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Investigating alternative materials to EPDM for automatic taps in the context of Pseudomonas aeruginosa and biofilm control

Investigating alternative materials to EPDM for automatic taps in the context of Pseudomonas aeruginosa and biofilm control
Investigating alternative materials to EPDM for automatic taps in the context of Pseudomonas aeruginosa and biofilm control
Background Automatic taps use solenoid valves (SVs) which incorporate a rubber (typically EPDM) diaphragm to control water flow. Contaminated SVs can be reservoirs of opportunistic pathogens such as Pseudomonas aeruginosa; an important cause of healthcare-associated infection. Aims To investigate the attachment and biofilm formation of P. aeruginosa on EPDM and relevant alternative rubbers to assess the impact on water hygiene in a laboratory model. Methods Biofilm formation on EPDM, silicone and nitrile rubber coupons was investigated using a CDC biofilm reactor. SVs incorporating EPDM or nitrile rubber diaphragms were installed on to an experimental water distribution system (EWDS) and inoculated with P. aeruginosa. P. aeruginosa water levels were monitored for 12-weeks. SVs incorporating diaphragms (EPDM, silicone or silver ion-impregnated silicone rubber), pre-colonized with P. aeruginosa, were installed and the effect of flushing as a control measure was investigated. The concentration of P. aeruginosa in the water was assessed by culture and biofilm assessed by culture and microscopy. Findings Bacterial attachment was significantly higher on nitrile (6.2 × 105 cfu/coupon) and silicone (5.4 × 105 cfu/coupon) rubber than on EPDM (2.9 ×105 cfu/coupon) (P<0.05, N = 17). Results obtained in vitro did not translate to the EWDS where, after 12-weeks in situ, there was no significant difference in P. aeruginosa water levels or biofilm levels. Flushing caused a superficial reduction in bacterial counts after <5 min of stagnation. Conclusion This study did not provide evidence to support replacement of EPDM with (currently available) alternative rubbers and indicated the first sample of water dispensed from a tap should be avoided for use in healthcare settings.
Automatic taps, Biofilm, Healthcare acquired infection, Hospital taps, Pseudomonas aeruginosa, Water hygiene, Water safety
0195-6701
429-435
Webb, Jeremy
ec0a5c4e-86cc-4ae9-b390-7298f5d65f8d
Hutchings, Chloe
19752ebe-cd0d-4745-91b5-6f4fd4cb4810
Moore, Ginny
5e535ef1-a0c4-45ff-933d-0da67e7dd01f
Walker, T.J.
4f152cc7-2ea2-4e9b-95da-c52a29b78e48
Webb, Jeremy
ec0a5c4e-86cc-4ae9-b390-7298f5d65f8d
Hutchings, Chloe
19752ebe-cd0d-4745-91b5-6f4fd4cb4810
Moore, Ginny
5e535ef1-a0c4-45ff-933d-0da67e7dd01f
Walker, T.J.
4f152cc7-2ea2-4e9b-95da-c52a29b78e48

Webb, Jeremy, Hutchings, Chloe, Moore, Ginny and Walker, T.J. (2020) Investigating alternative materials to EPDM for automatic taps in the context of Pseudomonas aeruginosa and biofilm control. Journal of Hospital Infection, 106 (3), 429-435. (doi:10.1016/j.jhin.2020.09.013).

Record type: Article

Abstract

Background Automatic taps use solenoid valves (SVs) which incorporate a rubber (typically EPDM) diaphragm to control water flow. Contaminated SVs can be reservoirs of opportunistic pathogens such as Pseudomonas aeruginosa; an important cause of healthcare-associated infection. Aims To investigate the attachment and biofilm formation of P. aeruginosa on EPDM and relevant alternative rubbers to assess the impact on water hygiene in a laboratory model. Methods Biofilm formation on EPDM, silicone and nitrile rubber coupons was investigated using a CDC biofilm reactor. SVs incorporating EPDM or nitrile rubber diaphragms were installed on to an experimental water distribution system (EWDS) and inoculated with P. aeruginosa. P. aeruginosa water levels were monitored for 12-weeks. SVs incorporating diaphragms (EPDM, silicone or silver ion-impregnated silicone rubber), pre-colonized with P. aeruginosa, were installed and the effect of flushing as a control measure was investigated. The concentration of P. aeruginosa in the water was assessed by culture and biofilm assessed by culture and microscopy. Findings Bacterial attachment was significantly higher on nitrile (6.2 × 105 cfu/coupon) and silicone (5.4 × 105 cfu/coupon) rubber than on EPDM (2.9 ×105 cfu/coupon) (P<0.05, N = 17). Results obtained in vitro did not translate to the EWDS where, after 12-weeks in situ, there was no significant difference in P. aeruginosa water levels or biofilm levels. Flushing caused a superficial reduction in bacterial counts after <5 min of stagnation. Conclusion This study did not provide evidence to support replacement of EPDM with (currently available) alternative rubbers and indicated the first sample of water dispensed from a tap should be avoided for use in healthcare settings.

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More information

Accepted/In Press date: 10 September 2020
e-pub ahead of print date: 15 September 2020
Published date: 1 November 2020
Keywords: Automatic taps, Biofilm, Healthcare acquired infection, Hospital taps, Pseudomonas aeruginosa, Water hygiene, Water safety

Identifiers

Local EPrints ID: 444909
URI: http://eprints.soton.ac.uk/id/eprint/444909
ISSN: 0195-6701
PURE UUID: 083801c9-2446-4a2b-8c2c-be68d43d8b67
ORCID for Jeremy Webb: ORCID iD orcid.org/0000-0003-2068-8589

Catalogue record

Date deposited: 11 Nov 2020 17:31
Last modified: 18 Feb 2021 17:08

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