The recent outbreak of pseudomonas in Belfast with tragic consequences for three newborn babies and their families has put a previously low profile pathogen into the spotlight.

Although until last week not as well known to the layman as hospital super bugs MRSA and c difficil, pseudomonas is responsible for around 4000 infections a year in the UK.

Jill Cooper, group microbiologist at water treatment specialist B & V Water Treatment explains the steps hospitals and other healthcare organisations can take to help ensure such a tragedy doesn’t happen again.

“The first thing that should be considered when preventing the growth of pseudomonas species in water systems is that in many cases pseudomonas growth is also directly related to legionella growth, and similar treatment regimens should be used for the control of both.

“Pseudomonas species are widely present in the environment and in many cases will be present in low numbers in the incoming mains supply to healthcare premises. The majority of pseudomonas species are not harmful to humans but pseudomonas aeruginosa can cause infections in immunosuppressed patients. Pseudomonas aeruginosa causes numerous problems, such as wound, ear and respiratory infections in these patients.

“Pseudomonas species can cause problems within water systems as they will produce biofilm on surfaces. Biofilm is a layer of slime such as that you would find on a pebble in a stream. Obviously a biofilm layer on a pebble is not a problem. But when this is present on the pipework of a water system it protects and harbours harmful bacteria such as pseudomonas and legionella and is difficult to remove.

“Preventing the growth of pseudomonas species, and legionella bacteria, within water systems requires similar and relatively straightforward procedures.

“All healthcare premises should have a legionella risk assessment and regular review every 2 years as part of their legionella control programme. This should be carried out by a reputable water treatment company, who will have risk assessors with specific training and experience in conducting risk assessments. The risk assessment will primarily look at the risk associated with the development of legionella bacteria within the water system, but the remedial measures recommended in the risk assessment will also pinpoint ways in which pseudomonas growth within the system can be minimised.

“Actions such as the removal of unused pipework (deadlegs), oversized water tanks etc. are actions which can be taken to minimise the risk of pseudomonas growth. A quality risk assessment will also recommend a flushing regimen which will prevent stagnation of the water within pipework and this minimises the development of biofilm containing pseudomonas species.

“Such a risk assessment will also generally recommend a microbiological sampling regimen, which may include sampling for pseudomonas species. If a pseudomonas sampling regimen is implemented it is very important to sample the incoming mains so that any results obtained throughout the healthcare premises water system can be compared with incoming levels. If samples are found with much higher levels of pseudomonas at samples points within the premises than those present in the incoming mains, it is clear that conditions within the system are such that growth of pseudomonas species is supported. It is also likely that a biofilm is present.

“Such a risk assessment will also consider all aspects of the water system including taps, showers, water tanks and strainers etc., their suitability for use i.e. their compliance with Water Supply (Water Fittings) Regulations 1999 and any associated risks.

“The guidelines on which a legionella risk assessment are based can be found in ACoP L8 and the standard for healthcare premises HTM 04-01. Following the guidelines outlines in these two standards will go a huge way to minimising the proliferation of pseudomonas bacteria within the water systems at healthcare premises.

“One of the main differences between legionella species and pseudomonas species is the temperature range of growth. A legionella risk assessment will recommend a temperature monitoring regimen is implemented which will be in line with the temperatures at which legionella growth is minimised, for healthcare premises the temperatures for hot and cold water systems are specified in the Health Technical Memorandum 04-01. Legionella species grow very slowly, if at all, below 20°c and are killed at elevated temperatures above 50°c. Pseudomonas species will grow down to 5°c, their growth in cold water systems can therefore be more of a problem. To minimise the risk of pseudomonas it is therefore critical to ensure that there is no stagnation of the cold water system and cold water tanks are maintained, cleaned and disinfected as necessary. Your water treatment supplier will advise on and carry out maintenance and cleaning of these systems.

“Another significant difference between legionella bacteria and pseudomonas bacteria is the route of infection. Inhalation of very small droplets of water is the single root cause for the development of legionnelosis (Legionnaires Disease). Pseudomonas infection can be transferred from person-to-person, surfaces etc. which means that standard good hygiene practises, to prevent cross contamination within a healthcare setting, are essential in preventing pseudomonas infections.

“The first line of defence against pseudomonas colonisation and proliferation within the system should be considered as everything covered by the legionella risk assessment remedial actions and monitoring regimen. If all remedial actions have been completed and all on-going monitoring, such as flushing and temperature controls, are maintained and the problem persists it may be necessary to implement a chemical dosing regimen to the water system on site. There are a limited number of methods generally used to treat these problematic water systems. Standard treatments include continuous dosing of the water system with chlorine dioxide, the installation of silver-copper ionisation equipment and to a limited extent the use of UV and ozone. Point-of-use filters can also be used to reduce risk but do not, in any way, address any underlying microbiological problems. The type of treatment used is generally tailored to the specific requirements of a site. B & V Water Treatment also have a unique chemical solution called Absulox which can be considered for on-going dosing of water systems.

“A good water treatment provider will be able to advise on all aspects of microbiological control within water systems in healthcare premises. The incident at Belfast has given everybody in the healthcare industry a stark reminder of the importance of considering every aspect of microbiological control, including pseudomonas, within water systems.”

 Jill Cooper, group microbiologist at water treatment specialist B & V Water Treatment says there are steps hospitals can take to help ensure we don’t see a repeat of the tragic outbreak of pseudomonas in Belfast recently.