In 2014, approximately 14.2 million inpatient operations were performed in U.S. hospitals. A survey of healthcare-associated infection (HAI) prevalence, conducted by the Centers for Disease Control, revealed an estimated 157,500 surgical site infections associated with inpatient surgeries in 2011.

Although advances have been made in infection control practices, surgical site infections remain an alarming cause of morbidity, prolonged hospitalization, and death. In fact, these infections are associated with a mortality rate of 3 percent, and 75 percent of deaths are directly attributable to these infections.

It is well known that the operating room is a difficult area to control sterility and cleanliness, and Staphylococcus aureus (S. aureus) pathogens are frequently transmitted in this environment. Because infection control interventions are important for containing surgery-related infections, operating rooms should have well developed infection control policies.

The efficacy of these policies depends on how well the operating room staff adhere to them. Unfortunately, adherence to preventive measures has been suboptimal, which may explain why nearly 7 percent of patients undergoing surgery continue to contract at least one postoperative infection.

Eliminating the spread of dangerous S. aureus pathogens in the operating room and beyond has been the focus of recent research in this area. The goal of a recent study conducted by Randy W. Loftus, MD, of the Department of Anesthesia at University of Iowa Hospitals and Clinics was to characterize the epidemiology of intraoperative transmission of high-risk S. aureus sequence types (STs) to increase awareness.

S. aureus isolates collected from three academic medical centers underwent whole cell genome analysis, analytical profile indexing, and biofilm absorbance. Institutional infection control policies were tracked and recorded during the study period.

At all centers, usual infection control practices included routine and terminal environmental cleaning involving quaternary ammonium compounds with or without surface disinfection wipes. All providers had access to alcohol dispensers located on the wall or anesthesia carts, and gloves were immediately available for use.

The research team randomly selected 274 case pairs (first and second case of the day in each of 274 operating room environments) from three academic medical centers. They then collected 8184 environmental and hand samples from the centers during the following year.

The team found 178 S. aureus isolates; 173 were implicated in possible transmission (defined as at least two S. aureus isolates identified from 2 distinct reservoirs within or between cases in an intraoperative case pair). Five additional isolates were identified in postoperative patient infection cultures without a possible intraoperative link.

The research team also monitored and tracked the institutions’ infection prevention policies, including routine and terminal cleaning of the operating room and perioperative areas. They also tested for biofilms, which can be a place for organisms to proliferate and can reduce cleaning efficacy.

After anesthesia was administered to a patient, the researchers sampled the patient’s nasopharynx and axilla, as well as providers’ hands, and they also tested for antibiotic susceptibility to identify if their isolates were resistant. The patients were tracked for 30 days post operation to monitor for infection.

Dr. Loftus and his colleagues found that S. aureus ST 5 is a more pathogenic strain associated with increased strength of biofilm formation and increased risk of transmission and infection. Two of the ST 5 isolates were linked by whole cell genome analysis to postoperative infection, an important finding that may underestimate the magnitude of the problem.

The researchers confirmed patient skin surfaces and healthcare provider hands as sources of ST 5 pathogen transmission. This suggests that strict compliance with processes to decolonize patients of bacteria before surgery and to maintain hand hygiene compliance during surgery will likely help control the spread of this strain.

They also noted that operating room environmental surfaces were linked with transmission, indicating the importance of continually assessing the effectiveness of environmental cleaning protocols. According to the researchers, continually assessing processes, and making necessary changes, will improve outcomes for every patient.