Patients who are at least 7 years old with stable Cystic Fibrosis who have Staphylococcus aureus in their Lungs will be enrolled into the study and receive one dose of Aurexis® intravenously on Study Day 1, and will be followed until Study Day 57. Aurexis is a humanized monoclonal antibody that is designed to combat Staphylococcus aureus.

The purpose of this study is to assess the safety and pharmacokinetic profile (concentration of Aurexis in blood and sputum) of Aurexis. Additionally, certain tests and measurements will be conducted to preliminarily determine if Aurexis demonstrates any benefit to these patients.

Inclusion Criteria:

• Male or female, ages > 7 years old

  • Diagnosis of CF as evidenced by sweat chloride test and/or genetic mutation testing
  • Sputum SA CFUs > 10,000 per mL
  • Ability to expectorate sputum
  • Ability to tolerate nasal lavage and collection of breath condensate
  • Willing to practice reliable birth control measures during the entire study period, if subject is of childbearing potential
  • Informed consent obtained from subject or legal guardian, and assent if appropriate

Exclusion Criteria:

• Burkholderia cepacia in sputum

  • Subjects who have had changes to their treatment regimen for CF in the past 6 weeks

    • Subjects can be screened 6 weeks after IV antibiotic completion
    • Subjects can be screened 7 days after oral antibiotic completion

  • Received an investigational drug within 30 days of study entry

  • Received any immune globulin or blood product within 30 days of study entry

  • History of hypersensitivity to immune globulin preparations

  • Undergoing any type of dialysis or expected to start dialysis within 30 days

  • Pregnant or nursing females

  • Considered unlikely to comply with the study procedures or to return for scheduled post-treatment evaluations