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Applied and Environmental Microbiology, August 2009, p. 5363-5372, Vol. 75, No. 16
0099-2240/09/$08.00+0 doi:10.1128/AEM.00658-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
Potentially Pathogenic Bacteria in Shower Water and Air of a Stem Cell Transplant Unit
Sarah D. Perkins,1
Jennie Mayfield,2
Victoria Fraser,3 and
Largus T. Angenent4*
Department of Energy, Environmental & Chemical Engineering, Washington University, St. Louis, Missouri 63130,1 Hospital Epidemiology & Infection Prevention, Barnes-Jewish Hospital, St. Louis, Missouri 63108,2 Division of Infectious Disease, Washington University School of Medicine, St. Louis, Missouri 63108,3 Department of Biological and Environmental Engineering, Cornell University, Ithaca, New York 148534
Received 20 March 2009/ Accepted 15 June 2009
Potential pathogens from shower water and aerosolized shower mist (i.e., shower aerosol) have been suggested as an environmental source of infection for immunocompromised patients. To quantify the microbial load in shower water and aerosol samples, we used culture, microscopic, and quantitative PCR methods to investigate four shower stalls in a stem cell transplant unit at Barnes-Jewish Hospital in St. Louis, MO. We also tested membrane-integrated showerheads as a possible mitigation strategy. In addition to quantification, a 16S rRNA gene sequencing survey was used to characterize the abundant bacterial populations within shower water and aerosols. The average total bacterial counts were 2.2 x 107 cells/liter in shower water and 3.4 x 104 cells/m3 in shower aerosol, and these counts were reduced to 6.3 x 104 cells/liter (99.6% efficiency) and 8.9 x 103 cells/m3 (82.4% efficiency), respectively, after membrane-integrated showerheads were installed. Potentially pathogenic organisms were found in both water and aerosol samples from the conventional showers. Most notable was the presence of Mycobacterium mucogenicum (99.5% identity) in the water and Pseudomonas aeruginosa (99.3% identity) in the aerosol samples. Membrane-integrated showerheads may protect immunocompromised patients from waterborne infections in a stem cell transplant unit because of efficient capture of vast numbers of potentially pathogenic bacteria from hospital water. However, an in-depth epidemiological study is necessary to investigate whether membrane-integrated showerheads reduce hospital-acquired infections. The microbial load in shower aerosols with conventional showerheads was elevated compared to the load in HEPA-filtered background air in the stem cell unit, but it was considerably lower than typical indoor air. Thus, in shower environments without HEPA filtration, the increase in microbial load due to shower water aerosolization would not have been distinguishable from anticipated variations in background levels.
* Corresponding author. Mailing address: Department of Biological and Environmental Engineering, Cornell University, 214 Riley-Robb Hall, Ithaca, NY 14853. Phone: (607) 255-2480. Fax: (607) 255-4080. E-mail: la249{at}cornell.edu
Published ahead of print on 6 July 2009.
Applied and Environmental Microbiology, August 2009, p. 5363-5372, Vol. 75, No. 16
0099-2240/09/$08.00+0 doi:10.1128/AEM.00658-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
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