MICROBIAL CAUSATIVE AGENTS AND THEIR ANTIMICROBIAL SUSCEPTIBILITY PATTERNS IN CHRONIC RHINOSINUSITIS – IMPACT ON ANTIBIOTIC PROPHYLAXIS AND TREATMENT

Chronic rhinosinusitis (CRS) is debilitating condition comprising inflammation of the mucosa of the nasal and paranasal sinuses, requiring conservative and often surgical treatment. Functional endoscopic sinus surgery (FESS) is a CRS treatment during which a microbiological diagnostic procedure may be conducted. Preoperative antibiotic prophylaxis is administrated before FESS. When indicated, the administered empiric antibiotic therapy must cover most common causing microbial agents. The aims of this study were to identify microbial pathogens isolated from sinonasal cavities in patients undergoing endoscopic sinus surgery, to determine bacterial antibiotic susceptibility patterns and compare them with guidelines for treatment and perioperative prophylactic use of antimicrobial agents. A retrospective cohort study on 456 samples collected between 2016 and 2019 was conducted at the Department of Otorhinolaryngology, Head and Neck Surgery and the Department of Microbiology, Parasitology and Hospital Infections in the Clinical University Centre Sestre milordnice, Zagreb. The most common isolated pathogens were Peptostreptococcus spp., Propionibacterium spp., Staphylococcus aureus, Pseudomonas spp., Fusobacterium spp. and Haemophilus influenzae. According to antibiotic susceptibility patterns, empiric antibiotic treatment with amoxicillin-clavulanic acid was appropriate. Due to high rates of antibiotic resistance of anaerobic bacterial isolates to metronidazole, it cannot be recommended in empirical antibiotic treatment or preoperative surgical antibiotic prophylaxis.