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Acute bacterial sinusitis — involving purulent nasal discharge and nasal obstruction; facial pain, pressure, or fullness; or both — persists for 10 days or more with no improvement or worsens within 10 days after improvement. However, the natural history of acute sinusitis in adults is very favorable; approximately 85% of persons have a reduction or resolution of symptoms within 7 to 15 days without antibiotic therapy. Nonetheless, antibiotics are prescribed for 84 to 91% of patients with acute sinusitis that is diagnosed in emergency departments and outpatient settings. Watchful waiting and antibiotic therapy are described in a new Clinical Practice article.
Q: How do temporal patterns of illness help distinguish between viral and bacterial sinusitis in adults?
A: The temporal pattern of a typical upper respiratory tract infection can be used as a proxy for acute viral sinusitis because nearly 90% of patients with colds have inflammation that extends to the mucous membranes in the paranasal sinuses. Viral upper respiratory symptoms generally peak rapidly, decline by the third day of illness, and end after 1 week, although in 25% of patients the symptoms last longer but decrease. In contrast, acute bacterial sinusitis persists for 10 days or longer without improvement or, less often, manifests with worsening of symptoms in the first 10 days after initial improvement, in a double-worsening pattern.
Q: What is the role of imaging in adults with acute sinusitis?
A: Purulent nasal discharge is associated with an increased likelihood of bacteria in the maxillary sinus and of radiographic evidence of acute sinusitis. However, neither this finding nor other individual signs or symptoms (e.g., fever or facial pain) can be used to accurately distinguish between bacterial and viral infection. Similarly, findings on plain radiographs and computed tomography cannot be used to distinguish between these two types of infection. Imaging studies are reserved for patients with suspected orbital or intracranial complications.
Morning Report Questions
Q: How does one choose between watchful waiting as compared to antibiotic therapy for the management of acute bacterial sinusitis?
A: The guidelines differ regarding watchful waiting in patients with acute bacterial sinusitis. Since some randomized trials include patients who have been ill for less than 10 days and who are likely to have viral sinusitis, there remains substantial uncertainty about which patients might benefit most from initial antibiotic therapy rather than watchful waiting. This uncertainty is compounded by restrictive inclusion criteria in many trials that exclude patients who are pregnant and those with diabetes and other coexisting conditions. There is also uncertainty about the course and relative incidence of suppurative complications among patients with acute bacterial sinusitis who do not receive antibiotic therapy as compared with those who do receive antibiotic therapy, since many trials include patients with viral sinusitis and exclude patients with severe illness, prolonged symptoms, or disease beyond the maxillary sinuses. Systematic reviews of placebo-controlled trials generally show a significantly higher rate of clinical improvement at 7 to 15 days (the primary outcome in most trials) with antibiotic therapy than with placebo, but they show small differences between groups. Success rates range from 77 to 88% with antibiotic therapy and from 73 to 85% with placebo. The numbers needed to treat with antibiotics (versus placebo) for 1 patient to have clinical improvement are high (7 to 18). The potential benefits of antibiotic therapy must be balanced against adverse effects, which may include allergic reactions and the emergence of drug-resistant bacteria. The numbers needed to harm (i.e., the numbers of patients who would have to receive antibiotics for one adverse effect to occur) range from 8 to 12; this indicates that adverse effects from antibiotics are as likely, or more likely, than benefits.
Q: What antibiotics are used to treat acute bacterial sinusitis?
A: Although up to 90% of patients with viral upper respiratory tract infections have concurrent acute viral sinusitis, only 0.5 to 2.0% have sinusitis that progresses to acute bacterial sinusitis. The most common pathogens in adults with acute bacterial sinusitis are Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and Staphylococcus aureus. Amoxicillin is the most commonly assessed antibiotic in placebo-controlled trials. Trials of the comparative efficacy of antibiotics have evaluated cefuroxime axetil, amoxicillin–clavulanate, levofloxacin, moxifloxacin, and clarithromycin. No differences in the comparative efficacy of antibiotics in the treatment of acute bacterial sinusitis have been reported, probably because of the high rate of spontaneous improvement and the noninferiority design of most trials. Comparative trials of amoxicillin versus amoxicillin–clavulanate are lacking; the argument for the use of amoxicillin–clavulanate is based on patterns of bacterial resistance. Current guidelines caution against the use of clarithromycin or azithromycin because of macrolide-resistant S. pneumoniae. In May 2016, a Food and Drug Administration advisory recommended that fluoroquinolone antibiotics (levofloxacin and moxifloxacin) be reserved for patients who do not have alternative treatment options. The potential serious side effects of these drugs can involve the tendons, muscles, joints, nerves, and central nervous system. Pregnant women may have nasal vascular engorgement (rhinitis of pregnancy) that can mimic acute sinusitis; this makes accurate diagnosis important. Acceptable antibiotics for the treatment of sinusitis in pregnant women include amoxicillin, amoxicillin–clavulanate, and, in patients who are allergic to penicillin (if the hypersensitivity to penicillin is not immediate [type I]), clindamycin plus cefixime or cefpodoxime. Patients with diabetes or other conditions that compromise the immune system are more likely than patients without these conditions to harbor resistant bacteria, and they should receive amoxicillin–clavulanate.
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