Infection in patients with cystic fibrosis.

Cystic fibrosis is the most common lethal genetic disease of Caucasians. The disease affects the exocrine gland secretions throughout the body, and as a result, major pathologic changes develop in the pancreas and in the bronchi. Obstruction of the respiratory airways results in chronic infection, and in time, this leads to progressive deterioration of lung function. In the initial stages of the disease, usually during infancy, infection with Staphylococcus aureus plays an important role. Hemophilus influenzae infections are also common. As the disease progresses, infection with Pseudomonas aeruginosa develops. Exacerbation of bronchopulmonary infection is often initiated by respiratory viral or mycoplasmal infection, with superimposed S. aureus and P. aeruginosa infections contributing to the severity of the infection. Frequent courses of antibiotic therapy are usually required, and some patients may have to receive antibiotics continuously. Oral cephalosporins, ampicillin, and the combination of trimethoprim/sulfamethoxazole are commonly used for relatively mild infections. In the treatment of exacerbation of infection, intravenous penicillinase-resistant penicillins and anti-Pseudomonas antibiotics are the drugs of choice. For Pseudomonas infections, ticarcillin, carbenicillin, the ureidopenicillins, and the aminoglycosides are indicated. The combination of an anti-Pseudomonas penicillin and an aminoglycoside are most commonly used. Of the third-generation cephalosporins, ceftazidime appears to be the most efficacious. The quinolones (such as ciprofloxacin) are also active against P. aeruginosa, and preliminary studies of these drugs in patients with cystic fibrosis appear to indicate that they are as efficacious as the already available antibiotics. In many centers, Pseudomonas cepacia has emerged as a serious problem in patients with cystic fibrosis. This organism tends to develop resistance to multiple antibiotics. In some centers, infection with P. cepacia has been associated with a severe, frequently fatal, pneumonia.