Oxacillin-resistant Staphylococcus aureus endophthalmitis after ganciclovir intraocular implant

Functionalization of ethylene vinyl acetate with antimicrobial chlorhexidine hexametaphosphate nanoparticles

Ethylene vinyl acetate (EVA) is in widespread use as a polymeric biomaterial with diverse applications such as intravitreal devices, catheters, artificial organs, and mouthguards. Many biomaterials are inherently prone to bacterial colonization, as the human body is host to a vast array of microbes. This can lead to infection at the biomaterial’s site of implantation or application. In this study, EVA was coated with chlorhexidine (CHX) hexametaphosphate (HMP) nanoparticles (NPs) precipitated using two different reagent concentrations: CHX-HMP-5 (5 mM CHX and HMP) and CHX-HMP-0.5 (0.5 mM CHX and HMP). Data gathered using dynamic light scattering, transmission electron microscopy, and atomic force microscopy indicated that the NPs were polydisperse, ~40–80 nm in diameter, and aggregated in solution to form clusters of ~140–200 nm and some much larger aggregates of 4–5 μM. CHX-HMP-5 formed large deposits on the polymer surface discernible using scanning electron microscopy, whereas CHX-HMP-0.5 did not. Soluble CHX was released by CHX-HMP-5 NP-coated surfaces over the experimental period of 56 days. CHX-HMP-5 NPs prevented growth of methicillin-resistant Staphylococcus aureus when applied to the polymer surfaces, and also inhibited or prevented growth of Pseudomonas aeruginosa with greater efficacy when the NP suspension was not rinsed from the polymer surface, providing a greater NP coverage. This approach may provide a useful means to treat medical devices fabricated from EVA to render them resistant to colonization by pathogenic microorganisms.

Responses of Staphylococcus aureus bacterial cells to nanocrystalline nickel nanostructures

A broad range of human diseases are associated with bacterial infections, often initiated by specific adhesion of a bacterium to the target environment. Despite the significant role of bacterial adhesion in human infectious diseases, details and mechanisms of bacterial adhesion have remained elusive. Herein, we study the physical interactions between Staphylococcus aureus, a type of micro-organism relevant to infections associated with medical implants, and nanocrystalline (nc) nickel nanostructures with various columnar features, including solid core, hollow, x-shaped and c-shaped pillars. Scanning electron microscopy results show the tendency of these bacterial cells to attach to the nickel nanostructures. Moreover, unique single bacterium attachment characteristics were observed on nickel nanostructures with dimensions comparable to the size of a single bacterium.

Endophthalmitis after ganciclovir implant in patients with AIDS and cytomegalovirus retinitis

PURPOSE

To describe the incidence, clinical course, and outcomes of endophthalmitis in patients treated with a ganciclovir implant.

DESIGN

Retrospective review of cases identified from a clinical survey.

METHODS

Cases of endophthalmitis were identified from a survey of 30 clinical practices known to treat a large number of patients with cytomegalovirus retinitis.

RESULTS

Twenty-four cases of endophthalmitis were identified from 5185 implants performed (incidence, 0.46%). Final visual acuity ranged from 20/20 to no light perception, with 50% (12/24) seeing light perception or worse. Vitreous cultures revealed Staphylococcus epidermidis in 29% (7/24) of patients, whereas other gram-positive organisms were responsible in 42% (10/24) of cases. In the remaining 29% (7/24) of cases, no organisms were cultured; these cases exhibited a better visual outcome (P =.007). Six of the eight late-onset cases were associated with wound problems such as implant strut or suture exposure. There was no significant relationship between implant removal and final visual acuity.

CONCLUSIONS

Endophthalmitis is an infrequent but potentially devastating complication associated with placement of a ganciclovir implant.

Endophthalmitis associated with extrusion of a ganciclovir implant

PURPOSE

To report a case of endophthalmitis with associated scleral defect after intravitreal positioning of a ganciclovir implant.

METHOD

Interventional case report. A 39-year-old woman developed acute endophthalmitis 1 month after insertion of a ganciclovir implant. The eye was enucleated.

RESULTS

Pathologic examination of the enucleated globe revealed an intrascleral location of the implant suture tab and a vitreous abscess.

CONCLUSION

Intraocular infection resulted from a scleral gap containing a foreign body (surgical implant). Appropriate surgical techniques should minimize the risk of ganciclovir implant extrusion.