Pneumococcal bacteriology after pneumococcal otitis media with special reference to pneumococcal antigens

Mucin production and mucous cell metaplasia in otitis media

Otitis media (OM) with mucoid effusion, characterized by mucous cell metaplasia/hyperplasia in the middle ear cleft and thick fluid accumulation in the middle ear cavity, is a subtype of OM which frequently leads to chronic OM in young children. Multiple factors are involved in the developmental process of OM with mucoid effusion, especially disorders of mucin production resulting from middle ear bacterial infection and Eustachian tube dysfunction. In this review, we will focus on several aspects of this disorder by analyzing the cellular and molecular events such as mucin production and mucous cell differentiation in the middle ear mucosa with OM. In addition, infectious agents, mucin production triggers, and relevant signaling pathways will be discussed.

Pneumococcal peptidoglycan-polysaccharides induce the expression of interleukin-8 in airway epithelial cells by way of nuclear factor-kappaB, nuclear factor interleukin-6, or activation protein-1 dependent mechanisms

Cell envelope compounds of bacteria trigger immune and inflammatory reactions by way of chemokines/cytokines. In this study, we demonstrated that pneumococcal peptidoglycan-polysaccharides (PGPS) induced the production of interleukin (IL)-8 by way of nuclear factor (NF)-kappaB, nuclear factor interleukin (NF-IL)6, and activation protein (AP)-1 dependent mechanisms in the human bronchial epithelial cells (NL-20) in a dose- and time-dependent manner in vitro, and the mutation of either the NF-kappaB, NF-IL6, or AP-1 binding sites in the promoter of IL-8 abrogated the IL-8 transcriptional activity. In a similar way, lipopolysaccharides induced the promoter activation of IL-8 in NL-20. However, the PGPS-induced IL-8 promoter activation in rodent middle ear epithelial cells required NF-kappaB and NF-IL6 but not AP-1.

Analysis by cDNA microarrays of altered gene expression in middle ears of rats following pneumococcal infection

OBJECTIVE

Streptococcus pneumoniae is the most common pathogen in otitis media. Infection of the middle ear with S. pneumoniae potentiates development of thick effusion in the middle ear which frequently causes hearing loss and communication disorders in children. What has changed immediately in the middle ear cleft following pneumococcal infection is extensively studied and characterized but what has changed ever after remains elusive. The purpose of this study is to explore the cellular and molecular basis that remains on a longer time after acute pneucmococcal middle ear infection and potentiates development of thick effusion in the middle ear.

METHODS

12 rats were intrabullarly inoculated with pneumococcus at 2.5x10(6) CFU/ear and profiles of gene expression in the middle ear were examined by cDNA microarrays in combination with reverse transcription-polymer chain reaction (RT-PCR) 6 weeks after infection while the morphologic changes in middle ear were simultaneously characterized by histopathologic techniques. Twelve rats receiving phosphate-buffered saline (PBS) served as controls.

RESULTS

it demonstrated that pneumococcus infected ears had the expression of the following genes at a high level compared to the controls: mitogenic signaling proteins (mitogen-activated protein kinase [MEK1 and MEK2], helix-loop-helix transcriptional regulators (Id3 and Id1), ion channels (sodium channel beta 1 and sodium channel 2), and mucin glycoproteins (Muc2 and Muc5). The morphology demonstrated a thickened mucosa and submucosa with increased expression of macroglycoconjugates compared to the controls.

CONCLUSION

the expression of several genes remains high even after the acute episode of pneumococcal otitis media has been resolved. The up-regulated expression of these genes may serve as the basis for the development of thick effusion and mucous cell metaplasia/hyperplasia once it is complicated with other factors such as dysfunction of the Eustachian tube.

Mucosal Immunity and Bacteriology of the Eustachian Tube

The pathogenesis of otitis media is a multifaceted process that is not completely understood. Eustachian tube dysfunction plays a central but uncertain role, as do viral and bacterial microorganisms. Of the latter, the three most important are Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis. This article reviews the various mechanisms of infection and the immune system's response to them.

Local production of IgG to pneumococcal C-polysaccharide in upper airway secretions from children with recurrent acute otitis media

Antibodies against C-polysaccharide (C-Ps), a common cell wall component of all pneumococci, may be of importance for the elimination of decaying pneumococci. By means of ELISA with phenylated C-Ps, anti-C-Ps IgG was measured in samples of plasma and upper airway secretions from otitis-prone children (OP), children with fewer episodes of recurrent acute otitis media (rAOM), and children with no previous history of AOM, but suffering from secretory otitis media (SOM). All children were free from acute illness at the time of sampling. No statistically significant differences of anti-C-Ps IgG in plasma or in nasopharyngeal secretions (NPS) were found between any of the groups. Based on calculations of the correlation between levels of anti-C-Ps IgG in plasma and NPS, and of the transudation ratios of anti-C-Ps IgG, total IgG, and albumin from plasma to NPS, we suggest that a significant amount of the anti-C-Ps IgG in NPS must be locally produced. The additional finding that OP children had significantly higher levels of anti-C-Ps IgG in their middle ear effusions (MEE) than SOM children points in the same direction. Anti-C-Ps IgA and IgM were detected in very low concentrations in plasma and secretion samples.

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.

Pneumococcal antigens and endotoxin in effusions from patients with secretory otitis media

Counterimmunoelectrophoresis revealed pneumococcus capsular polysaccharide antigen in 16% of 108 effusions from chronic secretory otitis media (SOM). Pneumococci were cultured from the effusion in only 1%. In an additional series of 23 SOM ears, only 4.3% were antigen-positive. Tests by means of pneumococcal coagglutination and C-polysaccharide detection gave identical results. Endotoxin was detected in 76% of the specimens. Control tests with aggregated NHS, IgG and IgA diluted 1: 10 were invariably positive. It appears that endotoxin positivity in SOM fluids results from the presence of activated immunoglobulins, most probably dimeric IgA, in the secretion, and so allows no conclusions as to the bacterial etiology of SOM.

Finnish approach to the treatment of acute otitis media. Report of the Finnish Consensus Conference

The theme of the first consensus conference to be held in Finland was the treatment of acute otitis media. The statements and recommendations accepted by the conference, which was organized according to the National Institutes of Health model, are presented in this report. On the basis of scientific knowledge, clinical experience, and conditions in Finland, the conference delegates concluded that penicillin V, in large doses, is still the drug of first choice in this disease. The importance of surgical drainage of the middle ear was stressed, as was the necessity of careful follow-up of the patient until the condition is completely healed. Decongestants were considered rather useless. In the prevention of recurrent attacks, adenoidectomy but not tonsillectomy was regarded as being of help, tympanostomy of probable benefit, antimicrobial (sulfonamide) prophylaxis worth considering in selected cases, but the effect of pneumococcal vaccination poor. The conference delegates agreed that uncomplicated acute otitis media should, as before, usually be treated by physicians taking care of children at the primary health care level.