Subconjunctival gentamicin prophylaxis against postoperative endophthalmitis in the rabbit

Area of Science:

• Ophthalmology
• Microbiology
• Pharmacology

Background:

• Postoperative endophthalmitis remains a significant risk following ocular surgeries like cataract extraction.
• Understanding the pathogenicity of common bacteria and their susceptibility to antibiotics is crucial for prevention.

Purpose of the Study:

• To evaluate the correlation between the clinical course of postoperative endophthalmitis and microbial recovery.
• To assess ocular antibiotic penetration of gentamicin.
• To determine the value of antibiotic prophylaxis in preventing experimental endophthalmitis.

Main Methods:

• An experimental aphakic rabbit model was used.
• Infection was induced with varying concentrations of Staphylococcus aureus and Staphylococcus epidermidis.
• Gentamicin sulfate was administered subconjunctivally to assess penetration and prophylactic efficacy.

Main Results:

• Staphylococcus aureus was more pathogenic than Staphylococcus epidermidis, causing higher infection rates.
• Bacteria were recoverable for a limited period post-infection, despite persistent inflammation.
• Subconjunctival gentamicin sulfate demonstrated rapid ocular penetration and maintained bactericidal levels for at least 4 hours.
• Prophylactic gentamicin sulfate (20 mg) significantly reduced or eliminated clinical signs and bacterial recovery of endophthalmitis.

Conclusions:

• Antibiotic prophylaxis with subconjunctival gentamicin sulfate is highly effective in preventing experimental postoperative bacterial endophthalmitis.
• Gentamicin sulfate exhibits excellent penetration into the aphakic rabbit eye, providing sustained therapeutic concentrations.
• The study highlights the importance of timely antibiotic administration in mitigating infection risk after ocular surgery.