WATER HYGIENE & SAFETY Pipe wall
Free-floating bacteria
Water
Biofilm- associated bacteria
Secreted slime
Cross-section of pipe. Figure 3: Biofilm formation in pipework.10
P. aeruginosa can survive on abiotic and biotic surfaces, and can easily be transmitted from one patient to the next.8 The bacterium also possesses many unfavourable characteristics towards its host, which makes it highly resistant to antibiotics, and has the ability to form a biofilm.
Other more common waterborne
pathogens are Enterovirus, adenovirus, Pseudomonas spp., legionella, salmonella, and Escherichia coli O157:H7. Outbreaks of these viruses and bacteria are harmful to our healthcare system, as they can be easily transmitted, can be resistant to chemical/ heat disinfection, and possess antibiotic resistance.
Biofilm formation Unfortunately, microorganisms are extremely clever species, which makes it more difficult for the human eye to detect them. Some microorganisms have the ability to manipulate their morphology as an adaptation and survival method. This method is commonly known as biofilm formation. This a key characteristic for many microorganisms, as it allows them to survive and replicate when conditions become unfavourable for them to sustain life. Biofilms allow some microorganisms (single celled) to survive, as they incorporate them into the ‘group’, so that they, along with multicellular bacteria, fungi, viruses, and protozoa, can continue to replicate and grow.9 In order for microorganisms to create a biofilm, they alter the regulatory networks that are responsible for signal generation.9
‘‘
This altered signal generation is then used for gene alteration, which results in temporary reconfiguration of the cell.9 These modified genes are responsible for nutrient usage, virulence factors, and the ability to use different surface molecules.8,9 This causes the formation of a biofilm. In this biofilm, the bacteria are wrapped up in a self-produced extracellular polymeric substance (EPS), carbohydrate binding proteins, Pilli and flagella, that allow the bacteria to stick to surfaces.8,9
This
EPS layer acts as a shield, that protects the microorganism from unfavourable environmental conditions such as heat and chemicals.
Resistant and hard to eliminate The longer that a biofilm is attached to a surface such as pipework, the stronger and more resilient it becomes, thus making it extremely hard to break down and eliminate. There are two main common causes of biofilm formation: 1) deadlegs – sections of pipework the water does not cover when flowing through the pipe and, 2) poor water quality. As water is a ‘naturally made’ product, its prototype can vary from one droplet to the next. This makes water particles very unpredictable, which has a significant effect on how water is used throughout healthcare.
Biofilm case study As previously mentioned, the formation of a biofilm is not always visible to the human eye. Normally a biofilm only becomes visible when it’s too late. This is why medical equipment through which water
Normally a biofilm only becomes visible when it’s too late. This is why medical equipment through which water flows is designed to ensure that there are minimal, or indeed no deadlegs present, reducing the opportunity for these microorganisms
120 Health Estate Journal October 2022
flows is designed to ensure that there are minimal, or indeed no deadlegs present, reducing the opportunity for these microorganisms to form a biofilm. That said, a few years ago, an Irish hospital had a confirmed outbreak of Pseudomonas aeruginosa in its water samples, taken as part of its regular validations in the Decontamination Department. The machine in question was taken out of use, and an investigation carried out. The first step was to re-sample to ensure that it was not a ‘false positive’ result. The results from the re-test showed Pseudomonas aeruginosa was present. The manufacturers of the Department’s washer-disinfectors and reverse osmosis units were called in to complete various disinfection activities and troubleshooting to identify the possible source of the contaminant. However, nothing was found in either the water supply or the washer- disinfectors. There were also no deadlegs found. It was only on further investigation of the
Decontamination Department that it was concluded that the PTFE tubing routinely used to take its water samples contained a biofilm. The majority of personnel wouldn’t know what a biofilm looks like, but in this case, the representative from one of the manufacturing companies knew what to look out for. Once it was discovered, the presumptive cause of the contamination was investigated, and it was confirmed by microscopy and laboratory analysis. The growth of this biofilm was as a result of the tubing remaining moist, and it being stored in optimal conditions in between the weekly water sampling. Luckily for the hospital, all that was required was to replace the tubing, and the contamination was eliminated.
Water treatment options As water is one of the main avenues of transmission of pathogenic bacteria in hospitals, a range of different water treatment systems have been developed, installed, and maintained, throughout hospitals to reduce the spread of them. Some of these water treatment systems included copper/silver ionisation, chlorine dosing, ion-exchange (water softeners), washer-disinfectors and reverse osmosis systems. A lot of these water treatments are used together to ensure that the risk of causing infection to the patient is significantly reduced, or even better, eliminated. Innovative technologies for water treatment are continuously being developed and improved to help reduce the number of HCAIs, and continue to target not only pathogenic microorganisms, but also various other pollutants.
Pre-treatment A key element of the water treatment process is the use of pre-treatment to
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