Avoiding contamination of water systems

He emphasises the importance of water monitoring via regular sampling, risk assessment, water safety plans, and best practice hand hygiene.

Contamination is caused by pathogenic bacteria such as Pseudomonas aeruginosa. In 2012, for example, an outbreak of this pathogenic bacterium occurred at the neonatal unit at Royal Jubilee Unit in Belfast, resulting in the deaths of four babies.1 This led to a major investigation by the Regulation and Quality Improvement Authority and from this a series of best practices for hospitals to avoid microbiologically contaminated water systems were proposed.2 Another risk-causing microorganism is Legionella pneumophila, a bacterium that can colonise hospital water supplies causing nosocomial infections over long periods of time. Contaminated water presents concern because water is both a growth source for certain microorganisms, allowing them to survive and to multiply, and it is an efficient vector for spreading contamination, through aerosols. All water systems contain levels of microorganisms. What is of concern in hospitals are the numbers of microorganisms and the presence of pathogens like Pseudomonas aeruginosa. Other microorganisms may also be objectionable and these should be assessed on the basis of risk. P. aeruginosa, as well as being a pathogenic risk in itself, is also a good indicator of other types of microbial risks. Pseudomonads do not present a problem to all patients, but can be lethal for the increasing number of immunocompromised individuals. Problematically, rapidly rising antibiotic resistance to commonly used broad spectrum antibiotics means that Pseudomonas infections are becoming increasingly difficult to treat. P. aeruginosa contamination is usually present in biofilms – mixed populations of bacteria that adhere to specific surfaces within the water storage, distribution and delivery systems.3 Microbial biofilms develop when microorganisms adhere to a surface by producing extracellular polymers that facilitate adhesion and provide a structural matrix. While the majority of bacteria are trapped within a biofilm, the biofilm will constantly generate bacteria that are released as free-floating individual cells and parts of the biofilm may slough off in clumps. As water is used and flows through the pipework or tap containing the biofilm, then the contamination risk arises at the point at which the water is used. With an organism like Legionella pneumophila, this is the causative agent of legionellosis or Legionnaires’ disease. The bacteria can occur in large plumbing systems and a point of transmission includes showers. This can present a concern for vulnerable patients, particularly the elderly. People contract Legionnaires’ disease when they breathe in a mist or vapour containing the bacteria. In addition, such bacteria can also be present in low numbers on occasion in the water supplied to the hospital. However, it is the formation of biofilms on pipes that present the biggest risk factor and the focus of a hospital’s Estate Service should be upon correctly designing and maintaining water systems to minimise the opportunity for microbial communities to colonise water systems.

Design and maintenance of good water systems