Answering the fat emulsion contamination question: three in one admixture vs conventional total parenteral nutrition in a clinical setting

Fat emulsions (FE) support microbial growth when inoculated in vitro; dextrose/amino acid solutions (D/AA) do not. Can FE be safely added to D/AA when delivered over 24 hrs? We attempted to answer this question by culturing both conventional (C) total parenteral nutrition (TPN), in which the FE and D/AA are given separately, and the 3-in-1 admixture TPN, in which all components are delivered in one bag. Two-hundred TPN fluid cultures were obtained serially by collecting 1 ml of fluid from the distal-most connection when the TPN was changed every 24 hrs. Quantiative and qualitative cultures were obtained. One hundred sixty-six (83%) were negative. Of the 34 (17%) positive cultures, 15 (17% of 88) were from the conventional system whereas 19 (17% of 112) were from the 3-in-1 system. Six clinically septic patients furnished 11 TPN fluid specimens which grew greater than 400 colonies/ml. Seven (8% of 88) of these were from the conventional system whereas four (3.6% of 112) were from the 3-in-1 system. All had distant sites of sepsis. The 23 remaining positive TPN fluid cultures grew less than 25 colonies/ml, with 20 growing Staphylococcus epidermidis. All of these patients were clinically well and there was no significant difference in the distribution of positive cultures between the conventional system (9%) and the 3-in-1 system (13%).(ABSTRACT TRUNCATED AT 250 WORDS)