Infection control experts at The Johns Hopkins
Hospital have found that a combination of robot-like
devices that disperse a bleaching agent into the air
and then detoxify the disinfecting chemical are
highly effective at killing and preventing the
spread of multiple-drug-resistant bacteria, or
so-called hospital superbugs.
A study report on the use of hydrogen peroxide
vaporizers, first deployed in several Singapore
hospitals during the 2002 outbreak of severe acute
respiratory syndrome, or SARS, and later stocked by
several U.S. government agencies in case of an
anthrax attack, is to be published Jan. 1 in the
journal Clinical Infectious Diseases.
In the study, the Johns Hopkins team placed the
devices in single hospital rooms after routine
cleaning to disperse a thin film of the bleaching
hydrogen peroxide across all exposed hospital
equipment surfaces, as well as on room floors and
walls.
Results showed that the enhanced cleaning reduced by
64 percent the number of patients who later became
contaminated with any of the most common
drug-resistant organisms. Moreover, researchers
found that protection from infection was conferred
on patients regardless of whether the previous room
occupant was infected with drug-resistant bacteria
or not.
Of special note, researchers say, was that enhanced
cleaning with the vapor reduced by 80 percent a
patient's chances of becoming colonized by a
particularly aggressive and hard-to-treat bacterium,
vancomycin-resistant enterococci (VRE).
In what is believed to be the first head-to-head
comparison between traditional hand-cleaning and
mopping with bleaching agents and robotic vaporizers,
researchers routinely tested patients and their
surroundings not only for VRE, but also for the more
common methicillin-resistant Staphylococcus aureus,
or MRSA, and lesser-known bacteria, including
Clostridium difficile and Acinetobacter baumannii.
Some 6,350 patient admissions to JHH were closely
tracked as part of the two-and-a-half-year analysis,
as patients moved into and out of 180 private
hospital rooms. Almost half the rooms received
enhanced cleaning with hydrogen peroxide vapor in
between patients, while the rest did not. Overall,
multiple-drug-resistant organisms were found on room
surfaces in 21 percent of rooms tested, but mostly
in rooms that did not undergo enhanced cleaning.
Technological solutions, when combined with standard
cleaning, can effectively and systematically
decontaminate patients' rooms and augment other
behavioral practices, such as strict hospital staff
compliance with hand-washing and bathing patients in
disinfecting chlorhexidine when they are first
admitted to the hospital.
After the room has been cleaned, the vents are
covered and the two devices are placed inside. The
sliding door is closed, and the room is sealed. Then,
the larger of the two devices disperses hydrogen
peroxide into the room, leaving a very tiny, almost
invisible layer (only 2 microns to 6 microns in
thickness) on all exposed surfaces, including
keyboards and monitors, as well as tables and chairs.
Because hydrogen peroxide can be toxic to humans if
ingested or corrosive if left on the skin for too
long, the second, smaller device is activated to
break down the bleach into its component water and
oxygen parts. The combined operation takes the
devices about an hour and a half to complete.
"What is so exciting about this new method of
infection control is that the devices are easy to
use and hospital staff embrace it very quickly,"
says surgeon and study co-investigator Pamela
Lipsett, M.D., M.H.P.E. Lipsett, a professor and
director of surgical and critical care fellowship
training at Johns Hopkins, says that during the
study and before room cleanings, staff were "wheeling
in" other pieces of equipment so these, too, could
be decontaminated by the hydrogen peroxide vapor.
Researchers say they next plan to study the devices'
effectiveness at decontaminating the outside
packaging of unused but potentially exposed hospital
supplies, which are typically discarded even though
their seals remain intact. The research team also
wants to coordinate study testing among other
hospitals to validate their Johns Hopkins findings.
Larger and longer studies may also be planned, to
precisely measure and determine how well the devices
work against the spread of each hospital superbug.
The current study had only sufficient numbers to
statistically validate the paired unit's
effectiveness against VRE.
In addition to Perl and Lipsett, other Johns Hopkins
University investigators involved in this study were
study lead investigator Catherine Passaretti, M.D.;
Nicholas Reich, Ph.D.; Jessica Meyers, M.P.H.; John
Shepard, M.B.A.; and Karen Carroll, M.D. Additional
study assistance was provided by Jonathan Otter, at
Bioquell Inc., and Tracy Ross, at the University of
Massachusetts, in Amherst.
For more information
The Johns Hopkins Medicine
(MDN)
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