Spectrum of pathogens causing acute rhinosinusitis in young adults and their antimicrobial susceptibility in prospective study using invasive technique

Abstract number: P1370

Kozlov R., Otvagin I., Kolosov A.

Objectives: Majority of published reports on etiology of acute rhinosinusitis use culture of nasal lavage samples and/or biopsy specimens of anterior ethmoidal mucosa. Historically, sinus aspirate was considered to be a 'gold standard' for microbiological diagnosis, though currently it is rarely used in many countries. The aim of our study was to determine the spectrum of pathogens causing rhinosinusitis and their susceptibility to the most commonly used antimicrobials.

Materials and Methods: Sinus aspirates were obtained from 112 patients with acute rhinosinusitis aged 19.4 + 1.4 years and transported within 2 hours to the single microbiological laboratory. Cultures were performed both in aerobic with increased CO2 concentration and anaerobic conditions, Susceptibility was determined used broth microdilution technique. Interpretation was performed using CLSI criteria (2009) were used for determination of susceptibility.

Results: Positive cultures were obtained in 62 (55.4%) of cases. Single pathogen was isolated in 90.3% of cases. The most common bacteria was H. influenzae (51.6%), followed by S. pneumoniae (21.0%) and S. pyogenes (11.3%). Susceptibility of H. influenzae to amoxicillin, amoxicillin/clavulanate and levofloxacin was 94%, 100% and 100%, respectively. S. pneumoniae was susceptible to penicillin, erythromycin and levofloxacin in 92%, 100% and 100% of cases.

Conclusion: In our study, H. influenzae was found to be the most prevalent pathogen, followed by S. pneumoniae and S. pyogenes with no M. catarrhalis isolated. In general, all predominant pathogens retain high percentage of susceptibility to the most commonly used antimicrobials in acute rhinosinusitis.