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Bacterial Reservoirs in the Operating Room

2015; Lippincott Williams & Wilkins; Volume: 120; Issue: 4 Linguagem: Inglês

10.1213/ane.0000000000000247

1526-7598

Harriet W. Hopf,

Medical Device Sterilization and Disinfection

Anesthesiologists have long been patient safety advocates. Thus, it is not surprising that anesthesia providers in the 21st century have taken on increasing responsibility for preventing health care-associated infections (HAI) including surgical site infections (SSI). The Surgical Care Improvement Project (SCIP) was developed in 2006 to reduce surgical complication rates,1 including SSI, by improving adherence to best practice process measures. Recent large database studies have demonstrated that SCIP compliance is not associated with a significant reduction in SSI.1 This is not terribly surprising, given that previous compliance was already quite good and that specific interventions only benefit a subset of patients. For example, many or most patients who don’t get prophylactic antibiotics don’t develop SSI, and some patients who get prophylactic antibiotics still develop SSI. Given that the current process measures don’t prevent all SSI, what potential new measures are we missing? Loftus et al.,2,3 in 2 articles in this issue of the journal, begin to define the role of patient, environmental, and anesthesia provider bacterial reservoirs in transmission of bacteria within and between patients. Their results suggest 2 previously recognized but inadequately implemented interventions: preoperative patient skin and other bacterial reservoir decontamination and hand hygiene by anesthesia providers. Anesthesia providers practice in a nonsterile environment within the operating room and frequently contact areas of the patient known to have a high rate of contamination, such as the axilla, nares, and pharynx. Therefore, it is not surprising that the study identifies these as important areas for intervention. Seminal studies by Loftus et al.4 and Koff et al.5 at Dartmouth Hitchcock Medical Center demonstrated that anesthesia providers directly impact bacterial transmission and infection rates. Specifically, (1) anesthesiologists rapidly and widely contaminate their work environment in the operating room4; (2) greater contamination of the work environment is associated with more frequent contamination of IV distribution access ports4; (3) without intervention, anesthesiologists commonly perform hand hygiene less than once per hour during a case5; (4) reminders increase the rate of hand hygiene5; (5) this increase in the rate of hand hygiene is associated with a reduction in work area contamination and a reduction in IV access port contamination from 32% to 8%5; and (6) this reduction in work area and IV port contamination is associated with a significant reduction in HAI.5 More recently, in collaboration with 2 other major academic health centers, the group performed a prospective, randomized, observational trial to study the frequency of bacterial transmission to IV ports within and between 274 patient pairs for first and second cases in the operating room.6 Stopcock contamination occurred in 23% of cases, with 14 between-case and 30 within-case transmission events. The 2 current studies provide secondary analysis of the transmission of the predominant pathogens in the multicenter study, Staphylococcus aureus2 and Enterococcus,3 that clinically cause most SSI and HAI. Transmission events were defined as a phenotype that was cultured at 2 or more reservoir sites (including patient nasopharynx and axilla, anesthesia provider hands, and the adjustable pressure-limiting valve and agent dial of the anesthesia machine) across a case pair. The most proximal reservoir was assumed to be the source of transmission. The results are sobering. From a total of 2170 environmental culture sites, 2640 hand cultures, and 1087 patient skin cultures, >6000 potential and 2184 true pathogens were isolated. For S aureus,2 2 phenotypes accounted for 65% of the 170 isolates and most transmission events. One (labeled the P phenotype) was predominantly cultured from patient sites and the other (labeled the H phenotype) from provider hands. The P phenotype was more likely to demonstrate methicillin resistance and more often cultured in 30-day postoperative cultures, indicating that the patient skin reservoir is a more common source of pathologic transmission events. This does not exclude a role for transmission to provider hands as an intermediate step in the case-pair transmission. For Enterococcus, 80% (39 of 49) of confirmed transmission events were explained by 2 phenotypes. For both phenotypes, provider hands were the common reservoir of origin for 86% of the transmission events. Despite the high rate of transmission events within and between case-pairs, Enterococci were cultured in only 6 of 548 patients in the 30-day postoperative period. Given that the vast majority of SSI are caused by S aureus, these results suggest that transmission of specific Staphylococcal phenotypes within and between patients is a major contributor to SSI and HAI. The role of anesthesia provider hand contamination in transmission of Enterococcus to the workspace and patient biome is concerning, even though it was not associated with actual infection, because of rising rates of antibiotic-resistant organisms and the observation that Enterococcus is becoming a more prevalent pathogen. The current studies suggest 2 approaches are indicated: improved methods of patient reservoir decontamination and more effective and frequent decontamination of provider hands. Previous preoperative patient decolonization efforts have shown mixed results, but the most effective approach focused on skin decontamination along with nasal decontamination in high-risk patients.7 The current results may help better target patient reservoir decontamination to render it more effective. The current studies also highlight a well-known and effective solution to the problem of bacterial transmission within and across patients: hand hygiene. It is somewhat discouraging that Ignaz Semmelweis demonstrated the almost magical value of hand washing in 1847, and yet health care providers have yet to embrace hand hygiene over 150 years later. Barriers to adequate hand hygiene include inconvenient access in the operating room, concern with dry skin, and outmoded education. Gel and foam hand sanitizers can be made available on the anesthesia cart for easy access. A variety of skin protectants and barrier creams are routinely available in hospitals to prevent skin irritation from frequent hand washing or hand hygiene. Previous World Health Organization (WHO) recommendations focused on performing hand hygiene only before entering and after leaving a patient room, and this may partly explain the low rate of hand hygiene by anesthesiologists (less than once per hour) seen in the Koff et al. study.5 Compliance with the current “5 moments” WHO guidelines (Fig. 1) could make a major inroad into provider hand and workspace contamination; the challenge is encouraging and auditing compliance.Figure 1: The WHO 5 Moments of Hand Hygiene. http://www.who.int/gpsc/tools/Five_moments/en/.Could preoperative decolonization or hand hygiene be the next SCIP process measure? Not yet. The evidence supporting decolonization is not sufficiently developed to merit a process measure, although it appears that we are getting closer to defining which patients will benefit and which interventions are required. The evidence supporting hand hygiene is much stronger, but the challenging logistics of implementing a process measure related to hand hygiene make it even less likely. Anesthesia providers don’t document hand hygiene on the anesthesia record, except perhaps for procedure notes for central lines and other invasive procedures. Creating a mechanism for documenting hand hygiene would be burdensome and distracting. Although the Dartmouth group’s 2009 study5 demonstrated a benefit of more frequent hand hygiene, there was no attempt to match the timing of hand hygiene with distinct opportunities for hand hygiene as defined by the WHO 5 moments. Studies of intensive care unit nurses suggest a target rate of 7 to 20 times an hour, but the timing of hand hygiene may be important. The first few minutes in the operating room are associated with the highest rate of contamination,4 which is not surprising given that anesthesia induction requires frequent contact with the patient for application of monitors, intubation, placement of lines, and positioning of the patient.8 The current studies, however, should cause each anesthesia provider to take stock of her/his own intraoperative practices and commit to reducing within and between patient pathogen transmission through decontamination of patient bacterial reservoirs and reducing cross-contamination of provider hands, the anesthetic workspace, and IV access ports. DISCLOSURES Name: Harriet W. Hopf, MD. Contribution: This author wrote the commentary and is completely responsible for the content. Attestation: Harriet W. Hopf approved the final manuscript. This manuscript was handled by: Sorin J. Brull, MD, FCARCSI (Hon).