When bacteria get into the blood, serious problems called bloodstream infections can result. The most serious bloodstream infections occur in sick, hospitalized patients or in people with complicated illnesses such as cancer or kidney failure requiring dialysis. Many of these people have tubes threaded into large veins (central venous catheters) to give medicines or fluids. The tubes sometimes become infected and cause catheter-related bloodstream infections (CRBSIs). Catheter-related bloodstream infections are often difficult to diagnose. Usually, doctors remove the catheter and culture its tip. With this approach, people without CRBSI end up having their catheters removed unnecessarily. Finding a way to diagnose CRBSI that does not rely on catheter removal would be helpful.