Microbiological Profiles of Sinus Infections After Endoscopic Sinus Surgery: Frequencies, Susceptibilities, and Resistances

Introduction: There is no agreement on the most probable microbiology of sinuses post-sinus surgery, thus empiric antibiotics are still the mainstay of treating post-surgical sinus infections. We aim to provide the most common bacteria isolated from post-surgical sinuses in a regional cohort.

Methods: Data from all patients between August 2020 to July 2023 with at least one culture taken in-office after an endoscopic sinus surgery performed by our fellowship-trained rhinologists for chronic rhinosinusitis was gathered retrospectively from the electronic health record. The frequency of each organism and associated susceptibilities were recorded. Data collection is ongoing and statistical analysis is forthcoming.

Results: In total, 94 patients met criteria for inclusion. The cohort's mean age was 37.5, 51% were male, 26/94 (28%) had asthma, and 34/94 (36%) were undergoing revision sinus surgery in this study. Int total, 239 cultures were obtained for suspected sinus infections and 284 organisms grew (15% of cultures were polymicrobial). The most frequent organisms were: Staphylococci (n=88), Enterobacteriaceae (n = 46), Pseudomonas spp. (n = 33), fungi (n = 14), Serratia spp. (n = 14), S. maltophilia (n = 13), Streptococci (n = 11), H. influenzae (n = 8), and anaerobes (n = 8). There were also 28 cultures which grew normal flora. Of the Staphylococci, 53% were methicillin-sensitive (n = 47), but had resistances to Penicillin (43%), macrolides (40%), and clindamycin (32%). 28% of Staphylococci were methicillin-resistant (n = 25), but were also resistant to macrolides (68%), quinolones (56%), and clindamycin and penicillins (40%). Enterobacteriaceae spp. were resistant to Augmentin and 1st-gen cephalosporins (39%) and penicillins (26%). A percentage of 12% of Pseudomonas spp. were resistant to quinolones and carbapenems.

Conclusions: By utilizing cultures taken in symptomatic patients with suspected sinus infections, we aim to provide an updated analysis of the potentially most likely etiology of post-surgery sinus infections in a regional cohort. This may help inform empiric antibiotic treatment with a consideration of common antibiotic resistances.