Pseudomonas bacteria contamination is an emerging health concern that most pool and spa companies are unaware of, and most water testing performed by these companies do not check for bacteria contamination.

"Hot tub rash" is many times incorrectly attributed to too much chlorine in the water when many times the culprit is actually  Pseudomonas bacteria contamination. Cutting back on chlorine in these situations actually exacerbates the problem. 

What is it?

Pseudomonas species are opportunistic pathogens that are part of the normal bacterial flora of the pharynx, mucous membranes and skin of humans. It flourishes in warm, moist areas which makes pools and hot tubs an ideal environment for this bacteria. In recent years the number of reported Pseudomonas outbreaks in recreational waters has risen dramatically. Pseudomonas is capable of causing significant illnesses including skin rashes (folliculitis), ear infections (swimmer’s ear), urinary tract infections, pneumonia and corneal ulcers (keratitis).

Pseudomonas is a very virulent opportunistic pathogen and is becoming increasingly resistant to antibiotics. It is the most commonly isolated bacteria from skin rashes and ear infections associated with recreational waters.

Otitis externa, commonly known as "swimmer’s ear", is caused mainly by the species Pseudomonas aeruginosa. Symptoms include redness and swelling of the ear canal, itching, fluid leakage and severe pain. Pseudomonas frequently causes skin infections (folliculitis) involving a mild to moderate red, itchy rash. These rashes are often mistaken for chicken pox. The bacteria is also a significant contributor to urinary tract infections as well as secondary infections in hospitalized patients. Pseudomonas aeruginosa is one of the leading (and most damaging) causative agents of microbial keratitis in contact lens wearers. This bacteria is of major concern in hospitals, since it can cause severe secondary infections, such as pneumonia, in burn victims or immunocompromised persons.

In rare circumstances, Pseudomonas can cause more serious infections. In diabetic, elderly or immunocompromised persons, a life threatening condition known as malignant otitis externa could occur. The bacteria in the ear spreads to the surrounding tissue and bone potentially leading to muscle paralysis, meningitis or brain abscesses. In severe cases of microbial keratitis, the lesions on the cornea can ulcerate within 24-48 hours. Blindness can occur rapidly due to destruction of the interior eye structures.

Pseudomonas is commonly isolated from water and soil. It is normally found in low quantities in the pharynx, skin and mucous membranes of normal healthy persons. It proliferates in wet or moist areas, particularly pools and hot tubs and surrounding carpeted areas. Any recreational waters which have multiple users, such as public pools, are also possible sources of the bacteria. Inside the home, handtowels and sinktraps, are the areas most likely to contain Pseudomonas. This bacteria is of major concern in hospitals, since it has been indicated in secondary infections.

Most hot tub mediated infections occur due to improper water maintenance or exceeding the maximum carrying capacity of the water. For example, when several bathers are in a small amount of water, the amount of water per person decreases. The disinfectants in the water are used up on the excessive amount of bacteria and debris supplied by each person so any remaining bacteria, such as Pseudomonas, will not be eliminated. When a person’s skin is heated, the follicles expand allowing the Pseudomonas bacteria to enter through the pores. Folliculitis, the most common result of this type of infection, is a mild to moderate skin rash. Swimmer’s ear occurs when the ear canal becomes sufficiently moist, usually while swimming, allowing the bacteria the opportunity to breed. They begin to colonize the canal and cause extreme discomfort, redness and swelling. Urinary tract infections are also regularly associated with Pseudomonas infections. In hospitals, Pseudomonas aeruginosa can infect persons with weakened immune systems, it can colonize catheters as well as therapeutic whirlpools.

When contact lens hardware or cleansing solution becomes contaminated, the risk for developing microbial keratitis is greatly increased. Since Pseudomonas is a normal inhabitant of the skin, the bacteria can be passed directly from the skin to the contact lens. It can also be transferred to handtowels, which when reused would transfer the bacteria back to the hands. Studies show that Pseudomonas is capable of surviving in many commercial saline solutions, in which case, contaminated lenses would not be properly cleansed by saline solution alone. Exceeding the recommended wear time of contact lenses has been reported as probably being the largest contributor to microbial keratitis. Pseudomonas aeruginosa has several structural and chemical components that make it especially adept at adhering to the corneal surface of the eye. Over wear of lenses weakens the eye’s defenses and makes the cornea more susceptible to bacterial infection and damage.

If you own a pool or a hot tub testing should be done to ensure that the bacteria is not present in your system. If Pseudomonas is detected, the extent to which it is present should be determined. Proper steps should be incurred to remove the bacteria. The rashes associated with Pseudomonas bacteria are often attributed to excess chlorination so people tend to under chlorinate their pools and hot tubs. Pseudomonas folliculitis and urinary tract infections can sometimes be avoided by bathing after swimming, removing wet swimsuits immediately, and avoiding public pools with multiple swimmers.

Proper pH of the water and attentive maintenance is vital to prevent Pseudomonas from establishing itself in your pool or hot tub. If Pseudomonas is left untreated, the bacteria will cover itself in a protective slime layer which is resistant to chlorine. It will then colonize your pool or hot tub, which is characterized by a slimy layer on the sides of the pool particularly in low flow areas. When this happens, the removal of the bacteria is much more difficult. The pool or spa may have to be drained and scrubbed. A professional should be consulted.

Indicators that Pseudomonas may be present in your pool are visible signs of the bacteria, frequent occurrences of swimmer’s ear, skin rashes, urinary tract infections etc. in you or your family members.

An ophthalmologist should be consulted in all cases of eye infections. Proper contact lens wear and maintenance is strongly recommended to avoid Pseudomonas corneal infections. Non-clinical surface samples (i.e. sinks, drains, carpet by pool areas) may be taken and analyzed by a laboratory to determine the source of the bacteria. Medical questions or concerns should be directed towards your ophthalmologist or physician.

Further Reading

What is Hot Tub Pseudomonas ?

Hot tub folliculitis

Pseudomonas Aeruginosa in whirlpools

Pseudomonas aeruginosa Infections in Contact Lens Wearers