LAUSR

PURPOSE To report the microbiologic profile and antibiotic susceptibility trends in orbital cellulitis. METHODS Retrospective review of microbiology records of orbital cellulitis between 2005 and 2019. Orbital pus or conjunctival swab underwent culture for bacteria and fungi and antibiotic susceptibility testing for bacterial isolates. The microbiological profile and trends in antibiotic susceptibility were analyzed over the three study periods: 2005-2009, 2010-2014, and 2015-2019. RESULTS Of the 203 patient samples, 189 (93%) were orbital pus samples, and 146 (72%) were culture positive. Organisms included bacteria (167/203, 82.3%), fungi (13/203, 6.4%), and mixed infection (25/203, 10.3%). Among bacteria, 79% were gram positive, with Staphylococcus aureus and Streptococcus species being commonest, and 21% were gram negative, with Pseudomonas aeruginosa and Enterobacteriaceae group being the commonest. Aspergillus flavus was the most common fungus isolated. Trend analysis revealed no change in the number of sterile cases and fungal cellulitis. Increase in gram positive bacteria was statistically significant (p = .0002) between 2005-2009 and 2015-2019. The increase in gram negative bacteria was statistically significant (p = .047) between all three time periods. Susceptibility patterns showed increasing trend of resistance to fluoroquinolones, that reached statistical significance for Ciprofloxacin, Moxifloxacin and Gatifloxacin (p < .05). Sterile sample was not found in any of the pediatric (0-16 years) cases (n = 55), compared to 28% in adults. CONCLUSION There was a significant rise in gram positive and negative orbital infections over the 15 year period, with increased resistance to fluoroquinolones. Fungal cellulitis and sterile samples showed a steady trend. Orbital aspirate provides accurate detection of the causative organism.