An Evaluation of the Antibacterial Action of Copper against Aerosolized Organisms

Abstract

The antibacterial properties of copper have been reported to be effective in reducing the infection rate in intensive care patients and in decreasing in-use contamination of respiratory therapy equipment. This study quantitatively measured the reduction of aerosolized organisms by copper mesh. A suspension of organisms matching a 0.5 McFarland Standard was injected into the micronebulizer of an intermittent positive pressure breathing (IPPB) device. Exhaled gas either passed through a copper mesh filter or bypassed it before being collected and plated. The effectiveness of the copper mesh was determined by taking the average colony count of two collection samples and calculating the reduction of organisms by comparing samples with copper to samples without copper. The antibacterial properties of copper were tested with Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter calcoaceticus var. anitratus. Survival of Escherichia coli and Pseudomonas aeruginosa was reduced 90 to 96.2 per cent. Reduction of Acinetobacter calcoaceticus var. anitratus ranged between 88.6 and 91.4 per cent. The effectiveness of the copper mesh was measured after in-line continuous nebulization of a standard suspension of Escherichia coli for 24- and 72-hour periods. The inhibitory effect of the copper did not diminish during this period, as shown by greater than 90 per cent reduction of organisms for all tests. This study demonstrated that use of copper in the exhalation line of an IPPB device markedly reduced the number of aerosolized organisms emitted.