Vol 96, No 2 (2019)

Aim. Study of the influence of bacteriophages on the formation  of resistance of opportunistic bacteria to antibacterial  drugs. Materials and methods. The sensitivity of 108 strains of Staphylococcus aureus to the staphylococcus  bacteriophage,  97 strains of bacteria of the genus Klebsiella to the bacteriophage Klebsiella polyvalent, and also to antibacterial  preparations  before and after interaction  with a specific bacteriophage has been studied. Results. The sensitivity of S. aureus bacteria to the staphylococcus bacteriophage was 66.7%, the lytic activity of the Klebsiella bacteriophage was polyvalent for strains of the Klebsiella genus, 83.5%. A decrease in the number of sensitive and moderately resistant strains of S. aureus to antibacterial  drugs after interaction  with a specific bacteriophage has been reported. The number of bacteria sensitive to antibiotics of the genus Klebsiella increased under the influence of the Klebsiella bacteriophage. Conclusion. The results of the study testify to the multidirectional influence of bacteriophages  on the antibiotic  susceptibility of opportunistic cultures and the need for additional  study of this issue with the help of modern  molecular genetic methods of research.

Aim. Comparative  analysis of the sequenced on our own effort genomes of non-toxigenic strains with different set of pathogenicity genes and assessment of their virulence on the model of intestinal inoculation of newborn rabbits. Materials and methods. Whole-genome DNA sequencing of 26 strains was carried out using semiconductor sequencing technology. Haemolysin and hemagglutinin-protease production was evaluated applying conventional methods. Virulence of the strains for newborn rabbits was determined  through intraluminal inoculation at the dose of 10⁷ CFU/ml. Results. On the basis of whole genome analysis of ctxA^-tcpA⁺ and ctxA^-tcpA^-  non-toxigenic strains, differences in composition  and structure stability of mobile elements associated with pathogenicity have been identified. Significant differences in nucleotide sequences of hlyA, hapA, and rtxA genes, encoding  production of additional  pathogenicity  factors, have also been detected. The paper provides the results of assessment of their phylogenetic relations. Experiments on animal models have confirmed the inability of non-toxigenic ctxA^-tcpA⁺ and ctxA^-tcpA^- strains to cause the development of typical cholera infection. Conclusion. New data on the genome structure of different non-toxigenic strains and their phylogenetic relations have been obtained. Based on the results of inoculation  of animal models with cells of non-toxigenic strains with the studied genome the inference is drawn on their inability to cause the development of typical cholera infection.

Aim. To analyze the epidemiological situation of rotavirus infection in the Orenburg region, taking into account  the manifestations  of the epidemic  process and the molecular  genetic characteristics  of rotavirus group. Materials and methods. We рresented the results of epidemiological and molecular genetic monitoring of rotavirus infection in the period 2013-2017. Molecular genetic typing was performed in 232 fecal samples of patients under 3 years of age with rotavirus infection. Were used methods of retrospective epidemiological analysis, ELISA, PCR. Results. The incidence of high tear and had a tendency to increase. The most affected were children under 14 years of age. The genetic potential of the rotavirus population in the region was represented by ten main genotypes. The leading significance in the epidemic process were genotypes with the highest frequency of occurrence:  G4[P]8  (56,9%), G9[P]8  (12,9%), Mixt (8,6%), G2[P]4  (7,7%), G1[P]8  (6,5%). Conclusion. Were revealed a significant increase in the incidence of rotavirus infection among children. Were revealed the dominant genotypes of rotaviruses, their regional diversity and change during several seasons.

Aim.  The  analysis  of  epidemiological  situation  on  natural  focal  infections  in  the  south  of  the European  part of the Russian Federation in 2017. Materials and methods. Data of statistical documentation of Departments of Rospotrebnadzor, Centers of Hygiene and Epidemiology in subjects of the Russian Federation, Plague Control Research Institutions  and Anti-Plague stations from 8 subjects of the Southern and 7 subjects of the North-Caucasian Federal Districts were used. The findings have been treated using by Microsoft Excel 2010 program. Results. On the territory of the south of the European  part of the Russian Federation 962 cases of natural focal infectious diseases (of which 89 per cent were bacterial etiology and 11 per cent were viral etiology) were identified in 2017. Compared  with 2016 the rate of bacterial natural focal infections increased by 2,3 per cent,  the rate of viral natural  focal infections decreased by 50,7 per cent.  The number  of natural  focal infections  patients  decreased  by 8 per cent compared  to the previous year. The most of epidemiological complications  were observed on the «tick-borne» infections, the rate of which in the general structure of the reported natural focal infections cases amounted  to 78,6 per cent (756 patients). Also 6 dengue fever cases were registered, but all of the patients might have acquired the disease after travelling to other areas. Conclusion. The analysis of natural focal infections morbidity in the south of the European  part of the Russian Federation in 2017 demonstrates  the retention  of activity of the natural foci of bacterial and viral infections,  therefore questions of prevention  of natural focal infectious diseases and constant  monitoring  of their natural  foci in subjects of the Southern  and North-Caucasian Federal Districts had the particular relevance.

Aim. To study the effect of exometabolites  of Bifidobacterium bifidum on the biological properties of causative agents of purulent-septic complications  in trauma and orthopedic  practice and to evaluate their effect on reparative bone tissue regeneration in the peri-implant zone in the postoperative period. Materials and methods. Using the museum cultures of B. bifidum 791, S. aureus 25923 ATCC,  P. aeruginosa 27853 ATCC  and  antibiotic-resistant hospital  strains,  isolated from patients  with periprosthetic  infection  and osteomyelitis (S.aureus 889, S. epidermidis 2041, P. aeruginosa 9672). The supernatant  (exometabolites)  of B. bifidum 791 was obtained from a broth culture, which was centrifuged and passed through a membrane filter. In studying the effect of exometabolites  of bifidobacteria  on the proliferative activity of bacteria, the two-day supernatant  of B. bifidum was co-incubated for 24 cultures of museum  and hospital strains. The biofilm formation  in vitro experiment  was studied after 24 and 96 hours. Treatment  of implants with exometabolites of bifidobacteria was carried out for 30 minutes. Experimental  research was carried out on rabbits of breed «Flandr». Titanium  implants  without  coating (control)  and with porous SBKFM  coating treated with exometabolites  of B. bifidum (experiment) were screwed into the tibial bones of animals. Histological examination  and computed  microtomography were performed  using a SkyScan 1172 instrument (BRUKER). Result. Depending on the time of cultivation of bifidobacteria, the supernatant B. bifidum 791 had a bacteriostatic  and bactericidal effect to varying degrees, and also inhibited the biofilm formation of the studied microorganism cultures, including antibiotic-resistant strains. In in vivo experiments, the use of porous SBKFM coatings on titanium implants treated with the supernatant of bifidobacteria made it possible to maintain the mineral density indices of the peri-implantation zone at a high level in comparison with the use of control titanium implants without coating. Conclusion. Positive results of preclinical experiments are promising for further clinical research in trauma and orthopedic  practice, which ultimately will reduce the risk of developing septic complications  and prevent the migration of metal structures and instability of endoprostheses in the postoperative period.

Aim. Study of biological properties of attenuated  variants of the virulent A/WSN/33 strain of influenza virus, obtained by the site-specific mutagenesis of PB2-gene. Materials and methods. Site-specific mutants of A/WSN/33 of influenza virus, having in PB2-gene ts-mutations from genome of cold-adapted (CA) master-strains: A/Ann  Arbor/6/60 (H2N2); A/Leningrad/134/17/57 (H2N2); A/Krasnodar/101/35/59 (H2N2) were obtained  with help of reverse genetics methods.  The ts-phenotype, att-phenotype, immunogenicity and protective efficacy in homologous and heterologous control infections were studied in the obtained site-specific mutants. Results. It was shown that the inclusion in the PB2-gene of the virulent A/WSN/33 strain as single mutations and a combination of mutations from the genomes of CA donor-strains leads to a change in the ts-phenotype and att-phenotype of the mutants obtained. These mutants had high protective efficacy in homologous and heterologous control infection. Conclusion. The results obtained allow us to consider the site-specific mutants of influenza virus as possible candidates for live influenza vaccines.

Aim. To determine  the qualitative and quantitative composition  of the oral microbiota in patients with medial osteonecrosis of the jaw (MOJ). Materials and methods. Microbiota was evaluated in 15 patients with medial osteonecrosis of the jaw. An assessment was made of 12 groups of optional and obligate-anaerobic microorganisms.  Evaluation of the qualitative and quantitative  composition  of oral microbiota  in patients with MOJ was performed by real-time polymerase chain reaction (PCR-RT). Results. The aerobic-anaerobic microbiota composition in patients with MOJ in the oral fluid and separated from the fistula is presented. The values of the total bacterial mass (TBM) and all anaerobic microorganisms  in the oral fluid in patients with MOJ before treatment were higher by 1-3 orders of magnitude than in healthy individuals. In the jaw, separated from the fistula in the zone of necrosis of the jaw, these parameters  were higher by 2-4 orders than in the oral fluid. Prior to surgery, a course of antibiotic  therapy was conducted  for 7 days. As a result of the therapy,  the parameters  of anaerobic  microflora  in the oral fluid decreased.  The use of cefazolin was more effective than lincomycin.  In 1 year after surgical treatment, the index of TBM and the indices of anaerobic  microorganisms  did not  differ from those of healthy  individuals. Conclusion. Patients  with medical osteonecrosis of the jaw have a high level of anaerobic pathogens in the oral microbiota. The course of antibiotic  therapy and surgical intervention  are effective methods  of treatment of MOJ,  as they lead to effective sanation, and allow further endoprosthetics.

Aim. To assess the prevalence of antimicrobial  resistance of Vibrio cholerae nonO1/nonO139 strains in water bodies in Rostov-on-Don. Materials and methods. Sampling was carried out at fixed points of open reservoirs in Rostov-on-Don from May to September in 2016 and 2017. Sensitivity/resistance of V. cholerae nonO1/nonO139 to antibacterial  drugs (ABP) recommended for emergency prevention  and treatment of cholera was determined  by serial dilution on Müller-Hinton agar. Results. 196 strains of V. cholerae nonO1/ nonO139 were isolated in 2016, 75 — in 2017. When serotyping it was found that all strains were assigned to 17 serogroups, representatives  of O16 and O76 serogroups prevailed. Analysis of the distribution  of strains on resistance to ABP showed that sensitive strains of V. cholerae nonO1/nonO139 were not detected.  All microorganisms  were resistant to furazolidone.  The proportions  of isolates resistant to co-trimoxazole and ampicillin were 35.2% and 40% in 2016, and 33.6% and 28.3% in 2017 respectively. All microorganisms were distributed over ten phenotypes and were characterized  by the presence of 1 to 4 determinants of resistance. Conclusion. The resistance of V. cholerae nonO1/nonO139 strains isolated in Rostov-on-Don water bodies to furazolidone increased from 47% in 2011 — 2014 to 100% in 2016 — 2017. Resistance to co-trimaxazole  increased from 7.8% to 35.2 — 40%. Strains resistant to gentamicin (1.5%) earlier absent were detected in 2016.

In the WHO African region (AFR),  measles is characterized  by severe complications  with a high risk of death due to malnutrition, vitamin А deficiency, concomitant infections. Measles viruses of genotype B (B1, B2, B3) are the endemic viruses in the African region (47 countries).  The strategy for the elimination of measles in AFR was based on the combination  of supplementary  immunization programmes (SIAs) for children under 14 years of age and routine vaccination of at least 90% of children 9-15 months of age. It was recommended to repeat the SIAs every 3-5 years. The number of measles cases decreased by 83-97% during the first year due to the strategy. The recommended age of routine vaccination in AFR is 9 months — this is a way to reduce measles-caused infant mortality. However, the level of seroconversion is not sufficient (85%). To eliminate measles completely by 2020, it’s recommended the use of two-dose regimens — vaccination and revaccination. Vaccination coverage with a single dose of measles vaccine in the African region increased to 74% in 2015, but the high incidence of measles in the region persists. In 2013-2016 there are 103,161 cases of measles among children under 6 years of age in AFR ; 79% of which were not vaccinated (or had unknown vaccination  status). In 2013, the measles vaccine program in several AFR countries  was disrupted  by the epidemic of Ebola. In countries where the epidemic has ended, the vaccination was recommended to be resumed for persons who may have missed routine immunization. There are problems in the implementation of measles elimination  in AFR: insufficient equipment  of medical centers and lack of qualified personnel, poor population awareness, poorly developed communication system, military conflicts.

The review discusses the pathogenetic  features of pseudotuberculosis, which predetermine the possibility of recurrence  of the disease and persistent  infection.  Among them  deserve attention  the damage of lymphoid organs with the development  of secondary immunodeficiency, granulomatous  inflammation, efferocytosis, associated with the absorption of apoptotic,  phosphatidyl-positive neutrophils.  Efferocytosis as one of the antimicrobial  strategies of polymorphonuclear leukocytes (PMNLs) reduces the damage to surrounding tissue and increases the production of anti-inflammatory molecules, while the Yersinia infected PMNLs  can act as an intermediate  host for the subsequent non-inflammatory infection of macrophages. The predisposition of Yersinia, including Y. pseudotuberculosis, to persistence is associated with genetically determined  bacterial pathogenicity  factors, mainly with their antiphagocytic  properties and the ability to produce a cytotoxic necrotic factor (CNFY).

К   120-летию   со   дня   рождения З.В. Ермольевой и 90-летию открытия пенициллина.

17 сентября 2018 г. на 91 году жизни скончался известный микробиолог доктор медицинских наук профессор Владимир Гаврилович Лиходед.

15 ноября 2018 г. на 73 году жизни скончалась известный лептоспиролог доктор медицинских наук профессор член-корреспондент РАН Юлия Васильевна Ананьина.