Neonatology Department, Hospital Universitario 12 de Octubre, 28041 Madrid, Spain; Pediatrics Department, Universidad Complutense, 28040 Madrid, Spain.
Neonatology Department, Hospital Universitario 12 de Octubre, 28041 Madrid, Spain; Pediatrics Department, Universidad Complutense, 28040 Madrid, Spain.
J Dairy Sci. 2018 Dec;101(12):10714-10719. doi: 10.3168/jds.2018-14984. Epub 2018 Oct 3.
Once pasteurized donor milk is thawed for its administration to a preterm or sick neonate, and until it is administered, it is kept refrigerated at 4 to 6°C for 24 h. After this time, unconsumed milk is discarded. This time has not been extended, primarily because of the concern of bacterial contamination. The aim of this study was to determine the changes in pH and bacterial count when pasteurized donor milk was kept under refrigeration for a prolonged period (14 d). In this prospective study, 30 samples of pasteurized donor milk from 18 donors were analyzed. Milk was handled following the regular operating protocols established in the neonatal unit and was kept refrigerated after thawing. pH measurements and bacteriology (on blood agar and MacConkey agar plates) were performed on each sample at time 0 (immediately after thawing) and then every day for 14 d. Changes in pH of samples over time were evaluated with linear mixed-effects regression models. A slow but gradual increase in milk pH was observed starting from the first day [mean (±SD) pH of 7.30 (±0.18) at time 0 and 7.69 (±0.2) on d 14]. No bacterial growth was observed in any of the samples throughout the complete trial except in one sample, in which Bacillus flexus was isolated. In conclusion, pasteurized human donor milk maintains its microbiological quality when properly handled and refrigerated (4-6°C). The slight and continuous increase in milk pH after the first day could be due to changes in the solubility of calcium and phosphate during refrigerated storage.
一旦巴氏消毒后的捐赠母乳解冻用于早产儿或患病新生儿，在给予婴儿之前，应在 4 至 6°C 下冷藏 24 小时。超过此时间未被消耗的母乳应丢弃。之所以未延长这一时间，主要是因为担心细菌污染。本研究的目的是确定在长时间（14 天）冷藏下巴氏消毒后的捐赠母乳的 pH 值和细菌计数的变化。在这项前瞻性研究中，分析了来自 18 位捐赠者的 30 份巴氏消毒后的捐赠母乳样本。母乳处理遵循新生儿病房制定的常规操作方案，并在解冻后冷藏。在每个样本的 0 时间（解冻后立即）和随后的 14 天内，每天进行 pH 值测量和细菌学检查（血液琼脂平板和 MacConkey 琼脂平板）。使用线性混合效应回归模型评估样本随时间变化的 pH 值变化。从第一天开始，就观察到母乳 pH 值呈缓慢但逐渐升高的趋势[0 时间时的平均（±SD）pH 值为 7.30（±0.18），第 14 天时为 7.69（±0.2）]。除了一个样本中分离出 Flexus 芽孢杆菌外，在整个试验过程中，所有样本均未观察到细菌生长。总之，在正确处理和冷藏（4-6°C）的情况下，巴氏消毒后的人乳捐赠者母乳可以保持其微生物质量。在第一天之后，母乳 pH 值的轻微且持续增加可能是由于冷藏储存过程中钙和磷酸盐溶解度的变化所致。
