[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.

[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.

[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.

[Use of antagonistic Bacillus subtilis bacteria for treatment of nosocomial urinary tract infections].

Effect of Bactisporin--a probiotic, containing spores of aerobic Bacillus subtilis 3H bacterium--for complex treatment of patients with nosocomial urinary tract infections was studied. 68 Cultures of different species of conditionally pathogenic bacteria were isolated from urine of the patients. Susceptibility of the isolated cultures to antibiotics before and after application of B. subtilis 3H metabolites was determined. The metabolites were accumulated on potato-glucose agar (PGA) while bacterium was cultivated on kapron membranes placed on surface of the medium. Influence of obtained metabolites on isolated strains was assessed by cultivation of each strain in metabolites-rich PGA during 24 h. Metabolites of B. subtilis led to decrease in resistance of isolated uropathogenic microflora to antibiotics. Use of Bactisporin in complex treatment of nosocomial urinary tract infections resulted in accelerated elimination of causative microorganism.

[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.