Healthcare workers, patients, and environment form "transmission triangle" Nurses' clothing often becomes contaminated with bacteria when caring for patients in the intensive care unit, underlining the importance of rigorous hygiene and cleaning practices to minimize the risk of disease transmission. Confirmed transmission of bacteria -- mostly from patients or surfaces in the room to nurses, or from patients to the environment -- occurred during 19% of nursing shifts, according to Deverick Anderson, MD, MPH, of Duke University. Nurses' clothing became contaminated with epidemiologically important organisms such as methicillin-resistant Staphylococcus aureus (MRSA) and Acinetobacter baumanniiduring more than 10% of ICU shifts, Anderson said at a press briefing at IDWeek, a joint meeting of the Infectious Diseases Society of America, the HIV Medicine Association, the Society for Healthcare Epidemiology of America, and the Pediatric Infectious Diseases Society. Hospital-acquired infections are a common problem affecting about one in 25 patients, according to the CDC. It is widely known that hand washing and surface cleaning are important strategies to reduce the risk of disease transmission in healthcare facilities, but the role of clothing is not well understood. Prior studies have found bacteria on surgical scrubs and white coats, which -- theoretically at least -- can lead to contamination of hands and moving germs around the hospital. Read Also: Hand Washing Among Doctors Steps of Hand Washing For Doctors Surgical Hand Washing Steps Anderson's team performed a microbiological analysis looking at the movement of bacteria within the "triangle of transmission" comprising the healthcare worker, the patient, and the environment. This was a subanalysis of the Antimicrobial Scrub and Transmission (ASCOT) study, a prospective randomized trial that evaluated whether antimicrobial-impregnated clothing could help reduce bacterial contamination during clinical care as compared with standard cotton-poly scrubs. The study enrolled nurses working in the ICU at Duke University Hospital. The researchers tested for bacteria on the nurses' clothing at the midriff, sleeves, and pocket at the beginning of three consecutive 12-hour shifts, and again at the end of the shifts. The nurses started with fresh scrubs on each shift and cared for patients in at least two rooms. In the environment, the researchers took samples from the bed, bed rails, and supply cart. They also cultured patient samples from three areas such as the nostrils, perianal area, or wounds (depending on the patient's specific condition). They focused on antibiotic-resistant bacteria including MRSA, Klebsiella pneumoniae, Pseudomonas aeruginosa, and vancomycin-resistant enterococci. The study included 40 nurses who worked 120 shifts and cared for 102 patients, yielding a total of 167 patient encounters. More than 2,000 cultures were obtained from nurses' clothing, 455 from patients, and nearly 3,000 from environmental surfaces. Slightly more than 20% of patients were under contact precautions, 42% were receiving mechanical ventilation, and half had wounds. The main trial did not see any significant decrease in clothing contamination when nurses wore antimicrobial-impregnated scrubs. The substudy identified 39 potential transmission events, occurring on 33% of all nursing shifts. Of these, 23 (19%) were confirmed transmissions as determined by identical pathogens on genetic sequencing. A variety of bacteria were transmitted, with resistant and susceptible S. aureus and A. baumannii being most commonly spread. Most events involved patients who were not under contact precautions. A nurse's clothing was contaminated in 12 of the confirmed events (seven from a patient, three from the room, and two from both), 11 involved environmental contamination with patients' bacteria, and there was one possible transmission to a patient from the room. Anderson noted that 30% to 40% of the time the nurses' scrubs were contaminated with organisms found in the environment but not in patients. While this study did not see any transmission from nurses to patients or the environment, this also likely occurs in hospitals, the researchers suggested. Bacterial contamination probably also occurs in non-ICU settings where healthcare workers juggle more tasks and patients, though this may be balanced by caring for less sick patients, Anderson told MedPage Today. "This is a complicated process; these bugs move probably much more frequently than we think they would," Anderson concluded. "Healthcare workers really need to be aware that not only can they become contaminated from their patients, but simply going into the hospital room poses a risk as well." These findings underscore the importance of following basic infection control procedures. These include hand-washing after all patient encounters and regular cleaning of patients' rooms, and for some patients more stringent contact precautions such as wearing disposable gloves and gowns are also indicated. Anderson said it was unlikely that ICU nurses were failing to wear gowns and gloves when appropriate, but that contamination likely happens when taking them off. "Many hospitals don't provide a lot of instruction," he said. "During the Ebola outbreak there was a lot of instruction, but usually we don't have that. This is something we should do a better job of teaching." Expanding use of gowns and gloves to more patient encounters is controversial, as there is not yet adequate evidence on whether it actually reduces pathogen transmission, University of Maryland associate professor Kerri Thom, MD, told reporters. "We certainly don't live in a sterile world and that includes our patient care areas," she said. "[This study] emphasizes the basic principles -- as we've been saying for decades now -- of hand hygiene and environmental cleanliness. It also emphasizes how little we know about transmission dynamics and there's still so much to learn." Source
