Pneumococcal antibodies and complement during and after periods of recurrent otitis

Impact of the Seven-valent Pneumococcal Conjugate Vaccine on Acute Otitis Media in Japanese Children: Emergence of Serotype 15A Multidrug-resistant Streptococcus pneumoniae in Middle Ear Fluid Isolates

BACKGROUND

Streptococcus pneumoniae is one of the most common bacteria causing acute otitis media (AOM). In Japan, a 7-valent pneumococcal conjugate vaccine (PCV7) was introduced for voluntary vaccination of children in 2010, and it became a recommended vaccination in April 2013. We surveyed the serotypes and antimicrobial susceptibility profile of S. pneumoniae isolates obtained from the middle ear fluid of Japanese children with AOM.

METHODS

Between April and September 2013, a total of 176 S. pneumoniae isolates were obtained from the middle ear fluid of children aged 0-3 years with AOM. Isolates were collected from various regions of Japan. Minimum inhibitory concentrations were measured by the broth microdilution method. Serotyping was performed by observing the Quellung reaction.

RESULTS

Although 45.5% of the strains were susceptible to penicillin G, 42.6% were penicillin-intermediate strains and 11.9% were penicillin-resistant strains. Serotype 19A (27.3%), serotype 15A (14.2%) and serotype 3 (11.9%) showed a high frequency. Although PCV7 types only accounted for 4.5% of all strains, 44.9% were PCV13 types and 55.1% were non-PCV types. Serotype 15A strains were 100% nonsusceptible to penicillin G and all of these strains showed multidrug resistance. Serotype 15A was frequent in children up to 1 year old.

CONCLUSION

After this research was completed, PCV7 was switched to a PCV13 that also contained serotype 3 and serotype 19A. We need to consider the possibility that serotype 15A, which is not included in PCV13, may increase and cause intractable AOM in the future.

Normalized immunoglobulin patterns in adults with recurrent acute otitis media and low IgG2 levels during early childhood

OBJECTIVES

Children who suffer from recurrent acute otitis media (rAOM) sometimes display low immunoglobulin levels. It is not known whether the differences in immunoglobulin levels remain during adulthood or if rAOM-patients have more episodes of AOM and airway infections as adults.

METHODS

A study on adults, with a history of rAOM during childhood, was performed. The immunologic status and individual disposition for upper airway infections were evaluated in 28 subjects who originally participated in a study on rAOM between 1979 and 1983. 13 subjects had suffered from rAOM during early childhood and 15 subjects without rAOM served as a control group. The study included analysis of immunoglobulins in serum and self evaluation regarding susceptibility to infections of the upper airway.

RESULTS

There was no difference between the groups neither regarding IgG2 concentrations nor specific antibody levels. No episodes of AOM were reported after 20 years of age in any of the study subjects. The history of airway infections was similar in both groups.

CONCLUSIONS

Study subjects who had rAOM combined with low IgG2 levels during childhood had a normalized immunoglobulin pattern as adults.

Otitis media among high-risk populations: can probiotics inhibit Streptococcus pneumoniae colonisation and the risk of disease?

Otitis media is the second most common infection in children and the leading cause for seeking medical advice. Indigenous populations such as the Inuits, indigenous Australians and American Indians have a very high prevalence of otitis media and are considered to be high-risk populations. Streptococcus pneumoniae, one of the three main bacterial causes of otitis media, colonises the nasopharynx prior to disease development. In high-risk populations, early acquisition of high bacterial loads increases the prevalence of otitis media. In these settings, current treatment strategies are insufficient. Vaccination is effective against invasive pneumococcal infection but has a limited impact on otitis media. Decreasing the bacterial loads of otitis media pathogens and/or colonising the nasopharynx with beneficial bacteria may reduce the prevalence of otitis media. Probiotics are live microorganisms that offer health benefits by modulating the microbial community and enhancing host immunity. The available data suggest that probiotics may be beneficial in otitis media. This review discusses the potential use of probiotics to reduce pathogen colonisation and decrease the prevalence of otitis media, providing justification for further investigation.

Serum antibody response to five Streptococcus pneumoniae proteins during acute otitis media in otitis-prone and non-otitis-prone children

BACKGROUND

Streptococcus pneumoniae (Spn) is one of the common bacteria responsible for episodic acute otitis media (AOM; non-otitis-prone), recurrent AOM (otitis-prone), and AOM treatment failure (AOMTF) in children.

OBJECTIVE

From a population of 268 children, we sought to compare the serum IgG antibody titers of 5 different Spn proteins (PhtD, LytB, PcpA, PhtE, and Ply) that are vaccine candidates in children with episodic AOM (n = 34), who were otitis prone (n = 35) and who had AOMTF (n = 25) caused by Spn.

METHODS

Antibody was quantitated by enzyme-linked immunosorbent assay.

RESULTS

At their AOM visit, anti-PhtD, -LytB, -PhtE, and -Ply IgG antibody titers in otitis-prone children were significantly lower compared with non-otitis-prone children (P < 0.05) and children with AOMTF (P < 0.05). On comparing acute to convalescent geometric mean IgG antibody titers after AOM against the 5 proteins we found that otitis-prone, AOMTF, and non-otitis-prone children had no significant change in titers (except for PhtE in children with AOMTF), but detailed analysis showed that about one-third of the children in each cohort had a 2-fold rise in antibody to the studied antigens. Although non-otitis-prone children had significant increases (P < 0.001) between 6 and 24 months of age in anti-PhtD, PcpA, PhtE, and Ply IgG antibody titers as a consequence of nasopharyngeal colonization and AOM, otitis-prone children either failed to show rises or the rises were significantly less than the non-otitis-prone children.

CONCLUSION

Otitis-prone and AOMTF children mount less of an IgG serum antibody response as compared with non-otitis-prone children to Spn proteins after AOM and nasopharyngeal colonization.

Immunological status in the aetiology of recurrent otitis media with effusion: serum immunoglobulin levels, functional mannose-binding lectin and Fc receptor polymorphisms for IgG

The objective was to study the role of serum immunoglobulin levels, mannose-binding lectin (MBL), and Fc gamma receptor (FcgammaR) polymorphisms on the development of recurrent otitis media with effusion (OME). Children aged between two and seven years with persisting OME received bilateral tympanostomy tubes and immunological parameters were investigated in relation with OME recurrence within six months after tube extrusion. No statistically significant differences in serum immunoglobulin levels were present between children with and without OME recurrence. In children with bilateral recurrence (n = 56), median levels of MBL were 1.39 mg/L compared to 2.48 mg/L in children with OME recurrence (n = 17) (p = 0.29). In addition, 34% of the children with bilateral recurrence were homozygous for the genotype FcgammaRIIa-R/R131, whereas less than 20% of the children with unilateral recurrence or those without recurrence were homozygous for this Fcgamma receptor (p = 0.26). Serum mannose-binding lectin and FcgammaRIIa-R/R131 polymorphism may play a role in the aetio-pathogenesis of recurrent OME.

Antimicrobial activity of innate immune molecules against Streptococcus pneumoniae, Moraxella catarrhalis and nontypeable Haemophilus influenzae

Background

Despite its direct connection to the nasopharynx which harbors otitis media pathogens as part of its normal flora, the middle ear cavity is kept free of these bacteria by as yet unknown mechanisms. Respiratory mucosal epithelia, including those of the middle ear and eustachian tube, secrete antimicrobial effectors including lysozyme, lactoferrin and β defensins-1 and -2. To elucidate the role of these innate immune molecules in the normal defense and maintenance of sterility of respiratory mucosa such as that of the middle ear, we assessed their effect on the respiratory pathogens nontypeable Haemophilus influenzae (NTHi) 12, Moraxella catarrhalis 035E, and Streptococcus pneumoniae 3, and 6B.

Methods

Two assay methods, the radial assay and the liquid broth assay, were employed for testing the antimicrobial activity of the molecules. This was done in order to minimize the possibility that the observed effects were artifacts of any single assay system employed. Also, transmission electron microscopy (TEM) was employed to evaluate the effect of antimicrobial innate immune molecules on OM pathogens. For the statistical analysis of the data, Student's t-test was performed.

Results

Results of the radial diffusion assay showed that β defensin-2 was active against all four OM pathogens tested, while treatment with β defensin-1 appeared to only affect M. catarrhalis. The radial assay results also showed that lysozyme was quite effective against S. pneumoniae 3 and 6B and was partially bacteriostatic/bactericidal against M. catarrhalis. Lysozyme however, appeared not to affect the growth of NTHi. Thus, lysozyme seems to have a more pronounced impact on the growth of the Gram-positive S. pneumoniae as compared to that of Gram-negative pathogens. Lactoferrin on the other hand, enhanced the growth of the bacteria tested. The results of the radial assays were confirmed using liquid broth assays for antimicrobial activity, and showed that lysozyme and β defensin-2 could act synergistically against S. pneumoniae 6B. Moreover, in the liquid broth assay, β defensin-1 showed a modest inhibitory effect on the growth of S. pneumoniae 6B. As assessed by ultrastructural analysis, lysozyme and β defensin-2, and to a much lesser extent, β defensin-1, appeared to be able to cause damage to the bacterial membranes.

Conclusions

Here we report that lysozyme and the β defensins can inhibit the growth of clinical isolates of otitis media pathogens – namely NTHi strain 12, S. pneumoniae strains 3 and 6B and M. catarrhalis strain 035E – and cause ultrastructural damage to these pathogens. Moreover, we demonstrate that lysozyme and β defensin-2 can act synergistically against S. pneumoniae. These findings are consistent with the concept that secreted antimicrobial peptides and other components of innate immunity constitute the first line of defense protecting host mucosal surfaces, including the tubotympanal (eustachian tube and middle ear cavity) mucosa, against pathogens.

Decreased serum and pharyngeal antibody levels specific to streptococcal lipoteichoic acid in children with recurrent tonsillitis

OBJECTIVE

Streptococcus (S.) pyogenes is a common cause of primary as well as recurrent tonsillitis (RT). Lipoteichoic acid (LTA) has been proposed as a possible candidate for vaccine formulation against streptococcal infections, because LTA is a common constituent of streptococci and the antibody to LTA inhibits bacterial attachment to epithelial cells in vitro. Streptolysin-O and streptococcal whole cell body are highly immunogenic and the antibodies to these antigens are reported to be better parameters for streptococcal infections The objective of the present study is to investigate how systemic and local immune activities against S. pyogenes may be associated with RT.

METHODS

Sera from 178 children with or without RT aged 1-15 years with a median age of 5 years were investigated for the levels of total immunoglobulins and antibodies specific to streptococcal antigens such as whole cell body, LTA, and streptolysin-O. Pharyngeal secretions from 67 children with or without RT aged 2-14 years with a median age of 6 years were subjects to secretory IgA (SIgA) antibody levels to streptococcal LTA. The antibodies to whole cell body and LTA were measured by enzyme-linked immunosorbent assay. Total immunoglobins and the anti-streptolysin-O antibody were assayed by nephelometry.

RESULTS

An age-matched comparison revealed that either levels of serum IgG antibody or pharyngeal SIgA antibody to streptococcal LTA at 2-5 years of age were significantly lower in RT children than in non-RT children (1.39 vs. 5.14 microg/ml, P=0.001; 10.6 vs. 29.9 units/ng/ml total SIgA, P=0.015; respectively) and correlated inversely to episodes of tonsillitis (r=-0.242, P=0.024; r=-0.3, P=0.024; respectively). Either serum total immunoglobulin levels of IgG or IgA correlated positively to episodes of tonsillitis in children aged 2-5 years (r=0.293, P=0.011; r=0.361, P=0.002; respectively). No difference was found on either serum levels of IgG antibody to streptococcal whole cell body or antibody to streptolysin-O between RT and non-RT children in any age-matched comparisons. High serum antibody levels to whole cell body was associated with high antibody levels to streptococcal LTA in non-RT children (r=0.198, P<0.05), but no association was found between these antibody levels in RT children.

CONCLUSIONS

Selective immunologic failure in systemic and pharyngeal antibody response to streptococcal LTA may be a potential cause of RT in young children.

A comprehensive model for the aetiology of otitis media with effusion

Otitis media with effusion is highly prevalent among young children. Adverse effects of this disorder are mainly restricted to the group of children with a history of recurrent or persistent otitis media with effusion. Early identification, assessment and intervention might prevent these adverse effects. Up to now it is not possible to distinguish these children from those with transient otitis media with effusion. This article presents a comprehensive model for the aetiology of otitis media with effusion. Eustachian tube functioning and the immunological response to environmental pathogens are the two core elements. This model can be used to formulate specific hypotheses about the interaction of several factors that may lead to the early identification of children who are likely to develop persistent or recurrent otitis media with effusion.

Mucosal immunity of the middle ear: analysis at the single cell level

OBJECTIVE

Studies have suggested that the middle ear is a potential site of immunological regulation and that the middle ear mucosa constitutes a part of the mucosal immune system. We clarify the characteristics of the middle ear mucosa with respect to immune potential.

STUDY DESIGN

We investigated lymphocyte subsets, mRNA of cytokines, and induction of antigen-specific IgA-producing cells in the middle ear mucosa in specific pathogen-free C57BL/6 mice.

RESULTS

Flow cytometric analysis showed a certain amount (10%-15%) of gammadelta T cells among CD3+ T cells. P6-specific IgA-producing cells were induced by intranasal immunization with P6 together with cholera toxin. RT-PCR assay of mucosal T cells detected mRNA of Th2 type cytokines such as IL-5 and IL-10.

CONCLUSION

These findings support the fact that the middle ear is potentially an effector site of the mucosal immunity.

The nasopharynx and the middle ear. Inflammatory reactions in middle ear disease

The host-parasite interactions in the nasopharynx with bacterial colonization and antigen uptake in the lymphoid tissue, the adenoid, has an impact on the maturation of local and systemic immunity. The adenoid is a part of mucosa associated lymphoid tissue and is responsible for both effector and inductor functions in the nasopharynx. Increasing evidence supports the role of serum antibody in protecting the middle ear cavity from disease. There is evidence for a minor immunologic defect in a number of children with recurrent episodes of AOM.

Stimulation of adenoidal lymphocytes by Alloiococcus otitidis

Otitis media with effusion (OME) is characterized by persistent effusion in the middle ear cavity and by chronic inflammation in the middle ear mucosa. Alloiococcus otitidis, a gram-positive aerobic bacterium, has been isolated in middle ear effusion, and by means of sensitive polymerase chain reaction detection assays it has been detected in as many as 20% of middle ear aspirates of patients with OME. Because A otitidis may freely interact with leukocytes in the middle ear effusion, it may potentially modulate the inflammatory reaction in OME. To study the nature of these interactions, we applied an in vitro assay in which killed A otitidis bacteria were incubated with peripheral blood and adenoidal mononuclear cells. The expression of the proliferation-associated surface marker CD69 was then measured in B lymphocytes and in CD4+ helper and CD8+ cytotoxic-suppressor T lymphocytes by means of multicolor flow cytometry. Alloiococcus otitidis induced the expression of CD69 in both peripheral blood and adenoidal T and B cells. Among the T cells, the cytotoxic-suppressor T lymphocytes were preferentially activated. It was also tested whether A otitidis would have an effect in another cytotoxic and immunoregulatory system, namely, the induction of natural killer cell activity in peripheral blood mononuclear cells. However, the effect was minimal compared with that of Salmonella minnesota or Staphylococcus aureus. The results show that A otitidis has a unique immunostimulatory capacity in vitro that is mainly confined to CD8+ T lymphocytes.

Pulsed-field gel electrophoresis analysis of nasopharyngeal flora in children attending a day care center

To investigate how bacterial pathogens spread from child to child in a day care center, we monitored six children, two boys and four girls, born between August 1995 and November 1997, attending a day care center and analyzed nasopharyngeal samples from them using pulsed-field gel electrophoresis (PFGE). We obtained nasopharyngeal cultures from all of the affected children and almost all of the unaffected children between September 1998 and March 1999 after some children presented simultaneously with purulent rhinorrhea. Moreover, when a child was found to have acute otitis media, nasopharyngeal secretions from the child were independently cultured during treatment. During this period, 28 isolates of Moraxella catarrhalis, 13 of Streptococcus pneumoniae, and 4 of Haemophilus influenzae were recovered. PFGE gave 8 patterns for M. catarrhalis, 10 for S. pneumoniae, and 1 for H. influenzae. PFGE patterns demonstrated spread of M. catarrhalis between children. However, each occurrence of clusters of infection with M. catarrhalis lasted 2 to 6 weeks, with a change in PFGE pattern between occurrences of clusters. The M. catarrhalis strain infecting each child also changed. Similarly, the S. pneumoniae strain in each child also changed. In contrast, infection with H. influenzae persisted for about 3 months in an affected child.

Sequelae of recurrent acute otitis media. Ten-year follow-up of a prospectively studied cohort of children

In a cohort of 113 children prospectively followed from birth to the age of 3, two subgroups were discerned: one with recurrent acute otitis media (rAOM), the other subgroup with no AOM at all ("healthy" children). At further follow-up at the age of 10, no child had AOM or secretory otitis media (SOM), but between 3 and 7 y of age the rAOM subgroup was characterized by a significantly higher incidence of AOM as well as protracted secretory otitis media (SOM) episodes than was the "healthy" subgroup. The two subgroups did not differ significantly in hearing-thresholds at pure tone audiometry. After the age of 7, the incidence of AOM was the same in both groups. It is concluded that children with frequent AOM episodes before the age of 3 need long-term follow-up to school age, but seem not be predisposed to chronic SOM.

Otitis-prone children and controls: a study of possible predisposing factors. 2. Physical findings, frequency of illness, allergy, day care and parental smoking

In a retrospective study of 179 otitis-prone children and 305 controls, various possible predisposing factors for acute otitis media (AOM) were compared. The children were matched with the controls for age and sex. There were 61% boys and 39% girls in the otitis-prone group and 58% boys and 42% girls among the controls. Information about the family and living conditions, the children's illnesses, ear, nose and throat (ENT) operations and possible allergies were obtained from a questionnaire, and the children were called for a physical examination. The otitis-prone children had more middle-ear problems with pathological tympanograms and conductive hearing loss than the controls. No differences were found in bacterial colonization of the nasopharynx. Besides AOM and secretory otitis media, the otitis-prone children had more other ENT diseases and had consequently undergone more ENT operations and hospitalizations than the controls. There were no differences between the two groups regarding allergy, day care or parental smoking alone, but on comparing children with combinations of these factors there were more otitis-prone children than controls exposed, indicating an additive effect. The combination of different factors, less important separately, may for some children mean the difference between becoming otitis-prone or not.

The role of immune complex in otitis media with effusion

Fifteen chinchillas were inoculated with immune complexes of Streptococcus pneumoniae into the tympanic cavity, and with formalin-killed bacteria into the opposite side. Middle ear effusion (MEE) were found in 14 ears having inoculation with immune complexes and in only four ears having inoculation with formalin-killed S. pneumoniae. In another experiment, 20 chinchillas received intra-tympanic inoculation with live S. pneumoniae after systemic immunization with formalin-killed S. pneumoniae of the same strain. As a control, 12 chinchillas were inoculated with live bacteria of the same strain into the tympanic cavity without pre-immunization. MEE was observed in nine of pre-immunized animals and persistent MEE lasting for more than 3 weeks was observed in seven of the animals. In control, persistent MEE was not observed. Though six animals developed otitis media with effusion (OME). The results suggest that the formation of immune complexes in the tympanic cavity plays an important role in the occurrence of persistent MEE after pneumococcal otitis media.

Are there microbiological markers to predict recurrent acute otitis media?

The nasopharynx is a natural reservoir for several bacterial species, including Streptococcus pneumoniae and Haemophilus influenzae. Carriership is a potential mechanism for pathogenicity, since bacteria might invade the Eustachian tube and cause middle ear disease. Whether the pattern of nasopharyngeal colonization is different in infection prone vs healthy children is still a matter of controversy. In several studies it has been shown that H. influenzae is carried significantly more often in otitis-prone children compared with healthy control children. Colonization with H. influenzae in young children may be regarded as a candidate for a microbiological marker for recurrent episodes of acute otitis media.

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.

HLA frequency in patients with chronic secretory otitis media

It is well established that relationships exist between the frequencies of certain HLA antigens and various disease entities. In an earlier study we found a significant correlation between the frequency of HLA-A2 and HLA-A3 and recurrent acute otitis media (rAOM). Of 34 HLA antigens analysed, HLA-A2 occurred in 80.0% and HLA-A3 in only 11.1% of children with rAOM as compared to 55.9% and 27.5%, respectively, in healthy controls. In the present study we investigated the frequencies of the same 34 HLA antigens in 40 children who had been regularly controlled at our clinic for chronic secretory otitis media (SOM) for at least 6 years. HLA-A2 was found in 52.0% (21/40) and HLA-A3 in 27.5% (11/40) of these children, figures on a par with those of healthy controls. The HLA-A2 frequency was significantly lower in chronic SOM patients than in rAOM children. Some other non-significant differences were also found between these two groups. The results indicate a difference in hereditary influence on the pathogenesis of rAOM and that of chronic SOM.

Anti pneumococcal antibody activity in nasopharyngeal secretions in healthy adults and children

The local antibody activity to Streptococcus pneumoniae serotype 6B was measured in nasopharyngeal secretions from 20 healthy adults and 43 children, 1-3 years of age, 14 of whom were healthy and 29 were at risk for developing recurrent episodes of acute otitis media (RAOM) according to the criteria described below. In children, anti pneumococcal IgA and IgG antibody activity was of the same magnitude in both groups. Adults showed significantly higher specific IgA activity. Antibody activity of the IgG isotype was also higher in adults, possibly reflecting the higher serum antibody levels. The children at risk of developing RAOM had significantly higher levels of secretory component (SC) in their nasopharyngeal secretions. Our data suggest that local immunity in the nasopharynx is not fully developed in young children, which might contribute to bacterial survival and colonization in the region.

Antibody response to outer membrane protein of nontypeable Haemophilus influenzae in otitis-prone children

One of the major outer membrane proteins of nontypeable Haemophilus influenzae, P6, is highly conserved among strains, serves as a target for bactericidal antibody, and has been proposed as a possible vaccine candidate. The serum antibody response to P6 was studied in otitis-prone and normal children by an enzyme-linked immunosorbent assay. Of 20 otitis-prone children, 12 (60%) had a serum IgG antibody response to P6 after otitis media; however, the mean acute antibody level for the group, 4.6 micrograms/ml, was not significantly different from the convalescent level, 5.4 micrograms/ml. Anti-P6 antibody levels were also measured longitudinally for 10 to 25 months in 30 otitis-prone and 13 healthy children. Antibody levels increased sevenfold in the normal group compared with less than three-fold for the otitis-prone group and were significantly higher in the normal children after the age of 18 months (p < 0.05). Finally, otitis-prone children who had two or more episodes of otitis media with nontypeable H. influenzae did not have an anamnestic antibody response to P6. The failure to recognize P6 as a specific immunogen may account for recurrent infections. Moreover, the data suggest that otitis-prone children may not respond adequately to a vaccine containing P6.

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.

Mucosal immunoreactivity in experimental pneumococcal otitis media

A rat model was used to investigate immunological events in the middle ear mucosa during pneumococcal acute otitis media (AOM). Twelve healthy male Sprague-Dawley rats were challenged in the right middle ear with Streptococcus pneumoniae type 3, the presence of AOM being confirmed by otomicroscopy. Randomly selected rats, four at a time, were sacrificed on days 7, 14 and 56 after bacterial challenge. Immunohistochemical staining for IgG, secretory IgA (SIgA), and IgM was performed on tissue specimens from four separate locations in the middle ear and tubal mucosa. Immunoglobulins, especially IgG, were found around blood vessels in the middle ear mucosa. Immunoreactive lymphoid cells of all three Ig classes investigated, undetectable before bacterial challenge, appeared within 7-14 days after middle ear challenge, and the location of these cells in the middle ear mucosa suggests the presence of IgG, SIgA, and IgM, respectively. On the other hand, reactivity with anti-SIgA (but not with anti-IgG or anti-IgM) in Eustachian epithelial cells, and also in the subepithelial glands of tubal mucosa was present both before and after challenge. The results suggest that the middle ear mucosa is an immunoreactive site only after it has been activated with pathogens. In contrast, the tubal mucosa exhibits immunological activity also prior to the antigenic stimulation of present interest.

Immune response to outer membrane antigens of Moraxella catarrhalis in children with otitis media

The systemic and local antibody responses to homologous strains of Moraxella catarrhalis were investigated in 14 children with otitis media. A total of 8 children (57%) demonstrated a rise in serum antibody of the immunoglobulin G (IgG) (5 of 14), IgM (5 of 14), or IgA (6 of 14) classes of immunoglobulin to outer membrane antigens. Local antibody consisted of IgG (100%), IgM (29%), and IgA (71%). The IgG and IgA specific antibody present in middle-ear effusions appeared to represent local production rather than passive diffusion from the systemic circulation. These data suggest that young children develop an antibody response to M. catarrhalis in the middle ear during otitis media but fail to develop systemic antibody in a uniform manner.

HLA antigens and recurrent acute otitis media

The frequencies of a number of HLA antigens were investigated in 45 individuals with clinical recurrent acute otitis media (rAOM), defined as six or more episodes of AOM during a 12-month period, and were compared to those in a control group from the same district. HLA-A2 was found to occur in 80% of the rAOM group, as compared to 55.9% of controls (p less than 0.01). HLA-A3 antigen occurred in only 11.1% of the rAOM group in contrast to 27.5% of controls (p less than 0.05). Among 22 prospectively followed children without any AOM during their first 3 years of life, the frequencies of HLA-A2 and HLA-A3 antigens were comparable with those among controls.

Nasopharyngeal bacterial flora in otitis prone children treated with immunoglobulin

The present study was undertaken to evaluate possible beneficial effects of regularly given, long term immunoglobulin prophylaxis of children below 2 years of age with recurrent acute otitis media (RAOM). The nasopharyngeal bacterial flora and the frequency of acute otitis media (AOM) and secretory otitis media SOM were studied. Every second of 44 children with 3 or more periods of AOM during the last year received immunoglobulin intramuscularly (Gammaglobulin Kabi 165 mg/l, 0.45 ml/kg b.w.) every third week for 6 months, while the other 22 children served as controls. All children were followed for 12 months. Immunoglobulin prophylaxis neither influenced the nasopharyngeal flora, nor the frequency of AOM or SOM periods. Children with AOM or SOM more often harbored bacterial pathogens in their nasopharynx than children with normal middle ear status. Also, the immunoglobulin prophylaxis did not influence the increased frequency of bacterial pathogens in the nasopharynx of children attending public day care or family day care as compared to those taken care of at home.

Mucosal changes induced by experimental pneumococcal otitis media are prevented by penicillin V

Penicillin V (pcV) was administered to 50 rats, either before bacterial challenge (prevention group), or after bacterial challenge but before fulminant purulent acute otitis media (AOM) was established (early treatment group). Five animals from each group were killed on days 4, 8, and 12, and 2 and 6 months after challenge. Middle ear mucosa was sampled at six different sites and studied in the light microscope. Untreated pneumococcal AOM in the rat has been shown to cause persistent structural changes of the middle ear mucosa. Both in the early treatment group and in the prevention group, the structural changes were diminished, as compared with those of untreated infected controls. The persistent structural changes seen after 6 months in untreated controls were not seen in animals that had received pcV in conjunction with the AOM episode. Though the beneficial effect on the mucosal changes during the first 2 weeks was more pronounced when pcV was given prophylactically, its use as early treatment would seem to be almost as effective in preventing the persistence of mucosal changes.

Experimental recurrent pneumococcal otitis media. Protection and serum antibodies

To elucidate immune mechanisms in otitis media, middle ear infection was induced in 12 rats by intratympanic inoculation of Streptococcus pneumoniae type 3, either the ipsilateral or the contralateral middle ear being re-challenged 4 weeks later. Otomicroscopy inspection confirmed the presence of acute otitis media (AOM) in all rats after the first challenge. After re-challenge, protection against AOM was noted both in the ipsilateral and contralateral ears. Serum antibody concentrations increased after the initial challenge, reaching a maximum at 4-7 days, but had decreased to pre-immune levels at re-challenge, after which no new increase was noted. Serum IgG-antibodies to pneumococcal type 3-polysaccharide were triggered following the initial induction of unilateral pneumococcal AOM, but mucosal immune mechanisms are argued to be a more probable explanation of the ipsilateral protection seen after re-challenge.

Treatment failure in otitis-prone children with prophylactic tympanostomy tubes is correlated with nasopharyngeal Haemophilus influenzae colonization

Tympanostomy tubes are used to prevent recurrent otitis media among otitis-prone children. However, not all children benefit from this treatment. In the present study 28 children (19 boys, 9 girls) were given bilateral tympanostomy tubes at age 9-22 months (mean 14 months). They were observed 6 months before and after tube insertion. The treatment was considered successful for 20 children. Among these, 16 completely lacked or had one episode of middle ear discharge and 4 had otorrhea on two occasions. A total of 8 children suffered from three or more episodes of otorrhea and were considered as treatment failures. In the failure group, the nasopharyngeal average carrier rate of H. influenzae 6 months before and after tube insertion was 64% vs. 29% in the group responding well to the treatment (p less than 0.001). Nonencapsulated forms of H. influenzae were in a great majority. In the failure group 7 out of 8 presented middle ear discharge as soon as within 2 weeks after tube insertion whereas this occurred in only 3 out of 20 in the responding group. IgG, IgG1 and IgG2 antibody response to pneumococcal polysaccharide (6A, 19F) were equally distributed in the two groups. The present data suggest that one reason for an unsatisfactory response to treatment with prophylactic tympanostomy tubes is nasopharyngeal colonization and subsequent middle ear infections caused by H. influenzae.

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.

Effect of gammaglobulin on pneumococcal otitis media in the rat

Previously it has been found possible to induce pneumococcal AOM that closely resembles human infections, in the rat. In this study, the rat model has been used to study the possibilities to affect the infection by administration of gammaglobulin. The gammaglobulin was administered either systemically by intravenous injection of 0.2 g/kg bodyweight in 15 rats, or topically when 8 mg was instilled into the middle ear cavity of 18 rats. Although intravenous administration in this model failed to provide protection from AOM, topical administration simultaneously with the bacterial challenge was successful.

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.

Occurrence of middle ear pathogens in the nasopharynx of young individuals. A quantitative study in four age groups

Colonization of middle ear pathogens (S. pneumoniae, H. influenzae and B. catarrhalis), potential pathogens (S. aureus and coagulase-negative staphylococci) and non-pathogens was determined quantitatively on the posterior wall of the nasopharynx (NPH) of children (four age groups: under 2 years, 2-5 years, 6-10 years and 11-15 years). None of the 90 individuals examined was suffering at the time of bacterial sampling from acute otitis media (AOM), sinusitis, or tonsillitis. All individuals under 2 years of age harboured middle ear pathogens in the NPH, but only 40% of the individuals of the oldest age group (p less than 0.001). Furthermore, in the youngest group, 57% of the cases had pathogens in the NPH, which completely dominated the bacterial flora, i.e. constituted more than 90% of the total bacterial count when calculated as CFU/cm2. The corresponding count in the oldest age group was only 20% (p less than 0.01). One important reason for the high incidence of AOM among young children in particular seems to be the noticeable accumulation of middle ear pathogens in huge quantities in the NPH in this age group.

C1q and C1 subcomponent complexes in otitis-prone and non-otitis-prone children. A prospective study of children during their first years of life

Children with recurrent acute otitis media (rAOM) often show reduced C1q concentrations and an excess of (C1r-C1s)2 complexes. It is not known if such C1 aberrations precede development of rAOM or are a consequence of the infections. For this reason, serial investigation of C1q and C1 subcomponent complexes from birth until the age of three was performed in 113 children, 13 of whom developed rAOM. C1q concentrations at birth were found to be lower in the rAOM group than in children who did not experience acute otitis media, and were also correlated with age at the time of the first AOM episode. However, the wide variation of C1q within the groups precluded the use of C1q as a predictive marker. Excess (C1r-C1s)2 complexes were consistently absent at birth. High concentrations were found in children with established otitis media and the complexes persisted in association with recurrent disease. In conclusion, the C1 aberrations characteristic of rAOM were mainly acquired as a result of infection.

Serum antibodies against respiratory tract viruses: a prospective three-year follow-up from birth

Acute otitis media (AOM) has been epidemiologically related to viral respiratory tract infections, and viral antigens have also been detected in middle ear secretion in some AOM episodes. Successive serum samples from children followed prospectively for three years from birth were analysed for IgG antibodies against respiratory syncytial virus (RSV), adenoviruses and influenza A virus. Values from serum antibody activity gradually decreased during the first six months of life, followed by a gradual increase. Various relationships were found to obtain between age and the increases of antibody activity against the different viruses. Thus, three quarters of those tested had manifested increased antibody activity against RSV by 18 months of age, and against adenoviruses by 30 months of age. No increase of antibody activity against influenza A was noted before 12 months of age, and then only seen in two thirds of those tested during the entire three-year observation period. With regard to age, however, the proportion of children with increased antibody activity to RSV, adenoviruses or influenza A virus did not differ between otitis-prone and non-otitis-prone children. Thus, as compared to non-otitis-prone children, development of the ability to produce antibodies against these viruses was not found to be delayed in otitis-prone children.

Pneumococcal serum antibody concentrations during the first three years of life: a study of otitis-prone and non-otitis-prone children

One hundred and thirteen children were followed prospectively from birth until the age of 3, serum being obtained from cord blood, and at the ages of 3, 6, 12, 18, 24, 30 and 36 months. Thirteen children developed recurrent acute otitis media (rAOM), 29 remained very healthy and the remaining children formed an intermediate group. Cord serum concentrations were determined of total IgG class, of IgG1 and IgG2 subclasses, as well as of specific IgG antibodies against the pneumococcal capsular types, 3, 6A and 19F. The specific pneumococcal IgG as well as IgA and IgM antibodies were also followed in the sequential serum samples up to the age of 3 in the rAOM and healthy children. Despite total IgG class and IgG1 and IgG2 subclass concentrations being of the same magnitude in cord serum of rAOM (median: 11.15, 7.48 and 2.16 g/l for IgG, IgG1 and IgG2, respectively) as in that of healthy children (median: 10.21, 8.16 and 2.16 g/l, respectively), both in cord serum and in most serum samples drawn during the first year of life, specific IgG antibodies against types 6A and 19F, but not against type 3, were significantly lower in the rAOM group than in the healthy children. In the intermediate group, cord serum concentrations of specific IgG antibodies to type 6A were of the same magnitude as in the healthy children. The only significant difference in specific IgM and IgA antibody concentrations against types 3, 6A and 19F between the two groups was noted for type 6A antibodies at 36 months of age where rAOM children exhibited lower values. The results indicate an association between pre-existing low specific IgG antibody levels against AOM-associated pneumococcal types and the development of rAOM.

Recurrent acute otitis media. A prospective study of children during the first three years of life

To evaluate possible risk factors for developing recurrent acute otitis media (rAOM), 113 children were followed prospectively from birth to the age of 3 years. One of the aims was to determine whether such risk factors could be identified before the onset of the recurrences, so that optimal care and prophylactic measures could be made available at an early stage in such cases, on the basis of continuous follow-up by an ENT specialist. During the follow-up, 13 children developed rAOM, defined as six or more episodes of acute otitis media (AOM) during a 12-month period, 57 children had occasional episodes of AOM, and 43 children had no AOM at all. Of the children with onset of AOM before 6 months of age, 80% developed frequent episodes of AOM. The frequency of other respiratory tract infections and of family histories of otitis-proneness was higher among rAOM children than among the other children. The development of rAOM was unrelated to such factors as sex, familial history of allergy, duration of breast-feeding, or domestic environment. Nor could attendance at day-care centres be concluded as constituting a risk factor for the development of rAOM. An onset of AOM before 6 months of age was highly predictive of subsequent recurrent bouts of AOM, which emphasizes the importance of correct diagnosis in infants.

Plasma IgG, IgG subclasses and acute-phase proteins in children with recurrent acute otitis media

Quantitation of IgG, IgG subclasses and acute-phase proteins was performed in plasma samples from 156 children, aged 2 to 162 months, with varying degrees of otitis proneness. None of the children had acute otitis media or had received any antibiotics 3 weeks before the examination. Children with recurrent acute otitis media (rAOM) had significantly higher levels of total IgG, IgG1, and significantly lower levels of IgG2 than healthy children (p less than 0.02, p less than 0.0003, and p less than 0.03, respectively). However, the low levels of IgG2 found in the rAOM children could at least, to some extent, be explained by the observation that these children were somewhat younger than the healthy children. Except for recurrent episodes of common colds, children suffering from secretory otitis media (SOM) most often show no clinical signs of inflammatory events. Nevertheless, children with SOM had raised levels of plasma IgG1, indicating recurrent polyclonal stimulation of the immune apparatus, which seems to be less pronounced than that of rAOM children. Levels of acute-phase proteins, haptoglobin, orosomucoid and alpha 1-antitrypsin were evenly distributed in the children investigated, reflecting that they had no acute illness at the time of plasma sampling.

Nasopharyngeal secretory immunoglobulins in children with recurrent acute otitis media and secretory otitis media

Secretory IgA (SIgA) and secretory IgM (SIgM), total IgA and total IgM were measured in plasma and nasopharyngeal secretions (NPS) from young children with different degrees of otitis proneness. Significantly higher levels of plasma IgM and lower levels of NPS-SIgM were found in children with recurrent episodes of acute otitis media (rAOM) compared with children suffering from secretory otitis media (SOM) and healthy controls. Both plasma IgA and NPS-SIgA were evenly distributed in the three groups of children investigated, and in most children the levels of NPS-SIgA exceeded plasma IgA levels. Plasma SIgA was significantly increased in children with rAOM and SOM, probably resulting from frequent occurrence of inflammatory events at the nasopharyngeal level. No correlation could be demonstrated between NPS-SIgA and plasma IgA, or between NPS-SIgM and plasma IgM. Also, for both NPS-SIgA and NPS-SIgM, there was no correlation with age. A negative correlation was observed between the transudation index of albumin to the nasopharynx and the ratio of NPS-SIgA to total NPS-IgA. A ratio of 1 (100%) corresponded to a transudation index of 8%. The ratios of NPS-SIgA to total NPS-IgA varied considerably and a range of 39%-88% could only to some extent be explained by transudation of plasma IgA to NPS. The results of the present study show that the children with rAOM and SOM are well furnished with locally produced SIgA antibodies at the nasopharyngeal level. In children with SOM, the nasopharyngeal hypofunction in the case of low NPS-SIgM seems to be less pronounced compared with that of otitis-prone children.

Humoral immune response in acute otitis media

A short summary of the middle ear mucosal defence system and the characteristics of the infecting bacteria associated with purulent acute otitis media (AOM) is given. Data on humoral immune factors in middle ear effusions and serum during AOM are presented and the possibility that children with frequent recurrences of AOM exhibit an impaired ability to produce antibodies against AOM-associated antigens is discussed.

Relapse of acute purulent otitis media: antibiotic sensitivities of nasopharyngeal pathogens

The present investigation was conducted to find out if a relapse of acute purulent otitis media is associated with a decreased sensitivity of nasopharyngeal pathogens to commonly used antimicrobial agents. All but one of 63 children with relapse included in this study yielded one or more of the classical middle ear pathogens (Streptococcus pneumoniae, Haemophilus influenzae, Branhamella catarrhalis, S. pyogenes) in their nasopharynx (NPH) secretions. S. pneumoniae was the predominating isolate from NPH (71% of the patients) as well as from middle ear effusion (53%). At a control visit 4 weeks after the start of antibiotic therapy, 91% were NPH carriers of potential pathogens and S. pneumoniae was still the most common isolate (53%). Beta-lactamase was produced by 55% of B. catarrhalis isolates from the NPH specimens on the first visit, but only by 33% of B. catarrhalis isolates on the control visit. Two NPH isolates of H. influenzae produced beta-lactamase. One isolate of S. pneumoniae (serotype 18) was intermediately sensitive to phenoxymethylpenicillin. Generally low MICs were found for erythromycin and cefaclor. H. influenzae isolates were generally sensitive to ampicillin in vitro, but only 1 isolate was fully sensitive to erythromycin. B. catarrhalis isolates were uniformly sensitive to doxycycline and trimethoprim/sulphamethoxazole. No tolerance to penicillin was demonstrated in S. pneumoniae and H. influenzae. The present data indicate that the relapse of acute otitis media is not associated with development of tolerance or resistance to therapeutic antimicrobials commonly used.

The effect of serial intravenous immunoglobulin infusion on type-specific anti-pneumococcal antibodies in children

The effect of a series of five immunoglobulin G infusions--at 3-4 week interval--on serum IgG antibody concentrations against some pneumococcal types commonly associated with acute otitis media (AOM) was studied in 11 children, 1-4 years old, suffering from recurrent AOM. Increase of specific IgG antibody concentrations was observed when the initial concentrations were low. However, once higher antibody concentrations had been achieved as a result of the treatment, subsequent infusions resulted in a decrease of the antibodies. In two children with initially high specific antibody concentrations, antibodies successively decreased in response to repeated immunoglobulin infusions.

The effect of intravenous immunoglobulin treatment in recurrent acute otitis media

The effect of serial intravenous infusion of human immunoglobulin on the frequency of acute otitis media (AOM) episodes and on other upper respiratory tract infections was prospectively studied in a group of 22 otitis-prone children, 1-4 years old. After pair-matching, the children were allocated to immunoglobulin treatment or to a control group. Increased specific IgG antibody activities against pneumococcal types associated with recurrent AOM (rAOM) were generally achieved, but no significant difference was noted in the frequency of AOM attacks or other respiratory tract infections between the immunoglobulin-treated children and their pair-matched untreated controls. The results indicate that, although serum antibody activities against bacteria associated with AOM are increased by immunoglobulin infusions, this does not prevent the development of AOM in children suffering from rAOM.

Antibody activity before and after pneumococcal vaccination of otitis-prone and non-otitis-prone children

The antibody activity of the IgM class and subclasses of IgG and IgA against pneumococcal bacteria of types 3, 6A and 19F was studied before and after administration of a pneumococcal vaccine (Pneumovax) in a group of children with recurrent acute otitis media (rAOM) and in groups of non-otitis-prone children. Only occasionally was there a significant rise in antibody activity after vaccination in any of the groups. There was no difference in the response to vaccination between rAOM children and healthy children. However, rAOM children exhibited lower antibody activities in most Ig subclasses against pneumococcus type 6A--a common causative agent in AOM--before as well as after vaccination compared with the healthy children. The results indicate that the response to vaccination is equally poor in all children, irrespective of whether they have a history of frequent attacks of acute otitis media, but, in contrast to healthy children, the rAOM children seem to have an inability to mobilize antibodies in response to infections with some pneumococcal types.