American Journal of Infection Control 43 (2015) 528-9
Contents lists available at ScienceDirect
American Journal of Infection Control
American Journal of Infection Control
journal homepage: www.ajicjournal.org
Brief report
Use of an ultraviolet light at point-of-dispense faucet to eliminate Pseudomonas aeruginosa Charles P. Gerba PhD * Department of Soil, Water and Environmental Science, University of Arizona, Tucson, AZ
Key Words: Point of use Tap water Pseudomonas aeruginosa Ultraviolet light Firewall Point of dispense
Tap water is believed to be a significant source of Pseudomonas aeruginosa in health care environments. This study evaluated an ultraviolet (UV) light point-of-dispense water treatment system for control of P aeruginosa. No P aeruginosa was detected in 30 different water dispensers in which the UV light device had been operating for 1-34 months. In comparison, P aeruginosa was found in other taps that did not feature this UV light system. Copyright Ó 2015 by the Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.
Infections with waterborne Pseudomonas aeruginosa and other waterborne pathogens are major contributors to serious infections in health care environments.1 Droplets of contaminated water or contaminated hands of staff can come into contact with patients exposing them to the organism. One study found that 14% of health care workers’ hands were positive for Pseudomonas when washed with contaminated water.2 Studies have found significant reductions of Pseudomonas infections in hospitals when point-of-use filters are placed on the tap to eliminate the organism.3,4 The goal of this study was to evaluate the point-of-dispense system (Firewall, Waterlogic, Omaha, NE) for control of P aeruginosa at the tap. The system consists of a cyst-rated activated charcoal filter followed by a patented, NSF/ANSI-55 Class A and NSF/P231 certified ultraviolet (UV) light system mounted at the tap (outlet) of a cooler, which allows disinfection of the faucet during use. Based on biologic actinometry using MS-2 coliphage, the unit delivers a dose (fluence) of >100 mWs/cm2 to the water passing through the faucet. This dose is some 10 times greater than is known to be lethal to P aeruginosa. The UV system is supervised by a sensor which shuts the system down and stops flow of water when the UV dose drops below 40 mWs/cm2. This dose is about 4 times greater than is known to be lethal to P aeruginosa.
* Address correspondence to Charles P. Gerba, PhD, Department of Soil, Water and Environmental Science, University of Arizona, Tucson, AZ 85721. E-mail address: [email protected]. Funding/Support: This study was supported by a grant from Waterlogic, Omaha, Nebraska, to the University of Arizona. Conflicts of interest: None to report.
Samples were collected from sink and cooler cold water taps located in offices, break rooms, conference rooms, hospital patient rooms, nursing homes, and laboratories. The sample sites were located in Arizona, Nebraska, Maryland, and Florida. The UV light units tested had been in operation for periods lasting from 6-34 months. Point-of-use units containing only activated carbon that had been in operation for 1-4 months were also tested. As much as possible, control samples (no device attached) were collected from the same buildings or adjacent buildings. The water was supplied by local water utilities and disinfected with chlorine. Samples were collected without running water through the tap. They were collected from taps by rotating a 3M Swab Sampler containing 1 mL Letheen Broth (3M, St Paul, MN) on the inside of the faucet tap, replacing it in the sterile container provided, and shipping (overnight) it on ice to the University of Arizona. Volumes of 0.1 mL of the broth were spread plated on Pseudomonas selective agar (Cetrimide agar) (Difco, Detroit, MI) and incubated at 37 C. Appearance of green colonies indicates the presence of Pseudomonas. The results are shown in Table 1. Pseudomonas was isolated from taps with no treatment and those with an activated charcoal filter. None was isolated from the taps which had the UV light system installed. Higher levels of Pseudomonas were expected in activated charcoal filtered water because Pseudomonas can grow in these types of filters because they remove chlorine and organic matter on which the organism can grow.5 In the study of a liver transplant unit, Zhou et al isolated Pseudomonas from 8% of the taps.6 In another study in an intensive care unit in Hungary, P aeruginosa colonization was detected in 5 of 7 taps.7
0196-6553/$36.00 - Copyright Ó 2015 by the Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.ajic.2015.01.016
C.P. Gerba / American Journal of Infection Control 43 (2015) 528-9 Table 1 Occurrence of Pseudomonas aeruginosa in faucet taps Type Tap Tap with carbon filter Ultraviolet light system
No. of samples
% positive
52 30 30
15.4 33.3 0
An advantage of the units is they do not have to be replaced on a regular basis such as point-of-use membrane filters and thereby are considerably more cost-effective over long-term use. References 1. Cevrvia JS, Ortolano GA, Canonica FP. Hospital tap water. A reservoir of risk from health care-associated infection. Infect Dis Cin Pract 2008;16:349-53.
529
2. Rogues AM, Boulestreau H, Lasheras A, Boyer A, Gruson D, Merie C, et al. Contribution of tap water to patient colonization with Pseudomonas aeruginosa in a medical intensive care unit. J Hosp Infect 2007;67:72-8. 3. Trautmann M, Halder S, Hoegel J, Royer H, Haller M. Point-of-use filtration reduces endemic Pseudomonas aeruginosa infections on a surgical intensive care unit. Am J Infect Control 2008;36:421-9. 4. Cervia JS, Farber B, Aemellino D, Klocke J, Bayer RL, McAllister M, et al. Point-ofuse water filtration reduces healthcare associated infections in bone marrow transplant recipients. Transpl Infect Dis; 2010:238-41. 5. Chaidez C, Gerba CP. Comparison of the microbiologic quality of pointof-use (POU)-treated water and tap water. Intl J Environ Hlth 2004;14: 253-60. 6. Zhou ZY, Hu BJ, Qin L, Lin YE, Watanabe Q, Zhou Q, et al. Removal of waterborne pathogens from liver transplant unit water taps in prevention of health careassociated infections: a proposal for cost-effective, proactive infection control strategy. Clin Microbiol Infect 2014;20:310-4. 7. Barna Z, Antmann K, Paszti J, Banfi R, Kadar M, Szax A, et al. Infection control by point-of-use water filtration in an intensive care unit e a Hungarian case study. J Water Hlth 2014;12:858-67.
Contents lists available at ScienceDirect
American Journal of Infection Control
American Journal of Infection Control
journal homepage: www.ajicjournal.org
Brief report
Use of an ultraviolet light at point-of-dispense faucet to eliminate Pseudomonas aeruginosa Charles P. Gerba PhD * Department of Soil, Water and Environmental Science, University of Arizona, Tucson, AZ
Key Words: Point of use Tap water Pseudomonas aeruginosa Ultraviolet light Firewall Point of dispense
Tap water is believed to be a significant source of Pseudomonas aeruginosa in health care environments. This study evaluated an ultraviolet (UV) light point-of-dispense water treatment system for control of P aeruginosa. No P aeruginosa was detected in 30 different water dispensers in which the UV light device had been operating for 1-34 months. In comparison, P aeruginosa was found in other taps that did not feature this UV light system. Copyright Ó 2015 by the Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.
Infections with waterborne Pseudomonas aeruginosa and other waterborne pathogens are major contributors to serious infections in health care environments.1 Droplets of contaminated water or contaminated hands of staff can come into contact with patients exposing them to the organism. One study found that 14% of health care workers’ hands were positive for Pseudomonas when washed with contaminated water.2 Studies have found significant reductions of Pseudomonas infections in hospitals when point-of-use filters are placed on the tap to eliminate the organism.3,4 The goal of this study was to evaluate the point-of-dispense system (Firewall, Waterlogic, Omaha, NE) for control of P aeruginosa at the tap. The system consists of a cyst-rated activated charcoal filter followed by a patented, NSF/ANSI-55 Class A and NSF/P231 certified ultraviolet (UV) light system mounted at the tap (outlet) of a cooler, which allows disinfection of the faucet during use. Based on biologic actinometry using MS-2 coliphage, the unit delivers a dose (fluence) of >100 mWs/cm2 to the water passing through the faucet. This dose is some 10 times greater than is known to be lethal to P aeruginosa. The UV system is supervised by a sensor which shuts the system down and stops flow of water when the UV dose drops below 40 mWs/cm2. This dose is about 4 times greater than is known to be lethal to P aeruginosa.
* Address correspondence to Charles P. Gerba, PhD, Department of Soil, Water and Environmental Science, University of Arizona, Tucson, AZ 85721. E-mail address: [email protected]. Funding/Support: This study was supported by a grant from Waterlogic, Omaha, Nebraska, to the University of Arizona. Conflicts of interest: None to report.
Samples were collected from sink and cooler cold water taps located in offices, break rooms, conference rooms, hospital patient rooms, nursing homes, and laboratories. The sample sites were located in Arizona, Nebraska, Maryland, and Florida. The UV light units tested had been in operation for periods lasting from 6-34 months. Point-of-use units containing only activated carbon that had been in operation for 1-4 months were also tested. As much as possible, control samples (no device attached) were collected from the same buildings or adjacent buildings. The water was supplied by local water utilities and disinfected with chlorine. Samples were collected without running water through the tap. They were collected from taps by rotating a 3M Swab Sampler containing 1 mL Letheen Broth (3M, St Paul, MN) on the inside of the faucet tap, replacing it in the sterile container provided, and shipping (overnight) it on ice to the University of Arizona. Volumes of 0.1 mL of the broth were spread plated on Pseudomonas selective agar (Cetrimide agar) (Difco, Detroit, MI) and incubated at 37 C. Appearance of green colonies indicates the presence of Pseudomonas. The results are shown in Table 1. Pseudomonas was isolated from taps with no treatment and those with an activated charcoal filter. None was isolated from the taps which had the UV light system installed. Higher levels of Pseudomonas were expected in activated charcoal filtered water because Pseudomonas can grow in these types of filters because they remove chlorine and organic matter on which the organism can grow.5 In the study of a liver transplant unit, Zhou et al isolated Pseudomonas from 8% of the taps.6 In another study in an intensive care unit in Hungary, P aeruginosa colonization was detected in 5 of 7 taps.7
0196-6553/$36.00 - Copyright Ó 2015 by the Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.ajic.2015.01.016
C.P. Gerba / American Journal of Infection Control 43 (2015) 528-9 Table 1 Occurrence of Pseudomonas aeruginosa in faucet taps Type Tap Tap with carbon filter Ultraviolet light system
No. of samples
% positive
52 30 30
15.4 33.3 0
An advantage of the units is they do not have to be replaced on a regular basis such as point-of-use membrane filters and thereby are considerably more cost-effective over long-term use. References 1. Cevrvia JS, Ortolano GA, Canonica FP. Hospital tap water. A reservoir of risk from health care-associated infection. Infect Dis Cin Pract 2008;16:349-53.
529
2. Rogues AM, Boulestreau H, Lasheras A, Boyer A, Gruson D, Merie C, et al. Contribution of tap water to patient colonization with Pseudomonas aeruginosa in a medical intensive care unit. J Hosp Infect 2007;67:72-8. 3. Trautmann M, Halder S, Hoegel J, Royer H, Haller M. Point-of-use filtration reduces endemic Pseudomonas aeruginosa infections on a surgical intensive care unit. Am J Infect Control 2008;36:421-9. 4. Cervia JS, Farber B, Aemellino D, Klocke J, Bayer RL, McAllister M, et al. Point-ofuse water filtration reduces healthcare associated infections in bone marrow transplant recipients. Transpl Infect Dis; 2010:238-41. 5. Chaidez C, Gerba CP. Comparison of the microbiologic quality of pointof-use (POU)-treated water and tap water. Intl J Environ Hlth 2004;14: 253-60. 6. Zhou ZY, Hu BJ, Qin L, Lin YE, Watanabe Q, Zhou Q, et al. Removal of waterborne pathogens from liver transplant unit water taps in prevention of health careassociated infections: a proposal for cost-effective, proactive infection control strategy. Clin Microbiol Infect 2014;20:310-4. 7. Barna Z, Antmann K, Paszti J, Banfi R, Kadar M, Szax A, et al. Infection control by point-of-use water filtration in an intensive care unit e a Hungarian case study. J Water Hlth 2014;12:858-67.
