Persistence factors of Francisella tularensis

The study of the persistence potential of 64 F. tularensis strains isolated from different sources was carried out. The wide spread of the antilysozyme, antilactoferrin and anticomplementory activities of F. tularensis were detected. F. tularensis, isolated from ticks and water, were characterized by the highest level of the expression of antilysozyme activity, while anticomplementory and antilactoferrin activities of the infective agents were characteristic of those microorganisms which were isolated from rodents and their excrements.     

Algorithm for prediction of reconvalescent salmonellosis carriage

Of total of 181 patients with Salmonella infection were examined by clinical and laboratory methods. As many as 124 indices characterizing biological properties of Salmonellae, a large intestine microbiocenosis status, systemic and local immunity, were investigated as well. Among these indices, the most revealing signs were defined to prognosticate the reconvalescent carrier state. Conclusion was made on the prevalence of immune mechanisms in the development of reconvalescent salmonella carriage and on the important role of the ability of a causative agent to inactivate the factors of host innate immunity in this process. Diagnostic prognosis algorithm for Salmonella bacterial carriage was worked out. Clinical testing confirmed its effectiveness.     

Pathogen persistence in infectious pathology

Problems of microorganism's persistence in infectious pathology are discussed in this work. Persistence of bacteria as the form of procaryotic and eucaryotic cells symbiosis unlimitedly long coexistence is considered. Questions of the microbial evolution formed in constant collision of the infective agent with macroorganism defense mechanisms are discussed. The spectrum of known mechanisms bacterial survival in conditions of an infected organism is considered. For discussion the problem of microbial persistence it is offered to include as model alongside with an independent cell, a microbial population as complex self-organizing system--the original "superorganism" having universal chemical regulation, the determining density of a population and equation of some physiological functions. It is offered to consider the host colonization resistance as a phenomenon of general biology directed on maintenance of a microecological homeostasis as a result of symbiotic interactions of an organism and it autochthonous microflora with the "key" kinds of biotope protection. The use of persistence characteristics of microorganisms is proved as a target in conditions of intermicrobial interaction of its allochthonous and autochthonous microflorae. Practical value of such approach in infectious pathology is shown.     

Persistence factors of Helicobacter pylori

Isolates of H. pylori from patients with chronic gastritis and peptic ulcer, were found to be capable of inactivating lysozyme and intercide (the bactericidal component of human leukocytic interferon). The expression and penetration capacity of their antilysozyme activity (ALA) and antiintercide activity was determined. The wide spread of ALA among H. pylori clinical isolates associated with inflammatory changes in bioptic specimens, confirmed the leading role of this microorganism in the pathogenesis of the gastric mucosal lesions. The retrospective analysis of clinical cases made it possible to recommend the use of the ALA sign as one of the criteria for choosing the scheme of eradication therapy even at the stage of the initial diagnostics of H. pylori infection.     

Persistent properties of protozoa-associated bacteria

The species structure and persistent properties (antilysozyme and antihistone activity) of bacteria forming associations with protozoa is revealed. Among them, 68.9% of the isolates were enterobacteria, the remaining organisms belonged to the families Aeromonas, Alcaligenes, Pseudomonas, Vibrio, etc. Within the family Enterobacteriaceae bacteria of the Escherichia group prevailed. 50.4% of the isolates were found to have antilysozyme activity and 97%--antihistone activity. The level of persistent properties in the representatives of allochthonous microflora was higher than that in the representatives of autochthonous microflora. In addition to antilysozyme activity antihistone activity was noted in protozoa-associated bacteria, which could be of importance for the formation of symbiotic links in natural associations. These data may be used in sanitary and hygienic practice for microecological monitoring of the environment.     

The ecological determinacy of the intraspecies diversity of pathogenic bacteria

The review deals with some theoretical and applied problems of the intraspecific diversity of pathogenic microorganisms. Special attention is given to the role of ecological factors in the formation of the phenotypic polymorphism of bacteria. The possibility of using the methods of mathematical analysis for the evaluation of the influence of the environment (ecotopes) on individual phenotypic characteristics of bacteria and their complex (bioprofile) is shown. The proposition on the bioprofile of microorganisms as a criterion of their ecological (ecotopic) marking is substantiated. The examples of using the data of the ecological marking of pathogenic bacteria in clinical epidemiology and ecological practice are presented.     

Phasic changes in reproductive potential, intracellular polyamines and antilysozyme activity in Escherichia coli in periodic culture

Growth-phase associated changes in and relationships between the specific growth rate (mu) characterizing the reproductive capacity of the cells, the contents of intracellular biogenic polyamines (BPA), such as putrescine (P), cadaverine (C), and spermidine (S), and antilysozyme activity (ALA) were studied in 37 strains of Escherichia coli grown in batch culture on solid medium. A decrease in mu upon the transition of the culture to the stationary growth phase was accompanied by a decrease in the pool of free BPA, mainly P and C, and by the appearance of ALA. The interrelations between the parameters studied were described as a complex of direct and negative correlations; the combination of low initial P and C contents, reduced P/S and C/S ratios, and a high level of ALA was designated as a factor of slight inhibition of E. coli reproduction. It is argued that BPA and ALA are integrated in a system controlling both the metabolism and stability of peptidoglycan in E. coli.     

Influence of cycloferon on the biological properties of bacterial intracellular pathogens

The influence of cycloferon on some biological properties of pathogenic (Shigella spp., Salmonella spp., Francisella tularensis, Brucella spp.) and opportunistic (Escherichia coli, Staphylococcus spp.) microorganisms has been experimentally determined in vitro. As revealed in these experiments, the preparation used at concentrations under study considerably suppresses the antilysozyme and anticomplementary activity of Gram-negative intracellular parasites (shigellae, salmonellae, F. tularensis, Brucella). These data reveal one of the possible mechanisms of the action of cycloferon on intracellular parasites in acute and chronic bacterial infections.     

Effect of vaginal Lactobacillus metabolites on biological properties of Staphylococcus epidermidis and Escherichia coli

The influence of supernatants and cell extracts of vaginal lactic acid bacilli on the growth, catalase, antilysozyme and anticomplementary activity of S. epidermidis and E. coli was studied. Changes observed in the persistence characteristics of these microorganisms were found to develop in different directions: in S. epidermidis a decrease in antilysozyme activity was mainly observed, while in E. coli the suppression of anticomplementary activity was registered. The modifying influence of lactic acid flora, revealed in this investigation, is regarded as one of the mechanisms facilitating the formation of microbiocenosis and ensuring colonization resistance.