Related Experiment Video
Updated: Oct 11, 2025
Intravitreal Injection and Quantitation of Infection Parameters in a Mouse Model of Bacterial Endophthalmitis
Published on: February 6, 2021
In vitro study examining the effectiveness of antiseptic prophylaxis for antibiotic-resistant bacterial
Micheal O'Rourke1, Susan J Knowles, Anya Curry
1From the Department of Ophthalmology, Royal Victoria Eye and Ear Hospital, Dublin, Ireland (O'Rourke, Barry, Khan); Department of Microbiology, The National Maternity Hospital, Dublin, Ireland (Knowles, Curry, Kealy); European Society of Cataract and Refractive Surgeons, Dublin, Ireland (Barry, Khan).
Purpose:
To assess the effectiveness of current antiseptic agents on multidrug-resistant (MDR) isolates in an in vitro setting.
Setting:
Department of Microbiology, The National Maternity Hospital, Dublin, Ireland.
Design:
Organisms were selected based on current review of endophthalmitis literature: methicillin-resistant Staphylococcus aureus (MRSA), methicillin-resistant Staphylococcus epidermidis (MRSE), Pseudomonas aeruginosa, carbapenem-resistant and extended-spectrum β-lactamase Klebsiella pneumoniae, and vancomycin-resistant (VRE) Enterococcus faecalis.
Methods:
Samples were exposed to povidone-iodine (PVI) 5% and chlorhexidine (CHX) 0.05% for 0.5 minutes, 1 minute, 3 minutes, and 5 minutes. After inactivation, organisms were incubated under standard conditions and growth assessed after 16 hours.
Results:
MRSA and MRSE responded to 3-minute PVI exposure. CHX eradicated MRSA growth after 5 minutes but failed to completely suppress MRSE. Pseudomonas and Klebsiella required 3-minute CHX exposure and 5-minute PVI exposure for complete clearance. Eradication of enterococci (VRE positive and negative) was not achieved at 10 minutes of CHX or PVI exposure. Comparison of PVI vs CHX showed a benefit for PVI in MRSA (P < .01) and MRSE (P < .001) eradication at 3 minutes.
Conclusions:
Current recommendations of 3 minutes of antisepsis prior to intraocular surgery are not sufficient for complete eradication of MDR organisms from the ocular surface. A bespoke approach is suggested to patients at risk for carriage of MDR organisms to minimize the risk of endophthalmitis.
Insights
Current antiseptic agents like povidone-iodine (PVI) and chlorhexidine (CHX) are insufficient for eradicating multidrug-resistant (MDR) organisms. Longer exposure times and tailored approaches are needed to prevent endophthalmitis.
Area of Science:
- Ophthalmology
- Infectious Diseases
- Microbiology
Background:
- Multidrug-resistant (MDR) organisms pose a significant threat in healthcare settings.
- Endophthalmitis, a severe intraocular infection, can be caused by MDR pathogens.
- Current antiseptic protocols may not be adequate against emerging resistant strains.
Purpose of the Study:
- To evaluate the efficacy of povidone-iodine (PVI) and chlorhexidine (CHX) against clinically relevant MDR isolates in vitro.
- To determine optimal antiseptic exposure times for eradicating specific MDR organisms.
Main Methods:
- In vitro susceptibility testing of MDR isolates including MRSA, MRSE, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Enterococcus faecalis.
- Exposure of isolates to PVI 5% and CHX 0.05% for varying durations (0.5 to 5 minutes).
- Assessment of microbial growth after incubation to determine antiseptic effectiveness.
Main Results:
- Povidone-iodine (PVI) demonstrated superior efficacy against methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus epidermidis (MRSE) at 3 minutes compared to chlorhexidine (CHX).
- Complete eradication of Pseudomonas and Klebsiella required 3 minutes of CHX or 5 minutes of PVI.
- Vancomycin-resistant Enterococcus (VRE) strains were not eradicated by either antiseptic agent within 10 minutes.
Conclusions:
- Standard 3-minute antiseptic application is insufficient for complete MDR organism eradication on the ocular surface.
- A personalized approach to antisepsis is recommended for patients at risk of MDR organism carriage.
- Enhanced antiseptic strategies are necessary to mitigate the risk of endophthalmitis caused by MDR pathogens.
