WASHINGTON, DC-- Acute bacterial rhinosinusitis is the fifth most common diagnosis for which antibiotics are prescribed in the United States each year.[1] In many cases, however, the antibiotics may not have been administered appropriately. Overprescribing of antibiotics to treat this condition has contributed to the overall growth of antimicrobial resistance in the US. Reducing unnecessary antibiotic use and choosing the best agent when antimicrobial treatment is appropriate are essential for restricting the future development of resistant bacteria.

In an effort to address these concerns, the Sinus and Allergy Health Partnership recently developed clinical guidelines for the diagnosis and treatment of acute bacterial rhinosinusitis.[2] According to the Partnership, one of the problems with current approaches to the diagnosis and treatment of this infection is that patients with viral illnesses of only a few days' duration are frequently misdiagnosed as having bacterial sinusitis. As a result, antibiotics are often inappropriately prescribed for viral infections. In addition, even when acute bacterial rhinosinusitis is present, the wrong antibiotics are often administered initially.

The Sinus and Allergy Health Partnership was created through the joint efforts of the American Rhinologic Society, the American Academy of Otolaryngic Allergy, and the American Academy of Otolaryngology--Head and Neck Surgery. Representatives of the Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) and other specialists, including infectious disease physicians, clinical pharmacologists, and microbiologists, collaborated with the Partnership to develop these guidelines.

STEP-BY-STEP APPROACH

Differentiating between a viral upper respiratory infection with sinus involvement and acute bacterial rhinosinusitis--especially in children--remains challenging. When should the bacterial infection be diagnosed?

According to the guidelines, adults and children with a viral upper respiratory illness that does not improve after 10 days or that worsens after five to seven days should be given a diagnosis of acute bacterial rhinosinusitis if they have some or all of the following symptoms: nasal drainage, nasal congestion, facial pressure/pain (especially when unilateral and focused in the region of a particular sinus), postnasal drainage, hyposmia/anosmia, fever, cough, fatigue, maxillary dental pain, and ear pressure/fullness.

ANTIBIOTIC SELECTION

Choosing the best antibiotic depends on the specific organism, disease severity and progression, recent antibiotic use, and resistance rates in the community. The most common organisms causing acute bacterial rhinosinusitis in adults include Streptococcus pneumoniae (20% to 43% of cases), Haemophilus influenzae (22% to 35%), Moraxella catarrhalis (2% to 10%), and other streptococcal species (3% to 9%). In children, the most common causative organisms are S pneumoniae (35% to 42%), H influenzae (21% to 28%), and M catarrhalis (21% to 28%). Because complications are often associated with S pneumoniae infection, initial therapy in adults and children should be effective against this organism. In addition, any agent given to adults should also be active against H influenzae; a drug given to children should also cover H influenzae and M catarrhalis.

Thus, the best antimicrobial agents for treating acute bacterial rhinosinusitis in adults include amoxicillin/clavulanate, gatifloxacin, levofloxacin, and moxifloxacin (Table 1). These agents are effective in treating this infection 90% of the time. Other agents with good efficacy against S pneumoniae and H influenzae include amoxicillin alone, cefpodoxime, and cefuroxime. Erythromycin, azithromycin, clarithromycin, trimethoprim-sulfamethoxazole, and doxycycline have more limited coverage for these organisms. However, they may be appropriate for patients with mild disease who are intolerant of ß-lactams. Although the CDC does not recommend a fluoroquinolone (eg, gatifloxacin, levofloxacin, or moxifloxacin) as a firstline choice because of concerns about resistance, these drugs are appropriate for patients with moderate disease who cannot take ß-lactams and also for patients who have been given antibiotics within the past four to six weeks.

Table 1 Selecting Antibiotics for Adults With Acute Bacterial Rhinosinusitis
Clinical setting	Initial therapy	Efficacy (%)
Patient has mild disease and has not taken antibiotics in past 4 to 6 weeks	Amoxicillin/clavulanate	93.3
	Amoxicillin	88.8
	Cefpodoxime	86.7
	Cefuroxime	84.4
	ß-Lactam--allergic patients:
	Trimethoprim/sulfamethoxazole	81.4
	Doxycycline	79.9
	Azithromycin, clarithromycin, or erythromycin	74.8
Patient has mild disease; has taken antibiotics in past 4 to 6 weeks or Patient has moderate disease and has not taken antibiotics in past 4 to 6 weeks	Amoxicillin/clavulanate	93.3
	Amoxicillin	88.8
	Cefpodoxime	86.7
	Cefuroxime	84.4
	ß-Lactam--allergic patients:
	Gatifloxacin, levofloxacin, or moxifloxacin	95.4
Patient has moderate disease and has taken antibiotics in past 4 to 6 weeks	Gatifloxacin, levofloxacin, or moxifloxacin	95.1
	Amoxicillin/clavulanate	94.4
	Combination therapy*	--
* Combination therapy should be based on in vitro evidence of activity and may include high-dose amoxicillin (3.5 g/d) or clindamycin for gram-positive coverage plus cefixime for gram-negative coverage. Data extracted from Otolaryngol Head Neck Surg. 2000.[2]

For children, amoxicillin/clavulanate and amoxicillin have the best overall coverage for S pneumoniae, H influenzae, and M catarrhalis. Alternative agents with good, albeit slightly lower, efficacy are cefpodoxime proxetil and cefuroxime axetil. Neither doxycycline nor fluoroquinolones are recommended for use in children.

Although the FDA has not approved it, the use of high-dose amoxicillin (3 to 3.5 g/d in adults; 80 to 90 mg/kg/d in children) is recommended for patients with moderate disease who have taken antibiotics within the past four to six weeks, as well as for patients who live in areas with a high prevalence of drug-resistant S pneumoniae. These groups have a heightened risk of treatment failure.

HOW LONG TO TREAT

The recommended duration of antimicrobial treatment for acute bacterial sinusitis is 10 to 14 days. Although the infection resolves spontaneously in about 47% of adults and 50% of children, a different therapy should be considered if there is no improvement or if symptoms worsen after 72 hours.

If a change appears warranted, limitations in the initial antibiotic's coverage need to be taken into account. For example, amoxicillin lacks complete coverage of H influenzae; cefuroxime and cefpodoxime, which are effective against intermediate strains, are ineffective against penicillin-resistant S pneumoniae. In addition, the guidelines recommend a renewed clinical investigation (including further history taking, physical examination, cultures, and/or a computed tomography scan), as well as consideration of less common pathogens.

The Partnership hopes that the guidelines will "provide a rational approach to the need for antimicrobial therapy in acute bacterial rhinosinusitis, reduce the use of antibiotics for nonbacterial infections, and [encourage] the appropriate use of antibiotics when bacterial disease is likely." Nevertheless, they noted that additional research is necessary to develop better methods for diagnosing this infection, to explore the clinical application of the guidelines, and to monitor resistance levels among causative organisms, especially S pneumoniae and H influenzae.

--Debra Hughes

References
1. McCaig LF, Hughes JM. Trends in antimicrobial drug prescribing among office-based physicians in the United States. JAMA. 1995;273:214-219.
2. Antimicrobial treatment guidelines for acute bacterial rhinosinusitis. Sinus and Allergy Health Partnership. Otolaryngol Head Neck Surg. 2000;123(1 pt 2):1-33.