Pseudomonas aeruginosa

Pseudomonas aeruginosa — commonly called P. aeruginosa — is a type of bacteria that is commonly found in the environment. It can live in water or soil in nature, and it thrives in households and hospitals in places with abundant moisture, like sinks, humidifiers, and hot tubs.

P. aeruginosa is an opportunistic pathogen. This means that the bacteria doesn’t usually make people sick, but if the circumstances are right — in other words, if given the “opportunity” — it can cause disease.

Infections with P. aeruginosa are a major contributor to lung disease in people with CF, and P. aeruginosa is considered the key bacterial agent in CF lung disease. It’s been estimated that more than 60% of adults with CF are infected with P. aeruginosa

The reason that people with CF are especially susceptible to Pseudomonas isn’t completely understood. However, factors like a weakened immune response and abnormally thick mucus are thought to contribute.

How does someone get infected with P. aeruginosa?

The bacteria can spread person-to-person, so it’s possible to get infected with P. aeruginosa from someone else who’s already infected. This spread can occur by direct contact — for instance, kissing — or by indirect contact, like touching an object that’s been touched by an infected person. It’s thought that many people with CF who get infected acquire the bacteria from their environment.

To reduce the risk of getting the infection, it’s important to follow good hygiene practices like regularly washing hands and following appropriate guidelines in hospitals or other care centers where infection risk is a concern.

How is P. aeruginosa diagnosed?

Healthcare workers can test for the presence of the bacteria in a sample from the respiratory tract by culturing — essentially, putting the sample on a dish in a lab, and seeing if the bacteria grow. Usually, the sample used is sputum (phlegm) that is coughed up; sometimes a swab of the throat will be used, especially in infants and children who are unable to expectorate or expel sputum.

Testing the blood for antibodies against P. aeruginosa, made when the immune system tries to fight off the infection, also may be helpful in establishing a diagnosis.

What are the symptoms of infection?

Symptoms of lung infection by P. aeruginosa are generally similar to what might be expected in any kind of lung infection: cough, fever, abnormal mucus production, and shortness of breath are common. In more serious cases, the lungs’ ability to function may be impaired.

How is Pseudomonas treated?

Treatment usually involves antibiotics — a broad class of medications that can kill bacteria. However, Pseudomonas is often resistant to some common antibiotics, which can make treatment difficult.

The choice of antibiotic for a specific person will depend on a variety of factors, and should be discussed with healthcare providers in detail. In some cases, the infection can be cleared with aggressive antibiotic use. In other circumstances, patients may need to keep taking antibiotics regularly to prevent flare-ups.


Last updated: Sept. 14, 2021


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