The microbiology and the efficacy of antibiotic-based medical treatment of chronic rhinosinusitis in Singapore

BACKGROUND: Medical therapy including appropriate antibiotic treatment is advocated for the management of chronic rhinosinusitis (CRS), with sinus surgery reserved for treatment failures. This study investigates the microbiology of CRS and their response to culture-directed antibiotic treatment. METHODS: Sinus aspirates of mucopus from 172 consecutive CRS patients, with (n=89) and without (n=83) previous antibiotic treatment, were obtained for bacterial culture at their first visit. Medical treatment which included initial empirical and subsequent culture-directed antibiotics was instituted. Endoscopic sinus surgery (FESS) was performed for patients with persistent CRS and/or complications of CRS. A follow-up of 12 months was scheduled for all patients. RESULTS: One hundred and twenty (69.8%) patients were treated successfully by with antibiotic-based medical therapy. Thirty-eight patients (22.1%) did not respond to medical treatment and eventually underwent FESS. The incidence of CRS with nasal polyps (CRSwNP) was higher in FESS group (n=13, 34.2%) than patients with medical treatment only (n=9, 6.7%). Staphylococcus aureus was the most common pathogen (n=43, 25%) and amongst patients with no prior antibiotic treatment, the incidence was higher in patients with CRSwNP (n=8, 53 %) than CRS without NP (CRSwoNP) (n=20, 27%). The rate of sensitivity of the cultured microbes to amoxicillin with clavulanate and cephalosporins was 78% and 70%, respectively. CONCLUSION: The microbiology of CRS in Singapore is described. Staphylococcus aureus appears to be the most common bacterial isolates in both CRS with and without nasal polyps. Medical treatment with CRS using culture-directed antibiotics is effective in the majority of patients, especially in patients without nasal polyps.