[INTRA-ERYTHROCYTE INVASION OF ESCHERICHIA COLI STRAINS WITH VARIOUS LEVELS OF ANTI-HEMOGLOBIN ACTIVITY IN EXPERIMENT].

AIM: Study of intra-erythrocyte invasion of Escherichia coli strains with various levels of anti-hemoglobin activity on a model of generalized infection. MATERIALS AND METHODS: Experiments were carried out on 72 male mice. Generalized infection was induced by intravenous administration of E. coli strain day culture suspension with various values of hemolytic and anti-hemoglobin activity. The levels of hemoglobin in animal blood was determined by hemoglobin-cyanide method. Intra-erythrocyte invasion of E.coli was studied by using laser scanning confocal microscopy (LSCM). RESULTS: The largest decline (p < 0.05) of hemoglobin levels was detected in animals, infected with E. coli strains with a high levels of antiHbA and HA (58.3 ± 0.6 g/l and 69.7 ± 1.1 g/l). Using LSCM, microogranisms with a high levels of antiHbA were established to penetrate erythrocytes more frequently (70 ± 3.4%), than with a low (5.5 ± 1.7%). CONCLUSION: The largest frequency of bacteria detection in erythrocytes and the highest decline of blood hemoglobin levels were noted during infection of animals with E. coli strains with high anti-hemoglobin activity.

Role of Biological Characteristics of Staphylococcus epidermidis in Intraerythrocytic Invasion and in Modulation of Erythrocyte Catalase and Superoxide Dismutase Activities in Experimental Generalized Infection.

Studies on mouse model of generalized Staphylococcus epidermidis infection have demonstrated that erythrocytes more often contained microorganisms with pronounced antihemoglobin activity and less frequently with hemolytic activity. Infection with S. epidermidis strains characterized by pronounced hemolytic or antihemoglobin activities was associated with inhibition of erythrocyte catalase and superoxide dismutase activities in all cases, except infection with strains with high antihemoglobin activity, when superoxide dismutase activity increased.

[Formation of biofilms by agents of surgical soft tissue infections].

AIM: To determine the ability of agents of surgical soft tissue infections to form biofilms. MATERIALS AND METHODS: Material for the study was strains of microorganisms causing surgical soft tissue infection (phlegmon): 38 strains of Staphylococcus aureus, 16 strains of coagulase-negative staphylococci, 20 strains of enterococci, and 10 strains of pseudomonades. Ability of microorganisms to form biofilms was determined by photometric method. Microscopic evaluation included study of pathologic material from wounds as well as biofilms obtained in vitro. RESULTS: All strains of pseudomonades and 80% of enterobacteria strains had marked ability to form biofilms. This characteristic was less prevalent and expressed in staphylococci. Direct relation between ability of microorganism to form biofilm and duration of illness (correlation coefficient - 0.68) was revealed. Biofilms in wounds were detected only 3 or more days after surgery. CONCLUSION: Agents of surgical soft tissue infections are able to form biofilms. This ability of microorganisms realizes not onlyin vitro but in wound too. Direct correlation between expression of ability to form biofilms and duration of illness allows to consider this characteristic as marker of switch of infectious process to chronic state.

[Biorhythms of antibiotic resistance of microorganisms].

AIM: To study of circadian dynamics of antibiotic susceptibility and resistance of Gram-positive and Gram-negative microorganisms. MATERIALS AND METHODS: Circadian dynamics of antibiotic susceptibility was studied on clinical strains of enterobacteria, non-fermenting Gram-negative bacteria, and staphylococci which were isolated and identified by common methods. During a day, with 3-hours intervals, studied strains were tested on susceptibility to ampicillin, oxacillin, ceftriaxone, meropenem, gentamycin, and ciprofloxacin using method of serial dilutions in agar. RESULTS: Circadian biorhythms of resistance to antibiotics in studied microorganisms were revealed. Along with common patterns, differences in temporal changes of microrganisms' susceptibility to antibacterial drugs were noted. Chronobiologic approach allowed to reveal significant amplitude of changes of minimal inhibitoryconcentration (MIC) of antibiotics versus resistant Gram-positive cocci reflecting presence of susceptibility periods, whereas in susceptible Gram-negative bacteria peaks of resistance were observed. Circadian dynamics of MIC of majority of antibiotics versus resistant Gram-negative bacteria and susceptible Gram-positive cocci was characterized by lower amplitude of changes without shifts from antibiotic resistance to susceptibility and vice versa. CONCLUSION: Obtained data open perspective of using biorhythmological approach in study of susceptibility of microorganisms to antibiotics during the elucidation of mechanisms of pathogens adaptation to environmental conditions and creation of new strategies of control for antibiotic resistance strains.

[Circadian rhythms of antibacterial resistance, coagulase and antilysozyme activity of Staphylococcus aureus].

AIM: To determine daily dynamics of antibacterial resistance as well as antilysozyme and coagulase activity of S. aureus strains. MATERIALS AND METHODS: On an example of clinical strains of S.aureus isolated from patients with surgical infections daily dynamics of biological characteristics of staphylococci was studied. After 12 hours of incubation strains were tested for coagulase activity by standard method (test tube method), antilysozyme activity by photometric method, and antibacterial resistance by method of serial dilutions in agar. Tests were repeated each 3-hours during a day. RESULTS: Variation of levels of studied biological characteristics of staphylococci during a day was revealed. Structures of coagulase and antilysozyme circadian rhythms had some differences in different S. aureus strains. Alongside with it, similarity in temporal expression of such biological characteristics of staphylococci as antibacterial resistance and antilysozyme activity was noted. CONCLUSION: Obtained data open prospect to use biorhythmological approach in study of biological characteristics of microorganisms during evaluation of their mechanisms of adaptation to changing environmental conditions. Chronobiological approach allows to reveal periods of maximal expression of S. aureus characteristics that could be used for increasing of effectiveness of antibacterial treatment by the choice of optimal time for administration of antibiotic.

[Features of surgical infection of soft tissues]. / Osobennosti khirurgicheskikh infektsii miagkikh tkanei.

Microflora from surgical infection foci of soft tissues was studied in 92 patients with local, 78 patients with spread and 10 patients with generalized forms of pyo-inflammatory processes. Increase of bacterial contamination of surgical infection foci, more frequent detection of gram-negative bacteria, associations of microorganisms, high antibiotics resistance and persistent characteristics of bacteria in spread and generalized forms of surgical infections were found. Increase of persistent potential of infective agents is significant for prolongation of the disease and generalization of infectious process.

[Microbiological specifics in the course of suppurative inflammatory processes in soft tissues of patients with diabetes mellitus]. / Mikrobiologicheskie osobennosti techeniia gnoino-vospalitel'nykh protsessov miagkikh tkanei u bol'nykh sakharnym diabetom.

The focal microflora of pyo-inflammatory processes has been studied in dynamics in 200 patients with diabetes mellitus. It was found that a longer and more severe course was due to the changed specific composition of causative agents and to the increased specific diversity of the latter in the process of pyo-inflammatory progressing. It was established that the usage of the method of "close" wound management with the application of oxytocin inhibited the change of the causative agents in the course of the disease, led to a more rapid elimination of microorganisms from the pyo-inflammatory focus, to the less frequency of recurrent surgical interventions and shorter duration of courses of treatment in contrast to the results obtained with the other methods of treatment.

[The microbiological characteristics of soft-tissue surgical infection]. / Mikrobiologicheskie osobennosti khirurgicheskoi infektsii miagkikh tkanei.

The dynamic study of microflora in the foci of surgical infection of soft tissues was made. In 45 patients the course of the infectious process was characterized by the change of causative agents in the course of the disease. As established in this study the frequency of changes in the species composition of microflora in the foci of surgical infection in the course of the disease directly correlated with the occurrence of purulent septic complications requiring repeated surgical intervention. Changes in the species composition of causative agents should be regarded as their adaptation to the anti-infectious protection of the body, which is one of the regulatory mechanisms of the parasitic system.

[The dynamics of the species composition, antilysozyme activity and antibiotic resistance of the causative agents of soft-tissue surgical infection]. / Dinamika vidovogo sostava, antilizotsimnoi aktivnosti i antibiotikorezistentnosti vozbuditelei khirurgicheskoi infektsii miagkikh tkanei.

The dynamics of the microflora in the foci of surgical infection in 54 patients was studied. Staphylococci and streptococci prevailed among the primarily isolated causative agents. In complicated forms of surgical infection of soft tissues the change of causative agents, mainly to gram-negative opportunistic microflora with a higher level of resistance to antibiotics and high antilysozyme activity, was observed more often than in noncomplicated forms of such infection.