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2013 Agenda and Abstracts | < Previous | Next >

2013 OMIG Abstract 15

Biofilm Forming Capability and Relative Tolerance to Vancomyin of Bacterial Isolates Colonizing the Ocular Surface of Patients with Boston Type 1 Keratoprosthesis
Soledad Cortina1, Sarmad H Jassim1, Juan C Jimenez2, Assraa HJ Jaboori1, Michael J Federle3
1Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago,
2Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago,
3Department of Medicinal Chemistry and Pharmacology, Center for Pharmaceutical Biotechnology,
College of Pharmacy, University of Illinois at Chicago,
Chicago, IL

Purpose: To evaluate the biofilm formation potential of bacterial flora colonizing the ocular surface of patients with implanted Boston type 1 keratoprosthesis (K-Pro) and its effects on antibacterial resistance patterns.

Methods: Specimens were obtained from the surface of the K-Pro optic and/or the inferior conjunctival fornix (control eyes) and plated separately on culture media.  Antibiotic prophylaxis regimen at the time of culture was recorded. Standard microbiological methods were performed to identify bacterial strains and susceptibility patterns. Positive cultures were further processed to characterize the biofilm forming capability of each strain. Micro-titer plate adherence assay (MTPA) and Polymerase Chain Reaction (PCR) for ica and atlE genes were used. In-vitro assay of Vancomycin tolerance was performed on isolated strains and compared to standard controls with and without biofilm forming capability.

Results: 85% of K-Pro eyes and 69% of control eyes had a positive culture with the vast majority growing Coagulase Negative Staphylococci (CNS). Of the K-Pro eyes with positive cultures, 9 (39.1%) had isolates directly from the K-Pro. There was no difference on the antibiotic resistance patterns between eyes with implanted K-Pro and control eyes, with all bacterial strains exhibiting susceptibility to Vancomycin by standard testing. Biofilm forming bacterial isolates were detected in 57.7% of K-Pro eyes and 53.3% of control eyes. No statistical significant difference was observed in bacterial growth or biofilm formation between K-Pro eyes and control eyes. Biofilm Vancomycin Tolerance Assay showed the ability of bacterial biofilm colonies to survive despite the presence of Vancomycin. The overtime killing of CNS in biofilm form was statistically significant only in three of the five biofilm forming strains studied, P < 0.05. In the two other forms Vancomycin was ineffective in eradicating or killing CNS Biofilm cells in a statistically significant rate. In all forms there was a statistically significant killing of planktonic bacterial cells overtime in comparison to biofilm, P < 0.001.

Conclusion: Bacterial strains colonizing eyes with K-Pro were similar to those of control eyes, with similar susceptibility patterns and biofilm formation capability. CNS can be isolated from the surface of the K-Pro despite the use of Vancomycin prophylaxis and in vitro Vancomycin tolerance assays suggests that biofilm formation increases bacterial viability on the surface of the K-Pro that may contribute to the higher rate of infectious complications observed in these patients.

Financial Disclosure: N. Grant support: None

2013 Agenda and Abstracts | < Previous | Next >