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Total nutrient admixtures appear safer than lipid emulsion alone as regards microbial contamination: growth
M E Didier1, S Fischer, D G Maki
1Department of Medicine, University of Wisconsin Medical School, University of Wisconsin-Madison, USA.
Background:
The extraordinary growth properties of most microorganisms in 10% and 20% lipid emulsions has led to the Centers for Disease Control and Prevention recommendation that if lipids are given through an i.v. line, the administration set should be replaced every 24 hours rather than the usual 72-hour interval used for crystalloid solutions, including those used for conventional total parenteral nutrition. For nearly 15 years, parenteral alimentation has been given as a total nutrient admixture (TNA), with the glucose, amino acids, and lipid mixed within the same bag and infused continuously over 24 hours.
Methods:
We prospectively studied in a representative TNA (17.6% glucose, 5% amino acids, 4% lipid; pH 5.6, osmolality 1778) and in a control solution, 5% dextrose-in-water (D5%/W), the growth properties at 4, 25, and 35 degrees C of three isolates each of Staphylococcus epidermidis, Staphylococcus aureus, Enterobacter cloacae, Klebsiella oxytoca, Serratia marcescens, Acinetobacter calcoaceticus, Stenotrophomonas maltophilia, Pseudomonas aeruginosa, Burkholderia cepacia, Flavobacterium spp, and Candida albicans, and two isolates of Staphylococcus saprophyticus, the species that are most likely to contaminate TNA during preparation or administration and that have been implicated in >95% of all outbreaks and sporadic cases of nosocomial bloodstream infections traced to contaminated parenteral admixtures reported in the world literature.
Results:
Growth in TNA at 25 and 35 degrees C occurred with only two species, C. albicans and S. saprophyticus, and only after 24 to 48 hours; D5%/W allowed growth at 25 degrees C of two gram-negative species, S. marcescens and B. cepacia.
Conclusions:
We conclude that TNA is a poor growth medium for most nosocomial pathogens and is no better than D5%/W. The need to replace administration sets every 24 hours with TNA should be reconsidered and ideally be studied in a prospective randomized trial.
Insights
Total nutrient admixtures (TNA) support limited microbial growth, challenging the 24-hour intravenous line change recommendation. Further trials are needed to re-evaluate lipid emulsion administration guidelines for parenteral nutrition.
Area of Science:
- Microbiology
- Infectious Diseases
- Clinical Pharmacy
Background:
- Microbial contamination of intravenous lipid emulsions necessitates strict handling protocols.
- Current guidelines recommend changing lipid-containing parenteral nutrition administration sets every 24 hours due to microbial growth concerns.
Purpose of the Study:
- To evaluate the microbial growth potential of total nutrient admixtures (TNA) compared to dextrose solutions.
- To assess the necessity of the 24-hour intravenous administration set replacement for TNA.
Main Methods:
- Prospective study comparing microbial growth in TNA (17.6% glucose, 5% amino acids, 4% lipid) and 5% dextrose-in-water (D5%/W).
- Tested growth of common nosocomial pathogens (e.g., Staphylococcus, Enterobacter, Pseudomonas, Candida) at various temperatures (4°C, 25°C, 35°C).
Main Results:
- Limited growth of Candida albicans and Staphylococcus saprophyticus observed in TNA after 24-48 hours at 25°C and 35°C.
- D5%/W supported growth of Serratia marcescens and Burkholderia cepacia at 25°C.
Conclusions:
- Total nutrient admixtures (TNA) demonstrate poor growth medium properties for most nosocomial pathogens.
- The current 24-hour replacement recommendation for TNA administration sets may warrant reconsideration based on these findings.