WATER HYGIENE AND SAFETY ‘‘
Healthcare staff could have greater peace of mind that when their patients shower, they will be at reduced risk of contracting an illness caused by waterborne bacteria
within the samples, it was difficult to draw any firm conclusions about general trends.
The mean aerobic colony count within the antibacterial hoses remained below 10,000 cfu/mL until week 5, when it rose to approximately 11,500 cfu/mL. From week 5 to week 8, there was a significant increase, to 27,000 cfu/mL, that remained in week 12. The mean aerobic colony count of the control hoses increased to up to 371,000 cfu/mL, with the levels of bacteria in some of the hoses increasing in a linear fashion throughout all 12 weeks, and some ‘peaking’ in between and decreasing slowly afterwards. P. aeruginosa was measured during week 8 and week 12 of the experiment, with all samples found to contain the bacterium (Fig. 3). While the count in the antibacterial hose did not exceed 10,000 cfu/mL, control hose number 1 had a mean count of approximately 30,000-40,000 cfu/mL, which decreased again. The decrease could be due to the fact that P. aeruginosa is an opportunistic bacterium, that grows best when competing bacteria are not present, for example after disinfection treatment, but whose growth tends to decline when it is in competition with other bacteria. Although there was no indication of a strong increase in competing bacteria during week 12, the measurements were only a ‘snapshot’ before or after bacterial growth or the dying phase.
Effectiveness of the bacteriostatic additive
The effectiveness of the bacteriostatic additive was determined by comparing the mean aerobic colony count and mean P. aeruginosa count of the control hoses with the those of the T-Safe Antibacterial Hose. Measurements in Week 0 were not considered as part of the comparison, as all three hose samples had a mean aerobic colony count below 20 cfu/mL at this initial point. The antibacterial hoses reduced the mean aerobic bacterial count by 93-99% at five weeks, and by 88.5-91% from week 8 to week 12 compared with the control hoses (Fig. 4). The mean reduction of P. aeruginosa during week 8 was 95.5%, which fell to 53% during week
56 Health Estate Journal July 2020 100 90 80 70 60 50 40 30 20 10 0 Week 1 Week 2 Week 3 Week 5 Week 8 Week 12 Figure 4: Mean P. aeruginosa and aerobic colony count reduction vs. sampling week.
12. While there was a four-fold increase in the mean P. aeruginosa count for control hose number 1, and a six-fold rise for control hose number 2, the antibacterial hoses showed only an approximate 2.5-fold increase from 1,500 cfu/mL to 3,700 cfu/mL.
Conclusion
Showers subject to stagnating water can easily be a source of infection, especially for immunosuppressed patients in healthcare facilities. Antibacterial hoses incorporating a silver-based bacteriostatic additive show promising results for reducing the risk of microbiological contamination and infection through pathogenic bacteria, and could give healthcare staff greater peace of mind that when their patients shower, they will
be at reduced risk of contracting an illness caused by waterborne bacteria.
References 1 Falkinham JO, Hilborn ED, Arduino MJ, Pruden A, Edwards MA. Epidemiology and Ecology of Opportunistic Premise Plumbing Pathogens: Legionella pneumophila, Mycobacterium avium, and Pseudomonas aeruginosa. Environ Health Perspect 2015; 123 (8): 749-58.
2 Proctor CR, Reimann M, Vriens B, Hammes F. Biofilms in Shower Hoses. Water Res, 15 March 2018; 131: 274-86.
3 Webb R, Andreou G. Determination of the Antibacterial Activity of ABS Samples against Escherichia coli, MRSA, Pseudomonas aeruginosa and Legionella pneumophila ISO 22196: 2011. Scientific report. Berkshire: IMSL; 2019.
Joachim Otto Habel
Joachim Otto Habel is a Filtration Project manager at Johs. Tandrup A/S, a leading manufacturer of point-of-use filter and antibacterial shower products, marketed under the T-Safe brand, and exported to more than 25 countries worldwide. In the role he manages filtration-related R&D projects, as well as field and laboratory trials, filter certification, and validation. With eight years’ experience in water filtration technology and membrane materials, he has a PhD in membrane technology, and had a research secondment at Twente University, one of the leading universities in terms of membrane technology expertise. He has a proven scientific track record in disciplines including membrane and filter technology, water treatment, biotechnology, nanotechnology, polymer chemistry, biochemistry, microbiology, and hygiene management.
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n TVC@22˚C n P. aeruginosa
Mean reduction (%)
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