A Colorado hospital has been sued by three former surgery patients who say they were among nearly 3,000 people possibly exposed to a blood-borne disease carried by a drug-addicted former medical technician, court records showed on Tuesday. The Swedish Medical Center in suburban Denver is accused of negligence in its hiring and supervision of a surgical technologist who was caught trying to switch a syringe containing the powerful opiate fentanyl citrate with another substance during a patient's surgery in January.