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had decreased sensitivity to penicillin. Amoxicillin-clavulanate was the most active antibiotic in vitro. After sinus surgery, the bacterial flora found from cultures often changes and should be taken into consideration when determining the choice of antibiotic therapy. In one study by Bhattacharyya and Kepnes (41) looking at 203 sinus cultures in patients with a history of endoscopic sinus surgery, gram-positive cocci were found in 37.9% of isolates; gramnegative rods, such as Enterobacter species and Escherichia coli in 14.8%; and yeast and fungal forms in 1.7%. Antibiotics for Chronic Rhinosinusitis No antibiotic has been approved by the U.S. Food and Drug Administration for the treatment of CRS. Most recommendations on antibiotic use have been based primarily on historical practice rather than levels of evidence (42). Most experts agree that antimicrobials for treatment of CRS should provide broadspectrum coverage. Commonly used agents include amoxicillinclavulanate, clindamycin, sulfamethoxazole/trimethoprim, and levofloxacin or ciprofloxacin. Antibiotics play a role in the management of CRS to decrease bacterial load and to treat acute bacterial exacerbations of CRS. Acute exacerbations of CRS represent sudden worsening or new symptoms in a patient with CRS and are typically associated with purulence draining from the sinuses visualized on nasal endoscopy (43). As discussed in the previous section, the bacterial flora cultured from purulence in cases of CRS tends to demonstrate increased antibiotic resistance and different species when compared with simple acute rhinosinusitis. Typically, the acute (not chronic) symptoms return to baseline after treatment. Antibiotics are typically used for at least 3 to 4 weeks, so as to maximize the antiinflammatory effect and effectively lower bacterial loads in the sinuses. In a study with 251 adults with CRS, Legent and colleagues (44) found patients treated with ciprofloxacin for 9 days had significantly higher cure rates than those treated with amoxicillin/clavulanic acid (P 5 0.04) and fewer side effects (P 5 0.01). Namyslowski and coworkers (45) compared the efficacy of amoxicillin/clavulanic acid and cefuroxime for 14 days in the treatment of 206 patients with CRS and found similar rates of bacterial eradication and adverse events between the two groups. However, patients treated with cefuroxime had a significantly higher rate of disease relapse (P 5 0.005). Treatment of Sinonasal MRSA In a national study by the Centers for Disease Control, MRSA nasal carriage doubled between 2001 and 2004 (46). Recent literature also points to an increasing prevalence of MRSApositive cultures in CRS (47). Bhattacharyya and Kepnes (48), in a study of 392 cultures on sinonasal infections, found that 19% of isolates were S. aureus, with 19% of those being MRSA. Multiple studies have demonstrated Staphylococcus species in cases of acute exacerbations of CRS (47, 49). Patients with MRSA can be divided into two groups: those who are colonized in the sinuses and those with infection. The presence of a positive culture does not necessarily imply treatment in the absence of symptoms or purulence on endoscopy or anterior rhinoscopy. Sudden worsening of symptoms or the presence of new symptoms with purulence on physical examination implies an acute exacerbation of CRS, which should be treated (43). These patients are managed by microbiological culture, determination of antibiotic sensitivities, and appropriate antibiotic therapy. Treatment options for MRSA sinonasal infections include oral antibiotics, intravenous antibiotics, and topical antibiotics (50). Topical antibiotics have the theoretical advantage of high local levels of drug with minimal systemic
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