Reamer R H, Hargrove R E, McDonough F E
Appl Microbiol. 1969 Sep;18(3):328-31. doi: 10.1128/am.18.3.328-331.1969.
The necessity of developing a quick, sensitive, and reliable test for Salmonella in nonfat dry milk (NDM) is evident from the recent tracing of Salmonella outbreaks to this product. Normally, coagulation of casein occurs when assaying NDM under regular cultural conditions, raising the possibility of trapped bacteria. After 20 hr of incubation of NDM in preenrichment lactose broth, enrichment was achieved by using Selenite-Cystine Broth. Smears from the enrichment broth were examined by the fluorescent-antibody technique (FAT) with a commercially available polyvalent O globulin conjugated with fluorescein. Standard cultural methods (SCM) were performed for comparison with FAT. Sensitivity of FAT was definitely improved by the use of trypsin. Casein coagulation of NDM can be avoided by addition of trypsin to samples during initial preenrichment in lactose broth. Samples containing approximately one Salmonella per 10 g were easily detected by FAT with the use of trypsin-treated samples. The method required only 42 hr to complete. Additionally, the use of trypsin enhanced recovery of Salmonella by use of SCM, as evidenced by alteration in the observed coliform to Salmonella ratios.
从近期沙门氏菌疫情追溯到脱脂奶粉（NDM）这一情况来看，开发一种针对脱脂奶粉中沙门氏菌的快速、灵敏且可靠的检测方法很有必要。通常情况下，在常规培养条件下检测脱脂奶粉时会出现酪蛋白凝固现象，这增加了细菌被困住的可能性。将脱脂奶粉在预增菌乳糖肉汤中培养20小时后，使用亚硒酸盐胱氨酸肉汤进行增菌。通过荧光抗体技术（FAT），使用与荧光素偶联的市售多价O球蛋白对增菌肉汤涂片进行检测。采用标准培养方法（SCM）进行比较。通过使用胰蛋白酶，FAT的灵敏度得到了显著提高。在乳糖肉汤初始预增菌期间向样品中添加胰蛋白酶可避免脱脂奶粉的酪蛋白凝固。使用经胰蛋白酶处理的样品，FAT能够轻松检测出每10克中含有约一个沙门氏菌的样品。该方法仅需42小时即可完成。此外，使用胰蛋白酶通过SCM提高了沙门氏菌的回收率，观察到的大肠菌群与沙门氏菌比例的变化证明了这一点。
