Microorganisms causing vascular catheter-related sepsis gain access to the bloodstream through either the skin at the catheter insertion site or through the catheter hub. The catheter insertion site is probably the predominant portal for microorganisms in catheters in place for a short time, but the catheter hub may play an increasingly important role in infection in association with long-term catheters, particularly those that are subcutaneously tunneled. Although transient contamination of the catheter hub does not cause infection, certain microorganisms may migrate endoluminally and enter the bloodstream, causing bacteremia or fungemia.