Pseudomonas aeruginosa is a common bacterium (germ) that is present all around us. It often is found in soil and water or on plants and vegetables, and sometimes can be found on the skin or in the nose and throat of healthy people. It usually does not cause any problems for people because the body normally is able to defend itself against Pseudomonas infections.

On the other hand, there are times when Pseudomonas can cause illness, such as swimmer's ear (otitis externa), a painful infection of the skin of the ear canal. When children spend a lot of time in water, the skin lining the ear canal gets soggy, so it cannot fight infections well. Children who have problems with their immune (infection-fighting) system (for example, cystic fibrosis, cancer, or HIV/AIDS) are at risk of Pseudomonas infections. Being on strong antibiotics that kill both good and bad bacteria also increases the chance of finding Pseudomonas somewhere in the body.

While it is true that Pseudomonas infections are very common in patients with cystic fibrosis, it is less likely that your child has that disease if overall he has been healthy and growing well. Children with cystic fibrosis (CF) often have specific signs and symptoms that might suggest the disease, such as a cough that lasts a long time (chronic cough), repeated lung infections (pneumonia), poor growth, and unusual stools. Other serious illnesses also would tend to be accompanied by other symptoms in addition to a sinus infection. Raise your concerns with your child's doctor and ask if testing for cystic fibrosis or any other illness should be done.