Special Silver Carboxylate Coating On Implants May Help Decrease Spinal SSI Due To C. Acnes

Study on Silver Carboxylate-Doped TiO2-PDMS Coating

Providence, RI, USA: D.R. Garcia et al. have found in a study that silver carboxylate-doped titanium dioxide-polydimethylsiloxane (TiO2-PDMS) coating can decrease C. acnes adherence and biofilm formation on PEEK and four other commonly used spinal implant materials: stainless steel, cobalt chromium, titanium, and titanium alloy. This decreases spinal SSI secondary to C. acnes infection, especially in procedures with instrumentation.

Cutibacterium acnes (C. acnes) is a gram-positive facultative anaerobe found in the deep sebaceous follicles of the skin on the shoulder and back. C. acnes has been increasingly recognized as a pathogen in spinal surgical site infection (SSI), especially in the presence of instrumentation.

The authors compared the adherence of C. acnes over 24 hours between uncoated, 95:5 TiO2 to PDMS ratio with 10x silver carboxylate coating, and a 100% silver carboxylate coating on each implant material, which were uniformly saw cut and sterilized.

Implants were then subjected to scanning electron microscopy (SEM) and confocal scanning laser microscopy (CSLM).

Samples were coated using 95:5 TiO2-PDMS 10x silver carboxylate, 100% silver carboxylate, or left uncoated. C. acnes was applied onto the samples and allowed to adhere for periods of 4, 8, 12, 16, or 20 hours.

Nonadherent bacteria were then washed from the samples. These samples were then allowed to continue incubating for a total of 24 hours.

SEM and confocal laser scanning microscope were used to visualize all samples for the presence of biofilm and quantification of C. acnes adherence at each time point.

Observations of the Study

The 95:5 TiO2-PDMS 10x silver carboxylate coating was able to significantly decrease C. acnes adherence on PEEK after 8, 12, 16, and 20 hours of adherence.
No statistical difference was found between the 95:5 TiO2-PDMS 10x silver carboxylate coating and the 100% silver carboxylate positive control.
It was observed that extensive C. acnes biofilm formation occurred on uncoated PEEK, but none on PEEK coated with either the 95:5 TiO2-PDMS 10x silver carboxylate or 100% Ag coating.
No biofilm formation was observed on stainless steel, cobalt chromium, titanium, and titanium alloy coated with 95:5 TiO2-PDMS 10x silver carboxylate or 100% silver coating.

The authors concluded that a 95:5 TiO2-PDMS 10x silver carboxylate coating decreases C. acnes adhesion and prevents biofilm formation on PEEK and other common orthopedic implant materials.

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