Acute bacterial rhinosinusitis: clinical impact of resistance and susceptibility.

Sinusitis is a common disorder associated with notable direct and indirect economic costs. Acute bacterial rhinosinusitis (ABRS) is a relatively poorly defined clinical syndrome characterized by a high spontaneous resolution rate, wide variations in presenting symptoms, and an incomplete understanding of the pathogenesis and clinical course of the disease. Streptococcus pneumoniae and Haemophilus influenzae are the most common causative pathogens in adult ABRS. A relative lack of bacteriological eradication data compared with other respiratory illnesses, uncertainty on the part of many clinicians as to when to treat, and increasing rates of antimicrobial resistance hamper logical treatment strategies. Because it is impossible to know which cases of ABRS will spontaneously resolve and which will not, antimicrobials are recommended. In general, antimicrobial treatment for ABRS should cover both S. pneumoniae and H. influenzae while considering the risk of infection with resistant organisms. Treatment guidelines for ABRS were developed by the Sinus and Allergy Health Partnership in 2000 and were updated in 2004. This article discusses a Sinusitis Therapeutic Outcome Model, a data-driven model used in the development of the treatment guidelines, with respect to different scenarios involving ABRS to illustrate the implications of antimicrobial selection on therapeutic outcome.