The Role of Contaminated Surfaces in the Transmission of Nosocomial Pathogens - Use of Biocidal Surfaces for Reduction of Healthcare Acquired Infections - page 34

However, the thoroughness of cleaning and disinfection was not evaluated in these
studies, meaning that it is difficult to determine whether it is the products, the
procedures or a combination of the two that is responsible for the failure to
eliminate pathogens from surfaces. Nonetheless, the procedure rather than the
product is implicated by the fact that many of these studies were performed using
agents that are effective in vitro against the microorganisms cultured from surfaces
after the process [ 83 ].
The physiological state of bacteria cultured from dry hospital surfaces has not
been studied in detail. A recent study from Australia 'destructively sampled'
several hospital surfaces (i.e. cut the materials out of the hospital environment
and took them to the lab for analysis) after cleaning and disinfection using bleach
and identified biofilms on 5/6 surfaces [ 84 ]. Furthermore, MRSA was identified in
the biofilm on three of the surfaces. The presence of biofilms may partly explain
why vegetative bacteria can survive on dry hospital surfaces for so long, why they
are so difficult to remove or inactivate using disinfectants (bacteria in biofilms can
be 1,000 more difficult to kill than corresponding planktonic bacteria) and why it

is often difficult to recover environmental pathogens by surface sampling [ 85 ].

3.6 Nosocomial Pathogens Can Be Transferred
from Contaminated Surfaces
to the Hands of Healthcare Workers

In vitro studies present a picture of rapid dynamic transfer from surfaces to
hands and vice versa (Table 3.2 ). For example, DNA markers dried onto toys
were transferred readily to the hands of researchers and subsequently onto clean
toys, and the markers spread rapidly when introduced into a child care center
[ 87 , 90 ]. Similarly, experimentally contaminated fingers serially contaminated
multiple surfaces with norovirus [ 75 ]. Similar findings have been reported using
surfaces experimentally contaminated with bacteria and bacteriophage [ 86 , 88 ].
Importantly, experimentally contaminated fingers have been shown to transfer
more than 30 % of inoculated bacteria and bacteriophage to the mouths of volun-
teers, with clear implications for the fecal-oral transmission of nosocomial

pathogens [ 86 ].
Several studies have shown that various bacterial pathogens can be acquired on
the hands of HCP through contact with environmental surfaces in the absence of
direct patient contact (Table 3.2 )[ 16 , 22 , 23 , 54 , 55 , 89 ]. Patients and contaminated
surfaces can transfer VRE, MRSA and C. difficile to HCP hands at similar frequen-
cies [ 22 , 30 , 54 , 55 ]. However, in a recent study, compliance with hand hygiene was
80 % of 142 opportunities after patient contact compared with only 50 % of
196 opportunities after contact with a patient's environment (p 0.01, Fisher's

exact test) meaning that contamination acquired from a patient's environment is
less likely to be dealt with by hand hygiene [ 91 ].

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