Correlation of marker periodontopathogenic bacteria with the immune component sCD14 secretion level in inflammatory periodontal diseases.

Lipopolysaccharide of the cell wall of gram-negative bacteria is a highly active biological substance: its interaction with toll-like receptors-4 (TLR-4) of myeloid cells leads to the activation of a cascade of inflammatory reactions, which is accompanied by the release of the soluble CD14 receptor (sCD14), which can be considered not only as a marker of cell activation by endotoxin, but also as a marker of microbial translocation. The aim of the work was to assess the prognostic significance of the sCD14 level in the samples of the periodontal pocket in inflammatory periodontal diseases and the relationship of its secretion with marker periodontopathogens. For the study, washes were obtained from the periodontal pocket (88 samples in total) from patients with chronic periodontitis and intact periodontium. The sCD14 content was determined by ELISA; during real-time PCR, the marker periodontopathogens Aggregatibacter actinomycetemcomitans, Tannerella forsythia, Treponema denticola, Porphyromonas gingivalis, Prevotella intermedia, and Candida albicans were isolated. The study revealed differences in the level of sCD14 secretion by groups: in chronic periodontitis, its content was 8,5 times higher than in the control group and amounted to 17,2±4,06 ng/ml (p=0,006). The frequency of detecting genes of periodontal pathogenic bacteria was 89,3% in patients with periodontitis and 31,25% in the group with intact periodontium. An interesting dependence of the detection of periodontal pathogenic bacteria in the group of patients with chronic periodontitis was established depending on the content of sCD14. Thus, at high concentrations of soluble coreceptor, a greater number of periodontopathogenic bacteria of the I and II orders were released. Thus, in inflammatory periodontal diseases, the processes of sCD14 synthesis change, which is probably due to the colonization of periodontal pathogenic bacteria and the action of their toxins and aggression factors. The relationship of marker periodontopathogens with the level of secretion of the immune component sCD14 and its effect on the structure of the periodontal index reflect shifts in the processes of reparative regeneration of the oral mucosa and the regulation of local immunity in response to microbial invasion.

Role of antimicrobial peptides system in inflammatory periodontal diseases non-specific oral cavity protection.

The system of antimicrobial peptides (AMP) is one of the most ancient mechanisms of the macroorganism resistance to infectious pathogens invasion. The aim of the study was to determine the role of the antimicrobial peptides system and periodontal pathogenic markers in the development and progression of inflammatory periodontal diseases. Gingival pocket washes (91 samples in total) for the research were received from patients with inflammatory periodontal diseases (chronic periodontitis and gingivitis) and intact periodontium. Using ELISA, the content of antimicrobial peptides was determined: human alpha-defensin (HNP 1-3), beta-defensin (HBD 1-3) and cathelicidin (LL-37). Periodontal pathogenic markers were isolated during RT-PCR. The study revealed differences in AMP concentrations by groups: level of HBD 2 in patients with chronic periodontitis was 1,36 times higher than those in the group of patients with chronic gingivitis (p=0,023) and 2,39 times higher than those in the control group (p<0,001), the content of HNP 1-3 in the group of patients with chronic periodontitis was reduced by 1,23 times compared with the indicators of the group of patients with gingivitis (p=0,045) and by 1,97 times compared with the indicators of the control group (p<0,001). The frequency of detection of periodontal pathogenic bacteria genes was 88,0% in patients with periodontitis, 76,92% in patients with gingivitis and 33,3% in the group with intact periodontium. HBD 2 content moderately correlated with the definition of P. gingivalis (r=0,612; p=0,022), T. forsythensis (r= 0,434; p=0,015), A. actinomycetemcomitans (r=0,483; p=0,006), a moderate negative correlation was detected between the content of HNP 1-3 and the release of periodontal pathogens in associations (P. gingivalis with T. forsythensis and T. denticola) (r=-0,388; p=0,031) in the group of patients with chronic periodontitis. Thus, the revealed relationships and correlations indicate shifts in the processes of reparative regeneration of the oral cavity and the regulation of local immunity in response to microbial invasion.

Spectrum and resistance determinants of oral streptococci clinical isolates.

The profiles of oral streptococci sensitivity to antibacterial drugs may reflect information about the presence of macroorganism resistance determinants. The aim of the work was to isolate the spectrum of oral streptococci from the microbiota of the oral cavity of patients and to determine their sensitivity to a wide range of antibiotics. A total of 342 microbial streptococcal isolates were isolated from saliva samples and a periodontal pocket and tested for antibiotic sensitivity. Species identification of streptococci was carried out using biochemical API test systems. Evaluation of antibiotic resistance was performed using E-tests. Real-time PCR was used to identify the presence of tetracycline and macrolide resistance genes. The study identified six types of oral streptococci: S. oralis, S. salivarius, S. mitis, S. sanguinis, S. anginosus and S. mutans. All streptococci were sensitive to linezolid and meropenem. The proportion of penicillin-resistant streptococci in the subgroup S. oralis / mitis / mutans was 47,8% versus 23,5% in the subgroup S. salivarius / sanguinis / anginosus (p = 0.020). Significant levels of resistance were revealed to macrolides (erythromycin) - 47,9%, tetracyclines (tetracycline) - 44,4% and quinolones (ofloxacin) - 41%. Multiple drug resistance (MDR) was detected in 31,9% of oral streptococcal isolates, a combination of erythromycin, tetracycline and ofloxacin resistance was prevalent in 79 isolates (23,1%). The most common genotypes of macrolides and tetracycline resistant oral streptococci (in 127 streptococcal isolates with combined resistance) were ermB-mefE + and tetM + tetQ-, respectively. Thus, S. oralis / mitis / mutans group streptococci predominated in the structure of antibiotic-resistant oral streptococci, including MDR. So, being in one of the most densely populated biotopes of a macroorganism, oral streptococci can mediate the transfer of resistance determinants to more pathogenic and clinically significant microorganisms, which requires careful monitoring of their level of susceptibility to antimicrobial agents.

[General principles of antibiotic resistance evolution in bacteria (review of literature).]

Currently, the impact of antibiotic resistance on human health is a worldwide problem and its study is of great interest from a molecular genetic, environmental and clinical view-point. This review summarizes the latest data about antibiotic resistance, the classification of microorganisms as sensitive and resistant to the action of antibiotics, reveals the concept of minimum inhibitory concentration from modern positions. The resistance of microorganisms to antibacterial agents can be intrinsic and acquired, as well as being one of the examples of evolution that are currently available for study. Modern methods of whole-genome sequencing and complex databases of nucleotide-tagged libraries give an idea of the multifaceted nature of the mechanisms of intrinsic resistance to antibiotics and are able to provide information on genes encoding metabolic enzymes and proteins that regulate the basic processes of the physiology of bacteria. The article describes the main ways of spreading the resistance of microorganisms, reflects the concepts of "founder effect" and the fitness cost of bacteria, which underlie the emergence and evolution of antibiotic resistance. It is shown that the origin of antibiotic resistance genes that human pathogens currently possess can be traced by studying the surrounding not only clinical, but also non-clinical (ecological) habitats. As well as microorganisms of the surrounding ecosystems are the donors of resistance genes in horizontal gene transfer.

Epidemiological and molecular characterization of Streptococcus pneumoniae carriage strains in pre-school children in Arkhangelsk, northern European Russia, prior to the introduction of conjugate pneumococcal vaccines.

BACKGROUND: The 13-valent Pneumococcal Conjugate Vaccine (PCV-13) was introduced in the National Immunization Programme (NIP) schedule in Russia in March 2014. Previously, the 7-valent Pneumococcal Conjugate Vaccine (PCV-7) was marketed in Russia in 2009 but has never been offered for mass vaccination. A carriage study was performed among children in Arkhangelsk in 2006. The objective was to determine the prevalence of carriage, serotype distribution, antimicrobial susceptibility and the molecular structure of Streptococcus pneumoniae strains before marketing and introduction of PCV-13. METHODS: A cross-sectional study was conducted on a cluster-randomized sample of children and a self-administrated questionnaire for parents/guardians.  Nasopharyngeal samples were collected from 438 children younger than 7 years attending nurseries and kindergartens in the Arkhangelsk region, Russia. Detailed demographic data, as well as information about the child's health, traveling, exposure to antimicrobials within the last 3 months and anthropometric measurements were collected for all study subjects. Variables extracted from the questionnaire were analysed using statistic regression models to estimate the risk of carriage. All pneumococcal  isolates were examined with susceptibility testing, serotyping and multilocus sequence typing. RESULTS: The overall prevalence of asymptomatic carriage was high and peaking at 36 months with a rate of 57%. PCV-13 covered 67.3% of the detected strains. High rates of non-susceptibility to penicillin, macrolides and multidrug resistance were associated with specific vaccine serotypes, pandemic clones, and local sequence types. Nine percent of isolates represented three globally disseminated disease-associated pandemic clones; penicillin- and macrolide-resistant clones NorwayNT-42 and Poland6B-20, as well as penicillin- and macrolide-susceptible clone Netherlands3-31. A high level of antimicrobial consumption was noted by the study. According to the parent's reports, 89.5% of the children used at least one antimicrobial regime since birth. None of the hypothesised predictors of S. pneumoniae carriage were statistically significant in univariable and multivariable logistic models. CONCLUSIONS: The study identified a high coverage of the PCV-13-vaccine, but serotype replacement and expansion of globally disseminated disease-associated clones with non-vaccine serotypes may be expected. Further surveillance of antimicrobial resistance and serotype distribution is therefore required.

[Competence-oriented exam in clinical laboratory diagnostics for students studying in the specialty «Medical Biochemistry¼.]

In connection with the introduction of annexes and changes to the Federal State Educational Standard of Higher Education in the specialty 30.05.01 «Medical Biochemistry¼, a need arose to improve the assessment tool of general professional and professional competencies formation in the discipline - clinical laboratory diagnostics. A competence-oriented exam (COE) in the studied discipline is developed and implemented. Admission to the exam is the development of practical skills by students in the discipline modules, portfolio design and posting the results on the "Moodle" platform. COE includes two stages: testing to assess the level of theoretical knowledge deepening and solving a situational problem to assess the skills and abilities, interpret the results of laboratory tests and prepare a clinical and laboratory report. Situational tasks and checklists have been developed that make it possible to conduct an objective and comprehensive assessment of the competencies formed by students during the training process, which allows the graduate completed the program to solve professional problems.

[Mechanisms of microorganism resistance to beta-lactam antibiotics].

Literature data on molecular mechanisms of resistance to beta-lactam antibiotics have been summarized. The following mechanisms are examined: appearance ofpenicillin-binding proteins (PBP) with lower affinity to beta-lactam antibiotics; production by microorganisms of enzymes (beta-lactamases) that hydrolyze beta-lactam ring; disruption of microbial cell outer membrane permeability and active secretion of antibiotics from the microbial cell (effiux-effect). Characterization of extended spectrum beta-lactamases (ESBL) as well as data on structure of SCCmec element of MRSA and bacterial efflux system (RND) is presented.

[Influence of antibiotics on formation of microecology in premature children with low and extremely low body weight at birth].

AIM: Study the influence of antibiotic therapy on the formation of main biotope microflora nasopharynx, large intestine, urinary system) of the premature child organism weighing less than 500 g at birth in hospital. MATERIALS AND METHODS: Bacteriological study of upper respiratory tract discharge, urine, large intestine contents in 58 premature children during admission and discharge from newborn and premature children pathology department was carried out. Factor analysis method was applied to construct factor models of antibiotics influence on main biotope microbiocenosis formation. RESULTS: Deficiency of obligatory normal flora members in all the 3 biotopes was noted in all the children during admission to the department. Colonization of all the biotopes by obligatory members was noted by discharge, however the parameters do not reach age norm. Antibiotics therapy is the main factor, in all the biotopes opportunistic and pathogenic microorganisms prevail. CONCLUSION: The formation of main biotope microbiocenoses does not occur and carriage of pathogenic and opportunistic microorganisms is noted in premature children receiving massive antibiotic therapy.

Clinical isolates of Staphylococcus aureus from the Arkhangelsk region, Russia: antimicrobial susceptibility, molecular epidemiology, and distribution of Panton-Valentine leukocidin genes.

A total of 91 consecutive clinical isolates of Staphylococcus aureus were collected at the Regional Hospital of Arkhangelsk, Russia, from May to December 2004, and examined for antimicrobial susceptibility, methicillin resistance and presence of Panton-Valentine leucocidin (PVL) genes. Epidemiological typing was performed by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Methicillin-resistant S. aureus (MRSA) isolates were examined by staphylococcal cassette chromosome mec (SCCmec) typing. High-to-moderate rates of resistance to penicillin (beta-lactamase production; 93%), tetracycline (40%), erythromycin and clindamycin (32%) were observed. Forty out of ninety-one (44%) isolates were positive for PVL genes. Thirty-six (40%) PVL-positive methicillin-susceptible S. aureus (MSSA) strains were shown by PFGE and MLST typing (ST121, ST681, ST837) to be part of a nosocomial outbreak caused by clonal complex (CC) 121. PFGE, MLST and SCCmec typing revealed three MRSA clones. Sequence type (ST) 239-III (n=11), ST1097-III (n=1) and ST8-IV (n=3) belong to CC8 of epidemic multiresistant MRSA, whereas ST426-MRSA-IV/CC395 (n=1) has not been reported previously. All MRSA strains were PVL negative. The overall results underline the necessity of microbiological sampling, antimicrobial susceptibility testing, and epidemiological typing as a rational basis for antimicrobial treatment of S. aureus infections, and infection control measures to limit the spread of multiresistant MRSA and epidemic MSSA clones.

[Microflora of the bronchial contents in chronic lung diseases]. / Mikroflora bronkhial'nogo soderzhimogo u bol'nykh s khronicheskimi zabolevaniiami legkikh.

The parallel bacteriological and mycological study of the contents of the bronchi in patients with various forms of chronic pneumonia provided a clearer picture of the causative agents of the disease. The composition of microflora in the bronchial contents corresponded to the severity of the process. Uncomplicated chronic pneumonia took its course with a bacterial monoculture, belonging predominantly to the family of pyogenic cocci, present in the discharges. The formation of abscesses and the development of bronchioectases proceeded of bacterial and mycotic associations. The development of malignant tumors was accompanied by the colonization of the pulmonary ways by a variety of organisms, including bacteria of the fecal flora.

[Antibiotic sensitivity of bacteria isolated in association with fungi]. / Chuvstvitel'nost' lc antibiotikam bakterii, vydelennykh v assotsiatsii s gribami

Sensitivity of bacteria isolated from the bronchial contents of 414 patients with chronic non-specific lung diseases was studied with respect to 8 antibiotics. A significant decrease in the antibiotic sensitivity of cocci, i. e. staphylococci and streptococci isolated in association with fungi, i. e. Candida, Aspergillus and Penicillium was shown. The results of the study were confirmed experimentally in mixed incubation of the staphylococci with Candida albicans in vitro.