Microbiologic Trends and Biofilm Growth on Explanted Periorbital Biomaterials

Abstract

To investigate microbiologic trends and role of biofilm on periorbital biomaterials surgically explanted for recalcitrant infection. A search of the Bascom Palmer Eye Institute, University of Miami Miller School of Medicine microbiology laboratory electronic database was conducted from 1980 to 2010. Culture results were analyzed from submitted periorbital biomaterials explanted for nonresolving infections or exposure. Random select samples cultured during the study were sent for electron microscopy. Twenty-one explanted biomaterials were identified from 18 patients. Five orbital plate implants included 2 made of nylon, 1 of porous polyethylene, 1 of silicone, and 1 metallic. Of 4 anophthalmic socket sphere implants, 2 were silicone, 1 was porous polyethylene, and 1 was poly-2-hydroxyethyl methacrylate. Lacrimal intubation devices included 10 silicone stents and 2 pyrex glass Jones tubes. All biomaterials were culture positive with 40 total isolates identified. The most common organisms overall were Mycobacterium chelonae (N = 9), Staphylococcus aureus (N = 8), and Pseudomonas aeruginosa (N = 3). One hundred percent of orbital spheres had Gram-positive organisms, 90% of lacrimal silicone stents grew atypical mycobacterium, and 60% of orbital plates were culture positive for yeast species. Mixed organism growth was documented on 58% of the specimens. Ten of 12 implants (83%) examined with electron microscopy exhibited organisms encased in glycocalyx, suggestive of biofilm. A diverse array of microorganisms can colonize biomaterials implanted within the orbit and lacrimal drainage system. The authors' study showed that the majority of infected periocular and orbital alloplastic implants display biofilm when studied with electron microscopy (83%). The cultured organism type depended on the implant location and composition. Most infected silicone lacrimal stents grew atypical mycobacterium, whereas infected orbital fracture repair plates demonstrated yeast species. Biofilms are known to be antibiotic resistant, explaining the need to explant most infected alloplastic implants. Further research concerning treatment of biofilms may prevent explantation and improve surgical outcomes.