OPPORTUNISTIC MICROBES

From Big Medical Encyclopedia

OPPORTUNISTIC MICROBES — the microbes capable at decrease in natural resistance of a macroorganism to cause diseases, for to-rykh lack of nosological specificity is characteristic.

At. - items of m occur among all categories of microbes: bacteria

(Staphylococcus, Corynebacterium, Clostridium, Escherichia, Erwinia, Pseudomonas, Proteus, Providencia, Serratia, Moraxella, Veillonella, Haemophilus, etc.), mycoplasmas (Mycoplasma). fungi (Candida, Aspergillus), protozoa (Trichomonas, Lamblia), and also viruses (Herpes, Enterovirus, etc.) - As a rule, At. - items of m are representatives of normal microflora of the person (see) not only its optional part which is not constantly found normal but also obligate (bacteroids, lactobacilli, enterococci). As a result of interaction of a macroorganism and the microbes surrounding it there was a selection of the certain types which occupied the corresponding ecological niches of a macroorganism. Important condition of development inf. the process caused At. - the item of m, overcoming kolonizatsionny resistance by them is (see. The selection decontamination), to-ruyu create certain combinations of representatives of normal microflora of the person. At the same time activators inf. process can be as representatives of own microflora of a macroorganism, and At. - the item of the m getting to it from the outside.

For the diseases caused At. - the item of m, a row osoben

nost is characteristic: they develop at the premature and weakened children, people with lowered immunol. reactivity as a result of somatopathies, operative measures, use of the pharmaceuticals possessing an immunodepressive effect (hormones, cytostatics, etc.). Inf. the processes caused At. - items of m, are deprived nozol. specificity: the same species of microbes can cause inflammatory processes of various bodies and fabrics, and, on the contrary, different types of microbes are capable to cause pyoinflammatory processes of the same body or fabric. The Pleyo-tropnost At. - the item of m. i.e. ability to breed in various bodies and fabrics, depends on existence at them a large number of factors of pathogenicity (see Pathogenicity). Carry the adhesins (e.g., saw) promoting an attachment of microbes to cells of a macroorganism, the capsule to them To - and the O-antigens, proteins of an outer membrane reporting to microbes resistance to phagocytosis and bactericidal effect of normal serum, the enzymes promoting penetration and distribution of microbes, ekzo-and endotoxins, hemolysins, factors of a kolitsi-nogennost, etc. (see Virulence). Various strains of the same look At. - items of m can be characterized by various combination of signs. Relative communication of nek-ry signs of microbes with localization inf is observed. process. So,

availability of the K1 antigen specific to meningokokk of group B is characteristic of the strains of E. co li (see Colibacillus) allocated at meningitis.

At. - items of m are capable to cause diseases in various associations: bacteria of different types, bacteria and viruses, bacteria and mycoplasmas, etc. (see Multi-infections). At the mixed bacterial infections a synergism of activators in case of their pathogenic impact on an organism is possible. So, poorly pathogenic veyllonella can stick to an epithelium under the influence of the extracellular glyukozotransferaza produced by Streptococcus salivarius, aerobic bacteria, reducing the redox potential of fabrics, can promote reproduction of anaerobe bacterias.

Etiol. structure of the diseases caused At. - the item of m, differs in dynamism: there is postoyan

Nye a change of activators of pyoinflammatory processes which is defined by environmental factors, and also variability biol. properties of microbes. One of the major factors influencing on etiol. structure of these infections, use of antibiotics is. Sharply increased role At. - the item of m in inf. pathologies of the person it is connected using antibiotics of a broad spectrum of activity, to-rye caused disturbance of ecological balance (see Dysbacteriosis) and development of multiple medicinal resistance of microorganisms (see). At. - items of m are the main causative agents of intrahospital infections (see). Their natural or acquired antibacterial drugs resistance is the main reason for it. The acquired stability in most cases is determined by R-plasmids (see a R-factor), to-rye are found practically in all types At. - the item of m. Especially often they are present at hospital strains of the microbes allocated in to lay down. institutions where favorable conditions for distribution of R-plasmids as a result of the selection action of antibiotics are created. Communication of polyresistance with defined fagotipy (fagovary) at hospital strains of stafilokokk, a serotype (serovar) kleb-siyell, pseudo-monads, etc. is noted. Also cointegration (association) of plasmids with factors of virulence is possible that it increases pathogenic potential At. - the item of m.

Relativity of division of certain species of microbes on pathogenic and opportunistic is obvious. So, Salmonella typhimurium is the activator of zoonoz (see) and food toxicoinfections (see Toxicoinfections food). The created clones of salmonellas, resistant to antibiotics, shall be considered as At. - the item of m: they cause intrahospital infections in pediatric and obstetrical hospitals.

Hospital strains of microbes, resistant to antibiotics, survive in the environment better

and have the increased ability to colonization (settling) therefore in the conditions of a hospital they intensively extend and cause development of a serious illness in the weakened people. At healthy people formation of a bacteriocarrier is, as a rule, observed (see Nositeljstvo of causative agents of infections).

Mikrobiol. diagnosis of the diseases caused At. - the item of m, has the features caused by properties of this group of microbes and the nature of the processes caused by them. Polymicrobial etiology and absence nozol. specificity define need to allocate and study all species of the microbes which are contained in patol. material. It distinguishes mikrobiol. researches at the diseases caused At. - the item of m, from researches at the diseases caused by truly pathogenic microbes when search of a certain (specific) activator is conducted. In this regard allocation of activators from a wedge, material is carried out on the mediums allowing to grow up the maximum number of species of microbes. — to identification and definition of sensitivity to antibacterial drugs — the cultures having etiol are exposed to further studying. value. Level of identification of microbes (see) can be various. For performing the corresponding therapy identification of the activator is enough to be carried out to a sort or a look. During the carrying out epidemiol. researches — establishment of a source of contagiums, ways of distribution of microbes in to lay down. establishment — identification of the marked-out cultures is carried out to a strain (see).

Accessory At. - the item of m to normal microflora of a macroorganism complicates definition etiol. the importance of these microbes in inf. process. In this regard at mikrobiol. to diagnosis of the diseases caused At. - items of m, use the methods allowing to distinguish contamination (pollution) of the studied material normal microflora. Quantitative methods of definition of degree of a microbic obsemenennost of the studied material concern to them. To establish etiol. a role At. - the item of m is helped by repeated allocation of culture from the patient and increase in its quantity with the studied material in the course of a disease. Essential value has definition of pathogenic properties at the marked-out cultures of microbes that testifies about them etiol. importance. At the same time define belonging of culture of the activator to certain serotypes (serovars), sensitivity to bacteriophages, colicines and other signs correlating with pathogenicity.

Serological researches (see) are very important for confirmation etiol. the importance of cultures At. - and. the m allocated from patients. However these researches are less informative, than at the infections caused by truly pathogenic microbes that is connected with slow accumulation of antibodies to At. - the item of m and a low antiserum capacity. In this regard serological researches are conducted more often at hron. it is long the current processes, and also for the purpose of retrospective diagnosis of acute diseases. Optimum results receive at a research of process of accumulation of antibodies in the pair serums taken from the patient in dynamics of a disease. At the same time use reaction of passive hemagglutination (see Hemagglutination), a method of an immunofluorescence (see the Immunofluorescence) and other methods.

Treatment of the diseases caused At. - items of m, carry out by means of antibiotics, streptocides and other chemotherapeutic means. Appointment them depends on a type of the activator and its sensitivity to medicines. It is desirable to use the drugs which are not operating on normal microflora (see. Selection decontamination). Use also the drugs increasing protective forces of an organism of the patient, napr, Prodigiosanum (see) and also the bacterial drugs adjusting structure of normal microflora, napr to-libakterin (see), bifidumbakpgerin (see), etc.

In prevention of the diseases caused At. - the item of m, the significant role belongs to observance a dignity. - a gigabyte. the mode and rules of prevention in to lay down. establishment (see. Intrahospital infections). The rational use of antibiotics (see) in the conditions of a hospital reducing distribution in the hospital environment of drug resistant strains At is of great importance. - the item of m.

For specific prevention of a staphylococcal infection (see) use staphylococcal anatoksinony vaccines against pyocyanic and proteyny infections Are developed.

Bibliogr). : V. D.'s white hares, etc.

Hospital infection, L., 1976; Kagan G. Ya. About pathogenic potentialities of the family Mycoplasmataceae, Zhurn. mikr., epid. and immun., No. I, page 33, 1972; To at dl and y D. G. Extra chromosomal factors of heredity of bacteria and their value in infectious pathology, M., 1977; L Osh about N of c and. Intrahospital infections, the lane with Wenger., M., 1978; Petrovsky V. G. O so-called conditionally pathogenic microorganisms, Zhurn. mikr., epid. and immun., No. 6, page 94, 1974; T and m and to about in V. D. and Petrov

skaya V. G. Urgent problems of medical microbiology: achievements,

tasks and perspectives, in the same place, No. 9, page 3, 1977; Costerton J. W., I-V of i n R. T. Cheng K. J. The bacterial glycocalyx in nature and disease, Ann. Rev. Microbiol., v. 35, p. 299, 1981; Microbial pathogenicity in man and animals, ed. by H. Smith a. J. H. Pearce, Cambridge, 1972; M i m s C. A. The pathogenesis of infectious disease, L. — N. Y., 1976; S m i t h H. Microbial surfaces in relation of pathogenicity, Bact. Rev., v. 41, p. 475, 1977.

V. G. Petrovskaya; S. D. Voropayeva (diagnosis, treatment, prevention).

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