COLIBACILLUS

From Big Medical Encyclopedia

COLIBACILLUS (synonym: Bacterium coli commune, Escherichia coli) — gram-negative stick of the Enterobacteriaceae family, sort Escherichia. It is for the first time allocated and described in 1885 by T. Esherikh. On a systematics of committee of society of the American bacteriologists (Soc. Amer. Bact, committee, 1920) treats the sort Escherichia Castellani and Chalmers including 22 look.

The subcommittee on enterobakteriya (Enterobacteriaceae Subcommittee, 1962) carried E. coli to the Escherichia — Shigella group, edges on Ewing's classification and Kauffmanna is presented by the trib of the same name including two sorts — Escherichia and Shigella. The sort Escherichia on this classification and classification of determinant of bacteria of Bergey's Manuel of Determinative Bacteriology includes only one look — E. coli. The last on an antigenic structure is subdivided on About - and OK - serogroups and into various biotypes: serological, enzymatic, fagotipa, kolitsino-and kolitsinogenotipa.

One of biotypes To. the item (so-called banal strains) are commensals of an intestinal path of people and animals, others concern the parasites causing diseases.

Many banal strains To. items have antagonistic properties, interfering with development in intestines of pathogenic enterobakteriya, yeast-like fungi and other microbes. Some strains To. items synthesize polyneuramin 12 and other growth factors, covering in a certain measure of requirement of an organism of the owner in them. Prolonged use of antibiotics of a broad spectrum of activity leads to death To. to the item and development dysbacteriosis (see).

To. the item as a resident of a .kishechny path (see. Intestines, microflora ) it is allocated with excrements to the environment (the soil, reservoirs) where she does not breed, but keeps the viability approximately the same term, as well as pathogenic enterobakteriya (shigellas, salmonellas). Therefore it is a sanitary and indicative microorganism. Detection To. p in the studied tests points to their fecal pollution (see. Coli-index, coli-index ), at Krom along with To. items can meet causative agents of intestinal infections.

Certain biotypes To. items can be causative agents of acute intestinal infections and other diseases of the person (see. Kolya infection ). They are carried to enteropathogenic To. item (synonym enteropathogenic escherichias). To. the items producing enterotoxin call enterotoxigenic. The differentiation of these bacteria is made on About - and to OK antigens that allows to carry them to certain serogroups and serotypes. The role E is established etiol. coli of serogroups 026, 055, 086, 0111, 0126, etc. at colienterites of children of early age; serogroups 025, 028 and, with, 032, 0124, 0144, etc. at dizenteriyepodobny diseases of adults and children; serogroups 01, 06, 015, 078, 0112 and, b, 0148 at choleroid diseases of people. At infections of urinary tract meet E. coli of serogroups 02, 06, 09, 018, etc., at appendicitis — 01, 02, 08, 015, etc., at cholecystitis — 01, 08, 011. At a kolibakterioza at animals are allocated from calfs E. coli of serogroups 08, 09, 078, 0115, etc., from pigs — 08, 0138, 0141, 0149, etc. Sometimes To. items cause kolisepsis, peritonitis, endotoxic (septic) shock (see. Endointoxication ), food toxicoinfections.

To. the item is used as universal model in the general and molecular genetics. Studying of huge number of various mutants of one of standard strains To. the item — E. coli K-12 gave the chance to make the gene card and the gene catalog of a bacterial chromosome (see. Bacteria ).

Ecology

the Tank To. the item in the nature is the person, the large intestine to-rogo becomes populated by different biotypes of this microbe from the moment of transition of the child to the mixed food, approximately by the end of the first year of life. Quantity To. the item in 1 g of excrements fluctuates from several million to 1 — 3 billion individuals. Over human life there is a repeated change of biotypes To. the item in intestines. A part in this process is played by a diet, the postponed infections, treatment of a himiopreparatama, antibiotics and other factors. Under natural conditions To. the item lives also in intestines of domestic animals, birds, wild mammals, reptiles, fishes and many invertebrates.

Morphology

Diffraction pattern of ultrathin section of a cell E. coli: 1 — nucleoid; 2 — cytoplasm; 3 — a cytoplasmic membrane; 4 — a cell wall.

Cells E. coli have the form of sticks with the rounded-off ends 1 — 2 micron long, (fig.) 0,4 — 0,6 microns thick.

To. the item of a gramotritsateln, the ultrastructure is similar to other gram-negative bacteria. Along with mobile motionless forms meet.

Flagellums are located peritrikhialno. The dispute is not formed. Strains meet the expressed capsule, cilia are found in some strains (drank).

Cultural signs

Cultures To. items well grow on usual mediums at pH 7,2 — 7,4 of optimum t ° 37 °. To. the item is a facultative anaerobe (see. Anaerobe bacterias ). On dense mediums forms smooth, convexo-plane, round, opal color rather turbid, colonies. On Endo's circle of colony To. items are painted in red-violet color with metallic luster. With a growth on fluid mediums To. the item gives opacification and a deposit.

Enzymatic properties

To. the item produces numerous sakharolitichesky enzymes, quickly ferments glucose and other carbohydrates, most often with kisloto-and gas generation. Almost all biotypes To. items constantly ferment a mannitol, pectine sugar, a maltose with education to - you; St. 90% of strains — lactose, sorbite; changeably — sucrose, raffinose, rhamnose, xylose, dulcite, salicin; as a rule, do not ferment adonit also an inositol. To. the item does not utilize ammonium citrate, sodium malonate, does not grow on the Wednesday with potassium cyanide, does not reduce nitrates in nitrites, does not split urea, does not liquefy to gelatin, the majority of strains forms an indole and does not distinguish H2S. To. the item gives positive reaction with metilroty and negative reaction of Foges — Proskauera (see. Fogesa-Proskauera reaction ), does not synthesize enzymes cytochrome oxydase and a fenilalanindezaminaza, changeably decarboxylizes a lysine, ornithine and arginine degidrolizut.

Antigens

To. the item contains About - To - and N-antigens. About (somatic) - antigens at To. items, shigellas and salmonellas have a similar chemical structure and are connected with lipopolisakharidy (LPS) of a cell wall (see. Lipopolisakharida ). Immunochemical, specificity of O-antigen is defined by structure of geksasakharid in the repeating links of the trailer site of a polisakharidny chain, edges other end is connected through 2-keto-Z-dezoksioktonat (KDO) with a lipid of A (I). So, structure of LPS E. coli 0111: B4 is presented as follows:

Designations: A stake — a kolitoza, Hl — glucose, Gal — a galactose, N-Atsgl — N-atsetilglyukozamin, Gep - heptose, x — an uncertain component.

Amount of sugars in the same trailer link, as well as number of determinant links at different serogroups of escherichias, unequal. Specificity of O-antigens K. the item usually is defined in reaction agglutinations (see) with About - or OV-agglyutiniruyushchimi kolisyvorotka on a slide plate, more rare by other methods.

K-antigens designate surface antigens which are connected with the capsule and with LPS K. item. They are subdivided on And - In - and the L-antigens differing from each other in sensitivity to high temperature and chemical agents. The highest resistance to heating (to 100 ° during 2,5 hours), to alcohol and 1 N to HCl solution A-antigen has, L-antigen is least steady. At the majority To. item. K-antigens represent the acid polysaccharides containing uranium to - you. Some K-antigens (To 88) support only squirrels. To. the items having K-antigens are not agglutinated homologous About - if - serum. This feature is inherent in live cultures and is lost after their boiling or autoclaving. Availability of K-antigens is established also in reaction of adsorption of agglutinins and at an immunoelectrophoretic research (see. Immunoelectrophoresis ).

N-flagellates, or flagellyarny, antigens are inherent in actively mobile strains. They are connected with protein-flagellinom and define standard immunochemical, specificity To. item. N-antigens of a termolabilna. They completely collapse at boiling within 2,5 hour.

U K. by the item it is described apprx. 170 O-antigens, 97 K-antigens and 50 N-antigens. Strains To. the items supplied with cilia contain proteinaceous ciliate antigens. They are found in reaction hemagglutinations (see).

St. 123 O-serological groups of escherichias are connected with each other by unilateral or bilateral antigenic ties. More than at 56 serogroups antigenic connection with shigellas and at 42 serogroups is established with other representatives of the Enterobacteriaceae family.

To. items are designated on antigenic formulas: on the first place number of O-antigen, on the second — K-antigen, on the third N-antigen is put. The type of K-antigen is specified in brackets. E.g., To (A), K (B) or K(L). Number O - To - and N-antigens are divided by colons. On antigenic formulas accessory of the studied strain to defined serol, group [e.g., E is established. coli 026:K60 (B6)] and serol, to type [e.g., E. coli 026:K60 (B6): H2]. Distinctions in receptors (factor structure) of O-antigens are designated by small letters of armor. alphabet. E.g., serogroup 0111: K58 (B4) is divided on 0111a, b:К58(В4) and 0111a, by c:К58(В4).

Plasmids

To. items may contain various plasmids (see): prophase, F (factor of fertility), Col (colicinogenic factor), R (factor of resistance), K88 (antigenic factor), Ent (enterotoxigenic factor), etc. Prophases can cause changes of separate signs To. item, e.g. O-antigen (see. Lysogeny ). F-plasmids define sexual polarity and cause formation of sexual cilia (sex-pili). Col-plasmids control formation of the colicines suppressing growth phylogenetic of related bacteria. R-plasmids are responsible for resistance To. the item to antibiotics. The plasmid of K88 controls synthesis of the antigen of the same name and the threads defining adhesive properties enteropathogenic and enterotoxigenic To. item; plasmids can be two types. One of them defines synthesis thermolabile, another — thermolabile and thermostable enterotoxin.

Pathogenicity and virulence

To. items — commensals of a large intestine — can cause pyoinflammatory processes in bodies and fabrics at falloff of resistance of an organism.

Virulence To. the item is shown in adhesiveness To. the item, i.e. sticking to fibers of an epithelium of a gut, reproduction in a gleam of a small and large intestine, a penetration in cells of an epithelium and in intracellular reproduction, and also in suppression of phagocytal activity of macrophages and polymorphonuclear leukocytes (see. Virulence ). To. items — activators of colienterites at children of early age and choleroid diseases at adults — breed on a surface of epithelial cells of a gut. To. items — causative agents of dizenteriyepodobny diseases — get into cells of an epithelium and breed in them the same as shigellas. Manifestation of virulence To. the item depends on a dose of the bacteria which got into intestines of the person. Virulence To. the item is defined in fabric cultures, experiences on laboratory animals at reproduction of an experimental colienteritis, pneumonia and other processes. Penetration ability is established by keratokonjyunktivalny test Sherenya by introduction of culture To. the item on a conjunctiva of an eye of a Guinea pig. To. the item forms the endotoxin connected with LPS which is a part of O-antigen. Biol, activity of endotoxin is expressed unequally at equal serogroups To. item. Toxic properties of endotoxin are defined by the whole molecule LPS as one lipid or polysaccharide of a malotoksichna. Endotoxin strikes coagulant system of blood, causes Shvarttsman's phenomenon (see. Shvarttsmana phenomenon ) and other phenomena, has the pyrogenic, adjuvant, protective and mitogenetic properties. Stimulates in small doses, and in big oppresses phagocytal reaction.

Many serogroups To. items produce enterotoxins. More constantly they are formed by E. coli of serogroups 06, 08, 015, 075, 078, 0148, etc. Believe that one serogroups To. items cause choleroid diarrhea in people, others only in animals (pigs, calfs).

To. items produce two types of enterotoxin. Thermostable enterotoxin is inactivated only after boiling within 30 min., slowly dialyzed through cellophane, keeps activity at acid pH values and after processing by trypsin and pronazy. Molecular weight 10^3 — 10^4. Has no antigenic properties. Thermolabile enterotoxin is inactivated after 30-minute warming up at 60 °, pH 4,0 — 5,0, under the influence of a pronaza and is not dualized. Pier. weight is definitely not established. Antigenic specificity of the thermolabile enterotoxins produced by different serogroups To. the item, and choleragen it is identical. They stimulate activity of adenyl cyclase and cause accumulation of cyclic adenosinemonophosphate (tsAMF) that leads to disturbance of secretion and development of acute diarrhea.

For detection enterotoxigenic To. items use their ability to cause expansion of the tied-up sites of a small bowel of a rabbit and formation of serous and hemorrhagic exudate. Other methods are based on ability of thermolabile enterotoxin to activate adenyl cyclase and to cause accumulation in culture of fabric (ovaries of the Chinese hamsters, a thyroid gland of a pig) of tsAMF that leads to induction of synthesis of different metabolites and morfol, to changes of cells.

Resistance

Stability K.p. to influence of external factors — usual for asporogenic bacteria. In external environment (water, the soil) she survives depending on specific conditions within several months During the heating in suspensions perishes at 55 ° in an hour, at 60 ° — in 15 min., in 1% solution of phenol — in 10 min., in solution of corrosive sublimate 1:4000 — in 2 min. To. the item has selective sensitivity to tetraethyl-diamino-triphenyl-carbohydride sulfate and salts tetrathionic to - you. Use of a number of the selection environments is based on it. Many strains To. items are highly sensitive to Monomycinum, Kanamycinum, gentamycin.

Methods of allocation and identification. Material for allocation To. items are objects of external environment (water, the soil, washouts from different objects), at diseases — excrements, the emetic masses, urine, duodenal contents or blood, and also the foodstuff suspected as a source of infection. Material is sowed on differential and diagnostic environments (see) with the subsequent release of pure growth K. item. Identification of the last is carried out by studying morfol., cultural, biochemical, and antigenic signs. The final stage is definition of a biotype To. item, especially serogroup and serotype.

See also Escherichia .



Bibliography: Borisov L. B. Enteropathogenic colibacilli and their phage, L., 1976, bibliogr.; Kauffman F. Family of colibacilli, the lane with English, M., 1959, bibliogr.; Methods of a sa-nitarno-microbiological research of objects of the environment, under the editorship of G. I. Sidorenko, M., 1978; M and Oil Company e in and the p I. E. Bakteriya of group of colibacillus as a sanitary indicator - nye microorganisms, L., 1949; Acute intestinal infections, under the editorship of T. V. Pe-radze, page 73, L., 1973, bibliogr.; T and-bachnik A. L., Girshovich E. Page and Distempers P. M. Enterotoxigenic E. coli, Zhurn, mikr., epid, and immun., No. 3, page 31, 1977, bibliogr.; Bergey’s manual of determinative bacteriology, ed. by R. E. Buchanan a. N. E. Gibbons, Baltimore, 1975, bibliogr.; Cooke E. M. Escherichia coli and man, Edinburgh — L., 1974; Medearis D. N., Cammit-t a B. M. a. H e a t h E. C. Cell wall composition and virulence in Escherichia coli, J. exp. Med., v. 128, p. 399, 1968; 0 r s k o v I. a. o. Serology, chemistry and genetics of O and To antigens of Escherichia coli, Bact. Rev., v. 41, p. 667, 1977, bibliogr.


L. B. Borisov.

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