Effect of pulsed xenon ultraviolet disinfection on methicillin-resistant Staphylococcus aureus contamination of high-touch surfaces in a Japanese hospital

概要

American Journal of Infection Control 48 (2020) 139−142

Contents lists available at ScienceDirect

American Journal of Infection Control
journal homepage: www.ajicjournal.org

Major Article

Effect of pulsed xenon ultraviolet disinfection on methicillin-resistant
Staphylococcus aureus contamination of high-touch surfaces in
a Japanese hospital
Hiroki Kitagawa MD a,b,*, Minako Mori RN c,d, Seiya Kashiyama MT a,e, Yayoi Sasabe RN d, Kiyoko Ukon RN d,
Naomi Shimokawa RN d, Nobuaki Shime MD, PhD f, Hiroki Ohge MD, PhD a,g
a

Project Research Center for Nosocomial Infectious Diseases, Hiroshima University, Hiroshima, Japan
Department of Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
c
Department of Infection Control, Hiroshima University Hospital, Hiroshima, Japan
d
Department of Nursing, Hiroshima University Hospital, Hiroshima, Japan
e
Section of Infection Diseases Laboratory, Department of Clinical Support, Hiroshima University Hospital, Hiroshima, Japan
f
Department of Emergency and Critical Care Medicine, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
g
Department of Infectious Diseases, Hiroshima University Hospital, Hiroshima, Japan
b

Key Words:
Ultraviolet light
Decontamination
Hospital-associated infections
Methicillin-resistant Staphylococcus aureus

Background: The hospital environment is an important source of multidrug-resistant organisms such as
methicillin-resistant Staphylococcus aureus (MRSA). Here, we evaluated the efficacy of pulsed xenon ultraviolet (PX-UV) disinfection in addition to manual cleaning in a Japanese hospital.
Methods: Environmental samples were collected from inpatient rooms that had been occupied for at least
48 hours by patients infected or colonized with MRSA. High-touch surfaces from 11 rooms were sampled
before and after manual cleaning and then after PX-UV disinfection. Changes in bacterial counts and in the
number of aerobic bacteria (AB)- and MRSA-positive samples between sampling points were assessed. The
time taken to complete PX-UV treatment of patient rooms was also recorded.
Results: A total of 306 samples were collected. PX-UV disinfection resulted in a significant decrease in abundance of AB and MRSA (mean colony-forming units 14.4 § 38.7 to 1.7 § 6.1, P < .001 and 1.1 § 3.9 to 0.3 §
2.0, P < .001, respectively) and in the number of AB- and MRSA-positive samples (58.8%-28.4%, P = .001 and
19.6%-3.9%, P < .001, respectively) compared with manual cleaning. The median time of in-room use of the
PX-UV device was 20 minutes.
Conclusions: The addition of PX-UV disinfection to the manual cleaning process significantly reduced AB and
MRSA contamination of high-touch surfaces in hospital inpatient rooms.
© 2019 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All
rights reserved.

Multidrug-resistant organisms such as methicillin-resistant
Staphylococcus aureus (MRSA) and Clostridioides difficile are common
causes of health care−associated infections that negatively affect
patient outcomes, including length of hospital stay and mortality.1-4

*Address correspondence to Hiroki Kitagawa, MD, Department of Surgery, Graduate
School of Biochemical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-Ku, Hiroshima 734-8551, Japan.
E-mail address: hkitaga@hiroshima-u.ac.jp (H. Kitagawa).
Funding/support: This study was funded in part by a grant from the Terumo Corporation, Tokyo, Japan. The Terumo Corporation took no part in the collection and
analysis of data or in the preparation of the manuscript.
Conflicts of interest: Ohge Hiroki has received research grant from the Terumo
Corporation, Tokyo, Japan. The other authors have no conflicts of interest to disclose.

In Japan, MRSA is the most common multidrug-resistant nosocomial
pathogen.5 The hospital environment is a major reservoir of bacterial
pathogens and plays an important role in their transmission.6,7 Admission to a room previously occupied by a patient harboring a multidrugresistant organism significantly increases the risk of acquisition of these
pathogens.8-10 Furthermore, manual cleaning using chemical disinfectants, which is the standard cleaning procedure used in most hospitals,
may be inadequate if not carried out correctly.11,12
There are an increasing number of reports regarding no-touch disinfection in health care environments using ultraviolet light or
hydrogen peroxide vapor.13 The microbiological and clinical efficacy
of pulsed xenon ultraviolet (PX-UV) light devices has been described
previously, mainly in the United States.14-17 However, health care
environments can vary greatly between countries, and there are no

https://doi.org/10.1016/j.ajic.2019.08.033
0196-6553/© 2019 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

140

H. Kitagawa et al. / American Journal of Infection Control 48 (2020) 139−142

reports about PX-UV disinfection in Japanese hospitals. Therefore, in
this study, we evaluated the microbiological efficacy of PX-UV disinfection in addition to manual cleaning for elimination of aerobic bacteria (AB) and, more specifically, MRSA from high-touch surfaces in a
Japanese hospital.
METHODS
Study design
Samples were collected from the intensive care unit (ICU), emergency intensive care unit (EICU), and high care unit (HCU) of Hiroshima University Hospital, Hiroshima, Japan, from February to June
2019. Hiroshima University Hospital is a 740-bed tertiary care hospital. As part of the standard infection prevention and control measures
undertaken by the hospital, all patients admitted to the ICU or EICU
undergo nasal swab culture at the time of admission or transfer to
determine their MRSA status (positive or negative). The rooms
selected for inclusion in the study were identified using medical
records by infection prevention and control staff. The inclusion criteria were as follows: (1) single occupancy room, (2) occupied for at
least 48 hours by a patient with MRSA colonization or infection, and
(3) weekday and daytime discharge.
Initial baseline microbiological samples were collected immediately after patient discharge. After initial sampling, ward nurses performed standard manual cleaning as per ward protocols. Standard
manual cleaning included cleaning visible dirt and surface cleaning.
Surface cleaning was performed using disposable ready-to-use cleaning-disinfecting wipes containing 0.5% benzalkonium chloride (Seifukipu; Kao Corporation, Tokyo, Japan). Manual cleaning of high-touch
surfaces in patient rooms with this type of wipe was performed daily.
After manual cleaning and once environmental surfaces were dry,
the second set of microbiological samples were collected. No-touch
disinfection using the PX-UV device was then performed as per the
manufacturer’s instructions. Final microbiological samples were collected at the completion of no-touch disinfection. Nurses who performed manual cleaning and no-touch disinfection using the PX-UV
device were aware that samples were being collected but were
blinded to the chosen sampling surfaces to prevent any bias or
changes in standard cleaning procedures. It was confirmed that PXUV disinfection was carried out with appropriate cycles and irradiation time in the investigated rooms. The patients who were in the
investigated rooms were blinded to this study to prevent any bias or
variation in their activity.
PX-UV disinfection
A PX-UV device (Xenex Healthcare Disinfection Services, San
Antonio, TX), containing a xenon flash lamp that emits a broad spectrum of light covering the germicidal spectrum (200-280 nm, UV-C)
as well as the visible light spectrum, was used in this study. The ICU,
EICU, and HCU wards are located on the same floor of the hospital.
During the study period, the PX-UV device was stored on the same
floor. Ward nurses were trained on the appropriate use of the PX-UV
device. Single rooms without a separate bathroom and measuring 18
m2 were the most common type of patient room on these wards. PXUV disinfection was conducted in 5-minute cycles, with 1 cycle conducted on each side of the patient bed. If the patient room had a separate bathroom, preparation room, or waste treatment room, one
5-minute cycle was conducted in each additional room.
Sample collection
Samples were collected from the following 8 high-touch surfaces
in each of 11 patient rooms: bed rails, bed control panels, overbed

tables, vital sign monitor control panels, infusion pump control panels, bedside tables, door handles, and sink counters. Samples were
collected at each of the sampling stages, that is, before manual cleaning (baseline), after manual cleaning, and after PX-UV disinfection. If
the room had a toilet, additional samples were collected from the toilet seat at each of the sampling stages. In cases in which a suction
machine or a treatment cart were used prior to discharge, samples
were also collected from the suction machine control panel and treatment cart at each of the sampling stages. Microbiological sampling
was performed using 25-cm2 trypticase soy agar with lecithin and
polysorbate Replicate Organism Detection and Counting Contact
Plates (Becton, Dickinson and Company, Franklin Lakes, NJ). For flat
surfaces, the contact plate was firmly pressed onto the surface for 10
seconds. For nonflat surfaces, a rolling plate technique was used to
ensure coverage of the appropriate surface area. The resident microbiologist was blinded to the sample site and the timing of the sample.
Bacterial culture and identification
After sample collection, the contact plates were immediately
transferred to the clinical laboratory at Hiroshima University Hospital
and incubated for 48 hours at 36°C. Plate counts were then conducted
to estimate the total number of colony-forming units (CFUs) for all AB
present in each sample. ...