问题 问答题 简答题

实验室采用传统的试验方法对肠杆菌科细菌进行鉴定,请论述其总体鉴定方法和思路。

答案

参考答案:

将目的菌进行革兰染色,若为革兰阴性杆菌,再作氧化酶和葡萄糖氧化发酵(O/F)试验,如氧化酶阴性,葡萄糖为发酵型则可认为是肠杆菌科细菌。进而根据葡萄糖酸盐和苯丙氨酸脱氨酶试验将肠杆菌科细菌分为三大类,再根据细菌在选择性培养基上的颜色和形态、克氏双糖培养基上的反应,动力、吲哚、脲酶试验(MIU),IMViC试验结果,综合分析鉴定到种。在肠杆菌科细菌中,EPEC、志贺菌、沙门菌除生化反应鉴定符合外,还须进行血清学试验将其鉴定到群、型。例如某菌,在麦康凯(MAC)平板和SS平板上生长为红色菌落,血平板上为灰色湿润中等偏大的菌落,革兰染色阴性,KIA上:斜面与底层均产酸产气,H2S(-),MIU上为(++-),IMViC为(++--),通过以上生化反应可鉴定为大肠埃希菌。此菌来源于8个月龄的婴儿腹泻粪便,故将MAC上红色菌落与EPEC抗血清作凝集试验,结果与EPEC多价抗血清凝集阳性,再做H抗原测定,鉴定结果为EPECO119:H6,此时可发出最终鉴定报告。

单项选择题
单项选择题

Looking back on my childhood, I am convinced (1) naturalists are born and not made. Although we were all brought (2) in the same way, my brothers and sisters soon gave up their pressed flowers and insects. (3) them, I had no ear (4) music and languages, I was not an early reader and I could not do mental arithmetic.Before World War I we (5) our summer holidays in Hungary. I have only the memory of the house we lived (6) , of my room and my toys. I can hardly (7) clearly the large family of grandparents, aunts, uncles and cousins who gathered (8) door. But I do have a clear memory of the dogs, the farm (9) , the local birds and, (10) all, the insects.I am a (11) , not a scientist. I have a p (12) of the natural world, and my enthusiasm has led me into varied investigation. I love discussing my favorite topics and enjoy (13)  the midnight oil  (14)  reading about other people’s observations and discoveries. Then  (15)  happens that brings these observations together  (16)  my conscious mind. Suddenly you fancy (想象), you see the answer  (17)  the riddle, and books, of which some might honor with the title of scientific research.But curiosity, a keen eye, a good memory and enjoyment of the animal and plant world do not make a scientist; one of the outstanding and essential  (18)  required is self-discipline, a quality I lack. A scientist requires not only  (19)  but also hard training, determination and a goal. A scientist, up to a point, can be made. A naturalist is  (20) . If you can combine the two, you get the best of both worlds.

 

第(17)空应选择()

A.of

B.on

C.to

D.at