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Pseudomonads are environmental gram-negative, oxidase-positive bacterial organisms. Pseudomonas aeruginosa is the type strain of the genus and has been the cause of several high profile Hospital Acquired Infections (HAIs).

Commonly found in soil and ground water, Pseudomonas aeruginosa is increasingly important clinically as it is both a major cause of healthcare associated infections and is increasingly resistant to many antibiotics.  Pseudomonas is an opportunistic pathogen being more likely to infect those patients who are already unwell and particularly those that are immunocompromised.  In hospitals the organism contaminates moist/wet reservoirs such as respiratory equipment and indwelling catheters and infections can occur in almost every body site but are particularly serious in the bloodstream (bacteraemia).  Most community-acquired infections are associated with prolonged contact with contaminated water.

Regulatory Information

HTM 01-06 (formerly CFPP 01-06) – Part E, HTM 04-01 Part B Appendix F and the Microbiology of Drinking Water Part 8 all detail the requirements for the sampling, methods of analysis and remediation of Pseudomonas aeruginosa in water in various settings including healthcare establishments and public buildings.

Analytical Methods

HTM 01-06 requires that the presence of Pseudomonas aeruginosa is tested on a Quarterly basis.  Samples are membrane filtrated onto selective Pseudomonas CN supplemented agar and incubated at 37±1°C for 48 hours. Confirmation is carried out using Milk Cetrimide agar for Casein Hydrolysis and Pyocyanin production.

Health Effects


Pseudomonas aeruginosa is an opportunistic pathogen that exploits a break in the host defences to initiate an infection.  Transmission often occurs through contact with Pseudomonas contaminated water, soil and as a result of contaminated medical devices.


Pseudomonas infections can develop in many anatomic locations, including skin, subcutaneous tissue, bone, blood, lungs, ears, eyes, urinary tract, and heart valves. The site of infection varies with the portal of entry, and the patient’s particular vulnerability. Infections of the skin tend to be less severe than those that occur in the blood or lungs.

Blood (bacteremia) – fever, chills, fatigue and muscle/joint pain
Lungs (pneumonia) – fever, chills, productive cough and difficulty breathing
Skin (folliculitis) – itchy rash and bleeding ulcers and open sores
Ear – swelling, pain, itching inside the ear, discharge from the ear and difficulty hearing
Eye – inflammation, pus, pain, swelling, redness and impaired vision


Certain Pseudomonas infections, particularly those of the skin may resolve themselves.  Where treatment is required infections are generally treated with antibiotics. Unfortunately, many hospital acquired Pseudomonas infections are becoming more difficult to treat, the bacteria having developed a resistance to the antibiotics commonly used to treat infections.

The increase in antibiotic resistance has made treating infections much more challenging with treatment regimens often consisting of one or more different types of antibiotics.

Risk Factors

Pseudomonas aeruginosa rarely infects uncompromised tissues however, there are hardly any tissue types that it cannot infect if the tissue defences are compromised in some manner.  Particularly at risk of Pseudomonas infection are those patients who are immunosuppressed such as patients with severe burns, those with cystic fibrosis, cancer, AIDS and vulnerable neonates.

Prevention and Control

Prevention of infection is the most effective way of controlling Pseudomonas aeruginosa.  The effective disinfection and sterilisation of medical devices along with the routine screening of water sources including taps and endoscopy final rinse water for the presence of Pseudomonas is directed at prevention of infection along with routine infection control practices, hand hygiene and environmental cleaning all of which can substantially lower the risk of infection.  HTM 01-06 and the HTM 04-01 describe the requirements for routine sampling and analysis to identify locations where Pseudomonas is present and where remedial action to prevent the transmission of infection is required.

Hospital Analysis

A vast suite of standard and specialist analyses are available. Read More

Potable Water Testing

A range of tests available as required by the MODW and HTM 04-01. Read More

Pseudomonas Aeruginosa

The detection and enumeration of Pseudomonas aeruginosa according to HTM 04-01 and the MODW. Read More

Legionella Testing

Accredited to ISO 11731-2:2008 to carry out detection and enumeration of Legionella. Read More

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