Microbial Growth Patterns in a Total Parenteral Nutrition Formulation Containing Lipid Emulsion

Abstract

Microbial growth of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans was evaluated in a standard amino acid-dextrose-based total parenteral nutrition (TPN) solution, 10% lipid emulsion, and a combined TPN formulation containing amino acids, dextrose, and lipid emulsion. At an initial inoculum of 10⁴ CFU/ml, all three bacterial organisms grew well in 10% lipid emulsion, died in the standard solution and grew only minimally or died in the combined formulation. C. albicans grew in all three formulations at an initial inoculum of 10 ⁴ CFU/ml; however, at an initial inoculum of 10² CFU/ml, which approximates touch contamination, growth of Candida in the standard and combined formulations was <1 log at 24 hr in contrast to the 10% lipid emulsion which showed significant growth >2 log at 24 hr.

It is concluded that a 24-hr infusion time is safe for the combined TPN formulation used in this study. This should result in significant cost savings compared to the previously recommended 12-hr infusion time. (Journal of Parenteral and Enteral Nutrition 10:494-497, 1986)