The definition and determination significance of E. coli

(1) Definition and scope of E. coli
According to the food hygiene test method
biology
issued by the state in 1994, coliform bacteria refers to a group of Gliland negative infested bacillus at 37 degrees C, 24 h can ferment lactose, acid production, gas production, oxygen demand and anaerobic Gliland negative bacteria.
E. coli group is mainly composed of some bacteria in the four strains of E. coli, namely, the E. coli genus, the Cillusacid genus, the Creeber genus and the E. coli genus, whose
bio-chemical
characteristics are classified in Table 5-4.as can be seen from the table above, E. coli type I and III. type in the E. coli group are characterized by the use of four biotransmission reactions for indigo, methyl red, v-P and
(ii) the significance of the determination of colium
1. Indicator bacteria of fecal contamination
As early as 1892, Schardinger first proposed E. coli as an indicator of pathogen contamination in water sources, since E. coli is a common bacteria found in the intestines of humans and animals. A year later, Seubold's "Theobold. Smith's noted that E. coli is common in the intestines and can be thought to be caused by fecal contamination in humans or animals if found outside the gut;
study found that the E. coli in adult faeces was 108/g1109/g. If E. coli is found in water or food, it can be confirmed that it has been contaminated with feces, and there may be intestinal pathogens. For this reason, it can be considered unsafe to eat water or food containing E. coli. Therefore, in order to assess the hygienic quality of food testing, also use E. coli or E. coli as an indicator of fecal contamination bacteria. Of course, there is fecal pollution, there is not necessarily intestinal pathogens, but even if there are no pathogens, as long as the feces contaminated water or food, is also unhygienic, not like people.
2． The choice of faeces pollution index bacteria
as the ideal indicator of fecal pollution bacteria should have the following characteristics, in order to play a more correct indicator role.
(1) bacteria present in the intestines to show the specificity of the indicator.
(8) is extremely high in the intestines and can be detected even when highly diluted.
(8) in the environment outside the intestine, its resistance is greater than the intestinal pathogenic bacteria or similar, into the water no longer reproduce.
(4) inspection method is simple, easy to check out and count.
In food hygiene microbial testing, can be used as an indicator of fecal contamination bacteria based on the above conditions, the largest number of feces is colium, and E. coli groups with feces excreted after the body, its survival time and the main pathogenic bacteria in the intestines are roughly similar, in the test method, but also to E. coli test count is simple. Therefore, it is more appropriate to use colium as an indicator of fecal pollution in China.
addition, as an indicator of fecal contamination, bacteria are: Bifidobacterium, Bacterides, Lactobacillus, Bacillus difficile in E. coli and streptococcus, etc., reportedly Bacillus is the second largest bacterium group in the human intestine; anorexic lactic acid bacteria account for more than 50% of the bacterial composition of the human intestine, the amount of the bacteria in the general faeces is 109 / g - 1010 / g. Bacteria belonging to the E. coli family in the intestines, in addition to the bacteria mentioned above, as well as Klebsiella genus Klebsiella, Ophthalmology and E. coli, etc., can also act as an indicator of fecal contamination bacteria.
Many researchers believe that E. coli is more likely to die than many other pathogens in cold-traced foods or frozen foods, so it is not ideal to use E. coli as an indicator of E. coli as an indicator of bacteria, while streptococcus is resistant to low temperature, as an indicator of fecal contamination of such foods. These other bacteria in the intestines, although related to feces, because they are not comparable to the E. coli group has the specificity of indicators, so there is currently no inclusion as a recognized indicator of fecal contamination bacteria.
Of course, E. coli as an indicator of fecal contamination bacteria also have some shortcomings:
(1) drinking water contains a smaller amount of E. coli, sometimes can still cause the prevalence of intestinal infectious diseases.
(8) Coli colonies can grow and reproduce in water under certain conditions.
(2) In the external environment, some salmonella is more resistant than E. coli.
3． E. coli group as an indicator of fecal pollution bacteria significance
Fecal contamination of food, is often the main cause of intestinal infectious diseases, so check whether there are intestinal bacteria in food, which is to control the occurrence and prevalence of intestinal infectious diseases, has a very important significance.
by many researchers have proved that pollution of the outside environment by human and animal waste is the main cause of the presence of E. coli in nature. In the excreta of patients with diarrhea, atypical E. coli often has an increasing trend, which may be related to the body's intestines disorder, E. coli group in the proportion of different types of composition caused by the change; The bio-chemical characteristics are mutated and thus transformed into atypical E. coli. From this point of view, the E. coli group, whether in the faeces or in the external environment, are as a whole, its bacterial composition is often a variety, but in proportion, depending on the conditions and differences. Therefore, the detection of E. coli groups not only reflects the overall situation of proofing contaminated with faeces, but also, to a certain extent, the health status of food in the process of production and processing, transportation, preservation, etc., so it has a wide range of health significance.
Because E. coli is included in the food hygiene
biology
routine testing program as an indicator of fecal contamination, if the E. coli group in food exceeds the prescribed limit, it means that the food is likely to be contaminated with feces, and feces if it is from the intestinal pathogenic bacteria or diarrhea patients, the food may contaminate the intestinal pathogenic bacteria. Therefore, where the number of coliforms exceeds the prescribed limit of food, it can be determined that its hygiene is not qualified, the food is not safe to eat.