From Big Medical Encyclopedia

RICKETTSIAE (Rickettsiae) — the polymorphic intracellular microorganisms having a cell wall, similar to gram-negative bacteria.

The term «rickettsiae» is entered E. Roche-Lima in 1916 into honor G. Rikkets . Pathogenic for the person R. cause acute feverish diseases — rickettsioses (see).

Fig. 1. The microdrugs Rickettsia prowazekii in culture of cells: kokkovidny and rhabdoid forms (are specified by shooters); x 900.
Fig. 2. The diffraction pattern of ultrathin section of the sharing cell of Rickettsia prowazekii: 1 — a cell wall; 2 — a cytoplasmic membrane; 3 — a ribosome; 4 — nucleoid.

R.'s most of a nepatogenna for the person, live in an organism of the arthropods which are their carriers or primary owners. According to the 8th edition «Berdzhi's Guides by Definition, Bacteria» (1974) rickettsiae important in pathology of the person make three sorts (Rickettsia, Coxiella, Rochalimaea), to-rye enter a tribe of Rickettsieae Philip 1953, the Rickettsiaceae Pinkerton 1936 family, an order of Rickettsiales Gies-zczkiewicz 1939. P. — small, 0,2 in size — 0,6 microns of X 0,4 — 2,0 microns, a kokkovidny and rod form gram-negative microorganisms (fig. 1). On R.'s structure are close to gram-negative bacteria, nucleoid and the cytoplasm with ribosomes surrounded with a cytoplasmic membrane and a cell wall (fig. 2) are found in them.

Distinguish two main forms P. — vegetative and based. R. binary division breed. Rubles are painted by the main fuchsin in red color; by Makkiavello's method alkaline solution of fuchsin is applied by 0,25%, in P.F. Zdrodovsky's modification (1948) alkaline fuchsin are replaced with carbolic fuchsin.

Rubles are cultivated in a vitellicle of a chicken embryo, in easy white mice, in a number of stable cells of mammals. The worrying cellular cultures on Tirod a serumal agar and organ cultures are seldom used for cultivation of River. With a growth in cellular cultures of fibroblasts of a chicken embryo and stable lines of cells of R. form plaques.

Ten types combined in three groups (biotype) belong to the sort Rickettsia. Enter into group of a sapropyra: R. prowazekii, R. typhi, R. Canada, in group of tick-borne spotty fever — R. rickettsii, R. sibirica, R. conorii, R. australis, R. akari, R. parkeri, in group of fever of a tsutsugamusha — R. tsutsu-gamushi. Type-species of the sort Rickettsia da Rocha-Lima 1916 — R. prowazekii. The name of a look is given in honor of S. Provachek.

Rubles of the sort Rickettsia are obligate parasites of a cell. Time of generation at the largest growth rate — apprx. the 8th hour. Growth happens preferential in cytoplasm of a cell. River of group of tick-borne spotty fever (lips. Dermacentroxenus) can get also into a kernel of a cell.

Contents guanine + tsitozin in DNA at R. of group of a sapropyra equally in 28,5 — 29,3 pier. %, R. have groups of tick-borne spotty fever — 32,5 pier. %. The size of a genome of rickettsiae — apprx. 109 dalton. Rubles of the sort Rickettsia possess special transport system for exchange processes with a host cell. They have the limited enzymatic activity independent of a host cell; have toxicity, hemolitic activity, property of active implementation in a cell. Are unstable in the environment.

At R.'s processing the sorts Rickettsia are allocated with ether: so-called soluble antigen, in to-ry enter an erythrocyte - a sensitizing antigen; the antigens causing development of antibodies to Proteus OH 19 and OH k  ; lipopolisakharidny and protein antigens. Soluble antigens of a gruppospetsifichna, and corpuscular (vysokoochshtsenny suspensions P.) — are species-specific.

Almost all types of the sort Rickettsia pathogens for the person (see. Flea typhus local , Vesicular rickettsiosis , Tick-borne rickettsioses , Marseilles fever , Spotty fever of the Rocky Mountains , North Asian tick-borne rickettsiosis , Sapropyra epidemic , Tsutsugamusha ).

Type-species of the sort Coxiella Philip 1948 — S. burnetii. The name of a sort and look is given in honor of Cox (H. R. Dried) and F. Burnett. Pages of burnetii at modification of coloring across Gram can be painted grampolozhitelno; obligate parasites of a cell, breed in lizosomalny vacuoles of a host cell. At optimal conditions of growth the period of generation apprx. the 12th hour. Contents guanine + tsitozin in DNA equally in the 43rd pier. %. The size of a genome apprx. the 109th a distance tone. Pages of burnetii differ from representatives of the sorts Rochalimaea and Rickettsia in existence of a phase variation in antigenic, immunogene and virulent properties. Are steady against environmental factors. S.'s ecology of burnetii, the activator of the Q fever, is connected with a natural ochagovost and the centers among domestic animals (see. Q fever ).

The name of the sort Rochalimaea (Macchiavello) Krieg 1961 is given in honor of E. Roche-Lima. Type-species — Rochalimaea quintana, representatives to-rogo are morphologically similar to representatives of other childbirth of a tribe of Rickettsieae. Are cultivated in the acellular environment. Contents guanine + tsitozin is equal in DNA 38,5 pier. %. Have no antigenic affinity neither with the sort Rickettsia, nor with the sort Coxiella. The ecology of R. quintana is closely connected with the person and a carrier (see. Trench fever ).

Bibliography: Balayeva H. M. Izmenchivost of rickettsiae, Zhurn. mikr., epid. and immun., No. 3, page 8, 1976, bibliogr.; Zdrodovsky P. F. both Golin in and the p E. M. The doctrine about rickettsiae and rickettsioses, M., 1972, bibliogr.; Veg-gey's manual of determinative bacteriology, ed. by R. E. Buchanan a. N. E. Gibbons, p. 882, Baltimore, 1975; Rickettsiae and rickettsial diseases, ed. by J. Kazar a. o., p. 137, Bratislava, 1978, bibliogr.; d a Rocha-Lima H. Zur Atiologie des Fleckfiebers, Berl. klin. Wschr., S. 567, 1916.

V. F. Ignatovich.