Adaptive bone modeling and remodeling in acute otitis media caused by non-typeable or type B Haemophilus influenzae or Moraxella catarrhalis

Experimental studies have shown that acute otitis media caused by Streptoco ccus pneumoniae alters modeling dynamics in bone tissue structures surround ing the middle ear cavity. Initial resorption of bone is followed by format ive activity, seen as massive osteoneogenesis. However, neither resorptive nor formative activity occurs in the otic capsule, supporting the existence of a perilymphatic zone of specialized bone. This study investigates adapt ive bone modeling in acute otitis media caused by other bacteria frequently encountered in this disease. Seventy-five rats were inoculated with either non-typeable or type b Haemophilus influenzae, or Moraxella catarrhalis (2 5 rats in each group). Five rats from each group were sacrificed on days 4, 8, 16, 60 and 180 post-inoculation. Qualitative as well as quantitative hi stopathology revealed increasing apposition of new bone on both sides of th e original bony wall of the middle ear bulla, i.e. at the inner and outer p eriosteum. Remodeling activity was seen on later days of sacrifice, as typi cal osteone (Haversian system) formation. Measured bone thickness in four a natomically well-defined localities progressed to a peak 2 months post-inoc ulation, followed by some degree of normalization. However, bone thickness was still massively increased 6 months after the acute incident. Except in the otic capsule, resorptive and formative activity was found in all bone t issue structures surrounding the middle ear cavity. These findings were irr espective of the type of inoculated bacteria. However, non-typeable or type b Haemophilus influenzae induces significantly more new bone formation tha n Moraxella catarrhalis. We conclude that acute otitis media caused by eith er of the bacteria is accompanied by massive and progressive net osteoneoge nesis, already evident on day 4 and peaking 2 months post-inoculation, foll owed by some degree of normalization. Non-typeable and type b Haemophilus i nfluenzae induce more new bone formation than Moraxella catarrhalis, wherea s other features of bone histomorphology were equivalent. The present findi ngs further support the existence of a perilymphatic zone of specialized bo ne.