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Stopcock Contamination: The Source Does Not Explain It All

Zingg, Walter MD*; Pittet, Didier MD, MS

doi: 10.1213/ANE.0b013e31824f689d
Editorials: Editorials

From the *Infection Control Program, University of Geneva Hospitals, Geneva, Switzerland; Infection Control Program and WHO Collaborating Centre on Patient Safety, University of Geneva Hospitals and Faculty of Medicine, Geneva, Switzerland.

Funding: None.

The authors declare no conflict of interest.

Disclaimer: The World Health Organization takes no responsibility for the information provided or the views expressed in this report.

Reprints will not be available from the authors.

Address correspondence to Didier Pittet, MD, MS, Infection Control Program, University of Geneva Hospitals, 4 Rue Gabrielle Perret-Gentil, 1211 Geneva 14, Switzerland. Address e-mail to

Accepted February 6, 2012

Central line–associated bloodstream infections (CLABSI) are linked with prolonged length of hospital stay and mortality and additional health care costs.1 CLABSI incidence densities for catheters placed by anesthesia providers have been shown to be higher when compared to those placed by physicians in the intensive care unit or in internal medicine.2 Although central venous catheter placement today is highly standardized by using bundled insertion protocols,3,4 the handling of aseptic catheters and catheter hubs during anesthesia is still a neglected field. Equipment may become colonized with potentially harmful bacteria during anesthesia,5 and lapses in aseptic techniques may result in infections, as reported some years ago when propofol use was associated with outbreaks of bloodstream infections.6,7 Hand hygiene compliance among anesthesia providers is low, particularly before handling intravascular lines.8,9 Hands of care providers in the operating room have been identified as a potential source of pathogen cross-transmission.10 In this context, stopcock contamination during anesthesia can be an indicator of compliance with aseptic procedures in the operating room because hub contamination has been repeatedly associated with subsequent bloodstream infections.7,11,12

In this issue, Loftus et al. report the results of a randomized, multicenter study to determine risk factors for stopcock contamination and, in particular, to distinguish the roles of care providers' hands, anesthesiology equipment, and endogenous patient flora in cross-transmission.13 Swabs from patients and ventilator touch sites, as well as colony counting of care providers' hands using the glove juice technique, were assessed before, within, and after care of sequential patient pairs, always the first 2 patients in the morning. Two hundred seventy-four case pairs in 3 hospitals were analyzed. Stopcock contamination was 23% (126 out of 548) and significantly associated with increased mortality. The source was defined by biotyping the pathogens and timely concurrency. Of the 44 cases for which a source could be determined, the ventilator was the most likely source of cross-transmission. Care providers' hands were the source in only 12 cases (27%); gloves were not tested for microorganisms. No source could be identified for the majority of contaminated stopcocks. The most important risk factors for stopcock contamination were the hospital site and being the second patient on the operating list. Patients were the more likely reservoir for methicillin-resistant Staphylococcus aureus and methicillin-sensitive S. aureus, and care providers' hands before patient care were the more likely reservoir for vancomycin-resistant Enterococcus. In addition, care providers were more likely than patients to harbor enterobacteria during any phase of care. Some cross-transmissions were confirmed by pulsed-field gel- electrophoresis, and most pathogens that were identified originated from the patient flora. Only 1 cross-transmission could be attributed to the hands of a health care worker by pulsed-field gel-electrophoresis.

This well-performed study shows that multiple reservoirs contribute to intraoperative cross-transmission, as exemplified by stopcock contamination at the end of anesthesia. Because care providers' hands were not screened during the procedure and no inguinal swabs were obtained from patients, the role of hands as vectors in distributing the pathogens between the reservoirs cannot be conclusively assessed, especially in the case of enterobacterial cross-transmission. Compliance with hand hygiene guidelines was very low, and care providers frequently used gloves. Mean numbers of hand hygiene opportunities during anesthesia have not been formally determined. However, on the basis of studies performed in postanesthesia care and our past experience, the number of opportunities for hand hygiene during anesthesia must be in the range of 20 to 30 per hour.9

Frequent glove use interferes with appropriate hand hygiene.14,15 Gloves can reduce the likelihood of hand contamination upon patient contact and thus reduce transmission of pathogens.16,17 However, this is only true if gloves are removed after each patient contact. Importantly, gloved hands act as a carrier in the same way as nongloved hands.18,19 If the patient is not a carrier of a multidrug-resistant pathogen or suffers from Clostridium difficile infection, gloves should be used only to protect the health care worker from contact with body fluids.20 Accessing the catheter hub only for drug injection purposes does not require gloving. Health care workers perceive gloves as a means of self-protection, but as gloves should not be disinfected, continuous wearing of them throughout patient care is likely to reduce compliance with hand hygiene. When anesthesia providers wear gloves during anesthesia, pathogens will not be found on their hands at the end of the procedure, but microorganisms may have been distributed between the patient, ventilator, and catheter hubs by the gloved hands. Gloving may have been one of the reasons why hand contamination of the anesthesia providers was low in comparison with the high proportion of contaminated hubs.

The central role of care providers' hands in the pathogenesis of stopcock contamination was shown by the same authors in a previous study in which increasing hand hygiene compliance among anesthesia providers significantly reduced the number of colonized stopcocks.7 Hand hygiene should always be performed before accessing an invasive device, regardless of whether gloves are used.20,21 Every stopcock access would require hands to be cleansed previously; the study by Loftus et al. exemplifies the need for such action. Given the presumed high number of hand hygiene opportunities during anesthesia or in postanesthesia care, high compliance with hand hygiene practices is most unlikely and thus needs to be addressed.9 Further studies are needed to establish appropriate policies and practices for catheter care by staff during anesthesia in more detail. The study by Loftus et al. promotes a multimodal approach in the process of stopcock contamination, but it also well demonstrates that a multimodal strategy is needed for CLABSI prevention in this setting, including interventions to improve hand hygiene practices and cleaning of equipment between patients.22

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Name: Walter Zingg, MD.

Contribution: This author reviewed the literature and acted as the principal writer of the manuscript.

Attestation: Walter Zingg has approved the manuscript in the present form.

Name: Didier Pittet, MD, MS.

Contribution: This author helped write the manuscript.

Attestation: Didier Pittet has seen and approved the manuscript in the present form.

This manuscript was handled by: Sorin J. Brull, MD, FCARCSI (Hon).

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