Continuous Risk Recognition from Drinking Water Sources

Recent publications have supported recognition of risk relevant to in-premise water services, and this month our attention has been captured by three American publications.

Firstly, Najjar-Debbiny et al. report a high prevalence (>40% of environmental samples positive) of Carbapenemase-Producing Enterobacteriaceae within 1 meter of any water source.  This data is highly relevant for Water Safety Groups, and in particular infection prevention colleagues.  The source could be a shower, sink or handwash basin, and located in high risk patient areas or in non-clinical areas such as storage rooms or staff rooms.  Regardless of water source location or type of use, environmental samples collected within 1 metre were highly positive.  This reinforces the critical nature of having water located in high risk patient care areas, and the diligent scrutiny required when designing, installing and maintaining water outlets.  Strict infection control measures must be in place for all areas surrounding water sources when within healthcare facilities.  Inadvertent transmission could easily occur.

Secondly, Diorio-Toth et al., whose research published by the American Society for Microbiology, investigated the long-term colonisation of Intensive Care Unit sinks and water from two hospital sites (one in the United States and one in Pakistan) over a period of 27 months.     Hospital sinks are frequently linked to outbreaks of antibiotic-resistant bacteria, and the authors utilised whole-genome sequencing to track long-term colonization patterns in over 100 different microbial species. They found long-term contamination by opportunistic pathogens, as well as transient appearance of other common pathogens.  Bacteria recovered from the ICU had the highest level of antibiotic resistance genes.  Water source locations, particularly in the ICU, are a significant hazard to patients.

Considerable evidence links multi-drug resistance with the periphery of the water and associated infections with the placement and proximity of water sources.  Is it time to revisit and review your Risk Assessments?  It is important for Water Safety Groups to adopt a continuous improvement mindset, review recent evidence and advocate for vulnerable users by challenging areas of concern.

The third publication (Gerdes et al) is from the Centers for Disease Control & Prevention (CDC) team from Atlanta.  They have diligently interrogated more than 7 million cases of domestically acquired infectious waterborne illnesses which occurred in the US during 2014.  These cases were

  • “Recreational” which made up the bulk of waterborne illness numbers (78%; 5.61 million cases)
  • “Drinking” which included washing, showering, bottled waters, mains and private supply (16%; 1.13 million cases).  An interesting statistic within the paper refers to 6 million miles of domestic in-premise plumbing in the US.  That is certainly a big undertaking to operationally manage safely and effectively
  • “Non-Recreational/Non-Drinking” (e.g. agriculture, industry, flood waters) which was the minority group (6%; 0.41 million cases)

Of the 1.13 million illnesses recorded in the “drinking” group, not surprisingly Norovirus was the leading illness causing 53% of cases.  The major cause of A&E visits (~31,600 cases) was Acute Otitis Externa, however there were 47,700 hospitalisations and of these 73% (34,800) cases were due to Non-Tuberculous Mycobacterium (NTM) infections.  The leading cause of “Drinking” waterborne deaths (3300 deaths) was NTM (73%).  This is a shocking figure.  Legionella didn’t come anywhere near the numbers seen with this highly resistant  waterborne pathogen (see previous blog post Non-Tuberculous Mycobacteria – a 21st Century Waterborne Pathogen, Sept 2022). 

Despite “Drinking” representing only 16% of the total cases of waterborne illness in the United States, it absorbed the largest portion of direct healthcare costs;  $1.39 billion, reflecting 42% of all waterborne illness costs.  Costs attributed to the major waterborne pathogen groups were as follows

  • Legionnaires disease, 12%
  • Pseudomonas pneumonia and acute otitis externa 31%
  • Non-Tuberculous Mycobacteria, 46%

The authors confirm that only the waterborne infectious diseases with adequate and available data were included in the analysis, which means there is a degree of underestimation. Additionally, the data reflects that from 2014 and illness burdens and costing structures will have changed since then.  However, the burden of illness linked to non-healthcare environment “drinking” water is critical.  Analysis such as this is needed to better understand disease burdens by route of exposure, and to help prioritise resources for improved and validated guidance in controlling biofilm associated waterborne pathogens, surveillance, outbreak investigations and reporting of illness. 

If you would like to discuss risks relevant to any of these selected papers or review your risk assessments and control measures for pathogens other than Legionella, please contact us:

  1. Najjar-Debbiny R, Feldman M, Groizberg-Schwartzman D, Sobeh S, Khoury L, Yassin R, Weber G, Salach O, Shaked-Mishan P, Schwartz N, Saliba W. Unveiling the Hidden Threat of Carbapenemase-Producing Enterobacteriaceae in Hospital Water Environments: A single center study. Am J Infect Control. 2023 Jul 25:S0196-6553(23)00520-5. doi: 10.1016/j.ajic.2023.07.006. Epub ahead of print. PMID: 37499760.
  2. Diorio-Toth, L., Wallace, M. A., Farnsworth, C. W., Wang, B., Gul, D., Kwon, J. H., Andleeb, S., Burnham, C. D., & Dantas, G. (2023). Intensive care unit sinks are persistently colonized with multidrug resistant bacteria and mobilizable, resistance-conferring plasmids. mSystems, e0020623. Advance online publication.
  3. Gerdes ME, Miko S, Kunz JM, Hannapel EJ, Hlavsa MC, Hughes MJ, Stuckey MJ, Francois Watkins LK, Cope JR, Yoder JS, Hill VR, Collier SA. Estimating Waterborne Infectious Disease Burden by Exposure Route, United States, 2014. Emerg Infect Dis. 2023 Jul;29(7):1357-1366. doi: 10.3201/eid2907.230231. PMID: 37347505; PMCID: PMC10310388.

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