Pseudomonas aeruginosa in swimming pools and spas

Pseudomonas aeruginosa (P. aeruginosa) is a common type of bacteria that can grow and multiply easily in water.

Characteristics of Pseudomonas aeruginosa

• Organism size ranges from 0.5 µm – 1.0 µm x 1.5 µm – 4.0 µm.
• Resistant to a wide range of antibiotics and disinfectants.
• Grows well at temperatures up to 41 ˚C.

Pathogenesis of P. aeruginosa

Common P. aeruginosa infections include:

• folliculitis – this is a pustular rash of hair follicles on the skin that occurs within 8 hours to 5 days after the event and usually resolves within 5 days. It is most common in heated spa-pools
• otitis externa (swimmers ear) – most common for swimming pools
• urinary and respiratory tracts infections
• wounds and cornea infections.

Occasional symptoms of P. aeruginosa include:

• head and muscle aches
• burning eyes and fever - resembles inhalation of P.aeruginosa endotoxins.

Infection can occur to healthy individuals at levels of >1000 organisms/mL.

Environment and contamination sources

• Ubiquitous in water, vegetation and soil skin shedding from infected humans is the predominant source of contamination in swimming pool or spa.
• Warm or damp environments surrounding pools and spas can cause contamination, such as decks, drains, benches and floors.
• P.aeruginosa tends to accumulate in biofilms in filters that are poorly maintained and in areas where swimming or spa pool hydraulics are poor such as under moveable floors.
• Bathers are likely to pick up the organism on their hands or feet and transfer them to the water.
• Elevated organic loads in spas (particularly skin cells) protect organisms from disinfection, reduce the residual disinfectant level and provide a source of nutrients for organism growth.

Risk management

There are a number of ways to mitigate risk of P.aeruginosa at an aquatic facility including:

• maintaining adequate residual disinfectant levels in swimming pools and spas
• frequent monitoring and adjustment of pH and disinfectant levels is essential
• routine and thorough cleaning of swimming pool and spa interiors, surroundings and surfaces including pipe-work
• using chlorination that is superior to bromination in controlling P.aeruginosa
• strongly encouraging patrons to shower, before using a swimming pool or spa
• controlling the numbers of bathers and duration of spa exposure.

More information

• Environmental Health Directorate, Water Unit
  Postal Address: PO Box 8172, Perth Business Centre WA 6849
  Phone: 9222 2000
  Email: swimmingpools@health.wa.gov.au

Acknowledgement

WHO - 2006, Guidelines for safe recreational water environments Volume 2 - Swimming Pools and Similar Environments