Porter Adventist Hospital has admitted the infection breach at the Denver hospital was caused by human error, according to an article on the Fox31 Denver website.
Orthopedic and spine surgery tools go through a multistep cleaning process, including a mechanical cleaning and heat sterilization.
But before those processes, the surgical tools undergo a pre-cleaning. This is where hospital staff soak and scrub the tools.
The breach comes from the tools not being cleaned properly and potentially containing bioburden, the article said.
Designing for Distraction: Benefits for Children, Families
Staffing and Consolidation Reshape Outpatient Facility Strategies
Adams Health Network Falls Victim to Phishing Attack
Ventilation and Filtering for Infection Control 
ChristianaCare Opens Aston Campus Neighborhood Hospital