Bacterial interactions

The review deals with specific features of interactions in microbial biocenoses. The subdivision of the mechanisms of microbial interactions in associations into direct and indirect ones is proposed. The formation of intercellular contacts and matrix belongs to one group of mechanisms, the second group includes the products of metabolism (changes in the physical and chemical composition of the medium, specific growth regulators) and secreted factors (antibacterial substances, pheromones and signal molecules, vitamins, specific mediators). The applied aspects of the knowledge of microbial interactions in the human body are presented.     

Effect of medicinal plants on the antilysozyme activity of microorganisms]

Medicinal plants effect on antilysozyme activity of E. coli, Klebsiella, S. aureus, Candida, Bifidobacterium, Bacteroides, Clostridium was evaluated in vitro. It was demonstrated that the effects differed substancially according to the microorganism taxonomy. The experimental data on the plants inhibitory activity may be used for elaboration of effective regimes of infections and disbiosis treatment.     

Interaction between bacteria and erythrocytes and their role in the development of infectious anaemia

The concentration of hemoglobin in blood of patients with pyoinflammatory diseases was shown to depend on the ability of bacteria to interact with erythrocytes. Bacteria with high hemolytic activity (> or = 70% hemolysis) and anti-hemoglobin activity (>3 g/1) were isolated from pyoinflammatory foci of patients suffering from anaemia. Structural changes were investigated in vitro and in vivo erythrocytes in terms of their interaction with microorganisms by electron microscopy. For the first time, the phenomenon of coccal location within erythrocytes was established. Staphylococci with a high level of hemolytic and anti-hemoglobin activity appear to survive and multiply within erythrocytes that results in destroying hemoglobin. Staphylococci with a low level of mentioned activities are subjected to destructive changes within erythrocytes and subsequent killing.     

Method of determining the antilysozyme activity of microorganisms

The method for the determination of the antilysozyme activity of microorganisms is described. The method consists in the cultivation of the strains under study in a lysozyme-containing medium, and the effect of lysozyme inactivation is determined from the growth of Micrococcus luteu S indicator strain adjacent to active strains. The quantitative evaluation of this property is presented. The study of 1 296 strains belonging to 9 genera has disclosed that antilysozyme activity occurs most frequently among Gram-negative bacteria.     

Experimental and clinical studies of drug regulation of the anti-lysozyme activity of microorganisms causing opportunistic infections

Experimental materials on choosing antibiotics for etiotropic therapy of opportunistic infections with an account of the regulating effect of the drugs on the ++anti-lysozyme activity of pathogens (the factor of intracellular parasitism) are presented. The in vitro data were applied to the clinical trials in 30 patients with chronic and acute pyelonephritis of the Proteus etiology and to 25 patients with chronic inflammatory diseases of Staphylococcus etiology. It was shown that the use of the antibiotics which lowered the ++anti-lysozyme activity of microorganisms promoted a more rapid disappearance of the disease clinical signs, increased 2- to 3-fold the terms of the remission and resulted in an increase in the number of the persons with complete remission (54.5 to 63.6 per cent) as compared to the use of the drugs which stimulated the pathogen property or were indifferent to it.     

Effect of gastrointestinal tract secretions on the anti-lysozyme activity of enterobacteria

The effect of the duodenal contents and its components on the antilysozyme activity (ALA) of enterobacteria was studied. Under the action of native bile and the preparation of dried bile the stimulation of the expression of ALA factor in 86.6-93.3% of enterobacteria was observed. Pancreatin increased the level of the secretion of ALA factor by 50% in comparison with the control. The preparation of egg lysozyme produced no changes in the frequency and level of the expression of ALA factor. The study revealed the dose-dependant character of the action of duodenal contents: in the native form, as well as at concentrations of 50% and 25%, duodenal contents stimulated the expression of the ALA factor of enterobacteria; at concentrations of 12.5% and lower, its effect could be stimulating, inhibitory or neutral.     

Clinical importance of infective agent persistence in Salmonella infection in children

The persistence properties of 70 S. enteriditis cultures and 12 S. typhimurium cultures isolated from the feces of children of the earliest age groups with the gastrointestinal form of Salmonellosis infection were studied. The study revealed that the low level of persistence properties occurred in most cases of mild forms of the disease. Salmonellae with a high level of anticomplement and antilysozyme activity were more often isolated in cases of moderate and severe forms of salmonellosis. The presence of correlation between the expression of the factors under study and the severity of the symptoms of intoxication in combination with the duration of the diarrhea syndrome in moderate and severe forms of Salmonella infection in children of the earliest age groups was established. The suggestion was made that the evaluation of the persistence properties of bacteria may be used for the prognosis of the course of the infectious process.     

The role of persistence and virulence factors in microecological changes in a humans

The patterns of persistence and virulence factors expression in the representatives of human microbial biocenosis depends on a complex of the environmental conditions: influence of microbes-symbionts, biotope peculiarities, properties of microorganisms located within eukaryotes. Interactions of symbionts in pairs "indigen-indigen" isolated from mucous membrane of tonsils in healthy persons, did not lead to changes in expression of pathogenic properties. Interinfluence in pairs "pathogen-indigen" and "indigen-indigen", isolated from patients with chronic tonsilitis were accompanied by an increase of anti-lysozyme, hemolytic and lecithovitellase activities. Migration of strains of non-enzymatized gram-negative bacteria (NEYNB) from nasal into tympanic cavity in experimental acute purulent otitis is connected with an earlier increase of their number in the nasal cavity and the expression of anti-lysozyme activity. In acute and chronic pyoderma, expression of ALA is more marked in bacteria from a perifocal damage in contrast to focal damage of normal skin. In conditions of interaction between erythrocytes and staphylococcal clones with different levels of expression of pathogenic factors, differences were observed in dynamics of hemolytic and anti-hemoglobin activities.