Miwa N, Kawamura A, Masuda T, Akiyama M
Shizuoka Institute of Environment and Hygiene, Japan.
Int J Food Microbiol. 2001 Mar 20;64(3):361-6. doi: 10.1016/s0168-1605(00)00446-3.
An outbreak of staphylococcal food poisoning due to an egg yolk (EY) reaction-negative strain occurred in Japan. Twenty-one of 53 dam construction workers who ate boxed lunches prepared at their company cafeteria became ill, and eight required hospital treatment. The outbreak showed a typical incubation time (1.5-4 h with a median time of 2.7 h) and symptoms (vomiting and diarrhea) of staphylococcal food poisoning. Staphylococcus aureus, which produces staphylococcal enterotoxin (SE) A, was isolated from four fecal specimens of eight patients tested. Scrambled egg in the boxed lunches contained 20-40 ng/g of SEA, and 3.0 x 10(9)/g of viable S. aureus cells that produced this toxin. All isolates from patients and the food were EY reaction-negative, coagulase type II, and showed the same restriction fragment length polymorphism (RFLP) pattern. We concluded that the outbreak was caused by scrambled egg contaminated with EY reaction-negative S. aureus. In Japan, outbreaks of staphylococcal food poisoning are mainly caused by EY reaction-positive S. aureus, and EY reaction-negative colonies grown on agar plates containing EY are usually not analyzed further for detection of S. aureus. The present outbreak suggested that EY reaction-negative isolates should be subjected to further analysis to detect the causative agents of staphylococcal food poisoning.
日本曾发生一起由蛋黄（EY）反应阴性菌株引起的葡萄球菌食物中毒事件。在53名食用公司自助餐厅准备的盒饭的大坝建设工人中，有21人患病，8人需要住院治疗。此次疫情呈现出典型的葡萄球菌食物中毒潜伏期（1.5 - 4小时，中位时间为2.7小时）和症状（呕吐和腹泻）。从8名接受检测的患者的4份粪便标本中分离出了产生葡萄球菌肠毒素（SE）A的金黄色葡萄球菌。盒饭中的炒鸡蛋含有20 - 40 ng/g的SEA以及3.0×10⁹/g能产生这种毒素的活金黄色葡萄球菌细胞。从患者和食物中分离出的所有菌株均为EY反应阴性、凝固酶II型，且显示出相同的限制性片段长度多态性（RFLP）模式。我们得出结论，此次疫情是由被EY反应阴性金黄色葡萄球菌污染的炒鸡蛋引起的。在日本，葡萄球菌食物中毒疫情主要由EY反应阳性的金黄色葡萄球菌引起，在含有EY的琼脂平板上生长的EY反应阴性菌落通常不会进一步分析以检测金黄色葡萄球菌。此次疫情表明，对于EY反应阴性分离株应进行进一步分析，以检测葡萄球菌食物中毒的病原体。
