Since lipid in parenteral nutrition (PN) purportedly enhances microbial growth, recommendations limit infusion of lipid PN (or lipid emulsion) from a single container to 24 hours (48 hours for lipid-free PN)” Austin et al (2016).
Background: Since lipid in parenteral nutrition (PN) purportedly enhances microbial growth, recommendations limit infusion of lipid PN (or lipid emulsion) from a single container to 24 hours (48 hours for lipid-free PN). However, the associated evidence base is ambiguous.
Aim: To examine factors affecting microbial growth in PN.
Methods: A systematic review with meta-analyses examined effects of nutrients on microbial growth in PN infusates over a 48-hour period using the ‘growth ratio’, GR (log10).
Findings: Factors influencing GR in PN included glucose, microbial species, temperature, osmolarity, presence of vitamins, trace elements and lipid, and amino acid profile. Using unmatched datasets (n=306), a general linear model found lipid inclusion in PN represented 3.3% of the variability, less than that due to glucose concentration (5.8%), microbial species (35.3%) and microbe-infusate interaction (4.4%). Using matched datasets (n=38 pairs), lipid inclusion in PN represented 5.4% of the variability (P=0.076), less than that due to glucose concentration (8.5%; P=0.025), microbial species (75.5%; P<0.001) and microbe-infusate interaction (13.3%; P =0.382). Using meta-analyses of matched datasets the presence of lipid in PN at fixed glucose concentrations did not significantly increase GR of Candida albicans, Escherichia coli and Staphylococcus epidermidis, (P=0.352, P=0.025 and P=0.494 respectively; overall P=0.175).
Conclusion: Lipid inclusion in PN is only one of several factors that potentially influence microbial growth in PN. Any recommendations about the duration of PN infusion from a single container should account for all these factors and be weighted according to microbial species likely to contaminate PN.
Austin, P.D., Hand, K.S. and Elia, M. (2016) A systematic review and meta-analyses of the effect of lipid emulsion on microbial growth in parenteral nutrition. The Journal of Hospital Infection. September 7th. .
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