根据影响大肠杆菌和耐久肠球菌在含或不含脂肪乳肠外营养液中生长的因素决策输液最长持续时间
背景：专家建议有效地限制了单袋含脂质肠外营养（PN）的输注时间，主要因为与不含脂质PN相比，其有利于潜在微生物生长。由于包括渗透浓度在内的其他变量可能单独影响细菌生长，本研究仅检测在PN输注液中影响大肠杆菌和耐久肠球菌生长的变量。
资料与方法：对12种不同的含或不含脂质、葡萄糖浓度不同的PN输注液中大肠杆菌和耐久肠球菌的生长进行了评估。
结果：结果以48h时平均log10菌落形成单位（cfu）/mL±SEM表示。在调整了log10cfu/mL和pH基线后，大肠杆菌和耐久肠球菌的log10cfu/mL均相对增加，分别从1.093增加至2.241（P＜0.001）、从0.843增加至3.451（P＜0.001）。每种细菌的增长因PN液中包含脂质或脂质中非氮能量比例增加而增加，而因葡萄糖浓度或能量密度增加而减少。当利用葡萄糖或氯化钠增加含有脂质PN液的渗透浓度时，可以抑制细菌生长，但是仅氯化钠的抑制效果有统计学意义（大肠杆菌，P=0.025；耐久肠球菌，P=0.045）。人为改变pH对两种细菌的生长产生不同影响。
结论：PN液中脂质的存在以及脂质中能量比例增加均有利于大肠杆菌和耐久肠球菌的生长。渗透浓度改变和营养类型不同对两种细菌产生不同影响。当根据潜在污染物在不同类型PN中生长情况制定指南时，应考虑到各种效应。
JPEN J Parenter Enteral Nutr. 2015 Nov;39(8):953-65.
Factors Influencing Escherichia coli and Enterococcus durans Growth in Parenteral Nutrition With and Without Lipid Emulsion to Inform Maximum Duration of Infusion Policy Decisions.
Austin PD, Hand KS, Elia M.
Faculty of Medicine, University of Southampton, Southampton, UK.
Southampton Pharmacy Research Centre, University Hospital Southampton NHS Foundation Trust, Southampton, UK.
Faculty of Health Sciences, University of Southampton, Southampton, UK.
Institute of Human Nutrition, University of Southampton, Southampton, UK.
BACKGROUND: Recommendations effectively restrict the infusion duration of lipid-containing parenteral nutrition (PN) from a single bag, purportedly because it encourages growth of potential microbial contaminants more than lipid-free PN. Since other variables, including osmolarity, may independently affect microbial growth, this study examined variables affecting growth of Escherichia coli and Enterococcus durans in PN infusates.
MATERIALS AND METHODS: Growth of E coli and E durans was assessed in quadruplicate in 12 different PN infusates, with and without lipid, in varying glucose concentrations.
RESULTS: Results are presented as mean log10 colony-forming units (cfu)/mL ± SEM at 48 hours. The log10cfu/mL of both E coli and E durans in PN increased considerably after adjustment for baseline log10cfu/mL and pH, from 1.093 to 2.241 (P < .001) and from 0.843 to 3.451 (P < .001) respectively. Growth of each microorganism was independently increased by lipid inclusion, or increasing the proportion of nonnitrogen energy from lipid, and reduced by raising the glucose concentration or energy density. Increasing the osmolarity of lipid-PN with glucose or sodium chloride reduced growth but only significantly for sodium chloride (E coli, P = .025; E durans, P = .045). Induced changes in pH affected the growth of the 2 organisms differently.
CONCLUSION: The presence of lipid and an increasing proportion of energy from lipid in PN favored the growth of E coli and E durans. Osmolarity changes and the nutrient type causing these changes independently affect the growth of these microbes. Each effect needs to be considered when establishing guidelines based on the growth of potential contaminants in different types of PN.
KEYWORDS: administration; outcomes research/quality; parenteral nutrition; sepsis
PMID: 24969406
DOI: 10.1177/0148607114538456