Bacterial contamination of aerosol solutions containing antibiotics

In an investigation of microbial contamination of aerosol solutions containing antibiotics (hospital pharmaceutical preparations, no preservatives added), five of six residual solutions after multiple use for 7 days were contaminated at a concentration of 10(6) viable counts/ml. Contaminants were glucose-nonfermenting Gram-negative bacilli such as Pseudomonas cepacia and Flavobacterium meningosepticum. The major contaminant, P. cepacia, multiplied rapidly in the aerosol solution under simulated actual-use conditions. The contamination seemed to have been caused by storage, at room temperature instead of in a refrigerator, of the multiple-dose solutions and by frequent re-use of syringes to measure the solutions. Prompt refrigerator storage after each use of the solutions and abandonment of the syringes within 24 h eliminated bacterial contamination of the solutions. Sufficient attention is not paid to prevent bacterial contamination of aerosol solutions containing antibiotics because of the fact that they contain antibiotics. Thus aerosol solutions containing antibiotics should be handled with great care to prevent bacterial contamination.