[Impact of thermolabile enterotoxin of Enterobacter cloacae on levels of caspases 3, 7, and 10 under experimental infection].

AIM: To assess the role of thermolabile enterotoxin of Enterobacter cloacae on level of caspases 3, 7, and 10 in experiment. MATERIALS AND METHODS: Observation of apoptosis in mice splenocytes and peritoneal exudate cells. Experimental infection was created by intraperitoneal injection of live bacteria and cultural fluid of E. cloacae producing thermolabile enterotoxin. RESULTS: The study showed that thermolabile enterotoxin of E. cloacae does not have equal effect on apoptosis of studied cells: it slows apoptosis of splenocytes and virtually does not have any influence on peritoneal phagocytes. CONCLUSION: Apoptosis of infected cells is a protective reaction of microorganism to invasion of infectious agent. Cell death leads to rapid elimination of pathogenic agent. Furthermore, cell death by apoptosis compared to necrosis is more favorable for bacteria because it is not induce inflammatory reactions. In our experiments thermolabile enterotoxin of E. cloacae had had antiapoptogenic effect on mice splenocytes that could be a key element in pathogenesis of diseases caused by enterotoxin-producing strains of Enterobacter.

[Effect of Enterobacter cloacae thermolabile enterotoxin on immune system of mice].

AIM: To study the effect of Enterobactercloacae thermolabile enterotoxin (LT-enterotoxin) on different arms of immune system of mice. MATERIALS AND METHODS: Proprietary clinical strain E. cloacae 258 was used and intraperitoneal inoculation of outbred white mice with LT-enterotoxin-producing E. cloacae comprised experimental model. Phagocytic and lysosomal activity of peritoneal macrophages as well as level of APC to sheep erythrocytes were measured, spontaneous and induced NBT tests were also performed. RESULTS: Pleiotropic immunotoxic effect of LT-enterotoxin of studied bacteria was established, which characterized by suppres- sion of antigen-presenting and antigen-processing functions of macrophages, stimulation of mitotic activity of lymphocytes, decrease of activity of hexose monophosphate shunt enzymes in peritoneal macrophages as well as abnormalities in formation of specific B-lymphocytes. CONCLUSION: Obtained data allowed to reveal separate steps in pathogenesis of infectious process caused by LT-enterotoxin-producing bacteria from Enterobacter genus.

[Study of effect of thermolabile enterotoxin of Enterobacter cloacae on expression of cytokine genes in mice].

AIM: To study the role of production of several cytokines by macrophages and neutrophils in experiment. MATERIALS AND METHODS: Production of cytokines--IL-2, 4, 6, 10, 12, 15 as well as interferon gamma (IFN-gamma), tumor necrosis factor alpha (TNF-alpha), transforming growth factor beta (TGF-beta) by macrophages and neutrophils during experiment on mice inoculated with enterotoxigenic strain of Enterobacter cloacae was measured. Expression of cytokines was determined by reverse transcription PCR and dot-hybridization on the basis of specially synthesized nucleotide sequences. RESULTS: In macrophages of experimental animals inoculated with enterotoxigenic strain of E. cloacae increased production of TGF-beta, IFN-gamma and decreased level of TNF-alpha were revealed. Transcription of mRNAs of IL-15 and IL-6 was detected in macrophages and neutrophils of experimental animals at 24 h after inoculation. Transcription of mRNAs of IL-2, IL-4 and IL-10 was detected neither in macrophages nor in neutrophils. CONCLUSION: Thermolabile enterotoxin of E. cloacae renders negative effect on IFN-gamma, promotes enhanced expression of TGF-beta and suppresses production of IL-2, IL-4, IL- 10. Absence of expression of key cytokines suggests that effect of thermolabile enterotoxin of Enterobacter bacteria excludes it from cytokine regulation of immune response during infectious process.

[Influence of Enterobacter toxin on the cellular immunity].

Study of dynamics of formation of spontaneous and mitogen (phytohemagglutinin - PHA, concanavalin A - ConA)-activated blast lymphocytes showed increase of number of transforming T-lymphocytes under the influence of Enterobacter cloacae thermolabile enterotoxin. Itwas noted that PHA mainly stimulated mitosis of T-cell population, ConA - of natural killers, whereas enterotoxin stimulated mitotic activity of both cell types.

[Influence of termolabile enterotoxin of Enterobacter cloacae on phagocytic activity of mice peritoneal macrophages].

Influence of termolabile enterotoxin (LT-enterotoxin) of Enterobacter cloacae on functional activity of mice peritoneal macrophages was studied and following combinations were used: LT-enterotoxin-producing E. cloacae, its isogenic pair--LT-enterotoxin non-producing E. cloacae, supernatantof broth culture containing LT-enterotoxin, and physiological salt solution (in control group). Data showing decrease in phagocytic and lysosomal activity, disorder in functions of hexosemonophosphate shunt enzymes in peritoneal phagocytes were obtained.

[State of several parts of immune system in mice, infected by enterotoxigenic bacteria of Enterobacter genus].

Influence of thermolabile enterotoxin bacteria of Enterobacter genus on the immune system of mice was studied. Assessment of phagocytic functions of the immune system as well as antigen-presenting functions of macrophages during infection with enterotoxin-producing strains of bacteria from Enterobacter genus revealed pleiotropic effect of the toxin which is characterized by inhibition of antigen-presenting and processing functions of macrophages.

[Persistense of mono- and associated cultures of conditionally pathogenic enterobacteria].

The comparative study of adhesive, hemolytic, DNA-ase, lecithinase, antilysozymic, anticomplementary activities of mono- and associated cultures of 57 Enterobacter spp., 61 Citrobacter spp. and 55 Serratia spp. strains, isolated from patients with pyoinflammatory, intestinal and urological diseases is carried out. Different variations of cocultivated bacteria including Enterobacter and Citrobacter, Enterobacter and Serratia, Citrobacter and Serratia are used. It was shown, that cocultivated Enterobacter, Citrobacter and Serratia bacteria increased the persistent properties of mixt cultures.

[Morphological properties and adhesiveness of bacteria of the genus Proteus]. / Morfologicheskie svoistva i adgezivnost' bakterii roda Proteus.

Out of 100 Proteus strains isolated from patients with purulent inflammatory, urological and enteric diseases, from healthy persons and from the environment, 29 stains showed the positive D-mannose-resistant reaction of hemagglutination with chick red blood cells and 18 strains showed such reaction with goose and duck red blood cells. The results of these studies permit the use of chick red blood cells as target cells for the detection of Proteus adhesin. Human red blood cells of groups O, A, B and AB, sheep, bovine, dog, rat and rabbit red blood cells gave no positive D-mannose-sensitive reaction and D-mannose-resistant reaction of hemagglutination. In bacterial cells pili function as organelles which determine Proteus adhesiveness, while flagellae play no positive role.

[Ultrastructural characteristics of Proteus vulgaris and Proteus mirabilis cells differing in the capacity for swarming]. / Ul'trastrukturnye osobennosti mikrobnykh kletok Proteus vulgaris i Proteus mirabilis, razlichaiushchikhsia po sposobnosti k roeniiu.

Specific differences in the structure of colonies and the location of microbial cells in colonies, characteristic for aggregating and nonaggregating genetically related pairs of P. vulgaris and P. mirabilis strains, have been demonstrated by means of transmission and scanning electron microscopy. In calculating the number of flagellae per 100 outlines of microbial bodies revealed in negatively stained preparations, the fact that both aggregating and nonaggregating bacteria possess practically the same number of flagellae, on the average 4-8 flagellae per microbial cell outline, has been established. This fact indicates that the presence of flagellae in microbial cells is unrelated to their capacity for swarming.

[The detection of a choleriform thermolabile enterotoxin in clinical strains of Proteus isolated in different infections]. / Obnaruzhenie kholeropodobnogo termolabil'nogo énterotoksina u klinicheskikh shtammov proteev, vydelennykh pri razlichnykh infektsiiakh.

The capacity of Proteus strains, isolated from patients with purulent inflammatory, urological and enteric infections, for the production of choleriform thermolabile enterotoxin was studied by means of the enzyme immunoassay (EIA) with the use of antitoxic serum to Escherichia coli enterotoxin. Out of 125 strains, 27 (21.6%) showed the capacity for producing choleriform thermolabile enterotoxin in EIA experiments. The results thus obtained indicate that EIA techniques can be used, in principle, for detecting the capacity of Proteus for the production of choleriform thermolabile enterotoxin.

[Characteristics of various morphological and biological properties of bacteria of the genus Proteus]. / Kharakteristika nekotorykh morfologicheskikh i biologicheskikh svoistv bakterii roda Proteus.

The stable O-form of Proteus has been found to differ from the initial H-form in the absence of flagellae or in a few weakly developed flagellae, in decreased capacity for agglutination with polyvalent and typing sera and in virulence for laboratory animals. As revealed in this study, the conversion of the H-form of Proteus into the stable O-form leads to the loss of resistance to streptomycin, chloramphenicol, tetracycline, monomycin, ampicillin and neomycin.

[Conservative regions of the gene of thermostable enterotoxin in Enterobacteriaceae--the principal possibility of their practical use]. / Konservativnye uchastki gena termostabil'nogo énterotoksina Enterobacteriaceae--printsipial'naia vozmozhnost' ikh prakticheskogo ispol'zovaniia.

The nucleotide sequences connected with the production of thermostable enterotoxins (ST) by the representatives of Enterobacteriaceae were analyzed. The conservative area sized up to 30 pairs of nucleotides at the 3'-end of all ST-genes, present in the bank, and responsible for the enterotoxicity of ST-toxin molecules was detected. On its basis 3 oligonucleotides were synthesized; 2 of them were used as primers in experiments on the amplification of the DNA of enterotoxigenic strains of Citrobacter spp., Escherichia coli and Yersinia spp. and the third one was used as a probe in experiments on dot-blot hybridization with the DNA of the above-mentioned cultures. The universal diagnostic test system making it possible to detect the ST-enterotoxin of opportunistic enterobacteria irrespective of their species was proposed.

[The use of random amplification of polymorphous bacterial DNA for the typing of bacteria in the genus Citrobacter]. / Ispol'zovanie sluchainoi amplifikatsii polimorfnoi bakterial'noi DNK dlia tipirovaniia bakterii roda Citrobacter.

To obtain the profiles of randomly amplified DNA, isolated from bacteria of the genus Citrobacter, the method of polymerase chain reaction was used. Nine oligonucleotides were evaluated for the possibility of their use as primers for the amplification of random polymorphous sequences of DNA; of these, 2 oligonucleotides which generated profiles, sufficiently reproducible and typical for different C. freundii and C. diversus strains, were selected. The possibility of using the above oligonucleotides in pair for amplification of species-specific fragments of polymorphous bacterial DNA for typing was shown.

[Molecular mechanisms of relationships between the host organism and pathogenic enterobacteria]. / Moleculiarnye mekhanizmy vzaimootnoshenii organizma i patogennykh énterobakterii.

Modern data on the molecular mechanisms of relationships between the host organism and the pathogenic representatives of the family Enterobacteriaceae in the host-parasite system are presented. The process of cytokine and eicosanoid regulation of the immune process of the host in the norm and pathology states are analyzed. The examples of the mechanisms of immune suppression, false antigenic stimulation and the mimicry of pathogens are given.

[The enterotoxigenic capacity of hemolysin-producing strains of Proteus isolated in acute intestinal infections in children]. / Enterotoksigennaia sposobnost' gemolizinprodutsiruiushchikh shtammov proteev, vydelennykh pri ostrykh kishechnykh infektsiiakh u detei.

The capacity of P. mirabilis and P. vulgaris strains isolated in acute enteric infections in children for producing enterohemolysin, a new type of hemolysin, has been shown. The relationship between the capacity of Proteus cultures for producing enterohemolysin and their capacity for inducing toxic secretory reaction on a ligated loop on the small intestine of rabbits in the absence of known thermostable and thermolabile antitoxin in bacteria.

[Phenomenon of apoptosis in the survival of enterobacteria in the parasite-host system]. / Fenomen apoptoza v vyzhivanii énterobakterii v sisteme parazit-khoziain.

Data on the apoptosis phenomenon with enterobacteria used as a model are presented. One of the mechanisms regulating the vital activity of eukaryotic cells is, together with cell proliferation and differentiation, the phenomenon known as "apoptosis". This physiological process of the eukaryotic cells death is used by many parasites in parasite--host relationships in different epitopes. The system known to trigger programmed cell death, is the surface receptor Fas, the receptor of tumor necrosis factor (TNF alpha) activated by the corresponding FasL ligand and TNF alpha, which further triggers the cascade mechanisms of the execution program. In various representatives of enterobateria different proteins serve as Fas ligand, viz. protein IpaB in Shigella flexneri, SipB activating converting enzyme IL-1 beta, identical to capsase-1, in Salmonella spp., YopP in Yersinia spp. Still the mechanism triggering apoptosis in Yersinia spp. has some original features. In Escherichia coli alpha-hemolysin is the factor triggering the suicidal program, the triggering mechanism being mediated by an increase in intracellular calcium ions.

[Biological properties of microflora in pyo-inflammatory complications in hematologic patients]. / Nekotorye biologicheskie svoistva mikroflory gnoino-vospalitel'nykh oslozhnenii u gematologicheskikh bol'nykh.

The occurrence of opportunistic bacteria isolated from hematological inpatients with pyo-inflammatory complications and strain affiliation of these bacteria were investigated. Gram-negative and gram-positive agents made up 51.9 and 48.1%, respectively, of the 1699 bacterial strains obtained from 814 patients. Klebsiella, E.coli, Pseudomonas aeruginosa, Proteus strains were able to produce LT-enterotoxin showing weak enterohemolytic activity, were sensitive to gentamicin and claforan and insensitive to carbenicillin, ampicillin, oxacilin, tetracycline, erythromycin.