Differences in characteristics, aetiologies, isolated pathogens, and the efficacy of antibiotics in adult patients with preseptal cellulitis and orbital cellulitis between 2000-2009 and 2010-2019.

Background/aims: To understand whether the epidemiology, aetiologies, common pathogens and the antibiotic efficacy against the identified bacteria of periorbital cellulitis in adults have changed recently (2010-2019) compared with the past decade (2000-2009).

Methods: Adult patients (n=224) diagnosed with preseptal cellulitis and orbital cellulitis admitted to Kaohsiung Veterans General Hospital during 2000-2019 were retrospectively reviewed. Demographic and clinical characteristics, isolated pathogens and antibiotic susceptibility tests against the commonly cultured bacteria were analysed.

Results: Preseptal cellulitis showed a tendency of female predominance. Patients in their 60s showed an incidence peak; more cases were observed during winter. The most common predisposing factor was dacryocystitis (15.5%-30.5%), followed by hordeolum (15.5%-24.8%). Aetiology of sinusitis (p=0.001) decreased and that of conjunctivitis (p=0.007) increased significantly with time. Culture results of nasopharyngeal swabs and local abscess showed higher positivity rate than conjunctival swab. The most common isolates were methicillin-susceptible , methicillin-resistant , coagulase-negative staphylococci and . Antibiotics including fluoroquinolones and vancomycin were effective; in contrast, ampicillin/sulbactam and oxacillin showed decreasing efficacy against gram-positive bacteria. For antibiotic treatment against , fluoroquinolones, ceftazidime, piperacillin and imipenem were ideal choices.

Conclusion: In isolated pathogens, the increasing trend of methicillin-resistant detection was compatible with reducing oxacillin efficacy against periorbital infection. In our study, the report of antibiotic efficacy against the most common identified bacteria offered empirical choices for hospitalised patients with periorbital infection before obtaining culture results.