Established An Acute Otitis Media With Streptococcus Pneumomiae And The Role Of Capsular Polysaccharide In Otitis Media

ObjectiveAs a common conditioned gram-positive pathogens, Streptococcuspneumoniae is one of the main pathogenic bacteria of otitis media. Otitismedia (OM) is a common pediatric diseases, which will cause hearingimpairment or even missing, and with potentially delay on development oflanguage and intelligence. But the pathogenesis of the OM caused by S.pn isstill poorly understood. The aims of the present study were to develop amouse model for studies of acute otitis media (AOM) caused by S.pn, andevaluate the role of capsular polysaccharide in OM, which is the majorpathogenic factor of S.pn.Methods1．To establish a mouse model of acute otitis media,mouse wereanesthetized, and different concentration of S.pn suspension and equivalentphosphate buffer were puncture inoculation in the middle ear cavity throughtympanic membrane. After inoculation, the mouse weight and the incidencewere observed daily. Mouse from each group were taken heart blood and middle ear lavage fluid (MELF) after inoculation. Cell count, cellclassification, bacteria loads and cytokines were determinated. HE stainingof tissue sections with treated mouse was monitored.2．TIGR4and TIGR4Δcps were puncture inoculation in the middle earcavity through tympanic membrane. evaluate the role of capsularpolysaccharide in OM through observing the mouse weight, incidence, cellcount, cell classification, bacteria loads and cytokines level.Results1．After inoculated with Streptococcus pneumoniae, mouse weight lostin a dose-dependent manner. Along with time, middle ear mucosa epithelialcell necrosis, mucosal thickening, inflammatory cell infiltration in themiddle ear cavity and middle ear bone wall bone destruction were seen.Neutrophil recruitment phase was related with bacterial clearance phase.IL-6and TNF-α were significantly elevated in the MELF.2．TIGR4Δcps recovered less bacterial load in the middle ear cavity andwas cleared faster than TIGR4. Inflammatory cells recruited to middle earcavity and the level of IL-6and TNF-α were significantly lower inTIGR4Δcps group than wild type strain group.ConclusionThis study successfully established the mice model of acute otitis mediawith streptococcus pneumonia, and inflammatory cells as well as inflammatory cytokine in the microenvironment of middle ear increased.Besides, capsular polysaccharide has an important role in promoting bacteriato colonize, raising inflammatory cell recruitment and induction ofinflammatory cytokines release in acute otitis media with streptococcuspneumonia.