P0609 - The epidemiology and management of orbital cellulitis

Background/Purpose: Orbital cellulitis is a rare but serious bacterial infection of the post-septal tissues of the eye that can lead to significant complications, such as permanent vision loss, meningitis, and intracranial abscesses. Following the introduction of the pneumococcal conjugate vaccine (PCV) and emergence of methicillin-resistant Staphylococcus aureus (MRSA) over the past decade, the epidemiology of this condition has likely evolved, necessitating re-evaluation of current antimicrobial management strategies. Furthermore, a lack of standardized management guidelines has led to significant heterogeneity in antibiotic selection, treatment duration, and surgical intervention. We investigated the largest US cohort of patients reported to date to characterize the epidemiology of orbital cellulitis in children in the post-PCV era and examine outcomes over various therapeutic approaches to inform future guideline development.

Methods: We conducted a retrospective observational study of patients <21 years of age who were admitted to a large academic children’s hospital between 2008-2018 with orbital cellulitis. Charts were reviewed for demographic data, underlying comorbidities, presenting symptoms, microbiological and laboratory results, imaging results, surgical intervention antimicrobial selection and duration, and clinical outcomes. Patients with recent facial or orbital trauma were excluded from the study.

Results: We identified 220 patients with orbital cellulitis. Subjects’ mean age was 8.3 years, with males representing 61.3% and Caucasians representing 58.6% of patients. Ocular swelling was the predominant presenting symptom (95.9%), followed by eyelid erythema (77.7%) and fever (70.9%). Among the 99 patients with available culture data, Methicillin susceptible Staphylococcus aureus was the most common organism, isolated in 27.3% of patients, while MRSA was found in only 5.0%. However, rates of vancomycin use were relatively high throughout the study period, with a peak of 85% in 2010 and low of 41% in 2014 but no clear downward trend. The median duration of parenteral and oral antibiotic therapy was 17 days (IQR:14-26). Antibiotic durations of >3 weeks (38%) were associated with a higher rates of treatment failure (10%), with negative outcomes such as readmission or incomplete resolution, compared with durations of <2 weeks (1%) and >2 and < 3 weeks (0%) (p=0.049). 70 patients received adjunctive systemic corticosteroid therapy (range 20%-60%). Surgical intervention occurred in only 39.5% of cases. Despite a readmission rate of 7.7%, 96% of patients experienced clinical improvement by the end of treatment.

Conclusion: Our findings indicate that despite low rates of MRSA, vancomycin has remained a significant component of empiric management. In the post-PCV era, Streptococcus pneumoniae does not appear to be a major causative agent of orbital cellulitis. Treatment durations of < 2 weeks of antibiotic therapy seem to be adequate in some cases, whereas the higher rates of treatment failure were observed with durations of >3 weeks likely suggests incomplete adjustment for disease severity.