Background/Objectives Postoperative endophthalmitis is a rare but severe complication of cataract surgery. Intracameral moxifloxacin prophylaxis has been widely adopted, but concerns remain regarding bacterial resistance and clinical outcomes. This study aimed to evaluate the impact of intracameral moxifloxacin prophylaxis on endophthalmitis incidence, microbiological patterns, antibiotic resistance, and visual outcomes in a university hospital setting, with comparison to a private hospital cohort.

Subjects/Methods This retrospective cohort study analyzed 21,178 cataract surgeries performed at a university hospital (2014–2023). The incidence of endophthalmitis, microbiological profiles, resistance patterns, and visual acuity outcomes (LogMAR) were assessed. Intracameral moxifloxacin prophylaxis was introduced in 2019. A comparative analysis was conducted with 19,360 surgeries from a private hospital. Fisher’s exact test, Mann-Whitney U test, and Joinpoint regression were used for statistical analysis.

Results Endophthalmitis incidence at the university hospital was 0.109% (23/21,178 surgeries), significantly higher than the 0.021% incidence in the private hospital (p=0.002). Post-prophylaxis, infection rates declined from 0.219% in 2016 to 0.042% in 2023 (p=0.003). Staphylococcus epidermidis predominated (52.6%), and moxifloxacin resistance remained stable (pre: 45.5%; post: no increase).

Conclusions Intracameral moxifloxacin significantly reduced endophthalmitis incidence without increasing bacterial resistance. Post-prophylaxis infection rates aligned with national surveillance benchmarks (e.g., SES-SP threshold of 0.07%), reinforcing the efficacy of this preventive strategy in a public university setting. The worsening of final visual acuity post-prophylaxis underscores the need for continued clinical vigilance. Ongoing microbiological surveillance remains essential.

The authors have declared no competing interest.

This study did not receive any funding

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The study was approved by the Research Ethics Committee of the University of São Paulo (Comitê de Ética em Pesquisa da Universidade de São Paulo), Brazil (Approval number 0060/2018), and the requirement for informed consent was waived due to the retrospective nature of the study.

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All data produced in the present study are available upon reasonable request to the authors