Microbiology and management of sinusitis

The pathophysiology, microbiology, and treatment of acute and chronic sinusitis are reviewed.

The current literature is reviewed.

Sinusitis generally develops as a complication of viral or allergic inflammation of the upper respiratory tract. Bacterial pathogens contribute to the inflammatory process-Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis are predominant in acute sinusitis, while anaerobic bacteria and Staphylococcus aureus are predominant in chronic sinusitis. Pseudomonas aeruginosa has emerged as a potential pathogen in the immunocompromised patients and in those who have nasal tubes or catheters. Many of these organisms recovered from sinusitis became resistant to penicillins either through the production of beta-lactamase (H. influenzae, M. catarrhalis, S. aureus, Fusobacterium sp., and Prevotella sp.) or through changes in the penicillin-binding protein (S. pneumoniae). The pathogenicity of beta-lactamase-producing bacteria is expressed directly through their ability to cause infections, and indirectly through the production of beta-lactamase.

The indirect pathogenicity is conveyed not only by surviving penicillin therapy, but also by "shielding" penicillin-susceptible pathogens from the drug. The direct and indirect virulent characteristics of these bacteria require the administration of appropriate antimicrobial therapy directed against all pathogens in mixed infections. Proper therapy, with antimicrobial and decongestants combined when indicated with surgical drainage and correction of pathology, constitutes the cornerstone of management of sinusitis.