Austin Peter David, Hand Kieran Sean, Elia Marinos
Faculty of Medicine, University of Southampton, UK Southampton Pharmacy Research Centre, University Hospital Southampton NHS Foundation Trust, Southampton, UK
Southampton Pharmacy Research Centre, University Hospital Southampton NHS Foundation Trust, Southampton, UK Faculty of Health Sciences, University of Southampton, Southampton, UK.
JPEN J Parenter Enteral Nutr. 2015 Nov;39(8):953-65. doi: 10.1177/0148607114538456. Epub 2014 Jun 25.
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.
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 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.
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.
相关建议有效地限制了单袋含脂肠外营养（PN）的输注时长，据称是因为相较于无脂PN，它更易促进潜在微生物污染物的生长。由于包括渗透压在内的其他变量可能独立影响微生物生长，本研究考察了影响PN输注液中大肠杆菌和耐久肠球菌生长的变量。
在12种不同的PN输注液中，对有无脂质、不同葡萄糖浓度条件下的大肠杆菌和耐久肠球菌生长情况进行了一式四份的评估。
结果以48小时时每毫升的平均对数值（log10）菌落形成单位（cfu）±标准误呈现。在对基线log10cfu/mL和pH进行校正后，PN中大肠杆菌和耐久肠球菌的log10cfu/mL均显著增加，分别从1.093增至2.241（P <.001）以及从0.843增至3.451（P <.001）。每种微生物的生长均因添加脂质或提高脂质在非氮能量中的占比而独立增加，并因提高葡萄糖浓度或能量密度而降低。用葡萄糖或氯化钠提高含脂PN的渗透压会使生长降低，但仅氯化钠有显著影响（大肠杆菌，P = 0.025；耐久肠球菌，P = 0.045）。诱导的pH变化对这两种微生物生长的影响不同。
PN中脂质的存在以及脂质能量占比的增加有利于大肠杆菌和耐久肠球菌的生长。渗透压变化以及引起这些变化的营养物质类型会独立影响这些微生物的生长。在基于不同类型PN中潜在污染物的生长情况制定指南时，每种影响都需要考虑。
