral detections. In children younger than 2 years, RSV infection combined with Streptococcus pneumoniae or Hemophilus influenzae infection carried a higher risk for persistent middle ear effusion than infection with RSV infection alone or those bacterial infection alone.

CONCLUSIONS

Accordingly, vaccination of young children against RSV as well as S. pneumoniae and H. influenzae is important in improving the prognosis in AOM.

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.

Daily home tympanometry to study the pathogenesis of otitis media

A study was conducted to define the temporal relationship between a parent-identified cold episode and the diagnosis of otitis media. Forty children were studied in their homes with the use of daily tympanometry, symptom diaries and weekly otoscopy. A total of 136 patients identified colds, and 43 episodes of otitis media were recorded. New episodes of otitis media were observed in 22% of all colds, and 63% of all otitis media episodes occurred during a cold.

Influenza virus vaccines in children and their impact on the incidence of otitis media

Otitis media has been identified as the most frequent reason for outpatient antibiotic therapy. Several studies have linked viral respiratory infections with bacterial otitis media. In light of rising concerns about antibiotic resistance, the possibility of reducing the incidence of otitis media through vaccination against respiratory viruses has received increasing attention. This article reviews inactivated and live attenuated influenza virus vaccines and their possible impact on the incidence of otitis media. Inactivated and live attenuated influenza virus vaccines are safe and immunogenic in children older than 6 months and are linked to a decrease in the incidence of otitis media. Influenza vaccination of infants younger than 6 months has resulted in less predictable immunogenicity and deserves further investigation.

Bacterial and viral etiology of acute otitis media in Chilean children

BACKGROUND

Acute otitis media (AOM) is a main cause for antimicrobial prescription in Latin America. Pathogen diversity in different geographic regions underscores the need for updated knowledge on AOM microbiology.

AIM

To prospectively determine the role of bacteria and viruses in Chilean children with AOM.

METHODS

Between July, 1998, and June, 1999, children >3 months with a presumptive diagnosis of AOM were referred to the study ear, nose and throat physician. Middle ear fluid and nasopharyngeal aspirates were obtained from children with confirmed AOM and processed for common bacteria, Mycoplasma pneumoniae, Chlamydia pneumoniae and viruses. Antimicrobial susceptibility patterns and serotypes of Streptococcus pneumoniae strains were determined.

RESULTS

An ear, nose and throat physician confirmed diagnoses for 222 (42%) of 529 children referred with diagnosis of AOM, and 170 children met eligibility criteria for the study. One or more pathogens were detected in 140 of 170 (82%) children. Predominant bacteria were S. pneumoniae (37%), Haemophilus influenzae (24%) and Streptococcus pyogenes (13%). M. catarrhalis was detected in 2 children, C. pneumoniae was found in 1 and M. pneumoniae was not detected. Viruses were detected in 22 children (13%) from nasopharyngeal aspirates, and in 6 of them the same virus was detected in middle ear fluid. Penicillin-resistant (intermediate and high) S. pneumoniae represented 40% of isolates and 10% of H. influenzae were beta-lactamase producers. All 10 penicillin-resistant S. pneumoniae strains were resistant to cefuroxime. Eighteen S. pneumoniae serotypes were detected and 19F was associated with high level penicillin resistance.

CONCLUSION

This study can impact local management of AOM, and it should encourage continuous surveillance of AOM microbiology in Chile and other developing countries.

The role of respiratory viruses in otitis media

Evidence derived from numerous studies ranging from animal experiments to extensive clinical trials supports a crucial role for respiratory viruses in acute otitis media. Viral infection of the upper respiratory tract initiates the whole cascade of events that ultimately leads to development of acute otitis media, and viruses contribute to the pathogenesis of this disease by several mechanisms. Recent data indicate that at least some types of viruses actively invade the middle ear and may also interfere with the outcome of otitis media. The availability of effective vaccines against the principal viruses predisposing to acute otitis media could be expected to result in a substantial reduction in the incidence of this disease.

Role of viruses in the pathogenesis of acute otitis media

To date there is ample evidence suggesting a crucial role for respiratory viruses in the pathogenesis of AOM. Respiratory viral infection appears to initiate the cascade of events that finally leads to development of AOM (Fig. 1). The pathogenesis of AOM is complicated, involving a network of factors, some probably not yet identified, which affect each other in a time-dependent manner. Increased knowledge of the detailed mechanisms of viral infection, the host inflammatory response during URI and the interaction between viruses and bacteria could lead to major advances in the prevention of AOM.

Increasing importance of viruses in acute otitis media

Acute otitis media is generally considered a simple bacterial infection that can be effectively treated with antibiotics. However, despite the extensive use of broad-spectrum antibiotics, poor clinical response to treatment of acute otitis media is common in children. Numerous studies ranging from animal experiments to extensive clinical studies have clearly demonstrated that respiratory viruses play a crucial role in the aetiology and pathogenesis of acute otitis media. Viral infection of the upper respiratory tract initiates the whole cascade of events that finally leads to the development of acute otitis media as a complication. Respiratory viruses induce a release of inflammatory mediators in the nasopharynx, increase bacterial colonization and adherence, and have a suppressive effect on the host's immune defense. Recent data indicate that at least some types of viruses actively invade the middle ear. Viruses also seem to enhance the inflammatory process in the middle ear and impair the outcome of the disease. Vaccines against the major viruses predisposing to acute otitis media hold a great promise for the prevention of this disease. Major advances in the management of acute otitis media will require further research into the mechanisms of viral infection, viral-bacterial interaction and the host inflammatory response during viral infection.

Viral-Bacterial Synergy in Otitis Media: Implications for Management

Despite the extensive use of broad-spectrum antibiotics, poor clinical response to the treatment of acute otitis media is common. Evidence derived from numerous studies during the past two decades supports a crucial role for respiratory viruses in the etiology and pathogenesis of acute otitis media, and recent studies indicate that viruses may also have a profound adverse effect on the resolution of this disease. Viruses seem to interact with bacteria and enhance the local inflammatory process in the middle ear. Effective adjuvant therapies are needed to improve outcome in children with otitis media. Increasing knowledge of the role of viruses, viral-bacterial interaction, and host inflammatory mechanisms in otitis media may lead to major improvements in the management of this disease.

Relationship between herpesviruses and adult periodontitis and periodontopathic bacteria

BACKGROUND

Various mammalian viruses and specific bacteria seem to play important roles in the pathogenesis of human periodontitis. This study examined the relationship between subgingival herpesviruses and periodontal disease and potential periodontopathic bacteria in 140 adults exhibiting either periodontitis or gingivitis.

METHODS

A nested-polymerase chain reaction (PCR) method determined the presence of Epstein-Barr virus type 1 and type 2 (EBV-1, EBV-2), human cytomegalovirus (HCMV), and herpes simplex virus (HSV) and a 16S rRNA PCR detection method identified Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Bacteroides forsythus, Prevotella intermedia, Prevotella nigrescens, and Treponema denticola.

RESULTS

Using a logistic analysis, EBV-1 showed significant positive association with P. gingivalis (odds ratio [OR] 3.37), and with coinfections of P. gingivalis and P. intermedia (OR 4.03); P. gingivalis and B. forsythus (OR 3.84); P. gingivalis and T. denticola (OR 4.17); P. gingivalis, B. forsythus, and T. denticola (OR 4.06); and P. gingivalis, P. nigrescens, and T. denticola (OR 3.29). EBV-1 also showed positive association with severe periodontitis (OR 5.09), with increasing age (OR 1.03), and with periodontal probing depth at the sample sites (OR 1.77). HCMV was positively associated with coinfections of P. gingivalis and P. nigrescens (OR 3.23); P. gingivalis, B. forsythus, and P. nigrescens (OR 3.23); and P. gingivalis, P. nigrescens, and T. denticola (OR 2.59); with severe periodontitis (OR 4.65); and with age (OR 1.03). Patients with mixed viral infections revealed significant associations with P. gingivalis (OR 2.27), and with coinfections of P. gingivalis and B. forsythus (OR 2.06); P. gingivalis and P. nigrescens (OR 2.91); P. gingivalis, B. forsythus, and P. nigrescens (OR 2.91); and P. gingivalis, P. nigrescens, and T. denticola (OR 2.70) with the clinical diagnosis of slight (OR 3.73), moderate (OR 3.82), or severe periodontitis (OR 4.36), and with probing depth at the sample sites (OR 1.39). HSV and EBV-2 showed no significant associations with any of the variables tested.

CONCLUSIONS

The results indicate that subgingival EBV-1, HCMV, and viral coinfections are associated with the subgingival presence of some periodontal pathogens and periodontitis. Herpesviruses may exert periodontopathic potential by decreasing the host resistance against subgingival colonization and multiplication of periodontal pathogens.

Prevalence of various respiratory viruses in the middle ear during acute otitis media

BACKGROUND

Vaccines against respiratory viruses may be able to reduce the frequency of acute otitis media. Although the role of respiratory viruses in the pathogenesis of acute otitis media is well established, the relative importance of various viruses is unknown.

METHODS

We determined the prevalence of various respiratory viruses in the middle-ear fluid in 456 children (age, two months to seven years) with acute otitis media. At enrollment and after two to five days of antibiotic therapy, specimens of middle-ear fluid and nasal-wash specimens were obtained for viral and bacterial cultures and the detection of viral antigens. The viral cause of the infections was also assessed by serologic studies of serum samples obtained during the acute illness and convalescence.

RESULTS

A specific viral cause of the respiratory tract infections was identified in 186 of the 456 children (41 percent). Respiratory syncytial virus was the most common virus identified in middle-ear fluid: it was detected in the middle-ear fluid of 48 of the 65 children (74 percent) infected by this virus (P< or =0.04 for the comparison with any other virus). Parainfluenza viruses (15 of 29 children [52 percent]) and influenzaviruses (10 of 24 children [42 percent]) were detected in the middle-ear fluid significantly more often than enteroviruses (3 of 27 children [11 percent]) or adenoviruses (1 of 23 children [4 percent]) (P< or =0.01 for all comparisons).

CONCLUSION

Respiratory syncytial virus is the principal virus invading the middle ear during acute otitis media. An effective vaccine against upper respiratory tract infections caused by respiratory syncytial virus may reduce the incidence of acute otitis media in children.

Daily tympanometry in children during the cold season: association of otitis media with upper respiratory tract infections

The causal association between otitis media and viral upper respiratory tract infections (URI) suggests that early intervention during the course of a viral URI could prevent many episodes of otitis media. However, the feasibility of this approach can not be assessed at present since many aspects of the epidemiology and natural history of URI-associated otitis media are undefined. To address this deficiency, daily monitoring of middle ear status (tympanometry) and cold symptoms and weekly pneumatic otoscopy were done on a pilot cohort of 20 children. These children, between the ages of 2 and 6, were followed from November 1996 to April 1997. Compliance with symptom diaries was 85%, with tympanograms was 90%, and with weekly physician visits was 70%. During the study period, there were 53 'colds' (average 2.65 per child) and 28 new episodes of middle ear effusion (10 unilateral and 9 bilateral). Overall, 47.3% of the tympanograms were Type A, 17.2% Type C1, 9.4% Type C2, and 21.8% Type B. Children who developed MEE during the study spent more time with abnormal MEP (either MEP < -150 or flat) during both cold and healthy days than children who did not develop MEE. Temporally, during colds, high negative pressures preceded the development of Type B tympanograms in children who developed middle ear effusions. Children who did not develop effusions still had high negative pressures during colds, but recovered to a normal pressure within days. These observations document the feasibility of this investigational format for study of the sequential changes in middle ear status before, during and after a URI.

Detection of rhinovirus, respiratory syncytial virus, and coronavirus infections in acute otitis media by reverse transcriptase polymerase chain reaction

OBJECTIVE

To determine the frequencies of human rhinovirus (HRV), respiratory syncytial virus (RSV), and coronavirus (HCV) infection in children with acute otitis media (AOM).

METHODS

Middle ear fluids (MEF) collected by tympanocentesis and nasopharyngeal aspirates (NPA) at the time of the AOM diagnosis were examined by reverse transcriptase polymerase chain reaction for HRV, RSV, and HCV RNA.

PATIENTS

Ninety-two children aged 3 months to 7 years during a 1-year period.

RESULTS

Virus RNA was detected in a total of 69 children (75%) and in 44 MEF samples (48%) and 57 NPA samples (62%) at the time of AOM diagnosis. HRV RNA was detected in both MEF and NPA in 18 (20%), in MEF alone in 4 (4%), and in NPA alone in 10 (11%). RSV was detected in both MEF and NPA in 12 (13%), in MEF alone in 5 (5%), and in NPA alone in 9 (10%). HCV RNA was detected in both MEF and NPA in 5 (5%), in MEF alone in 2 (2%), and in NPA alone in 9 (10%). Dual viral infections were detected in 5% of children. HRV and RSV were detected simultaneously in 2 MEF samples and in 2 NPA samples; RSV and HCV were detected in 1 NPA sample. Bacterial pathogens were detected in 56 (62%) MEF from 91 children. Viral RNA was detected in 20 (57%) MEF of 35 bacteria-negative and in 25 (45%) of 56 bacteria-positive MEF samples. No important differences in the risk of treatment failure, relapse, or occurrence of late secretory otitis media were noted between children with virus-positive and virus-negative MEF aspirates.

CONCLUSION

These findings highlight the importance of common respiratory viruses, particularly HRV and RSV, in predisposing to and causing AOM in young children.

Acute otitis media in children with bronchiolitis

OBJECTIVE

We investigated the prevalence and the etiology of acute otitis media (AOM) in children with bronchiolitis to determine whether AOM in such children is due entirely or mainly to respiratory syncytial virus (RSV), in which case routine antimicrobial treatment would not be appropriate.

METHODS

The study group consisted of children aged 2 to 24 months with bronchiolitis. In patients with AOM at entry, nasal washings for RSV enzyme-linked immunosorbent assay were obtained, and Gram-stained smear, bacterial culture, and reverse transcriptase polymerase chain reaction to detect the presence of RSV were performed on middle-ear aspirates. Patients without AOM were reevaluated at 48 to 72 hours, 8 to 10 days, and 18 to 22 days.

RESULTS

Forty-two children with bronchiolitis were enrolled. Sixty-two percent had AOM at entry or developed AOM within 10 days. An additional 24% had or eventually developed otitis media with effusion. Only 14% remained free of both AOM and otitis media with effusion throughout the 3-week observation period. All patients with AOM had 1 or more bacterial pathogens isolated from one or both middle-ear aspirates. Of 33 middle-ear aspirates, Streptococcus pneumoniae was isolated in 15, Haemophilus influenzae in 8, Moraxella catarrhalis in 8, and Staphylococcus aureus in 2. Two middle-ear aspirates yielded 2 pathogens each; 2 aspirates had no growth. RSV was identified in 17 (71%) of 24 patients with AOM.

CONCLUSION

Bacterial AOM is a complication in most children with bronchiolitis. Accordingly, in patients with bronchiolitis and associated AOM, antimicrobial treatment is indicated.

Role of viruses in middle-ear disease

Taken together, there is ample evidence suggesting a role for viruses in the pathogenesis of OM. This evidence comes from numerous studies performed in animals and in vitro cell cultures, as well as in adults and children with URI and OM. Viruses induce host immune and inflammatory responses that result in pathology of the ET and the middle ear, and predispose the host in various ways to secondary bacterial infection. A suggested mechanism for the pathogenesis of OM following respiratory viral infection is presented in Figure 1.

Acute otitis media in children

Acute otitis media (AOM) is the most common reason parents bring children into the primary care physician's office. It is diagnosed by clinical symptoms of otalgia and often fever and irritability and by clinical otoscopy. Organisms common to the nasopharynx usually cause AOM. Many episodes of AOM resolve spontaneously. Because it is uncertain how many and which children will resolve without therapy, it is reasonable to treat all children with AOM with antibiotics. The first choice of antibiotics is amoxicillin. Other choices rest on a variety of factors.

Mammalian viruses in human periodontitis

A prior investigation has demonstrated a higher prevalence of human cytomegalovirus (HCMV) and Epstein-Barr virus (EBV) in subgingival specimens from periodontitis patients than from gingivitis patients. This study aimed to determine the frequency of HCMV, EBV-1, EBV-2, herpes simplex virus (HSV) and human immunodeficiency virus (HIV) in subgingival samples from 27 adults who each contributed both a periodontitis and a gingivitis site. Viral detection was performed using a nested-polymerase chain reaction method. Twenty-four subjects (89%) yielded at least one of the five test viruses from deep periodontal pockets, whereas only 15 (56%) showed viruses from shallow periodontal sites (P = 0.015; chi-square test). Viral co-infection occurred more frequently in deep than in shallow periodontal sites (P = 0.015). HCMV was detected with higher frequency in deep than in shallow periodontal sites (P = 0.023). The possible periodontopathogenic mechanisms of mammalian viruses in human periodontitis are discussed. The role and importance of HCMV and other mammalian viruses in the initiation and progression of destructive periodontal disease merits further investigation.

Aspects on the interaction of Streptococcus pneumoniae and Haemophilus influenzae with human respiratory tract mucosa

Haemophilus influenzae and Streptococcus pneumoniae are common causes of respiratory tract infections. H. influenzae attach to receptor epitopes in mucins and in epithelial cell membranes. Attachment is followed by an epithelial cell cytokine response. Secreted cytokines then initiate inflammation, upset the integrity of the mucosal barrier, and lead to disease. S. pneumoniae do not bind to mucins but attach to respiratory tract epithelial cells. Attachment is increased by viral infection of the epithelial cells. Unlike H. Influenzae, S. pneumoniae induce apoptosis in epithelial cells, thus disrupting the mucosal barrier. Attachment and persistence is counterbalanced by antiadhesive as well as bactericidal molecules in secretions such as human milk. These examples illustrate the balance between host defenses and microbial virulence as it has coevolved to maintain the health of the respiratory mucosa.

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

Acute otitis media (AOM) has been associated with respiratory syncytial virus (RSV) infection; AOM develops in up to one third of children with RSV illness. A masked multicenter trial used an immune globulin enriched with RSV-neutralizing antibodies (RSVIG) to prevent RSV infection of the lower respiratory tract in 249 children with either bronchopulmonary dysplasia, congenital heart disease, or prematurity. To determine whether monthly RSVIG therapy might decrease the incidence of AOM, we retrospectively analyzed the records of 109 children in two of the centers. RSVIG was administered during RSV season of a high dose of 750 mg/kg monthly or a low dose of 150 mg/kg monthly; control children received no RSVIG. Children were examined for AOM by masked observers using pneumatic otoscopy. No difference in sex, race, underlying diagnosis, number of persons in the home, exposure to smoking, or atopy was found between groups studied. In recipients of high doses of RSVIG, significantly less AOM developed per season than in control children (mean episodes, 0.15 vs 0.78; p = 0.003), and fewer episodes of RSV-related AOM occurred (0 vs 5; p = 0.047). Low doses of RSVIG did not have a clinically significant impact. High doses of RSVIG appeared to have a significant impact on preventing AOM (both RSV- and non-RSV-related AOM) in these-high risk populations. This finding may have important implications in the development of improved preventive modalities for AOM.

Antibodies to pneumococcal polysaccharides in human milk: lack of relationship to colonization and acute otitis media

BACKGROUND

This study analyzed antibodies to pneumococcal polysaccharides in human milk and their effect on nasopharyngeal colonization and acute otitis media in breast-fed infants.

METHODS

A total of 503 milk samples were collected from 310 mothers. Nasopharyngeal cultures were obtained from their children at 2, 6 and 10 months postpartum, and the capsular groups/types of the Streptococcus pneumoniae isolates were determined.

RESULTS

Types 6A, 6B, 19A, 19F and 23F accounted for 54% of the pneumococcal isolates, but type 3 isolates were uncommon. Milk samples were analyzed for antibody activity to the common capsular polysaccharide types 6A, 19F and 23F; to the type 3 polysaccharide; to C-polysaccharide; and to phosphorylcholine (PC), a major component of the pneumococcal cell wall polysaccharide (CWPS). Anti-capsular antibody activity was low or absent in > 90% of the milk samples. In contrast anti-PC antibody activity was detected in 88% and anti-CWPS in 84% of the samples. The frequency of acute otitis media did not vary with the milk anti-capsular, anti-PC or anti-CWPS antibody activity.

CONCLUSIONS

There was no reduction in nasopharyngeal carriage of S. pneumoniae among children fed milk with anti-capsular or anti-PC antibody activity, but carriage was increased in those children who received milk with anti-CWPS antibody activity. A protective role of antipolysaccharide or anti-CWPS antibodies in milk was not detected under the study conditions.

Incidence of adenovirus and respiratory syncytial virus in chronic otitis media with effusion using the polymerase chain reaction

The aim of this study is to investigate the role of adenovirus and respiratory syncytial virus in the cause of chronic otitis media with effusion by use of the polymerase chain reaction for detection. The polymerase chain reaction has proved to be more sensitive and specific than viral cultures and immunoassays in the detection of viruses in other specimens. Adenovirus and respiratory syncytial virus were chosen because these viruses have been the most commonly isolated viruses in middle ear effusions in studies using other techniques. The effusions (132 total) were sterilely collected from 88 children undergoing myringotomy and ventilation tube placement for chronic otitis media with effusion. Nine (6.8%) specimens were positive for adenovirus by the polymerase chain reaction, and 13 (9.9%) were positive for respiratory syncytial virus by the polymerase chain reaction. Only one specimen was positive for adenovirus and respiratory syncytial virus by viral culture and immunofluorescence, respectively. Our results show that the polymerase chain reaction can be used to detect adenovirus and respiratory syncytial virus in chronic middle ear effusions and that PCR is more sensitive than viral culture and immunofluorescence techniques.

Adenovirus infection enhances in vitro adherence of Streptococcus pneumoniae

Viruses are thought to facilitate bacterial infections of the respiratory tract, but the mechanisms are poorly understood. The present study analyzed the effect of adenovirus on bacterial adherence to human respiratory tract epithelial cells. The human lung carcinoma cell line A549 was infected with adenovirus of types 1, 2, 3, 4, 5, and 9. At a multiplicity of infection of 75 particles per cell, cytopathic effects occurred in 75 to 100% of the cells within 48 h. The virus-infected cells were harvested at various times after infection and analyzed for the ability to bind strains of Haemophilus influenzae and Streptococcus pneumoniae. Adenovirus (types 1, 2, 3, and 5) commonly causing respiratory tract infections increased the binding of adherent S. pneumoniae strains to the cells. This effect was not seen for other adenovirus types. Adenovirus infection did not change the adherence of cells of poorly adhering strains of S. pneumoniae or H. influenzae. The increase in adherence of S. pneumoniae could be inhibited by the DNA synthesis inhibitor cytosine arabinofuranoside, which is known to block the late phase of the adenovirus infection. When electron microscopy was used, there was no evidence that virus particles bound directly to bacteria. Adherence was not affected by pretreatment of the cells with virus particles or viral proteins. This suggested that adenovirus infection upregulated receptors for S. pneumoniae. The increased attachment may be one mechanism by which viruses precondition the respiratory mucosa for bacterial infection.

Studies on the survival of aerosolized bovine rotavirus (UK) and a murine rotavirus

The effect of relative humidity (RH) and temperature on the survival of airborne bovine rotavirus UK isolate (BRV-UK) and a murine rotavirus (MRV) was studied. In any one experiment, the virus under test was suspended in tryptose phosphate broth (TPB) supplemented with uranine (physical tracer) and an antifoam, was aerosolized using a Collison nebulizer into the rotating drum with the RH at either low (30 +/- 5%), medium (50 + 5%) or high (80 +/- 5%) level at 20 +/- 1 degrees C. Following a 15-min period of viral aerosol stabilization, sequential samples of drum air were collected using an All-Glass Impinger (AGI) for 24 h post-aerosolization. Both of the rotavirus isolates were found to survive best at medium RH level and high RH was found least favorable for the survival of these aerosolized rotaviruses. The survival pattern of aerosolized MRV was found to be the best when compared with survival pattern of all animal and human rotavirus isolates studies performed under aerosolized conditions in our laboratory. The findings of these experiments confirm and extend our previous reports on the survival of other animal and human aerosolized rotaviruses and emphasize the fact that air may be one of the vehicles for their dissemination and could explain why it is difficult to control nosocomial outbreaks of rotavirus gastroenteritis and to keep animal colonies rotavirus-free.

Nasal and otologic effects of experimental influenza A virus infection

Past studies showed that experimental rhinovirus colds in adults resulted in eustachian tube dysfunction and abnormal middle ear pressures. In the present study, the symptoms and pathophysiologic findings accompanying experimental influenza viral infection were documented. A total of 33 healthy adult volunteers were intranasally challenged with an influenza A/Kawasaki/86 (H1N1) virus and cloistered over a 9-day postchallenge period to monitor for evidence of infection, signs and symptoms of illness, and the extent and frequency of pathophysiologic responses of the nose, eustachian tube, and middle ear. Results showed a protective effect of high (> or = 16) prechallenge specific hemagglutination-inhibition antibody titer on the rate of infection and the magnitude and extent of provoked symptoms and pathophysiologic findings. Infected subjects with low (< 16) prechallenge serum antibody titers (n = 21) developed significant respiratory illness. These subjects also had objectively measurable increases in nasal secretion production, and decreased nasal patency and mucociliary clearance rates. More than 80% of the infected subjects developed eustachian tube dysfunction, and approximately 80% had middle ear underpressures of less than -100 mm H2O on study days 4 and 5. Five of 21 infected subjects with low prechallenge antibody titers had otoscopic evidence of otitis media with effusion. These results support a causal role for viral upper respiratory tract infection in the pathogenesis of otitis media, possibly mediated by the early development of eustachian tube dysfunction and abnormal middle ear pressure.

Effect of viral respiratory tract infection on outcome of acute otitis media

We prospectively studied 271 infants and children (2 months to 7 years of age) with acute otitis media (AOM) for viral and bacterial causes, outcome at the end of therapy, and frequency of recurrence within 1 month. Comprehensive virologic methods, including viral antigen detection, cell culture, and serologic studies, were used to diagnose viral infection of the respiratory tract, middle ear, or both. Evidence of viral infection was found in 46% (124/271) of patients with AOM. Sixty-six patients (24%) had virus or viral antigen in the middle ear fluid; 50 of these patients (76%) also had bacteria in middle ear fluid, and 16 (24%) had virus alone. More patients with AOM and combined bacterial and viral infection (51%) had persistent otitis (3 to 12 days after institution of antibiotic treatment), compared with those with only bacterial otitis (35%; p = 0.05) or patients with only viral infection (19%; p less than 0.01). Of patients with only viral infection, 4 of 10 with virus in middle ear fluid had persistent otitis, compared with none of 11 patients who had virus only in nasal wash specimens or whose viral infection was diagnosed only by serologic studies. Our data suggest that viruses interact with bacteria and that concurrent viral infection can significantly worsen the clinical course of bacterial AOM. The presence of virus in middle ear fluid may contribute to the pathogenesis and outcome of bacterial AOM. The mechanism of these interactions deserve further investigation.

Bacteriology of acute otitis media: a new perspective

Pathogenic bacteria were isolated from 90% of patients with acute otitis media. This higher-than-expected rate of positive cultures was probably related to the meticulous bacteriologic techniques used.

Serum antibodies against respiratory tract viruses in episodes of acute otitis media

Although the findings of epidemiological studies have suggested viral respiratory tract infection (RTI) to be crucially involved in the development of acute otitis media (AOM), the relationship between AOM and viral RTI remains unclear. Serum samples, obtained in the acute and convalescent phases of 57 AOM episodes (in 35 children during the first three years of life) were analysed for IgG antibodies against influenza A viruses, influenza B viruses, parainfluenza virus type 1, respiratory syncytial virus and adenoviruses. One third of the AOM episodes (18/57) could be related to viral RTI, as evidenced by significant increases in viral serum antibody activity. Treatment failure occurred in four AOM episodes where increases in serum viral antibody activity were noted. In three of these failures, antibiotic treatment was unsuccessful despite the bacterial strains not being resistant to the drug used. This suggests that concomitant viral infection may be a determinant of treatment outcome in some AOM episodes.

Branhamella catarrhalis and croup: toxicity in the upper respiratory tract

Branhamella catarrhalis has gained increasing recognition as a pathogen in the respiratory tract. During the past 18 years, since its transfer from the genus Neisseria, it has been associated with infection in cavities of the respiratory tract (sinuses and middle ear). It has been recognized as playing a role in laryngitis. Its isolation in large numbers from the surface and core of acutely and chronically infected tonsils indicates a possible role in these infections. Croup (two patients reported here) can now be added to this list. The toxic potential of B catarrhalis, its movement from commensal to pathogen for the upper respiratory tract, and the pathogenic mechanisms by which this has occurred are reviewed.

Respiratory syncytial virus: virology, diagnosis, and vaccination

Attempts to develop a respiratory syncytial virus vaccine have revealed the antigenic heterogeneity of the virus and have highlighted the difficulties of inducing protective responses in very young infants. Of the two subgroups of the virus, A and B, that cocirculate, A appears to be the most aggressive in infants, but protection against both will be required. Although a degree of protection is transferred from mother to the infant via the placenta and by breast feeding, the mechanisms of protection remain ill-understood and early hopes of exploiting this phenomenon have not been realized. The immune response to the virus in the very young is depressed but disease severity is not demonstrably linked to failure to control virus replication. Rather, immune mechanisms contribute directly to the development of bronchiolitis. The involvement of the immune response in the pathologic process increases the hazards of vaccination. Research is currently focused on the definition of viral epitopes necessary to induce only a protective immune response and their incorporation into a suitable vaccine vector.