The Effect of the Intra- and Extracellular Metabolites of Microorganisms Isolated from Various Ecotopes on the Catalase Activity of Staphylococcus aureus ATCC 6538 P

The cell extracts (i.e., intracellular metabolites) and culture liquids (i.e., extracellular metabolites) of microorganisms isolated from various ecotopes were found to inhibit the catalase activity of Staphylococcus aureus ATCC 6538 P, which resulted in a considerable inhibition of the growth of metabolite-treated S. aureus cells by hydrogen peroxide. The inhibitory effect of microbial metabolites on S. aureus catalase can be considered as a mechanism of intercellular interactions responsible for the formation of microbiocenoses.     

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.     

The effect of the intra- and extracellular metabolites of microorganisms isolated from various ecotopes on the catalase activity of Staphylococcus aureus 6538P

The cell extracts (i.e., intracellular metabolites) and culture liquids (i.e., extracellular metabolites) of microorganisms isolated from various ecotopes were found to inhibit the catalase activity of Staphylococcus aureus ATCC 6538P, which resulted in a considerable inhibition of the growth of metabolite-treated S. aureus cells by hydrogen peroxide. The inhibitory effect of microbial metabolites on S. aureus catalase can be considered as a mechanism of intercellular interactions responsible for the formation of microbiocenoses.     

Influence of Hydrogen Peroxide,Lactic Acid,and Surfactants from Vaginal Lactobacilli on the Antibiotic Sensitivity of Opportunistic Bacteria

We studied as hydrogen peroxide, lactic acid, or surfactants from clinical isolates of vaginal lactobacilli and cell-free supernatants from probiotic strain LCR35 can influence on the sensitivity of opportunistic bacteria to antibiotics. We found that the most effective in increasing sensitivity to antibiotics were hydrogen peroxide and surfactants or their combination but no lactic acid. In some cases, the effect of the composition of hydrogen peroxide and surfactants was clearly higher than the sum of effects of these substances alone. With using of the supernatant of LCR35 was shown that the combination of surfactant and lactate has greater effect compared with surfactants alone. In concluding, metabolites of vaginal lactobacilli are suitable for the role of “antibiotic assistants” and it can help solve the problems the antibiotic resistance.     

Active forms of oxygen as a factor regulating surface characteristics of bacterial cells

AIM: Effects of sublethal concentration of active forms of oxygen (hydrogen peroxide and hydroxyl radical) on cell surface properties of Escherichia coil, Staphylococcus aureus, Bacillus subtilis, and Klebsiella pneumoniae were studied. MATERIALS AND METHODS: Hydrophobicity of cell surface measured by transition of cells from water phase to hydrocarbomic phase and by the ability of bacteria to sorb lysozyme and hemoglobin. RESULTS: Treating of bacterial cells with hydroxyl radicals compared with hydrogen peroxide resulted in more marked decrease of bacteria's hydrophobicity and reduction of their ability to sorb on the surface the lysozyme and hemoglobin. Increasing of the number of R-forms in the bacterial population after contact with hydroxyl radicals was revealed. CONCLUSION: Active forms of oxygen generated in biological systems in concentrations which are not lethal for majority of microorganisms can regulate prokaryote and eukaryote interactions by changing their surface characteristics and therefore they are an ecologic factor determining forming and existence of microbial cenoses.     

Combined method of community-acquired pneumonia prevention in military staff

Efficacy of pneumococcal polysaccharide vaccine "Pneumo 23" or its combination with food products prepared from vegetative material for prevention of community-acquired pneumonias has been compared. Advantages of combined method of prophylaxis in setting where pneumonia caused by different pathogens have been noted. Variability in etiology of community-acquired pneumonia was demonstrated by serological tests of patients' blood. During spring-summer season antibodies to Mycoplasma pneumoniae, Chlamydia pneumoniae, and Streptococcus pneumoniae were detected in 25.9, 2.5, and 7.0% of the patients respectively. During autumn-winter season antibodies to M. pneumoniae and S. pneumoniae were detected in 30.0 and 50.0% of the patients respectively.     

Mechanisms for survival of bacteria in oxidative stress and iron ions deficiency

The influence of culture medium Fe2+ content on the resistance of Escherichia coli to hydroxyl radicals formed in the presence of Fe2+ and hydrogen peroxide in Fenton reaction was investigated. It was founded that a lack of Fe2+ in a culture medium increased resistance of bacteria to hydroxyl radicals but not to hydrogen peroxide. The suggestion was made that the lack of Fe2+ starts up synthesis of metabolites which inactivate hydroxyl radical or block Fe2+ ions participating in Fenton reaction. The phenomenon under study is considered to be a possible mechanism for survival of bacteria in oxidative stress and iron ions deficiency.