After how many hours of hospital admission does nosocomial infection occur?

Nosocomial infections can be defined as those occurring within 48 hours of hospital admission, 3 days of discharge or 30 days of an operation. They affect 1 in 10 patients admitted to hospital.  Nosocomial comes from the Greek word nosokomeion meaning hospital (nosos = disease, komeo = to take care of ). This type of infection is also known as a hospital-acquired infection.