infection control & hospital epidemiology october 2017, vol. 38, no. 10 concise communication


Contaminated Portable Equipment Is a Potential Vector for Dissemination of Pathogens in the Intensive Care Unit


Amrita John, MBBS;1,2 Heba Alhmidi, MD;2 Jennifer L. Cadnum, BS;2 Annette L. Jencson, BS, CIC;2 Curtis J. Donskey, MD3,4


A DNA marker inoculated onto shared portable equipment in surgical and medical intensive care units disseminated widely to surfaces in patient rooms and provider work areas and to other types of portable equipment. These results demonstrate the potential for contaminated portable equipment to serve as a vector for dissemination of pathogens.


Infect Control Hosp Epidemiol 2017;38:1247–1249


Effective disinfection of contaminated surfaces is needed to prevent transmission of healthcare-associated pathogens.1 Efforts to improve disinfection typically focus on surfaces in patient rooms that are frequently touched by the hands of healthcare workers and/or patients (eg, bed rails). Portable equipment that is shared among patients (eg, vital signs equipment, wheel chairs) can also be a potential source of pathogen dissemination.1–4 For such “noncritical” equipment that comes into contact with intact skin but not mucous membranes, low- or intermediate-level disinfection is recommended after each patient use.5 However, in busy healthcare settings, cleaning of shared medical equipment may be suboptimal. Benign surrogate markers, such as nonpathogenic viruses and


viralDNA, provideausefultool tostudy routes of pathogen transmission.6–10 For example, in a neonatal intensive care unit (ICU) a cauliflower mosaic virus DNA marker inoculated onto a telephone in 1 ICU pod was rapidly disseminated to surfaces throughout the ICU and to the hands of personnel.6 Here, we used a similar DNA marker to test the hypothesis that portable equipment can be a vector for dissemination of microorganisms in an ICU setting.


methods


The Louis Stokes Veterans Affairs Medical Center is a 215-bed acute-care hospital with a 10-bed surgical intensive care unit (SICU) and a separate 16-bed medical intensive care unit (MICU). Both units have central work spaces for nurses, physicians, and ancillary staff. Portable equipment is stored within the central work space when not in use. The Louis Stokes Veterans Affairs Medical Center Institutional Review Board approved the study protocol.


cauliflower mosaic virus 35S promoter DNA region using the methods of Oelberg et al,6 but a different DNA sequence was used. In brief, the 222-base-pair DNA fragment was synthesized, subcloned into a plasmid, and amplified in Escherichia coli. To produce the marker, plasmid DNA was extracted from E. coli. For detection of the DNA marker, polymerase chain reaction (PCR) was performed with forward primer CCTCAGCAA- TCGCAGCAAA and reverse primer GGAAGATCAATACAT- AAAGAGTTGAACTTC. Sterile swabs (Fisherbrand polyester-tipped applicators, Waltham, MA) premoistened with Dey-Engley neutralizing medium (Remel Products, Lenexa, KS) were used to sample surfaces; the swab tips were transferred to tubes containing 200 µL of DNAse free water, vortexed for 2 minutes, eluted, and amplified via PCR with visualization on an agarose gel. Preliminary experiments demonstrated that 1 µgof the DNA marker inoculated onto a benchtop surface remained detectable by PCRfor at least 16weeks andwas transferred to clean surfaces via handprints. The DNA marker became undetectable after a 2-minute application of bleach, but not with a similar application of 70% ethanol or a quaternary ammonium disinfectant. In addition, the marker was not consistently removed from hands with a 30-second soap-and-water wash. To assess the potential for dissemination from portable equipment, the DNA marker was inoculated onto a selected type of frequently used portable equipment in each ICU during separate time periods. In the SICU, 1 µg of the DNA marker in 1mLwas inoculated using a pipette onto 13 Doppler ultrasound machines that are frequently used to monitor pulses of patients. In the MICU, 1 µg of the DNA marker in 1mL was inoculated onto 3 electrocardiogram machines. Hospital personnel and patients were not aware of the study. At the time of inoculation of the DNA marker, a fluorescent marker was also placed on the portable equipment to allow an assessment of cleaning. On days 1, 2, and 6 after inoculation of the DNA marker,


We generated a 222-base-pair DNA marker from the


swabs were used to sample high-touch surfaces within patient rooms (ie, bed rails, bedside table, call button, infusion pumps, door handles, ventilator controls, light switches, and computer keyboards), surfaces in common work areas (ie, computer keyboards, telephones, and door handles), and other portable equipment (eg, medication carts, wheelchairs, pulse oximeters). For large surfaces, a 5-×5-cm area was sampled; for smaller surfaces, the entire surface area was sampled. For each day of sampling, negative control swabs opened in the patient room but not placed in contact with surfaces were processed identically.


results


As shown in Figure 1, the DNA marker disseminated throughout both units, including to patient rooms, common


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