The effects of copper in heated nebulizers

The antibacterial potential of copper mesh in heated nebulizers was evaluated by simulating clnical usage in the laboratory and comparing the relationship between the copper levels achieved in nebulizer water and the growth of Pseudomonas aeruginosa organisms. Mesh size, length of immersion, temperature, water replacement, and nebulization all affected copper concentration. Antibacterial acitivity was demonstrated over a wide range of copper levels for as long as three weeks. Nebulizers driven for one hour by 10 L/min of gas flow and containing 8 gm of copper mesh were inoculated with more than 31,000 organisms and became sterile within 60 minutes of inoculation. Units without copper showed a much slower decline in colony counts. Solutions of copper salts also proved to be effective antibacterial substances but only in much higher concentrations than those achieved with copper mesh. It it is concluded that metallic copper mesh is an effective antibacterial substance when used in water-containing heated nebulizers. Attempts to quantitate aerosolization of copper were not sucessful, and potential upper-airway deposition and human toxicity with this technique remain to be defined.