Which of the following causes highest risk of nosocomial infection to a patient?

The fact that at least 25-50% of nosocomial infections are due to the combined effect of the patient's own flora and invasive devices highlights the impoance of improvements in the use and design of such devices. Urinary tract infections (UTIs) account for ~34% of nosocomial infections. Pneumonia accounts for ~13% of nosocomial infections. Wound infections account for ~17% of nosocomial infections UTI is the most common cause of nosocomial infection. Other common cause is pneumonia and surgical procedures. Contaminated surgical equipments and from health care workers can be the cause of infection in surgical wound. Also Know: The most common pathogens in postoperative wound infections are S. aureus, coagulase-negative staphylococci, and enteric and anaerobic bacteria. In rapidly progressing postoperative infections, which manifest within 24-48 h of a surgical procedure, the level of suspicion regarding group A streptococcal or clostridial infection should be high. Ref: Weinstein R.A. (2012). Chapter 131. Health Care-Associated Infections. In D.L. Longo, A.S. Fauci, D.L. Kasper, S.L. Hauser, J.L. Jameson, J. Loscalzo (Eds), Harrison's Principles of Internal Medicine, 18e.