Case-control and vector studies of nosocomial acquisition of Pseudomonas cepacia in adult patients with cystic fibrosis.

OBJECTIVE: To examine factors associated with nosocomial acquisition of Pseudomonas cepacia in adult patients with cystic fibrosis.
DESIGN: A retrospective case-control study of 5 patients with nosocomial acquisition of P cepacia versus 20 matched controls who failed to develop P cepacia infection. Selective handwashing, air sampling, and respiratory equipment sampling also were performed.
SETTING: A university hospital providing tertiary care to 95 adult cystic fibrosis patients. PATIENTS: All patients are adults with known cystic fibrosis. Case definition required multiple negative sputum cultures for P cepacia prior to and during admission, with a positive sputum culture prior to discharge. Controls had negative sputum cultures for P cepacia prior to and throughout hospitalization. Controls were matched for age, gender, disease severity, and frequency of hospitalizations.
RESULTS: Factors associated with increased risk of nosocomial acquisition of P cepacia included receiving humidifier or nebulized treatments (60% versus 5%, p = .016, odds ratio = 28.5, 95% confidence interval = 1.93 to 420.58). Factors without significance included ward, room, teaching versus nonteaching status, use of steroids, sharing a hospital room with another cystic fibrosis patient, antibiotic use, presence of portocath in situ, or socializing with another individual with cystic fibrosis known to be P cepacia-positive. Air sampling studies failed to demonstrate aerosolization of P cepacia by coughing cystic fibrosis patients over a 1-hour sampling time. Handwashing studies failed to demonstrate P cepacia on hands of cystic fibrosis patients, nurses, or physiotherapists (before or after physiotherapy). Reservoirs from nebulizers consistently grew P cepacia following therapy.
CONCLUSIONS: Respiratory equipment may be an important source of nosocomial acquisition of P cepacia in adult cystic fibrosis patients.