Prevention of otitis media in children by pneumococcal vaccination

Acute otitis media in children-current treatment and prevention

Acute otitis media (AOM) is the most common bacterial infection in children and has a very varied clinical spectrum, ranging from spontaneous resolutions to serious complications. The effect of antibiotics in AOM depends on the chosen outcome, but has been shown to reduce pain somewhat, and have a greater beneficial effect in severe cases of AOM. Today, not all episodes of AOM are treated with antibiotics, but most countries have issued guidelines that include an option of watchful waiting in many cases. Prevention of AOM reaches from modification of environmental risk factors to vaccinations and surgery. Conjugate pneumococcal vaccines and influenza vaccines have been shown to somewhat reduce the number of AOM episodes in different groups of children. Grommets, with or without adenoidectomy, are effective at least during the first 6 months after surgery.

Vaccines for preventing pneumococcal infection in adults

BACKGROUND

Diseases caused by Streptococcus pneumoniae (S. pneumoniae) continue to cause substantial morbidity and mortality globally. Whilst pneumococcal polysaccharide vaccines (PPVs) have the potential to prevent disease and death, the degree of protection afforded against various clinical endpoints and within different populations is uncertain.

OBJECTIVES

To assess the efficacy and effectiveness of PPVs in preventing pneumococcal disease or death in adults. We did not assess adverse events.

SEARCH METHODS

We searched CENTRAL 2012, Issue 6, MEDLINE (January 1966 to June Week 2, 2012) and EMBASE (1974 to June 2012).

SELECTION CRITERIA

We considered randomised controlled trials (RCTs) in adults, provided the study outcome met the definition of the outcome considered in the review. We also considered non-RCTs in adults, where the study assessed PPV effectiveness against culture-confirmed invasive pneumococcal disease (IPD), provided the study controlled for important confounding factors.

DATA COLLECTION AND ANALYSIS

Two review authors assessed trial quality of RCTs and three review authors extracted the data. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) using a random-effects model. Two review authors assessed study quality and extracted data for non-RCTs. We calculated ORs and 95% CIs using a random-effects model following the conversion of each study outcome to a log OR and standard error (SE).

MAIN RESULTS

Twenty-five studies met our inclusion criteria (18 RCTs involving 64,852 participants and seven non-RCTs involving 62,294 participants). Meta-analysis of the RCTs found strong evidence of PPV efficacy against IPD with no statistical heterogeneity (OR 0.26, 95% CI 0.14 to 0.45; random-effects model, I(2) statistic = 0%). There was efficacy against all-cause pneumonia in low-income (OR 0.54, 95% CI 0.43 to 0.67, I(2) statistic = 19%) but not high-income countries in either the general population (OR 0.71, 95% CI 0.45 to 1.12, I(2) statistic = 93%) or in adults with chronic illness (OR 0.93, 95% CI 0.73 to 1.19, I(2) statistic = 10%). PPV was not associated with substantial reductions in all-cause mortality (OR 0.90, 95% CI 0.74 to 1.09; random-effects model, I(2) statistic = 69%). Vaccine efficacy against primary outcomes appeared poorer in adults with chronic illness. Non-RCTs provided evidence for protection against IPD in populations for whom the vaccine is currently utilised (OR 0.48, 95% CI 0.37 to 0.61; random-effects model, I(2) statistic = 31%). This review did not consider adverse events as it was outside the scope of the review.

AUTHORS' CONCLUSIONS

This meta-analysis provides evidence supporting the recommendation for PPV to prevent IPD in adults. The evidence from RCTs is less clear with respect to adults with chronic illness. This might be because of lack of effect or lack of power in the studies. The meta-analysis does not provide evidence to support the routine use of PPV to prevent all-cause pneumonia or mortality.

Pneumococcal vaccination in children at risk of developing recurrent acute otitis media - a randomized study

AIM

Acute otitis media (AOM) is a common childhood disease, which often becomes recurrent (rAOM). A small reduction in AOM episodes has been noted in unselected child cohorts after vaccination with heptavalent conjugate pneumococcal vaccine (PCV7). The purpose of this study was to investigate how vaccination affects young children at risk of developing rAOM.

METHODS

Ninety-six children with an AOM onset before 6 months of age, implying a high risk for rAOM, were closely monitored until the age of 2 years. Forty-six were vaccinated with PCV7 and 50 were not. All episodes of AOM, emergency visits and ventilation tube insertions were registered.

RESULTS

A total of 363 AOM episodes were diagnosed. The incidence was reduced by 26% (p = 0.03), the number of emergency visits because of suspected AOM by 36% (p = 0.01) and the proportion of children who received ventilation tubes was halved in the vaccine group (p = 0.02).

CONCLUSIONS

During the first 2 years of life, PCV7 significantly reduced AOM episodes, emergency visits and ventilation tube insertions in children with rAOM. Pneumococcal vaccine may be a future route to reduce antibiotic use and health care consumption in otitis-prone children.

Vaccines for preventing pneumococcal infection in adults

BACKGROUND

Diseases caused by Streptococcus pneumoniae(S. pneumoniae) continue to cause substantial morbidity and mortality throughout the world. Whilst pneumococcal polysaccharide vaccines (PPV) have the potential to prevent disease and death, the degree of protection afforded against various clinical endpoints and within different populations is uncertain.

OBJECTIVES

To assess the effectiveness of PPV in preventing disease or death in adults. Adverse events were not assessed.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2007, Issue 2); MEDLINE (January 1966 to June 2007); and EMBASE (1974 to June 2007).

SELECTION CRITERIA

A) Randomised controlled trials (RCTs) comparing PPV with placebo, control vaccines, or no intervention.B) Non-RCTs assessing PPV effectiveness against invasive pneumococcal disease (IPD).

DATA COLLECTION AND ANALYSIS

A) RCTs: trial quality assessment was conducted by two review authors and data extracted by three authors; odds ratios (OR) and 95% confidence intervals (CI) were estimated using a random-effects model.B) Non-RCTs: study quality, including measures to control for confounding, was assessed and data extracted by two review authors; OR and 95% CI were calculated using a random-effects model following the conversion of each study outcome to a log OR and standard error.

MAIN RESULTS

Twenty-two studies met our inclusion criteria (15 RCTs involving 48,656 participants and 7 non-RCTs involving 62,294 participants). Meta-analysis of the RCTs found strong evidence of PPV efficacy against IPD with no statistical heterogeneity (OR 0.26, 95% CI 0.15 to 0.46; random-effects model, I-squared (I(2)) = 0%). Efficacy against all cause pneumonia was inconclusive with substantial statistical heterogeneity (OR 0.71, 95% CI 0.52 to 0.97; random-effects model, I(2) = 87.3%). PPV was not associated with substantial reductions in all-cause mortality (OR 0.87, 95% CI 0.69 to 1.10; random-effects model, I(2) = 75.3%). Vaccine efficacy against primary outcomes appeared poorer in adults with chronic illness but the difference was not statistically significant. Non-RCTs provided evidence for protection against IPD in populations for whom the vaccine is currently utilised (OR 0.48, 95% CI 0.37 to 0.61; random-effects model, I(2) = 31.4%).

AUTHORS' CONCLUSIONS

This meta-analysis provides evidence supporting the recommendation for PPV to prevent IPD in adults. The evidence from RCTs is less clear with respect to adults with chronic illness. This might be because of lack of effect or lack of power in the studies. The meta-analysis does not provide compelling evidence to support the routine use of PPV to prevent all-cause pneumonia or mortality.

Assessing vaccine efficacy for the prevention of acute otitis media by pneumococcal vaccination in children: a methodological overview of statistical practice in randomized controlled clinical trials

Acute otitis media (AOM) is the most common bacterial infectious disease among children. Vaccination is proposed to prevent otitis and several clinical trials were performed to assess the efficacy of pneumococcal vaccines. The way vaccine efficacy is analysed varies among trials. However, the clinical meaning of an estimate of vaccine effect and its statistical test depends on the applied statistical method. We aim to bring the meaning and validity of statistical trial results to the attention of researchers. We consider all methodological approaches for analysing vaccine efficacy applied in pneumococcal vaccination trials included in a recent Cochrane Review. We demonstrate how different methods address different scientific questions on the effect of vaccination, how they can complement each other and why some methods can produce misleading results.

Current issues regarding the use of pneumococcal conjugate and polysaccharide vaccines in Australian children

OBJECTIVE

To present the results of child pneumococcal vaccination studies in the setting of current Australian disease epidemiology and immunization policy, and issues that clinicians should consider in discussions with families.

METHODS

This paper includes a narrative review of randomized, controlled, double blind studies and systematic reviews which evaluated the efficacy of child pneumococcal vaccination.

RESULTS

7PCV is expected to prevent > 80% of childhood invasive pneumococcal disease (IPD, includes meningitis, septicaemia/bacteraemia) and the associated mortality. 7PCV may prevent 6% of all pneumonia, 18% of radiographically-defined pneumonia, 6% of all otitis media (OM) and 20%-40% of tympanostomy tube procedures. It may also reduce IPD due to antibiotic-resistant pneumococci, and prevent IPD in unvaccinated individuals. The impact of replacement disease caused by non-vaccine serotypes is not yet known. Pneumococcal polysaccharide vaccines given to 2-year-old children may prevent approximately 19% of all and 26% of recurrent OM.

CONCLUSION

The Australian Standard Vaccination Schedule recommends universal infant immunization with seven-valent pneumococcal conjugate vaccine (7PCV). Universal infant 7PCV will prevent pneumococcal diseases and deaths. The potential for its impact to be reduced in the long-term by serotype replacement must be closely monitored. Information concerning disease epidemiology, vaccine efficacy and safety, disease risk perception and national costs may prove useful in discussions with families.

Advances in Pneumococcal Vaccines

The introduction of Haemophilus influenzae type b (Hib) vaccine into the universal immunisation schedules of many industrialised countries and the subsequent remarkable decline in the incidence of invasive Hib disease has further highlighted the impact of invasive pneumococcal diseases. Streptococcus pneumoniae is now the leading cause of bacterial meningitis in children in many settings and a leading cause of vaccine-preventable bacterial disease in children worldwide. The currently marketed 23-valent pneumococcal polysaccharide vaccine provides large serotype coverage at a relatively low cost. However, it is not efficacious in young children. Pneumococcal conjugate vaccines (PCVs) are highly effective in preventing invasive disease in infants and young children, with favourable safety and immunogenicity profiles. These vaccines have also shown efficacy in reducing cases of non-invasive disease (i.e. otitis media), nasopharyngeal acquisition of vaccine-specific serotypes of S. pneumoniae, and protection against pneumococcal disease caused by resistant strains. However, PCV contains a limited number of pneumococcal serotypes and, given adequate ecological pressure, replacement disease by non-vaccine serotypes remains a threat, particularly in areas with very high disease burden. Furthermore, although capsular-specific antibodies have been shown to be highly protective, it remains unclear what concentration of these serotype-specific antibodies protect against disease and, more recently, it has become clear that opsonic activity and avidity of these antibodies are more critical determinants of protection than concentration. Therefore, monitoring disease burden and defining immune correlates of protection after widespread use of conjugate vaccines are crucial for the evaluation of these new generation vaccines. Furthermore, a need exists to develop pneumococcal vaccines with lower cost and larger serotype coverage. Development of one or more protein vaccines that might be easier and, thus, less expensive to manufacture, and which might provide protection against multiple serotypes, is in progress. This article reviews the current state of pneumococcal disease and pneumococcal vaccines in clinical use.

Pneumococcal conjugate vaccines for preventing vaccine-type invasive pneumococcal disease and pneumonia with consolidation on x-ray in children under two years of age

BACKGROUND

Pneumonia, most commonly caused by Streptococcus pneumoniae (Pnc), is a major cause of morbidity and mortality among young children especially in developing countries. Recently, the prevalence of antibiotic-resistant Pnc has increased worldwide such that the effectiveness of preventive strategies, like the new pneumococcal conjugate vaccines (PCV) on rates of invasive pneumococcal disease (IPD) and pneumonia, needs to be evaluated.

OBJECTIVES

To determine the efficacy of PCV in reducing the incidence of IPD due to vaccine serotypes (VT) and x-ray confirmed pneumonia with consolidation of unspecified etiology in children who received PCV before 12 months of age.

SEARCH STRATEGY

We searched the following databases: the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 1 2004), MEDLINE (1990 to March 2004) and EMBASE (1990 to December 2003). Reference list of articles, and books of abstracts of relevant symposia, were hand searched. Researchers in the field were also contacted.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing PCV with placebo, or another vaccine, among children below two years with IPD and clinical/radiographic pneumonia as outcomes.

DATA COLLECTION AND ANALYSIS

Two reviewers independently identified eligible studies, assessed trial quality, and extracted data. Differences were resolved by discussion. The inverse variance method was used to pool effect sizes.

MAIN RESULTS

We identified four trials assessing the efficacy of PCV in reducing the incidence of IPD, two on x-ray confirmed pneumonia as outcome, and one on clinical pneumonia, with or without x-ray confirmation. Results from pooling HIV-1 negative children from the South African study with the other studies were as follows: the pooled vaccine efficacy (VE) for vaccine-type IPD was 88% (95% confidence interval (CI) 73% to 94%; fixed effect and random effects models), the effect measure was statistically significant (p <0.00001) and there was no heterogeneity (p = 0.77I2 0%); the pooled VE for all-serotype IPD was 66% (95% CI 46% to 79%; fixed effect model), the effect measure was statistically significant (p <0.00001) and there was no statistical heterogeneity (p = 0.09, I2 51%); the pooled VE for x-ray confirmed pneumonia was 22% (95% CI 11% to 31%; both fixed effect and random effects models) and there was no statistical heterogeneity (p = 0.80, I2 0%). Analyses that included all the children in the South African study (HIV-1 negative and HIV-1 positive children) and pooled with data from the other studies gave very similar results.

REVIEWERS' CONCLUSIONS

PCV is effective in reducing the incidence of IPD from all serotypes but exerts a greater effect in reducing VT IPD. Although PCV is also effective in reducing the incidence of x-ray confirmed pneumonia, there are still uncertainties about the definition of this outcome. Additional randomised controlled trials are currently in progress.

What can children gain from pneumococcal conjugate vaccines?

In excess of 1 million young children die every year as a consequence of disease caused by Streptococcus pneumoniae, the vast majority in developing countries. Although the first vaccine against the Pneumococcus was produced before the First World War, licensure of the first vaccine with documented efficacy against severe infections in infants and young children did not occur until February 2000 in the United States. This conjugate vaccine consists of purified polysaccharide, from each of seven pneumococcal serotypes, chemically linked to a carrier protein. A high degree of efficacy of the new vaccine against potentially life-threatening infections has been shown in both poor and affluent countries. The vaccine's potential to protect from acute otitis media, however, is very limited, although encouraging indirect effects, such as reduced antibiotic prescriptions, have been reported. An inherent problem with the new pneumococcal conjugate vaccines is that, while more than 20 pneumococcal serotypes may cause invasive disease, only a more limited number of polysaccharides, 11 or so, can in practice be conjugated to carrier protein as part of a single vaccine formulation. Because of variation in the ranking of serotypes most commonly responsible for pneumococcal disease, by region, age and disease manifestation, compromise was required in selecting serotype-specific saccharides for inclusion.

CONCLUSION

Complex conjugate technology comes at a price, and the present costs keep most of the world's children far out of reach of an effective vaccine. However, the pneumococcal conjugate vaccine is a highly functional weapon against deadly pneumococcal infections, and strenuous efforts are needed to maximise its accessibility to children most at risk.

Pneumococcal vaccines for preventing otitis media

BACKGROUND

Acute otitis media (AOM) is one of the most common diseases in early infancy and childhood. Long term effects of recurrent episodes of otitis media, rapid emergence of drug resistant bacteria associated with AOM worldwide and huge estimated direct and indirect annual costs associated with otitis media have emphasized the need for an effective vaccination program to prevent episodes of AOM.

OBJECTIVES

The object of this review was to assess the effect of pneumococcal vaccination in preventing AOM in children up to 12 years of age.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (issue 2, 2003) which contains the Cochrane Acute Respiratory Infection Group's specialised register (30th June 2003), MEDLINE (January 1966 to June 2003), EMBASE (January 1990 to June 2003) and reference lists of all studies and review articles retrieved. We also contacted two vaccine manufacturers and first or corresponding authors of some of the included studies.

SELECTION CRITERIA

Randomised controlled clinical trials of pneumococcal vaccination with prevention of AOM as outcome in children aged 12 years or younger and a follow-up of at least six months after vaccination.

DATA COLLECTION AND ANALYSIS

Five reviewers independently assessed trial quality and two reviewers extracted data. Two study authors were contacted.

MAIN RESULTS

Eight trials on 8-to 14-valent pneumococcal polysaccharide vaccine (PPV) and four trials on 7-to 9-valent pneumococcal conjugate vaccine (PCV) were included. The highest efficacy of PPV was found in children aged 24 months and older: the rate ratio was 0.779 [95% CI: 0.625-0.970]. PPV has little effect on the prevention of AOM in children without documented prior episodes of AOM and only a moderate effect in the group of children with documented AOM episodes prior to vaccination. Pooled results of the four PCV trials in infants vaccinated as early as two months of age and toddlers attending daycare and toddlers with recurrent AOM showed only a small effect on prevention of AOM (rate ratio 0.921; 95% CI: 0.894-0.950).

REVIEWER'S CONCLUSIONS

Based on the currently available results of the effectiveness of pneumococcal vaccination for the prevention of AOM, a large scale use of pneumococcal polysaccharide and conjugate vaccination for this specific indication is not yet recommended. So far, pneumococcal conjugate vaccinations are not indicated in the management of recurrent AOM in toddlers and older children. The results of currently ongoing trials of 9- and 11-valent conjugate vaccines should provide more information as to whether pneumococcal vaccines are more effective in specific high-risk populations like infants and older children with recurrent AOM or immunodeficiency.

Association of clinical signs and symptoms with bacterial findings in acute otitis media

In acute otitis media (AOM), a means of prediction of the bacterial pathogen based on symptoms and signs would be valuable in selecting appropriate antimicrobial treatment. Children in the control arm (n=831) in the Finnish Otitis Media Vaccine Trial were prospectively observed in a study clinic setting from the age of 2 to 24 months. In patients with AOM, myringotomy with aspiration was performed, and middle ear fluid samples were cultured for bacterial pathogens. Symptoms and signs of respiratory infections were thoroughly recorded. Streptococcus pneumoniae, Moraxella catarrhalis, and Haemophilus influenzae were the most common bacterial pathogens. Pneumococcal AOM was associated with more-severe AOM characterized by fever and earache. AOM due to H. influenzae was associated with eye symptoms and findings. Accurate prediction of a bacterial cause of infection based on symptoms and signs of AOM was not possible, but a specific cause was predicted in some situations, with a high probability of applicability to clinical practice.

Central role of complement in passive protection by human IgG1 and IgG2 anti-pneumococcal antibodies in mice

Streptococcus pneumoniae is an important cause of morbitity and mortality worldwide. Capsule-specific IgG1 and IgG2 Abs are induced upon vaccination with polysaccharide-based vaccines that mediate host protection. We compared the protective capacity of human recombinant serogroup 6-specific IgG1 and IgG2 Abs in mice deficient for either leukocyte FcR or complement factors. Human IgG1 was found to interact with mouse leukocyte FcR in vitro, whereas human IgG2 did not. Both subclasses induced complement activation, resulting in C3c deposition on pneumococcal surfaces. Passive immunization of C57BL/6 mice with either subclass before intranasal challenge with serotype 6A induced similar degrees of protection. FcgammaRI- and III-deficient mice, as well as the combined FcgammaRI, II, and III knockout mice, were protected by passive immunization, indicating FcR not to be essential for protection. C1q or C2/factor B knockout mice, however, were not protected by passive immunization. Passively immunized C2/factor B(-/-) mice displayed higher bacteremic load than C1q(-/-) mice, supporting an important protective role of the alternative complement pathway. Spleens from wild-type and C1q(-/-) mice showed hyperemia and thrombotic vessel occlusion, as a result of septicemic shock. Notably, thrombus formation was absent in spleens of C2/factor B(-/-) mice, suggesting that the alternative complement pathway contributes to shock-induced intravascular coagulation. These studies demonstrate complement to play a central role in Ab-mediated protection against pneumococcal infection in vivo, as well as in bacteremia-associated thrombotic complications.

Review of randomized controlled trials on pneumococcal vaccination for prevention of otitis media

BACKGROUND

Increasing resistance to antibiotics of the pathogens causing acute otitis media (AOM) emphasize the need for effective methods to prevent episodes of otitis media in young children.

OBJECTIVE

To assess the effectiveness of pneumococcal vaccination for prevention of AOM in children age 12 years and younger.

METHODS

Systematic review of 11 randomized controlled trials including 46 074 children in whom pneumococcal vaccination against AOM was compared with a control treatment. Vaccine effect was estimated as a rate ratio (RR): AOM episodes per child month in pneumococcal vaccination group divided by the AOM episodes per child-month in control group.

RESULTS

A moderate effect of pneumococcal polysaccharide vaccination was found in children 24 months of age and older [RR 0.78; 95% confidence interval (CI) 0.63 to 0.97]. Pneumococcal polysaccharide vaccine had little effect on prevention of AOM in children without previous documented episodes before vaccination (RR 0.92; 95% CI 0.85 to 0.99). Better efficacy was seen in those children with documented prior AOM before vaccination (RR 0.81; 95% CI 0.72 to 0.91). Pooled results of pneumococcal conjugate vaccine trials in infants vaccinated as early as 2 months of age and in toddlers attending day care showed only a small effect on prevention of AOM (RR 0.92; 95% CI 0.85 to 0.99).

CONCLUSION

Based on these results, a large scale pneumococcal vaccination program for a primary indication of preventing AOM in infancy is not indicated. The results of ongoing trials should provide more information whether the conjugate vaccine is effective in high risk (otitis-prone) children after 1 year of age.

Vaccine development for capsulate bacteria causing pneumonia

Pneumonia strikes the extremes of the age spectrum, causing maximal death and disability in children and the elderly. Despite its worldwide impact, there is a paucity of epidemiologic data regarding its incidence and the causative organisms. The two leading causes of bacterial pneumonia in childhood are Streptococcus pneumoniae (SP) and Haemophilus influenzae type b (Hib). SP is the major cause of pneumonia beyond the newborn period. In neonates, Group B Streptococcus (GBS) remains a major cause of sepsis and pneumonia despite recent reductions due to targeted perinatal antibiotic prophylaxis. Hib vaccine can prevent pneumonia in developing countries. SP conjugate vaccine prevents X-ray confirmed pneumonia in low incident populations, but protection appears more marginal in high incident populations. Non-vaccine SP serotypes have demonstrated increased carriage and mucosal disease, but not invasive disease following vaccination. GBS vaccines are in the early stages of clinical development as prenatal or antenatal vaccines.

Vaccines for preventing pneumococcal infection in adults

BACKGROUND

Diseases caused by Streptococcus pneumoniae (S. pneumoniae) continue to cause substantial morbidity and mortality throughout the world. Polysaccharide pneumococcal vaccines have been developed for over 50 years and may have the potential to prevent disease and death.

OBJECTIVES

To assess the effectiveness of polysaccharide pneumococcal vaccination in preventing disease or death in adults.

SEARCH STRATEGY

Trials were identified by electronic searches of the Cochrane Central Register of Controlled Trials (CENTRAL) issue 2, 2003 (which includes the Cochrane ARI Group's specialised register); MEDLINE (January 1966 to June 2003); and EMBASE (1974 to June 2003). We searched existing literature. The bibliographies of all newly revealed studies were read in order to identify further studies. The vaccine manufacturers, the lead authors of newly identified studies not included in existing meta-analyses were contacted.

SELECTION CRITERIA

A) Prospective, randomised or quasi-randomised studies comparing pneumococcal vaccines with placebo, control vaccines or no intervention.B) Case-control studies (including indirect cohort studies) assessing pneumococcal vaccine effectiveness against invasive pneumococcal disease. Cohort studies are excluded.

DATA COLLECTION AND ANALYSIS

A) Randomised studies. Trial quality assessment was conducted by two reviewers (JH and DT). Data extraction was done by three reviewers (JH, DT, KD). There were many instances of unclear or incomplete data in the trial reports, and the final dataset was arrived at after much deliberation and discussion, including comparison with the data used in two previous reviews of this question. Due to the age of the trials (dating back to 1954 in one case) it was not generally possible to obtain clarification from the authors, though a partial clarification was achieved in one case.B) Non-randomised studies. Study quality was assessed by two reviewers (RA and KD).

MAIN RESULTS

The combined results from the randomised studies fail to show that the polysaccharide pneumococcal vaccine is effective in preventing either pneumonia (outcome 6: odds ratio = 0.77, confidence interval 0.58, 1.02, number = 14) or death (outcome 8: odds ratio 0.90, confidence interval 0.76, 1.07, number = 11). Despite encouraging data from some very early trials, pooling trials published from 1977 on suggests there is no effect (outcome 6; odds ratio = 0.96, confidence interval 0.80, 1.15, number = 12; outcome 9: odds ratio = 0.98, confidence interval 0.88, 1.09, number = 10). The available data cannot distinguish whether this heterogeneity in results is due to improvements in trial methodology and reporting, to differences in trial setting or to real loss of efficacy over time. This is because the early, poorly reported trials were conducted in high-risk healthy populations where the expected benefit is greatest. The case-control studies show significant efficacy in preventing invasive pneumococcal disease: OR 0.47 (CI 0.37, 0.59) corresponding to an efficacy of 53%.

REVIEWER'S CONCLUSIONS

While polysaccharide pneumococcal vaccines do not appear to reduce the incidence of pneumonia or death in adults with or without chronic illness, or in the elderly (55 years and above), the evidence from non-randomised studies suggests that the vaccines are effective in the reducing the incidence of the more specific outcome, invasive pneumococcal disease, among adults and the immunocompetent elderly (55 years and above). Surveillance data suggest that infection rates vary widely between and also within countries, but a typical figure in developed countries is 0.01%, or 10 per 100,000 per year. Efficacy of 50% then corresponds to a number-needed-to-treat (NNT) of 20,000 vaccinations per infection avoided, and perhaps 50,000 per death avoided.

Current state of pneumococcal vaccines

Streptococcus pneumoniae is a leading cause of bacterial pneumonia, meningitis, and acute otitis media in children and adults worldwide. According to World Health Organization estimates, at least 1 million children under 5 years of age die each year from pneumococcal pneumonia. The emergence of resistant strains necessitates the development of an effective vaccine with a large serotype coverage. The 11 most common serotypes cause 72-83% of all serious pneumococcal diseases worldwide. Currently marketed 23-valent pneumococcal polysaccharide vaccine provides large serotype coverage and offers a less expensive option. However, it is efficacious only in adults but not in infants. Conjugate vaccines offer a solution by generating immunological memory already at early age. A recently licensed 7-valent conjugate vaccine is immunogenic and efficacious in infants. Its serotype coverage might be sufficient in Europe and North America, but not in Africa, Asia and Oceania. A need exists to develop pneumococcal vaccines with lower cost and larger serotype coverage. Several 11-valent pneumococcal conjugate vaccines are being evaluated in phase I-III trials. This study reviews the current state of pneumococcal problem and pneumococcal vaccines in clinical use.

Deficient IgA and IgG2 anti-pneumococcal antibody levels and response to vaccination in otitis prone children

OBJECTIVE

To evaluate the isotype and IgG subclass distribution of anti-pneumococcal antibodies and response to polysaccharide vaccination in otitis prone children.

METHODS

IgG1, IgG2 and IgA antibodies to pneumococcal serotypes 3, 4, 6B, 9V, 14, 19F and 23F were determined in otitis prone children and in an age-matched healthy control population. Patients were immunized with a 23-valent pneumococcal polysaccharide vaccine. The antibody response was measured 4 weeks later.

RESULTS

Geometric mean IgA and IgG2 antibody levels for all seven pneumococcal serotypes tested were significantly lower in otitis prone children than in the control population. After immunization, there was no significant increase in geometric mean IgG2 anti-serotype 6B, 19F and 23F pneumococcal polysaccharide (weak immunogenic), but also no increase for IgG2 anti-serotype 4 and 14. Post immunization IgG2 antibody titers for serotypes 6B, 9V and 19F even remained below titers of non-vaccinated controls. Nine out of 29 otitis prone children were colonized nasopharyngeally with Streptococcus pneumoniae during the time of vaccination; these children had an even more severely impaired systemic antibody response.

CONCLUSIONS

Otitis prone children, while having normal IgG1 antibody levels, have low IgG2 and IgA anti-polysaccharide antibody levels and fail to respond in these subclasses upon vaccination with pneumococcal polysaccharide vaccine.

Future vaccines: recent advances and future prospects

The 20th century has witnessed the introduction of over 20 vaccines that prevent or even conquer diseases such as smallpox, polio, and measles. The continued threat of infectious diseases demands the creation of many more vaccines, especially against common respiratory and gastrointestinal pathogens. Thanks to recent advances in molecular biology, immunology, and adjuvant technology, the next decade likely will bring a vaccine for HIV/AIDS also. We enter the 21st century with a tempered optimism, proud of past achievements, but mindful of the challenges that lie ahead.

Bacteriology of acute otitis media in a cohort of Finnish children followed for the first two years of life

BACKGROUND

Timely information on the bacteriology of primary, noncomplicated acute otitis media (AOM) may today be needed more than ever, because of the increasing antimicrobial resistance of its major bacterial causes and because of the potential of new pneumococcal and other bacterial vaccines for prevention of AOM.

METHODS

The study followed 329 children from 2 to 24 months of age at scheduled healthy visits and sick visits at the study clinic. Whenever AOM was diagnosed during the follow-up, myringotomy was performed and middle ear fluid was aspirated for bacterial culture.

RESULTS

At least one middle ear fluid sample was available from 772 AOM events; Streptococcus pneumoniae (Pnc) was isolated in 201 (26%), Moraxella catarrhalis (Mc) in 177 (23%) and Haemophilus influenzae (Hi) in 174 events (23%). The incidence of Pnc AOM peaked at 12 months of age, whereas the incidence of Mc AOM showed the first peak at 6 months and Hi AOM at 20 months. Pnc AOM showed less prominent seasonality in occurrence than Mc and Hi AOM. Hi was a rare cause of the first 2 AOM episodes (13%) but became increasingly common from the third episode on (32% on average).

CONCLUSIONS

Pnc, Mc and Hi were almost equally common findings in AOM. Pnc seems to be the most pathogenic of these three, the role of Mc is increasing and Hi is clearly associated with recurrent AOM.

Efficacy of a pneumococcal conjugate vaccine against acute otitis media

BACKGROUND

Ear infections are a common cause of illness during the first two years of life. New conjugate vaccines may be able to prevent a substantial portion of cases of acute otitis media caused by Streptococcus pneumoniae.

METHODS

We enrolled 1662 infants in a randomized, double-blind efficacy trial of a heptavalent pneumococcal polysaccharide conjugate vaccine in which the carrier protein is the nontoxic diphtheria-toxin analogue CRM197. The children received either the study vaccine or a hepatitis B vaccine as a control at 2, 4, 6, and 12 months of age. The clinical diagnosis of acute otitis media was based on predefined criteria, and the bacteriologic diagnosis was based on a culture of middle-ear fluid obtained by myringotomy.

RESULTS

Of the children who were enrolled, 95.1 percent completed the trial. With the pneumococcal vaccine, there were more local reactions than with the hepatitis B vaccine but fewer than with the combined whole-cell diphtheria-tetanus-pertussis and Haemophilus influenzae type b vaccine that was administered simultaneously. There were 2596 episodes of acute otitis media during the follow-up period between 6.5 and 24 months of age. The vaccine reduced the number of episodes of acute otitis media from any cause by 6 percent (95 percent confidence interval, -4 to 16 percent [the negative number indicates a possible increase in the number of episodes]), culture-confirmed pneumococcal episodes by 34 percent (95 percent confidence interval, 21 to 45 percent), and the number of episodes due to the serotypes contained in the vaccine by 57 percent (95 percent confidence interval, 44 to 67 percent). The number of episodes attributed to serotypes that are cross-reactive with those in the vaccine was reduced by 51 percent, whereas the number of episodes due to all other serotypes increased by 33 percent.

CONCLUSIONS

The heptavalent pneumococcal polysaccharide-CRM197 conjugate vaccine is safe and efficacious in the prevention of acute otitis media caused by the serotypes included in the vaccine.

Polysaccharide-based pneumococcal vaccines in the prevention of acute otitis media

New pneumococcal vaccines, consisting of 7-11 capsular polysaccharides coupled to protein carriers, are able to induce functionally active humoral and mucosal antibody responses. They also reduce mucosal carriage of pneumococci in the vaccinees. Preliminary results from efficacy trials suggest that about one-third of pneumococcal otitis could be prevented by using the seven-valent pneumococcal conjugate vaccine. If these efficacy estimates are true throughout childhood, up to 1.2 million episodes of acute otitis are preventable annually in the US. The true impact of the vaccine on otitis burden is dependent not only on the efficacy as demonstrated in the efficacy trials but also on the impact of the vaccine on the mucosal carriage of bacteria and on the herd immunity induced by vaccinations. Ongoing follow-up studies will reveal whether these factors increase or decrease the efficiency of the proposed vaccination programme.

treatment and prevention of otitis media

OBJECTIVE

To review and summarize recent advances in the treatment and prevention of otitis media (OM).

DATA SOURCES

A MEDLINE search (1996-March 2000) was performed to identify relevant primary and review articles. References from these articles were also reviewed if deemed important.

STUDY SELECTION AND DATA EXTRACTION

English-language primary and review articles focusing on the treatment and prevention of acute otitis media (AOM) were included. Studies focusing exclusively on OM with effusion or serous OM and chronic suppurative OM were excluded. Information regarding prevention and drug therapy was reviewed, with an emphasis placed on advances made in the last two years.

DATA SYNTHESIS

Recently, an expert panel of the Centers for Disease Control and Prevention recommended use of only three of 16 systemic antibiotics approved by the Food and Drug Administration for treatment of AOM: amoxicillin, cefuroxime axetil, and ceftriaxone. Controversy exists over the importance of key selection factors used by the expert panel in determining which antibiotics to recommend in a two-step treatment algorithm, that is, in vitro data, pharmacodynamic profiles, and necessity for coverage of drug-resistant Streptococcus pneumoniae at all steps of empiric treatment. Additional antibiotic and patient selection factors useful for individualizing therapy include clinical efficacy, adverse effects, frequency and duration of administration, taste, cost, comorbid infections, and ramifications should bacterial resistance develop to the chosen antibiotic. Presumed or past patient/caregiver adherence (especially when antibiotic failure has occurred) is also paramount in selecting antibiotic therapy. A three-step treatment algorithm for refractory AOM that employs amoxicillin, trimethoprim/sulfamethoxazole (TMP/SMX), or high-dose amoxicillin/clavulanate (depending on the prior dose of and adherence to amoxicillin therapy), and ceftriaxone or tympanocentesis at steps 1, 2, and 3, respectively, appears rational and cost-effective. The recent upsurge in antimicrobial resistance is highlighted, and recommendations are presented for the treatment of AOM and prevention of recurrent otitis media (rAOM).

CONCLUSIONS

Amoxicillin remains the antibiotic of choice for initial empiric treatment of AOM, although the traditional dosage should be increased in patients at risk for drug-resistant S. pneumoniae. In cases refractory to high-dose amoxicillin, TMP/SMX should be prescribed if adherence to prior therapy seemed good or complete, or high-dose amoxicillin/clavulanate if adherence was incomplete or questionable. Ceftriaxone should be reserved as third-line treatment. The increasing prevalence of drug-resistant S. pneumoniae emphasizes the importance of alternative medical approaches for the prevention of OM, as well as judicious antibiotic use in established cases. Removal of modifiable risk factors should be first-line therapy for prevention of rAOM. We support the use of conjugate pneumococcal vaccine per guidelines for prevention of rAOM from the Advisory Committee on Immunization Practice of the Centers for Disease Control and Prevention, with consideration given to influenza vaccine for cases of rAOM that historically worsen during the flu season. Sulfisoxazole prophylaxis should be reserved for children who are immunocompromised, have concurrent disease states exacerbated by AOM, or meet the criteria of rAOM despite conjugate pneumococcal and influenza vaccination. Therapy should be intermittent, beginning at the first sign of an upper respiratory infection, and should continue for 10 days. The invasive nature and risks of anesthesia relegate myringotomy, tympanostomy tubes, and adenoidectomy to last-line therapies for rAOM.

Immunogenicity of pneumococcal conjugate vaccines

BACKGROUND

Prevention of pneumococcal infections is a public health priority because of the high impact of the disease and because of the increasing problems due to antimicrobial resistance. Traditional vaccines, consisting of purified capsular polysaccharides (PSs) of Streptococcus pneumoniae, are not immunogenic in young children. In addition they confer only limited protection in patients with immunodeficiencies and hematologic malignancies.

IMMUNOGENICITY OF PNEUMOCOCCAL CONJUGATE VACCINES

Immunogenicity of the PS vaccine has been enhanced by coupling pneumococcal PSs to proteins to produce a conjugate vaccine. Conjugate molecules are designed to possess T cell dependent properties, such as immunogenicity in early infancy, stimulation of high levels of IgG isotype antibodies and enhanced immunologic memory responses. In the clinical studies multivalent pneumococcal conjugate vaccines have been shown to induce an IgG-dominating serum antibody response against common pneumococcal serotypes causing infections in children. A booster dose later in life creates a robust and rapid antibody response, indicating the existence of immunologic memory in primed children. Antibodies induced by conjugate vaccines are functionally active, as demonstrated by their high avidity and opsonophagocytic activity.

Prospects for pneumococcal vaccination in African children

Streptococcus pneumoniae (pneumococcus) remains a major cause of morbidity and mortality in both developed and undeveloped countries. Accurate disease burden estimates for developing countries and Africa in particular, where diagnostic facilities are less adequate and a disease surveillance system virtually non-existent, is difficult. However, from conservative estimates, the pneumococcus is probably responsible for at least 1 million of the 4 million deaths that occur from acute lower respiratory infections in children aged less than 5 years. The global burden of disease has been accentuated by the rising menace of multi-drug resistant strains, which defy geographic and racial borders. Thus, now more than ever before, there is an urgent need to identify and implement preventive measures to avert this problem. The currently licensed pneumococcal polysaccharide vaccine, comprises 23 capsular polysaccharides of the pneumococcus, many of which are poorly immunogenic in the very vulnerable age group of under-fives. A possible solution to the problem of poor immunogenicity is to use a protein/polysaccharide conjugate vaccine similar to that recently introduced successfully for Haemophilus influenzae type b (Hib) and using this approach, several workers have reported promising results from safety and immunogenicity studies. However, unlike Hib, the development of conjugate vaccine against pneumococcal disease is complicated by the existence of more serotypes than can be feasibly incorporated in a single conjugate vaccine formulation. Whilst this challenge has been taken on by some vaccine manufacturers, novel approaches such as the identification or construction of protective protein antigen, common to all clinically important strains are being explored. Novel application of the pneumococcal polysaccharide vaccines in pregnancy for protection of disease in early infancy is an approach that has not been evaluated. For maximum impact, the ultimate vaccine formulation should be affordable and available to resource poor countries where the burden of disease is highest. Establishing disease surveillance systems in such countries now will greatly facilitate the introduction of the vaccines.

The contribution of specific pneumococcal serogroups to different disease manifestations: implications for conjugate vaccine formulation and use, part II

To assess whether certain serogroups of Streptococcus pneumoniae are preferentially associated with specific disease manifestations, we analyzed all recent pneumococcal disease studies and assessed the relative frequency of isolation of each serogroup by clinical site (as a proxy for different disease states). In all age groups, serogroups 1 and 14 were more often isolated from blood, and serogroups 6, 10, and 23 were more often isolated from cerebrospinal fluid (CSF); in young children, serogroups 3, 19, and 23 were more often isolated from middle ear fluid (MEF). Serogroups represented in conjugate vaccines were isolated slightly less frequently from CSF than from blood or MEF. Nonetheless, serogroups in the 9-valent conjugate vaccine formulation still comprised approximately 75% of pneumococcal isolates from the CSF of young children in Europe and in the United States and Canada. These analyses indicate that pneumococcal conjugate vaccines could potentially prevent a substantial proportion of episodes of bacteremic disease, pneumonia, meningitis, and otitis media, especially in young children.

Potential and limitations of polysaccharide vaccines in infancy

Of infections caused by encapsulated bacteria, those due to Haemophilus influenzae b (Hib) are among the most restricted to infancy and require very early immunisation. Hib capsular polysaccharide (CPS) has the most typical T-cell independent profile. The absence of efficacy of this vaccine in infants triggered development of conjugate vaccines which are so effective that there is now no room for plain polysaccharide Hib vaccines. Pneumococcal infections pose similar problems to Hib, but are more complex. The immunogenicity of the different pneumococcal serotypes varies considerably in infancy. Although the current CPS vaccine provides limited protection in infancy, the burden of pneumococcal infection is so high that its use could be reconsidered should conjugate vaccines be available later than expected. Meningococcal infections are less a specific problem for infants. Again, serogroup immunogenicity varies widely. Group B meningococcal CPS is not immunogenic even in adults, Group C behaves as Hib CPS, whereas Group A is immunogenic as early as 6 months of age. Group A CPS may prove of interest for an infant vaccine, especially in epidemic situations. Typhoid fever is uncommon in infancy; Vi CPS is poorly immunogenic in infancy and is, therefore, of limited interest for use as an infant vaccine.

New prospects in the prevention of otitis media

Otitis media is the most common bacterial infection in children, accounting for a substantial economic burden to the health care system. Together with concern for long-term developmental sequelae, prevention of otitis media has become a high priority area of research. A wide range of factors has been associated with an increased risk of acute otitis media. Most of these factors, however, predispose to upper respiratory tract infection which, in turn, can be considered the most important risk factor for acute otitis media. Conventionally, antimicrobial prophylaxis, tympanostomy tubes and adenoidectomy have been used for prevention of otitis media. At present, the vaccine approach seems to hold the greatest promise for ultimate prevention of otitis media. In addition to the bacterial vaccines, vaccines against the most common viruses predisposing to acute otitis media may also prove valuable in the prevention of otitis media.

Correlates of Cochlear Implantation, 1986–1992

There is a paucity of information regarding the use of cochlear implants within large populations. This article describes correlates of cochlear implantation procedures using a statewide hospital discharge database. Among the 146 implant procedures, 55% involved female patients, whereas the largest groups of patients were represented by younger and older persons (27% between ages 2 and 9 years and 24% 60 years and older). A bimodal distribution was apparent for average annual age-specific rates of cochlear implantation, with the highest rates among persons aged 2 to 9 years (5.4 implants per 1 million) and persons aged 60 to 69 years (3.7 implants per 1 million). Total hospital charges, excluding professional fees, exceeded $12,000 per implant and were found to vary significantly when examined by length of stay and by calendar year of procedure. The data presented are unique with regard to the total number of cochlear implant procedures included and the large, diverse population used. This study expands knowledge concerning the epidemiology and utilization of cochlear implantation.

Immunological aspects of otitis media: present views on possibilities of immunoprophylaxis of acute otitis media in infants and children

The article reviews, based on current knowledge of immunological events affecting the middle ear, the possibilities and prospects for the prevention of otitis media (OM) by immunologic measures. While pneumococcal capsular polysaccharide vaccines proved not to be effective against infant acute otitis media (AOM), pneumococcal conjugate vaccines provide good immunogenicity even in infants, and call for trials with better prospects of clinical efficacy. The other future approaches currently under development are vaccines against nontypable Haemophilus influenzae and Branhamella catarrhalis, anti-viral immunoprophylaxis, combinations of the above alternatives, or passive immunization. Also, the use of new routes or ways of immunization are under study. Furthermore, the ways to modify the present treatment practices of AOM to favour good immunologic responses in infants and children must be studied.

Incidence of acute otitis media associated with group A and B respiratory syncytial virus infections

The comparative association of respiratory syncytial virus group A and B infections with acute otitis media was determined by analysing the hospital records of children with community-acquired respiratory syncytial virus infection during three successive outbreaks from 1987 to 1992. Of 326 episodes analysed, 192 (59%) were caused by group A and 134 (41%) by group B infections. Acute otitis media was diagnosed in 101 (75%) children with group B infection, compared with 119 (62%) with group A infection (p = 0.01). Group A infections were more often associated with wheezing (71% versus 59% in group B; p = 0.02) and oxygen therapy in inpatients (48% versus 31%, respectively; p = 0.008). The higher incidence of acute otitis media associated with group B infections was observed both after adjustment for potential confounding variables and during each outbreak.

Pneumococci in nasopharyngeal samples from Filipino children with acute respiratory infections

The presence of Streptococcus pneumoniae in the upper respiratory tract was studied in 318 Filipino children less than 5 years old with an acute lower respiratory tract infection. Nasopharyngeal samples were obtained from 292 children. With both quantitative bacterial culture and detection of capsular polysaccharide antigens by coagglutination, counterimmunoelectrophoresis, and latex agglutination, pneumococci were found in 160 (70%) of the 227 samples eligible for analysis. Culture was positive in 115 samples and antigen was positive in 140 samples. The culture isolation rate was significantly lower if the patient had received antimicrobial agents in the 48 h prior to the sampling. The seven most common types or groups of pneumococci were 6, 14, 19, 23, 15, 7, and 11, which together accounted for 64% of all pneumococcal findings.

Prevention of recurrent acute otitis media in otitis-prone children by intermittent prophylaxis with penicillin

The question whether penicillin V (pcV) given intermittently upon signs of upper respiratory tract infections (URTI) in otitis-prone children might prevent recurrent bouts of acute purulent otitis media (AOM) is addressed. As compared with continuous long-term antibiotic treatment as prophylaxis in otitis-prone children, intermittent administration would reduce the overall consumption of antibiotics. Seventy-six otitis-prone children less than 18 months of age were included in this double-blind, randomized, placebo-controlled multicentre study. Follow-up was from January till June. One hundred and twenty-three episodes of AOM occurred. The number of AOM episodes was reduced by 50% in the children on pcV during URTI episodes as compared with those on placebo. No obvious ecological drawbacks were noted. Thus, the described mode of pcV administration seems to be a rational and safe way to reduce the number of AOM episodes in otitis-prone children.

Facial nerve injury in cochlear implantation

We present eight cases of FN dysfunction after cochlear implantation. Four mechanisms of injury are proposed. The most common injury occurs from the heat of a bur shaft rotating over the FN in the facial recess. Several suggestions are made to help prevent the type of injuries we have seen. Preoperative imaging and intraoperative FN monitoring may be of general assistance in avoiding injuries to the FN, especially in cases of revision surgery and congenital malformations.

Prophylaxis for recurrent acute otitis media: a Brazilian study

We enrolled 60 children with recurrent acute otitis media (AOM) in a study of the effectiveness of antimicrobial prophylaxis. All children were entered into the study following an acute episode of infection treated with amoxicillin (AMX) for 10 days. Following therapy, the children were re-examined, and then randomly assigned to receive either trimethoprim-sulfamethoxazole (TMP-SMX), amoxicillin (AMX) or a placebo (PLA). Twenty children were included in each group. Each drug was administered once a day at bedtime, at 1/3 the therapeutic dose, for 3 months. Children were re-evaluated with pneumootoscopy during episodes of acute illness and with pneumootoscopy and impedance tympanometry (TYMP) at monthly intervals. We observed a significantly increased rate of recurrent AOM in children receiving placebo compared with those who received antibiotics (50% vs. 17% P < 0.005). Both prophylactic antibiotics were equally effective in preventing recurrent AOM (recurrence rate 20% TMP-SMX, 15% AMX). We also observed that recurrences in children receiving placebo occurred earlier in the study period than in those receiving antibiotics. These results suggest that antimicrobial prophylaxis in children with recurrent acute otitis media is effective in reducing subsequent disease. The similar efficacy of both antibiotics tested suggests that the less expensive agent should be used.

Active immunisation and resistance to experimental acute pneumococcal otitis media

The middle ear mucosal system and the humoral systemic immune factors are the two immunological systems whose involvement in the defence against acute otitis media (AOM) have been most intensively studied. However, their respective importance and their mutual influence is not clear. In the present study, a rat model for pneumococcal AOM was used to further elucidate the involvement of systemic immunity in protection against pneumococcal AOM. Six groups of male Sprague-Dawley rats were immunised with pneumococcal vaccine (PneumovaxRN) or live pneumococci (type 3) via one of three different routes: intraperitoneally, into the gastrointestinal tract (GIT) or into the right middle ear. A subsequent middle ear challenge (re-challenge in one group) with the same pneumococcal strain was performed after 4 days to 8 weeks in the different groups. Systemic immunity was found to be triggered, not only by systemic immunisation, but also by antigenic stimulation of the mucosa in the middle ear and in the GIT. In all groups but that immunised in the GIT, no new peak of specific IgG antibody response was demonstrated in serum after middle ear challenge/re-challenge. In contrast, half of the rats immunised in the GIT showed such a response not only after the inoculation into the GIT but also after a later performed middle ear challenge. Though a faster resolution of pus from the middle ear was observed in rats from all but one group, a significant reduction in the number of rats who developed AOM occurred exclusively among those rats that had previously manifested serological response to immunisation in the GIT.

Occurrences of antibodies against Streptococcus pneumoniae, Haemophilus influenzae and Branhamella catarrhalis in middle ear effusion and serum during the course of acute otitis media

The occurrence of IgG, IgM and IgA class antibodies against a type-specific capsular polysaccharide of Streptococcus pneumoniae (Pn) and against a whole cell antigen of Haemophilus influenzae (Hi) and Branhamella catarrhalis (Br) was studied using the ELISA method on middle ear effusion (MEE) samples of 85 patients and paired serum samples of 40 patients during the course of acute otitis media (AOM). Although specific antibodies to all of these three bacteria appeared in MEE during the course of an AOM episode, antibodies against the infecting bacteria of that particular AOM episode were more often prominent. The antibodies were also detectable in the MEE without simultaneous presence in the serum. The middle ear infection was prolonged more often if specific antibodies to the infecting bacterium could not be detected in the MEE obtained at the beginning of the AOM attack. The present study indicates that AOM caused by Pn, Hi or Br may induce both a systemic and a local production of specific antibodies against the causative organisms during the course of otitis media. The occurrence of such antibodies in MEE seems to play a major role in the resolution of AOM.

Responses to rubella, tetanus, and diphtheria vaccines in otitis-prone and non-otitis-prone children

Delayed immunologic maturation--among other things based on a selective lack of antibodies against some acute purulent otitis media (AOM)-associated pneumococcal types--has been proposed in children with recurrent AOM (rAOM). To further elucidate the immunologic response in these children, we compared the antibody responses to diphtheria, tetanus, and rubella vaccinations in 13 children with rAOM and 29 children without AOM. The children took part in a prospective study from birth to the age of 3 years. The antibody response to the rubella vaccine was significantly lower in the children with rAOM. The responses to tetanus and to diphtheria did not differ between children with and without rAOM. Thus, the results indicate that in addition to the known lack of antibodies against pneumococcal polysaccharide antigens, a lower antibody response against at least one protein antigen may exist in otitis-prone children.

Prevention of experimental acute otitis media with penicillin V

The preventive effect of penicillin V (pcV) in pneumococcal otitis media in the rat has been studied. The pcV was administered either before bacterial challenge (prevention group) or after challenge but before the establishing of acute purulent otitis media (AOM) (early treatment group). In both cases a fulminant infection was avoided. Thus, in the prevention group no animal developed AOM and in the early treatment group the fulminant AOM was avoided in all cases. These results give further support to the idea of using long-term treatment with an antibiotic with a narrow spectrum to avoid recurrent AOM (rAOM). Furthermore the observation that early treatment might stop the development of fulminant AOM indicates another more restrictive possibility to use antibiotic as a prophylactic measure in otitis-prone children.

Antibodies against Streptococcus pneumoniae, Haemophilus influenzae and Branhamella catarrhalis in middle ear effusion during early phase of acute otitis media

Serum type (IgG, IgM and IgA-class) and secretory type antibodies specific to Streptococcus pneumoniae (Pn), Haemophilus influenzae (Hi) and Branhamella catarrhalis (Br) were measured by enzyme-linked immunosorbent assay (ELISA) in 46 serum and 114 middle ear effusion (MEE) samples from 85 children with acute otitis media (AOM). The samples were obtained within 12 h from the onset of the ear symptoms. Serum (but not secretory) type antibodies to the infecting Pn serotype were found in 24% of the MEE samples of the patients with Pn AOM and, correspondingly, serum and/or secretory type antibodies to Hi and Br were seen in 54% and 63% of the MEE samples of the patients with Hi or Br AOM, respectively. Moreover, antibodies against bacteria other than the causative one could also be found in the MEE. The occurrence of the serum type antibodies against these bacteria in the MEE was closely correlated with their serum levels. The findings of this study indicate that during the very early phase of AOM, the MEE contains both serum type antibodies originating from the serum, and secretory antibodies of middle ear origin. Among them there are antibodies specific to the three most common bacteria causing AOM (Pn, Hi, and Br) regardless of the bacterial etiology of the AOM attack in question.

Epidemiologic patterns in childhood hearing loss: a review

In an attempt to clarify international epidemiologic trends, a review of the published literature pertaining to childhood hearing loss is presented. Inconsistencies of methodology and classification, which complicate the interpretation of data and make difficult the quantification of the influence of genuine population differences, are discussed. Selective review of the literature allows certain crude statements to be made regarding childhood hearing loss. In developed countries, serous otitis media is the most common cause of hearing loss in children, affecting up to two thirds of preschool children. In addition, 1.0-2.0/1000 children have bilateral SNHL of at least 50 dB. In underdeveloped countries, suppurative middle ear disease is common and is still frequently associated with either an intratemporal or intracranial complication. SNHL appears to occur almost twice as often as in developed countries, with a greater proportion being of infectious etiology. In specific populations, the Inuits, Amerindians and Aboriginals, acute and chronic suppurative otitis media are almost endemic, yet both cholesteatoma and serous otitis media are uncommon.

Hearing and hearing loss in 5-year-old children. Pure-tone thresholds and the effect of acute otitis media

Air and bone conduction pure-tone thresholds of 420 unselected urban children were measured with standard clinical audiometry. The mean of air conduction pure-tone averages (average threshold at 0.5, 1 and 2 kHz) was 8.6 dB HL in girls and 8.3 dB HL in boys. In only 5 ears (0.6%), was this average greater than or equal to 35 dB HL. The threshold greater than or equal to 35 dB HL at 4 kHz was found in 1.4% of the ears and at 8 kHz in 4.1%. The bone conduction threshold greater than 20 dB HL at any of the frequencies from 0.5 to 4 kHz was very rare, and only once, at 4 kHz, was it greater than 35 dB HL. Earlier attacks of acute otitis media seemed to have only a marginal long-term effect on air conduction hearing, and an almost negligible effect on bone conduction hearing.

Pneumococcal middle ear fluid antibodies after pneumococcal acute otitis media in infants

Forty-one infants, who during their first (initial) acute otitis media (AOM) had culturable S. pneumoniae (Pn) in 57 middle ear fluids (MEFs) which prolonged or recurred during the follow-up, were observed for 7-15 months for the presence of Pn, Pn-antigens (Pn-ags) and initial-type/group Pn-antibodies (Pn-abs) in these MEFs. Initially, Pn-abs were found in only 3 MEFs. During the follow-up a total of 20 ears (35%) were, at various time-intervals, positive for Pn-abs; they belonged to all three major Ig-classes, but were often slight in quantity. Most regularly, and often with distinct positivity, Pn-abs were found to type 3, 9N and 14. Secretory abs were detected in 5 ears. Within one month after initial AOM, Pn-abs appeared in 9 of the 41 ears with MEF (22%); six of them cleared soon after that. MEFs with Pn-abs usually did not show initial-type Pn/Pn-ag, but new Pn/Pn-ag could later be simultaneously present in recurrent MEF. So, pneumococcal AOM may cause a local and/or systemically mediated immune response in the middle ear in infants. The response may protect the ear from homologous, but still be present in apparently non-homologous otitis media.

Incidence of acute otitis media up to the age of 1 1/2 years in urban infants

The object of this prospective cohort investigation of 1,642 infants was to study the incidence of acute otitis media (AOM) in urban children during the first 18 months of life. The monthly incidence of AOM was greatest at the age of 10 months, and the largest proportion of children with AOM was also found in this 10-month age group. Before the age of 18 months, 56.7% of the infants had had at least one episode of AOM, while 26.9% had had one or two episodes and 29.8% three or more. The corresponding figures before the age of 12 months were: 45.3%; 26.8%; 18.5%, and before the age of 9 months: 30.5%; 22.1%; 8.4%. The AOM incidence, particularly as regards recurrent AOM, was rather higher in boys than in girls.