SA1 - Microbiology of Odontogenic Sinusitis and Optimal Antibiotic Treatment

Abstract: Background: Odontogenic sinusitis (ODS) is characterized by a polymicrobial microbiologic profile dominated by Staphylococcal species, streptococcal species, and anaerobes, distinguishing it from non-odontogenic rhinosinusitis.

Purpose: The purpose of this study was to characterize the antibiotic susceptibility profile of surgically confirmed ODS and to propose an evidence-based empiric treatment algorithm.

Study design, setting, sample: Retrospective case series of adults with surgically confirmed ODS who underwent combined endoscopic sinus surgery and dental source control at our institution between 2022 to 2025.

Predictor Variable: Odontogenic etiology of sinusitis confirmed by clinical, radiographic, dental, or intraoperative findings.

Main outcome variable(s): The primary outcome was antibiotic susceptibility rates of clinically significant isolates across 28 agents.

Covariates: Covariates included age, sex, race/ethnicity, sinus involvement, etiology, bacterial cultures, and antibiotic susceptibilities.

Analyses: Descriptive statistics were used throughout. Continuous variables were reported as mean ± standard deviation, categorical variables as frequency and percentage.

Results: Seventy-four patients met inclusion criteria (mean age 61.6 ± 14.8 years; 59.5% female). A total of 231 bacterial isolates were identified; gram-positive cocci predominated (n = 122, 52.8%), with anaerobic morphology in 29.9% (n = 69). The most prevalent organisms were Staphylococcus spp. (n = 66, 28.6%) and Streptococcus spp. (n = 38, 16.5%). Susceptibility testing of 84 clinically significant isolates demonstrated 100% susceptibility to carbapenems (58/58), glycopeptides (40/40), and anti-pseudomonal penicillins (27/27), with =95.5% susceptibility across all aminoglycosides. β-lactam/β-lactamase inhibitor susceptibility was agent-specific: ampicillin-sulbactam 71.4% (20/28) and amoxicillin-clavulanate 68.8% (11/16). Penicillin monotherapy susceptibility was low (23/56, 41.1%). Clindamycin susceptibility was 50.0% (23/46), with a resistance rate of 47.8% (22/46).

Conclusions and Relevance: ODS harbors a polymicrobial microbiologic profile with favorable susceptibility to β-lactam/β-lactamase inhibitor combinations and high clindamycin resistance, supporting ampicillin-sulbactam as first-line empiric therapy and amoxicillin-clavulanate as step-down therapy. These findings informed development of a tiered interdisciplinary antibiotic algorithm and provide a foundation for standardized ODS management pending prospective multicenter validation.


Key words: oral flora, polymicrobial infection, dental sinusitis, maxillary sinusitis, endodontic infection


References:

Saibene, A.M., et al, Odontogenic and rhinogenic chronic sinusitis: a modern microbiological comparison. International Forum of Allergy & Rhinology, 2016/01/01. 6(1).


Workman, A.D., E.J. Granquist, and N.D. Adappa, Odontogenic sinusitis: developments in diagnosis, microbiology, and treatment. Current Opinion in Otolaryngology & Head and Neck Surgery, February 2018. 26(1).