Risks at The Water’s Edge

Until recently it was a rarity to read about Cupriavidus pauculus – an occasional case study perhaps – it was certainly not a waterborne pathogen at the centre of outbreak investigations like Legionella pneumophila, Pseudomonas aeruginosa or non-tuberculous Mycobacteria. However, in 2018 the sad events unfolded from the new build Queen Elizabeth University Hospital, Glasgow, where multiple cases of C. pauculus bacteraemia in paediatric haemato-oncology patients that were associated with contaminated water system were reported and the first outbreak was confirmed. The investigation found 75/98 water outlets on the haemato-oncology unit tested positive for C. pauculus, and around half of their positive outlet counts exceeded 100 cfu/100ml. Many species of Cupriavidus are considered to be metal resistant, and there is a genetic link between metal and antibiotic resistance, adding to the concerns regarding this little known bacterium. Since 2018, there has been a creeping and daunting recognition of this emerging pathogen, and last month there were 2 papers published, both highlighting its prevalence and activity at the periphery of the drinking water system.

Butler and co-workers (University of Plymouth) reported isolation of Cupriavidus spp. from a hospital sink trap – a well-known reservoir of pathogens in clinical settings. Sink traps (n=2) were removed by hospital staff, sealed in individual sample bags and transferred to the University of Plymouth for analysis. Growing Cupriavidus by trying to mimic sink trap life is not straightforward. The (inappropriate) disposal of liquids and solids via sink traps creates a varied and complex nutrient load, and there is no established model to replicate such sink-trap conditions in the laboratory. Despite this challenge, the team demonstrated C. pauculus biofilms forming after 24 hours at both blood and ambient temperatures and in both nutrient rich and poor conditions. Indeed, at 37 °C the growth of C. pauculus biofilm outpaced that of P. aeruginosa, the model for water biofilm formation. The authors recognised its multidrug resistance, including the antibiotic of last- resort, colistin.

We have another eye-opening paper from the stable of Inkster/Weinbren, whose research has shown that Cupriavidus spp. are present in hospital water systems across the UK, and not restricted to in-premise water system conditions common in Scotland (e.g. steel pipe installations). Water samples were received from multiple locations within ten UK NHS hospitals and Cupriavidus spp. was detected in 4/10 assessed hospitals with isolates mainly detected in peripheral locations (multiple outlets and one expansion vessel). The majority of positive samples declared counts > 100 cfu/100ml. This study confirms that isolation of Cupriavidus spp. is not unique to Glasgow, and if a case of infection should occur then water testing is sensible to confirm the source.

With these two publications it is clear that Water Safety Teams need to not only look at the favoured niches of these emerging pathogens and eliminate, mitigate and/or control them, but also be vigilant in clinical surveillance and environmental monitoring to ensure they are not victims of a Cupriavidus outbreak. We have clear evidence of C. pauculus causing morbidity and mortality, which makes its colonisation of outlets or sink traps in the close proximity of vulnerable users in hospital a threat. It also poses a significant risk due to the transfer of antibiotic resistance genes. If you have concerns regarding opportunistic waterborne pathogens within your water systems and would like some independent advice, please contact the team here at Harper Water Management Group to discuss further.

Butler J, Kelly SD, Muddiman KJ, Besinis A, Upton M. Hospital sink traps as a potential source of the emerging multidrug-
resistant pathogen Cupriavidus pauculus: characterization and draft genome sequence of strain MF1. J Med Microbiol.
2022 Feb;71(2). doi: 10.1099/jmm.0.001501. PMID: 35113779.


Inkster T, Wilson G, Black J, Mallon J, Connor M, Weinbren M. Cupriavidus spp and other waterborne organisms in
healthcare water systems across the United Kingdom. J Hosp Infect. 2022 Feb 15:S0195-6701(22)00043-3. doi:
10.1016/j.jhin.2022.02.003. Epub ahead of print. PMID: 35181399.


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