Objectives: To compare aetiology, microbiological isolates and antibiotic susceptibilities of endophthalmitis between children and adults. Design: Retrospective observational study. Participants: Patients admitted to Zhongshan Ophthalmic Center between January 2013 and December 2019 with clinically diagnosed endophthalmitis were included. Outcome measures: The aetiology, microbiological isolates and antibiotic susceptibilities of endophthalmitis were analysed. Results: Of 1803 patients, 430 (23.8%) were aged ≤16 years. In both children and adults, the main aetiology was trauma (85.6% vs 64.7%, p<0.05). Streptococcus species (spp.) (28.8%) were most prevalent in paediatric post-traumatic endophthalmitis; whereas, coagulase-negative staphylococci (36.9%) were dominant in adults. In postoperative endophthalmitis, all children had bacterial infections, while fungal infections accounted for 12.5% in adults. In endogenous endophthalmitis caused by fungi, Candida was most prevalent in adults (26.9%); whereas, all causative fungi involved filamentous fungi in children. Isolated bacteria in children presented a higher susceptibility in 7 of 11 antibiotics compared with those in adults. Levofloxacin had the highest susceptibility rate in children (97.9%), and ofloxacin had the highest susceptibility rate in adults (90.6%). Conclusion: The main aetiology was trauma, with a higher proportion in children than in adults. The microbial profile of paediatric endophthalmitis was different from those of adults. Susceptibilities of causative bacteria to most antibiotics were higher in children than in adults.

Few articles have reported drug concentrations of different ophthalmic dosage forms in the ocular tissues. This study aimed to determine the ocular pharmacokinetics of gatifloxacin 0.3% eye gel (GTX-Gel) and gatifloxacin 0.3% eye solution (GTX-Sol) at different time intervals after topical instillation in rabbits. A total of 126 healthy New Zealand rabbits were included, of which six rabbits did not receive antibiotics (control group). The remaining rabbits were randomly divided into four groups. GTX-Gel and GTX-Sol (50 μL) were topically instilled every hour in groups A1 and B1, respectively, and every two hours in groups A2 and B2, respectively, for 12 h. Ocular tissues were collected 2, 4, 8, 12, and 24 h after administration. Gatifloxacin concentration was measured using high-performance liquid chromatography coupled with tandem mass spectrometry. The drug reached peak concentrations (C_max) in all tissues at 8–12 h. With the same administration frequency, the C_max was higher with GTX-Gel than with GTX-Sol (p < 0.05). Except for the iris-ciliary body, other ocular tissues did not show significant difference (p > 0.05) in gatifloxacin concentration between either pair of groups. Gatifloxacin ophthalmic gel was found to attain significantly higher concentrations than the ophthalmic solution in ocular tissues.