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marker was recovered from the sleeves of a physician’s white coat hung in a call roomon another ward (Fig. 1C) but not from other call rooms or from nursing stations. The marker was recovered from a table top in the cafeteria where personnel sat after use of the inoculated equipment (Fig. 1D). Overall, 7 of 96 swabs (7%) were positive. During observations of wound-care rounds, the DNA marker
was transferred from the inoculated cart to surfaces on 2 of 3 observation days. On 3 different wards, the marker was detected on surfaces touched by hands or gloves of personnel after contact with the wound-care cart, including a door knob, a bedrail, and a workstation on wheels. During observation of a phlebotomist, DNA marker was transferred to surfaces in 3 of 9 patient rooms (33%) on 2 wards.
DISCUSSION
In investigations of pathogen transmission, shared ward exposure is often required for classification as a plausible epidemiologic link. However, sharing of personnel and equipment is common, and patients from multiple wards regularly intersect in areas such as radiology.8,9 In a previous report, hospital-wide dissemination of methicillin-resistant Staphylococcus aureus was linked to a colonized healthcare worker caring for patients on multiple wards.10 In the current study, we used a DNA marker that behaves similarly to C. difficile spores (ie, prolonged survival on surfaces, inactivation by bleach but not alcohol or quaternary ammonium disinfectants, and removal through mechanical action) to study the potential for dissemination of pathogens from ward to ward. The DNA marker disseminated from portable equipment on 1 ward to other wards when equipment was shared and to a physician work room and to the hospital cafeteria. Contaminated wound care and phlebotomy equipment also dis- seminated the marker to surfaces on multiple wards. Our findings have important implications for infection control.
First, in investigations of pathogen transmission, routes of dis- semination between wards should be considered. Second, there is a need for improved strategies for disinfection of shared equipment. Although our policies recommend cleaning of equipment between patients, only 1 of the 6 inoculated devices was cleaned based on fluorescent marker removal. It is likely that cleaning of equipment between patients performed as recommended in current guidelines would have reduced the frequency of transfer.7 Finally, hand hygiene is indicated after touching portable equipment. It is likely that the hands of personnel contributed to transfer of the marker from inoculated devices to clean surfaces. Our study has some limitations. The study was conducted in
1 hospital and the marker was inoculated on 1 ward. Our results are likely to reflect a worst-case scenario because the concentra- tion of the DNA marker applied to equipment was high. Because the DNA marker is not affected by alcohol hand sanitizer, transmission might have been more frequent than would occur
Heba Alhmidi et al
with alcohol-susceptible surrogate markers or pathogens. How- ever, widespread dissemination of bacteriophage MS2 has also been demonstrated in a hospital setting.6 In summary, our findings demonstrate the plausibility of patho-
gen transmission in the absence of shared ward exposure. Future studies are needed to investigate routes and frequency of ward-to- ward transmission of pathogens in healthcare facilities. In addition, there is a need for studies are needed to determine the efficacy of interventions such as improved cleaning of portable equipment.
Acknowledgments. We thank the nursing staff at the Cleveland VA Medical Center for helpful discussions regarding potential routes of pathogen transmission.
Financial support. This work was supported by a Merit Review (grant no. 1 I01 BX002944-01A1) from the Department of Veterans Affairs to C.J.D.
Conflicts of interest. C.J.D. has received research grants from GOJO, Clorox, PDI, Pfizer, Avery Dennison, and Boehringer Laboratories. All other authors report no conflicts of interest relevant to this article.
References
1. Kong LY, Eyre DW, Corbeil J, et al. Clostridium difficile: investigating transmission patterns between infected and colonized patients using whole genome sequencing. Clin Infect Dis 2018. doi: 10.1093/cid/ciy457.
2. Donskey CJ, Sunkesula VCK, Stone ND, et al. Transmission of Clostridium difficile from asymptomatically colonized or infected long-term care facility residents. Infect Control Hosp Epidemiol 2018;39:909–916.
3. Walker AE, Eyre DW, Wyllie DH, et al. Characterisation of Clostridium difficile hospital ward-based transmission using extensive epidemiological data and molecular typing. PLoS Med 2012;9:e1001172.
4. Curry SR, Muto CA, Schlackman JL, et al. Use of multilocus variable number of tandem repeats analysis genotyping to determine the role of asymptomatic carriers in Clostridium difficile transmission. Clin Infect Dis 2013;57:1094–1102.
5. Alhmidi H, John A, Mana TC, et al. Evaluation of viral surrogate markers for study of pathogen dissemination during simulations of patient care. Open Forum Infect Dis 2017;4(3):ofx128. doi: 10.1093/ofid/ofx128.
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7. John A, Alhmidi H, Cadnum JL, Jencson AL, Donskey CJ. Contaminated portable equipment is a potential vector for dissemination of pathogens in the intensive care unit. 2017;38:1247–1249.
Infect Control Hosp Epidemiol
8. Jencson AL, Cadnum JL, Wilson BM, Donskey CJ. Spores on wheels: wheelchairs are a potential vector for dissemination of pathogens in healthcare facilities. Am J Infect Control 2018 in press.
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