Pseudomonas Aeruginosa in Cystic Fibrosis Patients

About 60% of people with cystic fibrosis have a chronic respiratory infection caused by a bacteria called Pseudomonas aeruginosa. This bacteria settles into the thick mucus trapped in the airways. Once Pseudomonas aeruginosa invades the respiratory tract, it is hard to get rid of. Respiratory failure caused by the infection is the ultimate cause of death in the majority of people with CF.

Doctor using a stethoscope on a patient
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The bacteria Pseudomonas aeruginosa lives all around us. This bacteria exists in moist environments like around soil, plants, sinks, showers and even the soles of tennis shoes. Most people encounter Pseudomonas aeruginosa every day without being infected. However, in people who are immunocompromised or in people with a break in the skin or mucous membranes, this bacteria can cause infection.

In addition to infecting people with CF, Pseudomonas aeruginosa infects severe burn victims as well as patients receiving chemotherapy. In recent years, the incidence of Pseudomonas aeruginosa infection due to causes other than CF has decreased; whereas, the incidence of infection among people with CF has remained unchanged.


Years ago, chronic Pseudomonas aeruginosa infection in people with CF was treated rather unsuccessfully with oral antibiotics or inhaled injectable formulations of antibiotics. In the late 1990s, an inhaled form of the antibiotic tobramycin, or TOBI, was developed specifically for the treatment of chronic respiratory Pseudomonas aeruginosa infections. TOBI is now the standard treatment for this infection and is a commonly prescribed medication in people with cystic fibrosis.

TOBI is made up of tobramycin. Tobramycin is an aminoglycoside antibiotic used to treat Pseudomonas aeruginosa infection. This antibiotic works by messing with bacterial protein synthesis. By messing with the protein synthesis of Pseudomonas aeruginosa, TOBI consequently disrupts the bacterial cell membrane and envelope thus causing cell death.

TOBI was originally administered using a nebulizer. A nebulizer is a machine that produces a fine mist for inhalation. In 2013, the FDA approved the TOBI Podhaler, which is a dry powder inhaler filled with dry powder tobramycin. This new medication makes it easier for the patient to take tobramycin.

Is TOBI for Everyone?

Unfortunately, TOBI is not for everyone. People with hearing problems, kidney problems, and neuromuscular problems should be prescribed TOBI very cautiously. More specifically, aminoglycosides are known to mess with hearing, the kidneys as well as exacerbating neuromuscular disease like myasthenia gravis. Additionally, people who are hypersensitive ("allergic") to aminoglycosides shouldn't take TOBI. Finally, tobramycin, which is the active ingredient in TOBI, is a teratogen and can cause harm to the fetus in pregnant women.

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  • Ramphal R. Infections Due to Pseudomonas Species and Related Organisms. In: Kasper D, Fauci A, Hauser S, Longo D, Jameson J, Loscalzo J. eds. Harrison's Principles of Internal Medicine, 19e. New York, NY: McGraw-Hill; 2015. 
  • Smith, A.L. “Inhaled Antibiotic Therapy: What Drug? What Dose? What Regimen? What Formulation?.” Journal of Cystic Fibrosis. 2002 1: S189–S193. 22 June 2008.

By Lori Alma
Lori Alma, RN, is a registered nurse and cystic fibrosis expert who assists families in a Florida Department of Health program for special needs children.