Hand hygiene.pdf

attributable to Salmonella spp. ever reported 128 ; in this outbreak in Brazil, there was a clear
relationship between understaffing and the quality of health care, including hand hygiene.
8. METHODS TO EVALUATE THE ANTIMICROBIAL EFFICACY
OF HANDRUB AND HANDWASH AGENTS AND
FORMULATIONS FOR SURGICAL HAND PREPARATION
With the exception of non-medicated soaps, every new formulation for hand antisepsis
should be tested for its antimicrobial efficacy to demonstrate that: (i) it has superior efficacy
over normal soap; or (ii) it meets an agreed performance standard. The formulation with
all its ingredients should be evaluated to ensure that humectants or rehydrating chemicals
added to ensure better skin tolerance do not in any way compromise its antimicrobial
action.
Many methods are currently available for this purpose, but some are more useful and
relevant than others. For example, determination of the minimum inhibitory concentration
(MIC) of such formulations against bacteria has no direct bearing on the “killing effect”
expected of such products in the field. Conditions in suspension, and in vitro 129 or ex vivo 130
testing do not reflect those on human skin. Even simulated-use tests with volunteers are
considered by some as “too controlled”, prompting testing under in praxi or field conditions.
Such field-testing is difficult to control for extraneous influences. Besides, and quite
importantly, the findings of field tests do not tell us much about a given formulation’s ability
to cause a measurable reduction in hand-transmitted nosocomial infections. While the ultimate
approach in this context would be clinical trials, they are generally quite cumbersome
and expensive. For instance, power analysis reveals that for demonstrating a reduction in
hand-transmitted infections from 2% to 1% by changing to a presumably better hand antiseptic
agent, almost 2500 patients would be required in each of two experimental arms at
the statistical pre-settings of α (unidirectional) = 0.05 and a power of 1-ß = 0.9 131 . This is
why the number of such trials remains quite limited 132-134 . To achieve a reduction from 7%
to 5% would require 3100 patients per arm (courtesy of Michael Kundi). This reinforces the
utility of well-controlled, in vivo laboratory-based tests to give enough information economically
to assess a given formulation’s potential benefits under field use.
8.1 CURRENT METHODS
Direct comparisons of the results of in vivo efficacy testing of handwashing, antiseptic
handwash, antiseptic handrub and surgical hand antisepsis are not possible because of wide
variations in test protocols. Such variations include: (i) whether hands are purposely contaminated
with bacteria before use of the test agent; (ii) the method used to contaminate
fingers or hands; (iii) the volume of hand hygiene product applied; (iv) the time the product
is in contact with the skin; and (v) the method used to recover bacteria from the skin after
the test formulation has been used.
Despite the differences noted above, most testing falls into one of two major categories.
One category is designed to evaluate handwash or handrub agents to eliminate transient
pathogens from HCWs’ hands. In most of such studies, the volunteer’s hands are artificially
contaminated with the test organism before applying the test formulation. In the second category,
which applies to pre-surgical scrubs, the objective is to evaluate the test formulation