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Iu G Stepanshin

Publications and source records attributed to Iu G Stepanshin.

18 recordsLinked to original sources
PubMed2000

[Molecular mechanisms of mycobacterium tuberculosis strains resistance to rifampicin and isoniazid].

The levels and spectra of the drug resistance of clinical M. tuberculosis strains were defined. There was a relationship of treatment regimens to the drug resistance of mycobacteria isolated from the strains. The fragments of genes rpoB, inhA, and katG were analyzed by polymerase chain reaction and sequencing. In addition to earlier identified substitutions, new mutations were found in rpoB: A-->T/233, G-->A/395, C-->T/232, G-->T/202, C-->T/221, C-->T/260, GA-->TT/202-203, delta 199-207 ATGGACCAG. Strain 12/7 was found to have 30 point mutations leading to substitution of only 3 amino acids and to have GGG(Gly)354 deletion as well. Most mutations in this strain are "silent". Substitutions at 944 and 463 positions were revealed in katG.

Antibiotics, Antitubercular↗
PubMed1998

[Sensitivity of Escherichia coli O157:H7, a pathogen of hemorrhagic colitis, to antibacterial drugs].

Antibioticograms of enterohemorrhagic strains of serogroup O157 Escherichia coli isolated in the Russian Federation and Japan were comparatively studied. Strains with multiple drug resistance were detected. The main biochemical characteristics of the isolates were investigated. Significant differences in susceptibility spectra of the isolates and in their fermentative properties were revealed.

Colitis↗
PubMed1997

[Pasteurella multocida: infections in man].

The literature data on human infection due to a representative of the genus Pasteurella, i.e. P. multocida are reviewed: the main clinical forms and signs of pasteurellosis, the results of the studies on susceptibility of P. multocida to antibiotics and chemotherapeutics and the results of their use in the treatment of the infection.

Anti-Bacterial Agents↗
PubMed1996

[Various indices of the infectious process in treatment of glanders in monkeys].

The time course of the clinical, biochemical and serological indices was studied during the treatment of malleus in monkeys. The internal organs of the animals infected with Pseudomonas mallei were investigated pathomorphologically. The efficacy of the biseptol/oxalinic acid combination in the therapy of malleus was estimated.

Animals↗
PubMed1996

[Erysipelothrix rhusiopathiae: plasmids, resistance to antibacterial drugs].

The plasmid profile, virulence and antibacterial drug susceptibility of various strains of E. rhusiopathiae were determined. No correlations between the virulence of the strains, their antibiotic resistance and the plasmid content were detected. Structural and functional analysis of one of the isolated plasmids was carried out to use the plasmid as a vector in the genetic study of E. rhusiopathiae.

Drug Resistance, Microbial↗
PubMed1994

[In vitro development of fluoroquinolone resistance in the glanders pathogen].

To improve the scheme for the therapy of malleus, the possible development of fluoroquinolone resistance in the cells of Pseudomonas mallei was studied. The frequency of the mutations determining the resistance to oxolinic acid, norfloxacin, enoxacin, ofloxacin and ciprofloxacin was detected. The spectrum of the cross resistance in the strains was investigated. The influence of the resistance mutations on the culture virulence was studied. Recommendations on the rational use of fluoroquinolones in the treatment of malleus are presented.

Anti-Infective Agents↗
PubMed1994

[Evaluation of the potential of chemotherapy of glanders caused by Pseudomonas mallei strains resistant to sulfanilamides and trimethoprim].

A sulfanilamide resistant strain Ts-5 of Pseudomonas mallei was isolated in the experiments on sulfazine therapy of malleus. The spectrum and level of the strain cross resistance to sulfanilamides and trimethoprim were studied. The frequency of the SurTrr mutants of P. mallei was determined. Efficient antibacterial drugs for the therapy of malleus caused by the sulfanilamide resistant strain are recommended.

Animals↗
PubMed1983

[Integration of plasmid RP1 with the chromosome of Escherichia coli K-12 recA. 2 classes of Hfr strains].

Integration of broad host range RP1 plasmid into the chromosome of Escherichia coli K-12 recA- cells has been studied. Using temperature-sensitive for replication plasmids pVD1 and pVD3, the derivatives of RP1, it has been shown that integration of RP1 into the bacterial chromosome results in formation of two classes of Hfr strains. Properties of these Hfrs have been examined. From the data obtained, it has been concluded that the plasmid integration and formation of one of the Hfrs classes appear to be mediated by transposon Tn1 residing on RP1. The other class of Hfr strains is formed due to a stable integration of RP1. In the course of analysis of R+ transconjugants arising at low frequency in crosses between stable Hfrs and E. coli rec+ recipients, it has been found that the significant part of them contain plasmid-chromosome hybrids (R-prim plasmids). On the basis of the latter results, a new simple method for R' plasmids selection has been proposed. Using restriction endonuclease analysis, the structure of plasmids that were excised from chromosomes of the stable Hfr strains and were comparable in their size to RP1, has been investigated. Probable mechanisms of the stable Hfr strains formation are discussed.

Chromosomes, Bacterial↗
PubMed1982

[Formation of stable Hfr strains in R factor RP1 integration with the chromosome of E. coli K12 recA and their use for R-plasmid selection].

Analysis of thermoindependent derivatives of E. coli K12 JC1553 recA (p VD1) carrying a replication thermostable mutant pVD1 of R factor RP1 IncP Ap Km Tc showed that formation of about 5 per cent of them was associated with stable integration of the plasmid with the bacterial chromosome. The respective bacteria had the following features: (1) preserved all the markers of plasmid pVD1, (2) according to the data of the electrophoretic analysis had no extrachromosomal DNA on prolonged cultivation under nonselective conditions, (3) were effective donors of the chromosomal genes, (4) had a low rate of the plasmid marker transfer on crossing with R- recipient. The latter feature was suggested to be used as a test for identification of stable Hfr strains. Investigation of the properties of the transconjugants obtained on crossing of stable Hfr strains with R-recipients rec+ showed that same of them had plasmid DNA with a higher molecular mass as compared to that of plasmid pVD1 DNA. The presence of this DNA was connected with formation of R' plasmid as a result of an irregular exclusion of plasmid pVD1 from the chromosome of stable Hfr bacteria. On the basis of the results a simple method was proposed for selection of R' plasmids having a number of advantages over the classical ones. The perspectives of using thermostable derivatives of RP1 for cloning the chromosome genes are discussed.

Chromosomes, Bacterial↗
PubMed1982

[New class of RP4 plasmid mutations inducing a mucoid-type of Escherichia coli K-12 cell growth].

A new class of mutations is described which induce mucoid growth of Escherichia coli K-12. Unlike classical capR and capS mutations, the mucoid phenotype of colonies of the cap forms obtained is determined by mutations in genomes of thermosensitive plasmids pEG1 and RP1-6Repts12, derivates of the RP1 Inc P1 Ap Tc Km factor and accompanied by a complete or partial loss of the thermosensitive character of maintenance. The morphological character induced by plasmids is not associated with changes in the sensitivity of bacteria to UV irradiation and is determined by superproduction of capsular polysaccharide differing in the chemical structure from colanic acid, a common capsular polysaccharide of E. coli K-12.

Conjugation, Genetic↗
PubMed1980

[Isolation and characteristics of deletion mutants of thermosensitive plasmid pEG1].

Phenotypic revertants of temperature-sensitive in self-maintenance plasmid pEG1 derived from R-factor RP4 were studied. The study indicated a sertain part of them to be variants without ampicillin resistance. The frequency of pEG1 ampicillin sensitive (Aps) derivatives is about 5.10(-7) and does not depend on the recA gene product. The Aps-derivatives of pEG1 plasmid can be classified in two phenotypic groups. The first group is temperature-independent and does not inhibit the growth of host cells by non-permissive temperature (43 degrees C). Agarose gel electrophoresis has revealed that plasmids of this group occur as a result of deletions in plasmid pEG1. The other group of Aps-derivatives still possess the property to be eliminated at 43 degrees C and they inhibit the growth of bacterial cells like pEG1. Agarose gel has demonstrated that some of them are deletion mutants while others are quite similar to pEG1 plasmid. The data obtained in the course of study of deletion mutants make it possible to suppose that the presence of gene with temperature sensitive mutation in pEG1 is not necessary for stable maintenance of R-factor.

Ampicillin↗
PubMed1978

[RP4 factor integration with E. coli chromosome].

Integration of R-factor RP4 with the chromosome of E. coli was studied with the use of replication thermosensitive mutant pEG1 of this factor. It was found that the frequency of integration of factor pEG1 containing the ampicillin transposone Tn1 with the chromosome of bacteria JC411 carrying transposone Tn1 previously inserted into it was very high and markedly exceeded that of its insertion into the same chromosome but not carrying this transposone. The frequency of factor pEG1 insertion into the chromosome of bacteria JC 1553 rec A defective with respect to genetic recombination was less than 2.10(-5) and did not depend on the presence of transposone Tn1 in it. Probably, insertion of factor RP4 into the bacterial chromosome may be realized through the rec A-dependent process of recombination between transposone Tn1 previously translocated into the chromosome and the same transposone contained in R-factor.

Ampicillin↗
PubMedDate not supplied

[Characterization of Escherichia coli strains O157:H7, isolated on the territories of the Central Federal District].

The characterization of E.coli strains O157:H7, isolated from humans and animals on some territories of the Central Federal District, is presented. Among the isolates from human outbreaks, related and, probably, related cultures prevailed, while among the isolates obtained from different animals mainly unrelated cultures have been detected. A conclusion has been made concerning the existence of several independent zoonotic reservoirs of E. coli O157:H7 infection on this territory. The advantages and drawbacks of the use of pulse electrophoresis in the characterization of E. coli O157:H7 are discussed. Grounds are given for the necessity of the patients examination with hemorrhagic enetrocolitis for the presence of E. coli O157:H7, as well as for the expediency of having a special item for the registration of this E. coli infection in relevant statistical forms.

Animals↗
PubMedDate not supplied

[Thermosensitive vector derived from RP1 plasmid for detection of transposable elements].

The involvement of the transposable DNA element of E. coli K12 chromosome in integrative recombination of RP1 plasmid was studied. Using temperature sensitive for replication plasmid RP1ts12--the derivative of RP1 which contains mutated transposon Tnl, it was shown that integration of RP1 into host chromosome and Hfr formation may occur according to a mechanism mediated by chromosome IS-elements. Plasmids that are desintegrated from the chromosome of these Hfrs contain discrete DNA segments (IS-elements) and possess elevated frequency of integration into chromosome of rec+ cells. The latter was used for selection of RP1ts12 recombinants carrying chromosome IS. For identification of IS involved in RP1 integration the number of independent RP1ts 12 recombinants was subjected to restriction and heteroduplex analysis. By analysing recombinants integrated into bacterial chromosome with frequency 5 X 10(-3), a new IS-element of E. coli K12 designated IS111 was discovered. IS111-element is about 1500bp of length, contains Smal, Pst1 and BamH1 restriction endonuclease sites and was found in the same position on the plasmid RP1 in two different orientations. IS-elements that have been revealed in a number of other RP1ts12 recombinants were preliminary identified as IS1-like elements. One recombinants plasmid was found to have an IS5-like elements. The activity of IS-elements inserted into RP1ts12 in recA-dependent integrative recombination was estimated. From the data of absolute and relative RP1ts12 integration frequencies mediated by IS111, IS1- and IS5-like elements a conclusion was made about the absence of E. coli K12 chromosome IS-elements in RP1 plasmid. The Hfr-formation and chromosomal gene transfer by recombinant plasmids RP1ts12: IS111 were studied. The possibility to use insertion RP1ts12 derivatives for the estimation of copies number, mapping and definition of orientation of IS-elements in bacterial chromosome and the possibilities for detection of transposable DNA elements using RP1ts12 in a wide range of gram-negative bacteria are discussed.

Bacterial Proteins↗
PubMedDate not supplied

[Resistance of Pseudomonas mallei to tetracyclines: assessment of the feasibility of chemotherapy].

The spectrum of cross resistance in tetracycline resistant strains of Pseudomonas mallei was studied. Possible use of antibacterial drugs in the prevention and treatment of mallel due to such strains was investigated in the experiments on golden hamsters and monkeys. It was shown that the efficacy of the minocycline therapy depended on the level of the strain resistance to tetracycline antibiotics. The combination of biseptol and ofloxacin proved to be highly efficient in the treatment of mallei.

Animals↗