Review
Evidence-based model for hand transmission during patient care and the role of improved practices

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Summary

Hand cleansing is the primary action to reduce health-care-associated infection and cross-transmission of antimicrobial-resistant pathogens. Patient-to-patient transmission of pathogens via health-care workers' hands requires five sequential steps: (1) organisms are present on the patient's skin or have been shed onto fomites in the patient's immediate environment; (2) organisms must be transferred to health-care workers' hands; (3) organisms must be capable of surviving on health-care workers' hands for at least several minutes; (4) handwashing or hand antisepsis by the health-care worker must be inadequate or omitted entirely, or the agent used for hand hygiene inappropriate; and (5) the caregiver's contaminated hand(s) must come into direct contact with another patient or with a fomite in direct contact with the patient. We review the evidence supporting each of these steps and propose a dynamic model for hand hygiene research and education strategies, together with corresponding indications for hand hygiene during patient care.

Introduction

Hand hygiene is considered the most important measure for preventing health-care-associated infections and the spread of antimicrobial resistant pathogens.1 However, non-compliance with hand hygiene remains a major problem in health-care settings. Following recent improvements in our understanding of the epidemiology of hand hygiene compliance, new approaches for promotion have been suggested. Guidelines for hand hygiene have been revisited and should improve standards and practices, and help to design successful intervention strategies.1, 2 A clear understanding of the process of hand transmission is also crucial for the success of education strategies.1, 2 We review the evidence for hand transmission of microbial pathogens during patient care, and propose a model to help develop strategies for education and to support the recently reviewed,2 recognised indications for hand hygiene practice. A related research agenda detailing areas where there is a lack of knowledge or a paucity of data is also proposed to help guide future studies.

Section snippets

Transmission of pathogens on hands

Transmission of health-care-associated pathogens from one patient to another via health-care workers' hands requires five sequential steps (panel 1). Evidence supporting each of these steps is given below.

Experimental models

Several investigators have studied the transmission of infectious agents with different experimental models. Ehrenkranz and Alfonso9 asked nurses to touch a patient's groin for 15 s as though they were taking a femoral pulse. The patient was known to be heavily colonised with Gram-negative bacilli. Nurses then cleansed their hands by washing with plain soap and water, or by using an alcohol-based handrub. After cleansing their hands, they touched a piece of urinary catheter material with their

Relations between hand hygiene and acquisition of health-care-associated pathogens

Despite a paucity of appropriate randomised controlled trials, there is substantial evidence that hand antisepsis reduces the incidence of health-care-associated infection.1, 87, 88 In what would be considered now as an intervention trial using historical controls, Semmelweis86 demonstrated in 1847 that the mortality rate in mothers who delivered children at the First Obstetrics Clinic at the General Hospital of Vienna was substantially lower when hospital staff cleansed their hands with an

Implications for hand hygiene practices

Indications for hand cleansing during patient care are closely related to the sequential steps involved in cross-transmission of microbial pathogens. Figure 7 illustrates the sequential steps and highlights the indications for hand hygiene according to the most recent expert recommendations.2 In particular, the current review of the dynamics of microbial pathogen hand transmission validates indications for hand hygiene after contact with inanimate objects in the immediate vicinity of the

Impact of improved hand hygiene

13 hospital-based studies of the effect of hand hygiene on the risk of health-care-associated infection have been published between 1977 and 2005 (table).31, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104

Despite study limitations, most reports showed a temporal relation between improved hand hygiene practices and reduced infection rates.

The hand hygiene promotion campaign at the University of Geneva Hospitals constitutes the first reported experience of a sustained improvement

Perspectives and future research

Heath-care worker education, in particular regarding indications for hand cleansing during patient care, is a crucial step within multimodal intervention strategies targeted to improve hand hygiene. We encourage educational materials to strongly consider steps in hand transmission to help promote hand hygiene practices (figure 7). Timing of hand hygiene indications is based on the dynamics of cross-transmission summarised here in accordance with the best current evidence. This review of the

Search strategy and selection criteria

Data for this review were identified by a Medline search and references taken from relevant articles; numerous articles were identified through a search of the extensive files of the authors. Search terms included “hand hygiene”, “handwashing”, “alcohol-based handrub”, “cross-infection”, “dynamics”, “modelling”, and “microbial pathogens”. English and French language papers were reviewed from January 1975–March 2006.

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