Legionella Risk Assessment Bromley
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Pseudomonas Aeruginosa

The main concern of the presence of Pseudomonas Aeruginosa is in the Hospital or Clinical Environment. A pseudomonas infection is caused by a bacterium, Pseudomonas aeruginosa (P. aer.), and may affect any part of the body. In most cases, however, pseudomonas infections strike only persons who are very ill, usually hospitalized due to the inherent oportunist nature of the organism. As direct consequence P. aer. has become increasingly recognized as an emerging opportunistic pathogen of clinical relevance. Recent reports have shown pseudomonas infections in hospital and clinical environments are on the increase.

The bacterium is the second most common cause of nosocomial pneumonia and the most common cause of intensive care unit (ICU) pneumonia. Pseudomonas infections can be spread within hospitals by health care workers, medical equipment, sinks, disinfectant solutions, and food. These infections are a very serious problem in hospitals for two reasons. Firstly, patients who are critically ill can die from a pseudomonas infection. Secondly, Pseudomonas bacteria are resistant to many antibiotics, which makes them difficult to treat and eradicate. As stated above, it is an opportunistic pathogen, meaning that it exploits some break in the host defence to initiate an infection. The bacterium almost never infects uncompromised tissues, yet there is hardly any tissue that it cannot infect once tissue defences are compromised in some manner. It commonly causes infection in:

1) Urinary tracts
2) Respiratory systems
3) Skin dermatitis
4) Soft tissues
5) Bacteremia
6) Bones and joints
7) Gastrointestinal tracts

Also a variety of systemic infections, particularly in patients with severe burns and in cancer and immunosuppressed patients. The case fatality rate in some of these types of infections can be as high as 50 percent. P. Aer. as an organism is a Gram-negative, aerobic rod belonging to the bacterial family Pseudomonadaceae. The family includes only members of the genus Pseudomonas which are divided into eight distinct groups. Pseudomonas aeruginosa is the type species of its group. which contains 12 other sub-species. P. aer. is a free-living bacterium, commonly found in the natural environment and particularly prevalent in soil and water. It occurs regularly on the surfaces of plants and occasionally on the surfaces of animals. It is one of the few groups of bacteria that are true pathogens of plants.

In its natural habitat Pseudomonas aeruginosa is not particularly distinctive as a pseudomonad, but it does have a combination of physiological traits that are noteworthy and may relate to its pathogenesis. It has very simple nutritional requirements. It is often observed growing in distilled water, which is evidence of its minimal nutritional needs. Its optimum temperature for growth is 37 degrees, but it is able to grow at temperatures as low as 5C and as high as 42C. Temperature control of P. aer. in water systems is therefore very difficult to control. It is resistant to high concentrations of salts and dyes, weak antiseptics, and many commonly used antibiotics. In water systems P. aer. Also tends to form biofilms within pipework and other wetted surfaces. This is a byproduct of the metabolic process of the organism and gives it the ability to attach itself to the system to "graze" on passing nutrients and can also provide a shelter for growth. Clearly the removal of biofilming is paramount to the fight against P. aer. and should be considered always when adopting the overall strategy.

Strategies for controlling P. aer. in water systems are very similar to that employed for the control of legionella peumophila and are widely understood as ways of controlling microbiological contamnants in building services water supply systems more generally. These control strategies include: Prevention of stagnation - Stagnation occurs through oversized or underused water systems or sections of water systems which are infrequently used. This is a prime factor in preventing microbiological growth and biofilming both in the systems and point of use. Control of temperatures - Careful control of water temperatures can inhibit and help control microbiological growth and in particular P. aer. Temperatures above 60°C will kill P. aer. within one minute but maintaining temperature at or below 5°C can be impossible in some cases, however, reduction of cold water temperatures can slow the metabolic rate of the organism. Avoiding use of non-approved materials - Ensuring that all materials and compounds used in water system construction (including flexible hoses and couplings) comply to the DWi and WRc Guidelines and the Water Regulations will help ensure that microbiological growth is minimised.

Maintaining System Hygiene - Keeping water systems clean and avoiding the build up of sediments and fouling which may provide nutrients or harbour growth.
Maintaining Systems in Good Operation - Making sure the water systems are operating at their optimum efficiency and that all items of plant and components are working correctly is essential to ensure the systems as a whole operate as intended.
Use of Water Treatments - The use of chemical or other treatment of the water may also provide a defence but should be carefully controlled within the guidelines of the Water Regulations.

Further to this, the use of water and the control of hygiene surrounding it within the clinical environment should be carefully controlled by:

Water Safety Group - Set up a water safety group to develop a water safety action plan.
Risk Assessment - Trusts should develop a risk assessment and a written scheme specific to Pseudomonas aeruginosa in addition to that in place for Legionella.
Code of Practice Policy - Ensure a policy is in place to demonstrate compliance with The Code of Practice for prevention of infections as directed under the Health and Social Care Act.
Responsible Person - Ensure the details of the responsible person are clearly defined and easily accessible.
Clean and Dirty Separation - Ensure the separation of clean and dirty facilities are maintained at all times along with sink free zones for high risk areas such as where intravenous drugs are prepared.
Taps and Mixing Valves - Ensure taps and mixing valves are commissioned, tested and maintained and routinely tested according to manufacturers recommendations.
Further Advice - Advice can be obtained form the Health Protection Agency via regional microbiologists and health protection units where concerns are identified.

An addendum to HTM04-01 to cover Pseudomonas aeruginosa is being developed by The Department of Health to provide guidance on the control of the organism in clinical and healthcare environments and will be available in March 2013. Until that time Amphibia advise following the above action plan in order to minimise the risk.