The Role of Contaminated Surfaces in the Transmission of Nosocomial Pathogens - Use of Biocidal Surfaces for Reduction of Healthcare Acquired Infections - page 36

3.7 Evidence That Surface Contamination Contributes
to Nosocomial Cross-Transmission
If environmental surfaces are involved in transmission, inadequate disinfection
after discharge of an infected or colonized patient will increase the risk of acqui-
sition of the same pathogen in the subsequent room occupant. This risk of increased
transmission to subsequent occupants has been shown in several studies for a range
of organisms, including C. difficile , MRSA, VRE and some multidrug-resistant
Gram-negative rods (MDR-GNRs), including A. baumannii (Table 3.3 , Fig. 3.2 )
[ 39 , 93 - 95 ].
The fact that conventional terminal cleaning and disinfection does not reliably
eliminate pathogens supports the findings of these 'prior room occupancy' studies.
Inadequate terminal disinfection may also result in a room becoming contaminated
with more than one strain of a particular pathogen due to a “build up” over time.
For example, MRSA with an average of 2.3 antibiograms were found in each
patient room in one study where there was sub-optimal terminal cleaning [ 17 ].
Similarly, in other studies approximately 30 % of MRSA environmental types were
not closely related to the MRSA type affecting the patient in the room [ 31 , 34 ].
Also, pathogens can be identified in empty rooms [ 39 , 96 ] and can be transferred to
the hands of healthcare personnel from surfaces in empty rooms [ 23 ].
These 'prior room occupancy' studies allow the assessment of the risks of
environmental contamination independent of common confounding variables of
hospital infection, such as patient age, co-morbidities and length of stay. In addi-
tion, since in these studies the source patients were already discharged, patient
acquisition directly from surfaces or via hand transfer from healthcare personnel is
most likely to have come from contaminated surfaces.
A further strand of evidence suggesting that the contaminated surface environ-
ment contributes to the transmission of nosocomial pathogens is the impact of
improved cleaning and disinfection on overall infection rates [ 4 ]. Specifically, the
findings of the prior room occupancy studies are supported by evidence that
improved terminal cleaning and disinfection can reduce the risk of infection for
the next occupant [ 13 , 96 ]. Datta et al. performed a retrospective cohort interven-
tion study on 10 ICUs at a US hospital to evaluate the impact of improved cleaning
and disinfection [ 13 ]. The intervention consisted of targeted feedback using a
black-light marker, the introduction of a “bucket method” for wetting cleaning
cloths, and increased education of housekeeping staff. Patient acquisition was
compared during 20-month baseline and intervention periods separated by
16 months. The acquisition of both MRSA and VRE fell significantly during the
intervention periods, by 50 % and 27 %, respectively. The risk associated with
the prior room occupant was successfully reduced for MRSA but not for VRE.
Passaretti et al. performed a prospective 30-month cohort intervention study on
six high-risk units in a US hospital to evaluate the impact of introducing hydrogen
peroxide vapor (HPV) for the terminal disinfection of select patient rooms [ 12 ].
HPV was introduced to disinfect the rooms of patients known to be infected or
colonized with multidrug-resistant organisms (MDROs) on three units following