title: Early inflammatory changes of the Haemophilus influenzae-induced experimental otitis media.
abstract: Haemophilus influenzae is one of the most frequent pathogens of acute otitis media. To determine the middle ear response during the early stage of acute inflammation, a small amount of H. influenzae was inoculated into the bullae of guinea pigs through the tympanic membrane. The bullae were harvested at 6, 12, 24, 36, and 48 hours after H. influenzae inoculation and washed with phosphate-buffered saline (PBS). The number of viable H. influenzae and inflammatory cells, the concentrations of myeloperoxidase (MPO) and lysozyme in the washing suspensions were measured, and compared with those in PBS-inoculated control ears. The number of viable H. influenzae increased very rapidly from 6 to 12 hours after inoculation and remained stationary up to 48 hours. The number of inflammatory cells and the MPO concentration were significantly higher in the H. influenzae-inoculated ears than in the control ears from 12 to 48 hours after inoculation. The lysozyme concentration was already significantly higher at 6 hours in the H. influenzae-inoculated ears; the lysozyme was released in the middle ear before the accumulation of inflammatory cells and degranulation of MPO from inflammatory cells. The results indicated that inflammatory reactions were present already at 6 hours after bacterial inoculation, and were rapidly accelerated during the subsequent hours. Consequently, acute middle ear inflammatory responses were seen immediately following inoculation of viable bacteria, and these responses originated in direct responses of middle ear mucosa, and oxidative and non-oxidative neutrophil metabolic products, which may cause tissue injury.
mesh_terms: D000208:Acute Disease; D000818:Animals; D004432:Ear, Middle / Q000737:chemistry / Q000503:physiopathology*; D006168:Guinea Pigs; D006193:Haemophilus influenzae / Q000472:pathogenicity*; D009113:Muramidase / Q000032:analysis; D010033:Otitis Media / Q000209:etiology* / Q000503:physiopathology*; D009195:Peroxidase / Q000032:analysis; D013997:Time Factors
chemical_list: D009195:Peroxidase; D009113:Muramidase