Fecal Patina in the Anesthesia Work Area

Since the 1970s, we have gained increasing knowledge about the transmission of multidrug-resistant pathogens in hospitals and about the spread of bacteria from patients to health care workers’ hands and to the hospital environment (Fig. 1). This understanding has driven many interventions that have reduced patients’ risk of acquiring antibiotic-resistant organisms and of developing health care-associated infections.1–3Figure 1: Epidemiological links for transmission of multidrug-resistant organisms.Studies on vancomycin-resistant enterococci (VRE) established the importance of a domino effect of contamination: spread of VRE that colonize patients’ gastrointestinal tracts (“rectal carriage”), to patients’ skin, to the hospital environment, to hands of health care workers, and then to other patients. Among patients with VRE bacteremia, Beezhold et al.4 showed that all these subjects had VRE in their stool. In addition, 86% and 57% of these patients had concomitant colonization of the skin in their inguinal areas and antecubital fossae (i.e., even at skin sites remote from the rectum), respectively. There was a higher proportion of VRE-contaminated environmental sites around patients who had diarrhea or who had received broad-spectrum antibiotics. The skin contamination of patients with enteric organisms inspired the rather graphic description, the patient’s “fecal patina.”5 Also referred to as a “stool veneer,” this coating with enteric organisms is not only limited to patients’ skin but also extends to surfaces in the surrounding environment that are touched, and thereby contaminated, by patients and by health care workers (Figs. 1 and 2). The environmental contamination spreads out from the patient in a target-like concentric pattern, with densest contamination closest to the rectum of patients who have rectal carriage of the problem bacteria.6 This interplay among organisms on patients’ body surfaces, hospital environment, and health care workers’ hands constitutes the foundation for the development of infection control interventions in the field of hospital epidemiology (Fig. 1). Bonten et al.7 described a direct association between the degree of environmental contamination with VRE and the number of VRE colonized body surfaces. In addition, VRE contamination of health care workers’ hands occurred after contact with either patients’ skin or their surrounding inanimate environment, and importantly, either type of contact resulted in the successful transfer of VRE within the patients’ hospital rooms.8Figure 2: Environmental site contamination with vancomycin-resistant enterococci (VRE) in rooms of patients colonized with VRE. This figure graphically depicts the concept of fecal patina. Objects (“X”) that grew VRE in a room that was previously occupied by a patient colonized with VRE in the rectum. Cultures were obtained after the room was terminally cleaned by environmental providers. Reproduced with permission from Elsevier.6The key role of the hospital environment as a reservoir of some multidrug-resistant bacteria1 is supported by the decrease in VRE patient-to-patient transmission after improved environmental disinfection.9,10 Studies on methicillin-resistant Staphylococcus aureus (MRSA) have demonstrated the relation of spread of MRSA to environmental contamination: colonization of patient skin is present,11 the hospital environment becomes contaminated with patient strains,12 health care workers contaminate their hands after contact with the environment or patient skin,13 and enhanced environmental disinfection decreases transmission within the hospital.14 Furthermore, patients admitted to rooms previously occupied by either MRSA- or VRE-positive patients have higher risks of acquisition of these organisms than do patients admitted to other rooms.15,16 Some Gram-negative bacilli have transmission pathways similar to those of VRE,3 including the establishment of fecal patinas. Doi et al.17 showed the presence of Acinetobacter baumannii on the skin of patients who had positive clinical cultures. Sites tested included forehead, nostrils, buccal mucosa, axilla, antecubital fossa, groin, and toe webs; arms, legs, and buccal mucosa had the highest sensitivity for the detection of A baumannii.17 Frequently touched environmental sites in patient rooms had higher likelihood of being contaminated with A baumannii when occupants were colonized.18 Patients admitted to a hospital room with unrecognized contamination with A baumannii (as determined by weekly environmental cultures) had significantly higher probability of acquiring this organism during their hospitalization.19 Furthermore, as with VRE and MRSA, contamination of health care workers’ hands, gloves, and gowns occurred after entry to a room that housed a patient colonized with A baumannii.13 In this issue of Anesthesia & Analgesia, Loftus et al.20 describe the transmission of Gram-negative bacilli within the anesthesia work area while anesthesia staff were providing care in the operating room. Until recently, the infection control community largely overlooked this hospital setting as a potential risk for health care-associated infection.21 However, in part because of the work of the authors, we have gained a better understanding of the relevance of this environmental site.22–25 Concern about Gram-negative bacilli is currently heightened because of multidrug-resistant strains and the lack of available effective antibiotics.26 This situation prompted the Centers for Disease Control and Prevention to name carbapenem-resistant Gram-negatives, including A baumannii, as serious public health threats for the American population.27 Given the lack of novel antibiotic options in the development pipeline, there is increased interest for determining ways to decrease the transmission of these bacteria among our patients. The study by Loftus et al.23 evaluated randomly selected first and second surgical cases throughout the span of 12 consecutive months at 3 academic institutions. A total of 274 case pairs were tested to determine the transmission of pathogens during the procedure and between cases. This was accomplished by culturing: hands of anesthesia providers before and after each surgical case; patient body sites (nasopharynx and axillae) after anesthesia induction; and environmental surfaces (anesthesia equipment such as adjustable pressure-limiting valve and agent dial, and IV tubing), at the beginning of the first case, between cases, and at the end of the second case. Cultures were performed, using sterile swabs and nonselective blood agar media, to determine bacterial contamination. The study classified patients as carriers of Gram-negative organisms based on the axillary and throat culture results. Because many potentially pathogenic Gram-negative bacilli colonize the lower gastrointestinal tract, the omission of rectal cultures means that patients who were rectal carriers but negative at the other 2 body sites could have been misclassified as noncarriers. Such misclassification would make it impossible to determine whether the presence of these organisms in the operating room environment was caused by contamination from patients with unrecognized rectal carriage (patient contaminating environment) or whether the patients became colonized and subsequently infected as a result of the contaminated environment (environment contaminating patient) (Fig. 3). In fact, endogenous Gram-negative bacteria have been demonstrated to be an overlooked cause of postoperative clinical infections.28 Although Loftus et al. used pulsed field gel electrophoresis to demonstrate the relationship of pairs of environmental and clinical bacterial isolates, this technique would not detect the direction of spread of the bacteria.Figure 3: Possible explanations of subsequent clinical infections caused by the same organism cultured in the anesthesia work area. A, Contaminated environment exposes patient to Gram-negative bacilli (GNB) with the subsequent development of a clinical infection. B, Patient with unrecognized rectal colonization undergoes surgery, contaminates the anesthesia area with his/her endogenous GNB, and later develops a clinical infection with the same organism.Despite the potential misclassification drawback, we believe that the study by Loftus et al. highlights the risk of transmission of Gram-negative bacilli within the anesthesia work area and demonstrates that the spread follows an epidemiologic pattern similar to that seen in intensive care units and inpatient wards: from patient, to environment and health care workers’ hands, and to other patients (Fig. 1). These findings have clinical implications for the risk of colonization and subsequent health care-associated infections, for example, surgical site infections. Thus, the work of Loftus et al. calls attention to the need to develop realistic hand hygiene guidelines for personnel who are giving anesthesia care, to monitor and ensure adherence to such guidelines, to assess the clinical impact of improved hand hygiene, to increase compliance with environmental disinfection of the operating room (between cases and terminal cleaning), and to study further the directions of the spread of pathogens in the operating room and anesthesia work areas. DISCLOSURES Name: L. Silvia Munoz-Price, MD, PhD. Contribution: This author helped write the manuscript. Attestation: L. Silvia Munoz-Price approved the final manuscript. Name: Robert A. Weinstein, MD. Contribution: This author helped write the manuscript. Attestation: Robert A. Weinstein approved the final manuscript. This manuscript was handled by: Sorin J. Brull, MD, FCARCSI (Hon).