Mucosal Pathology of the Nose and Sinuses: A Study in Experimental Maxillary Sinusitis in Rabbits Induced by Streptococcus Pneumoniae, Bacteroides Fragilis, and Staphylococcus Aureus

Unilateral maxillary sinusitis was experimentally induced in New Zealand White rabbits with Streptococcus pneumoniae serotype 3, Bacteroides fragilis NCTC 9343, and Staphylococcus aureus V8 in order to study possible differences in the inflammatory response of the sinus and nasal mucosa at different time-intervals during a 12-week period of infection. The initial sinus mucosal response, most pronounced in pneumococcal sinusitis, was characterized by leukocytosis, epithelial desquamation, and squamous cell metaplasia. Tissue reactions at later intervals included fibrosis of lamina propria, gland involution, polyp formation, and bone remodelling, and were most pronounced in S. aureus and B. fragilis sinusitis. The nasal mucosa was altered with a redistribution of goblet cells, development of polyps in the ethmoidal region, involution of Bowman's glands and locally, areas of degenerated olfactory sensory epithelium. These findings endorse that the degree of local pathology depends on the infecting microorganism's specific pathogenetic factors. However, local tissue factors guiding the cellular inflammatory proliferative and regenerative processes are also of fundamental importance for the type of pathological changes occurring in an infected nasal or sinus mucosa.