Growth of bacteria and fungi in total nutrient admixtures

Abstract

Total nutrient admixtures (TNAs) containing dextrose, amino acids, and fat emulsion were evaluated for their ability to support bacterial and fungal growth. The following solutions were tested: a standard adult total parenteral nutrient (TPN) solution with dextrose, amino acids, and electrolytes, a standard neonatal TPN solution with dextrose, amino acids, and electrolytes, a 10% fat emulsion, a 20% fat emulsion, a TNA with 40% of the total calories as fat, a TNA with 25% of the total calories as fat, a neonatal TNA with 25% of the total calories as fat, a control (fat emulsion was replaced with an equal amount of sterile water) for solution 5, and a control for solution 6. Serial dilutions of each solution were inoculated with 5 X 10(5) bacteria/mL or 5 X 10(3) fungi/mL, incubated, and visually rated on a scale of 0 (no growth) to 4 (maximal growth). Bacterial growth of Pseudomonas aeruginosa, Staphylococcus aureus, Staph. epidermidis, Streptococcus faecalis, and Group JK Corynebacterium was greater in the TNA solutions than in the control or standard TPN solutions. Escherichia coli, Candida tropicalis, and C. albicans grew in all solutions tested. Torulopsis glabrata grew better in solutions that did not contain fat emulsion. Growth characteristics did not differ significantly between the adult and neonatal (more dilute) solutions. The addition of fat emulsion to TPN solutions enhances the ability of these solutions to support bacterial growth; this possibility must be considered when evaluating patients for this type of total parenteral nutrition therapy.