Biomedical Engineering Reference
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and antimicrobial residues, i.e. from the last surfaces disinfection. However, little
dispute exists that beside the hands of healthcare workers surfaces in the close
vicinity of patients may play a key role for the transfer of nosocomial pathogens.
2.4 Mechanisms of Transmission from Inanimate Surfaces
to Susceptible Patients and Consequences Thereof
The main route of transmission of HAI is via transiently contaminated hands of
healthcare workers, but contaminated surfaces may serve as important vectors for
cross transmission after hand contact as well (Fig.
2.1
).
A single hand contact with a contaminated surface results in a variable degree of
pathogen transfer. Transmission from surfaces to hands was most successful with
E. coli
,
Salmonella
spp
.
,
S. aureus
(all 100 %),
C. albicans
(90 %), Rhinovirus
(61 %), Hepatitis A virus (22-33 %), and Rotavirus (16 %) [
64
,
65
]. Other transfer
rates were calculated for Echovirus, Poliovirus, and Rotavirus with 50 % transmis-
sibility, and for
Salmonella enteritidis
,
Shigella
spp., and
E. coli
O157:H7 with
33 % [
104
]. Contaminated hands can transfer viruses to 5 more surfaces or 14 other
subjects. Contaminated hands can also be the source of re-contamination of the
surface, as demonstrated with Hepatitis A virus [
64
,
65
].
Because of this, it is critical to note that healthcare workers' compliance with
hand hygiene varies between 13 % and 94 % with a median of less than 50 %
[
91
]. Moreover hand hygiene is performed less frequently after contact with the
environment than with the patient [
94
]. Both facts underline the necessity to
perform additional surface decontamination procedures to interrupt the transmis-
sion of nosocomial pathogens. Due to the overwhelming evidence of low compli-
ance of hand disinfection, the risk from contaminated surfaces cannot be
overlooked and must not be down played by hospital administrations.
Fig. 2.1 Transmission
routes for nosocomial
pathogens
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