A 62-year-old man on ICU develops a fever on day 7. He has a central venous catheter, urinary catheter, and an endotracheal tube. Blood cultures are drawn from the CVC and peripherally, and urine and tracheal aspirate samples are sent. Results: peripheral blood cultures grow coagulase-negative staphylococci (CoNS) in one of two bottles at 48 hours. CVC blood culture is negative. Urine culture shows mixed growth. Tracheal aspirate shows normal respiratory flora. What is the most likely interpretation of the CoNS result?