Prosthetic Material Could Reduce Infections from Intravenous Catheters

Human skin is home to about one million bacteria per square centimeter, with Staphylococcus, particularly Staphylococcus epidermidis, being the most common species and a typical resident of the skin microbiome. Infections often occur when the skin is broken, such as through cuts, wounds, or surgical procedures, allowing bacteria to enter the bloodstream. One frequent source of infection in hospitals is the insertion of tubes or catheters into veins. Annually, around 80,000 catheter-related bloodstream infections are reported in intensive care units alone, highlighting the public health challenge in the United States. Progress in preventing infections associated with intravenous catheters has been slow, partly due to the lack of effective platforms to test new catheter designs, and wearable biosensor technologies, and train healthcare staff to reduce infection rates. However, innovative prosthetics, particularly those made from materials like silicone rubber, may now have an unexpected yet promising application in reducing infections from intravenous catheters.

In a new study, researchers at Texas A&M University College of Engineering (TAMU, College Station, TX, USA) have developed realistic, skin-like replicas made from Ecoflex, a silicone rubber that could serve as a platform for evaluating infection risks from intravenous catheters and testing wearable sensors, among other biomedical applications. Published in Scientific Reports, the study demonstrates that Ecoflex-based skin replicas can be engineered to closely replicate the texture, wettability, and elasticity of real skin, simulating the conditions in which bacteria adhere and grow. To achieve this, the researchers used Ecoflex 00-35, a biocompatible, fast-curing rubber commonly used in prosthetics for special effects. The team created molds of typical intravenous insertion sites, such as the elbows, hands, and forearms, and then poured Ecoflex into these molds, which contained artificial bones and tubes designed to mimic veins, resulting in skin-like replicas.

Next, the team evaluated the Ecoflex replicas to determine if their properties matched those of real skin. They measured factors like wettability, bacterial adhesion, and mechanical properties, including elasticity and resilience. The researchers found that the Ecoflex models could replicate the roughness of human skin with only a 7.5% margin of error. High-resolution imaging confirmed that bacteria could adhere to the Ecoflex replicas and grow on them. In a key experiment, the researchers simulated an intravenous catheter insertion into an Ecoflex hand model, which successfully modeled bacterial growth at different stages, demonstrating the potential of these replicas in infection control and the design of medical devices like catheters. However, the researchers acknowledged that their current experiments do not fully replicate real-world conditions.

“We think that the material holds tremendous promise for studying infections at the insertion site due to bacteria that are naturally occurring on the skin,” said Majed Othman Althumayri, primary author of the paper. “Our goal was to create a skin-like material with ingredients that can be purchased off the shelf. Ecoflex is not just easy to use, it can be cured quickly with minimum additional steps, making it very convenient.”

“Developing realistic skin models that can mimic the human skin is an important initial step,” said Dr. Hatice Ceylan Koydemir, corresponding author on the study. “But we think that incorporating additional elements, like body fluids and other clinically relevant situations, in future experiments will bolster our findings and further validate Ecoflex’s potential for medical applications.”