Microbial growth on the anesthesia machine.

The purpose of this study was to determine the amount of microbial growth that develops on the anesthesia machine after a full day's use in the operating room. This descriptive bacteriology study is relevant to anesthesia practice because of the proximity of the oropharynx and multiple body fluids to anesthesia equipment and the potential for cross-contamination to patients and staff. The Wilcoxon signed rank test was used to evaluate the change in colony-forming units (CFUs) before and after use of equipment. The resulting P value of 0.12 indicated that the observed CFU increase was not statistically significant at the .05 level. The study identified many organisms that survive on the anesthesia machine tabletop, namely, coagulase-negative Staphylococcus, Bacillus, alpha Streptococcus, Acinetobacter, Staphylococcus aureus, and gram-negative rods. Several were expected to be found; however, alpha Streptococcus, Acinetobacter, S aureus, and gram-negative rods are pathogenic organisms causing respiratory infections and bacteremia, especially in patients with compromised conditions. Terminal cleaning methods may have changed during the course of the study, thereby contributing to the volume of microbes present before use and distorting the change in the number of CFUs before and after use.