A family of bacteria.Undergraduate includes spore free, whole body flagellated or flagellate freeGram staining negativeStraight bacilli。Chemical energy and organic nutrition, as well as respiratory metabolism and fermentation metabolism;Energy can be obtained by oxidizing a variety of simple organic compounds or fermented sugars, organic acids or polyols.
Enterobacteriaceae: chemical energy, organic nutrition, respiratory metabolism and fermentation metabolism;Energy can be obtained by oxidizing a variety of simple organic compounds or fermented sugars, organic acids or polyols.At present, the family is divided into 5 families and 12 genera.Fermentation reaction and serum reaction are the important basis for the classification of undergraduate bacteria.
Classification
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Some main genera and species of Enterobacteriaceae include:
② Salmonella, cell size (0.6~0.9) μ m × (1~3) μ m, noneSpore, generally noneCapsule, exceptSalmonella pullorum And Salmonella typhimurium, with flagella all over the body.Salmonella infects and causes disease through the digestive tract of animals, which is collectively called salmonellosis.The disease types include typhoid and paratyphoid fever (collectively referred to as intestinal fever), food poisoning, septicemia, and chronic enteritis.
③ Shigella is the pathogen of human bacillary dysentery, commonly known as Shigella.The cell size is (0.5~0.7) μ m × (2~3) μ m, without spore, flagellum and capsule. Some strains have fimbriae, aerobic or facultative anaerobic, and can grow on common culture medium.
④ Klebsiella.It is short and thick, without flagella, with capsule, and the cell size is (0.3~1.5) μ m × (0.6~6.0) μ m, arranged in single, double or short chain, facultative anaerobic, with low nutritional requirements, forming characteristic mucinous colonies on solid culture medium.It exists in nature such as soil, water, grain, and human or animal respiratory tract.When the body immunity is reduced, it can cause a variety of infections.Klebsiella pneumoniae, Klebsiella fetida andNasal induration3 species of Klebsiella.
⑤ Serratia.It can produce insoluble yellow, purple and red pigments.It generally exists in soil, water, plants, animals and human intestinal tract and respiratory tract.There are Serratia marcescens, Serratia liquefaciens, Serratia crimson, etc.Serratia marcescens, also known as Spirillum, is the smallest of the bacteria. It has flagella all over its body, can move, has no capsule, and has no spores. About half of the strains can produce redProdigiosin。Because of its small size and pigment, it is often used to test the quality of the filter.
⑥ Proteus is a kind of small bacillus without spore, capsule, flagella, active movement and round ends.The size of bacteria is (0.4~0.6) μ m × (1.0~3.0) μ m, facultative anaerobic, and most of water, soil, sewers, and all kinds of decaying animals and plants. They are conditional pathogens, which can cause human disease under special circumstances.
⑦ Yersinia.It is oval and short bacillus.The cell size is (0.5~1.0) μ m × (1.0~2.0) μ m.No spore, no capsule, facultative anaerobic.OwnYersinia pestis, pseudotuberculosis and enterocolitis.Yersinia pestis is the pathogen of plague.Plague often prevails among rodents before it spreads among people.People suffering from plague can passHuman fleaOr respiratory tract (pulmonary type) is transmitted from person to person.
Proteus
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Proteus
1 genus of Enterobacteriaceae.It is a gram-negative, spore free, capsule free, flagellate, active, and round at both ends.The cell size is (0.4~0.6) × (1.0~3.0) μ m.Facultative anaerobic.Some species showed migratory growth on ordinary solid medium, and 0.1% carbolic acid or 0.01% sodium azide could inhibit their growth.It is widely found in nature, with the largest number of water, soil, sewers and various corrupt animals and plants, and also in the intestines of healthy people and animals.They are conditional pathogens, which can cause disease to people under special circumstances.Such as food poisoning, urinary tract infection, summer diarrhea or other mixed infections.
The bacteria of this genus can decompose phenylalanine, and most of them can rapidly decompose urea.According to the difference of main biochemical reactions, it can be divided into five kinds: Proteus vulgaris, Proteus mirabilis, Proteus morgans, Proteus reggi and Proteus inconstans.See the table for its biological characteristics.
For example, the antigenicity of Proteus vulgaris X19, X2, Xk and some Rickettsia have common antigenic components, which are clinically used to assist in the diagnosis of Rickettsia disease (Waifei test,Weil-Felix reaction）。
It is easy to be killed by heat or commonly used disinfectant, generallyneomycin、Kanamycinandgentamicinsensitive.
Salmonella
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Salmonella
1 genus of Enterobacteriaceae.Because American pathologist DE. Salmon got its name from the discovery of Cholera suis in 1884.This genus is a group of Gram negative bacilli with similar antigenic structure and biological characteristics.There are many bacterial types, and more than 2000 serotypes have been found.It can cause disease to people and a few warm blooded animals.
Cell size (0.6~0.9) × (1~3) μ m No spores, generally noCapsuleExcept for Salmonella pullorum and Salmonella typhimurium, most of them have flagella.The nutritional requirements are not high, and the intestinal tract is often used to select the identification medium for isolation and culture.Biochemical reaction has important reference significance for the identification of this genus (see table).It does not liquefy gelatin, does not decompose urea, does not produce indole, does not ferment lactose and sucrose, can ferment glucose, mannitol, maltose and galactose, mostly produces acid and gas, and a few only produces acid and does not produce gas.VP testNegative, with lysine decarboxylase.The G+C content of DNA is 50-53%.It is not resistant to heat and can be killed at 60 ℃ for 15 minutes.Survive in water for 2-3 weeks.In 5% carbolic acid, he died within 5 minutes.
According to biochemical reaction, this genus can be divided into 4 subgenera.Subgenus I is the typical and most common Salmonella with biochemical reaction;Subgenera II and IV are Salmonella with atypical biochemical reaction;Subgenus III is Salmonella Arizona.
Salmonella has a complex antigen structure, which can be generally divided into three types: cell (O) antigen, flagella (H) antigen and surface (Vi) antigen.
Salmonella infects and causes disease through the digestive tract, which is collectively called salmonellosis.Salmonella causing human diseases mostly belong to serotypes A, B, C, D, and E, and the disease types are ① typhoid and paratyphoid fever (collectively referred to as intestinal fever): caused by Salmonella typhi, Salmonella paratyphi A, and Salmonella paratyphi B; ②Food poisoning: It can be caused by different bacteria types, among which Salmonella typhimurium, Salmonella enteritidis, Salmonella thompson, etc. are the most common; ③Septicemia: It is caused by Salmonella cholerae, and can also cause chronic enteritis.
Most salmonella strains that cause disease to poultry and animals belong to serogroup B~E.It mainly invades young animals, causing acute septicemia, gastroenteritis and other local inflammation.It often causes local chronic or recessive diseases in adult animals.Animals recovered from salmonellosis have certain immunity.It can resist reinfection.However, animals with local chronic diseases have weak immunity and often become carriers during disease recovery.At present, vaccines have been used for 11 infectious diseases such as swine typhoid fever and horse abortion.
Serratia
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Serratia
1 genus of Enterobacteriaceae.Gram negative bacilli that can produce insoluble yellow, purple and red pigments.It generally exists in soil, water, plants, animals and human intestinal tract and respiratory tract.
