A Day in the Life of a Nebulizer: Surveillance for Bacterial Growth in Nebulizer Equipment of Children With Cystic Fibrosis in the Hospital Setting

BACKGROUND: Cystic fibrosis (CF) is characterized by chronic lung infection. Minimizing exposure to pathogens is important. Treating a CF pulmonary exacerbation includes nebulizer therapies, but little is known about pathogen exposure from nebulizer equipment in CF.

OBJECTIVE: To assess microbial growth in nebulizer equipment used by hospitalized CF patients.

HYPOTHESIS: The small-volume nebulizer would not support the growth of the important CF pathogens: Pseudomonas aeruginosa, Staphylococcus aureus, Haemophilus influenzae, and Burkholderia cepacia.

METHODS: During a 6-month period, we prospectively enrolled 30 patients who were admitted for pulmonary exacerbation of CF and were prescribed an aerosolized bronchodilator 4 times daily. Bronchodilator was administered via disposable small-volume nebulizer, prior to airway clearance. The nebulizer was not cleaned or disinfected between treatments, but instead was replaced after 24 hours. Sputum or throat cultures were obtained prior to admission or on the day of admission, and standard culture techniques were used for CF microbes. After the first bronchodilator treatment, a sample was taken from the residual fluid inside the nebulizer cup. The second, third, and fourth samples were taken from the nebulizer cup after it was filled with a unit dose of the bronchodilator but prior to administering the bronchodilator. At the 24th hour, the nebulizer was filled with 3 mL of sterile water, from which the fifth sample was obtained, then the nebulizer was disposed of.

RESULTS: On respiratory culture, ten patients had Pseudomonas aeruginosa, 5 had both P. aeruginosa and S. aureus, 6 had only S. aureus, and 1 had both S. aureus and H. influenzae. Three had other organisms, 4 had normal flora, and 1 had no culture data. Of the 150 nebulizer sample cultures, only 3 showed bacterial growth. Bacillus species, Corynebacterium, coagulase-negative Staphylococcus, and Candida albicans were isolated at low colony counts.

CONCLUSIONS: We suspect that the organisms identified were caused by skin contamination of the samples rather than contamination of the nebulizer cup. We conclude that there is a low risk of microbial contamination with CF pathogens from the interior of a disposable nebulizer over a 24 hour period.