HAI (Hospital acquired Infection) Hospital-Acquired Infection (HAI). Introduction Hospital-acquired infections (HAIs), also known as nosocomial infections, are infections that patients acquire while receiving medical care in a healthcare facility. These infections typically develop 48 hours or more after hospital admission, within 30 days of surgery, or within 90 days of receiving healthcare treatment in a hospital or clinic. HAIs are a major concern in healthcare settings, as they can lead