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At least 1,171 records · Page 65Linked to original sources
PubMed1983

[Antibiotic sensitivity of different antigenic variants of Pseudomonas aeruginosa isolated in a hospital].

The serological typing of 96% of P. aeruginosa strains isolated in hospitals has been carried out by means of agglutinating sera, and the tendency towards the prevalence of the strains of group V (25.3%) and serovar O11 (18.1%) has been revealed. The determination of the antibiotic sensitivity of different variants has shown that the strains of groups I, V and serovar O11 possess pronounced resistance to a wide spectrum of antibiotics, their resistance to gentamycin and polymixin being higher than in the strains of other serotypes. The determination of antibiotic resistance can serve only as an additional test in the serological typing of P. aeruginosa.

Anti-Bacterial Agents↗
PubMed1983

Cephalosporin resistance in strains of Klebsiella oxytoca isolated during antibiotic therapy.

In the course of multiple antibiotic treatment of a seriously ill patient, a high level of resistance to cefamandole, cefuroxime and ceftriaxone was found among consecutive isolates of Klebsiella oxytoca, other species isolated remaining susceptible. Susceptibility to cefotaxime was less affected, and the activity of cefoxitin and moxalactam was unchanged. Resistant K. oxytoca strains synthesized a large amount of a broad-spectrum beta-lactamase, able to hydrolyze ceftriaxone, cefuroxime and cefotaxime. The enzyme level as well as the ability to hydrolyze different cephalosporins with different rates explained the in vitro susceptibilities observed reasonably well. The initially susceptible K. oxytoca strain easily converted in vitro to variants producing a high level of beta-lactamase after exposure to ceftriaxone, without concomitant acquisition of high-level resistance to this antibiotic, suggesting that additional and at present unknown factors also contributed to resistance of the clinical isolates.

Abdomen↗
PubMed1980

[Localization of the tetracycline resistance determinant in Streptomyces coelicolor A3(2)].

It was shown that the rate of segregation of variants sensitive to tetracycline by Str. coelicolor A3(2) was high, i. e. 0.1 per cent. The tetracycline sensitive variants in their turn had an ability to reverse tetracycline resistance at a rate of 10(-2)--10(-4). Such a genetically unstable determinant of tetracycline resistance is localized on the chromosome between markers ade C (V10) and arg A1. The data are indicative of the fact that formation of tetracyctine sensitive variants could not be associated with elimation of the plasmid carrying the tetracycline resistant determinant or deletion. Formation of such variants as a result of point mutations is also hardly probable. It is suggested that the genetic instability of tetracycline resistance is due to recombination events (transposition of the controlling element) involving and expelling expression of the tetracycline resistance gene(s).

Chromosomes, Bacterial↗
PubMedDate not supplied

[Primary selection method for microorganism producers of organic acids].

A method is suggested for primary selection of microorganisms producing organic acids. The methods is based on the use of diagnostic media containing the indicator bromocresol green. When yeast fungi of various taxonomic groups were grown in indicator media, 49 yeast cultures producing organic acids were found. Among these, 38 cultures accumulated from 5.0 to 30.0 mg% of citric acid when grown in a medium containing n-paraffins.

Bromcresol Green↗
PubMed1982

[Interpopulation variability of Staphylococcus aureus].

The comparative study of 830 hospital and 181 extrahospital S. aureus strains has revealed the existance of the interpopulation (group, geographic) variability of this species. Hospital strains differ from those inhabiting other places by the composition of phago- and resistovars, greater resistance to antibiotics, antiseptic and disinfecting agents, the inhibiting action of antagonist, as well as by pronounced antagonistic activity. The biological characteristics of such strains allow one to classify them with the hospital ecological variants (ecovars) of S. aureus. These properties of hospital strains give them selective advantages in hospitals over extrahospital strains, and the latter are thus ousted from the skin surface, mucous membranes, wound surfaces. The measures taken to prevent hospital infections must be aimed mainly against the hospital ecovars of these bacteria.

Anti-Bacterial Agents↗
PubMed1977

[Food additives and their possible genetic toxicity; microbiological determination].

In the present work we intend to find an accurat methodology to establish in an easy way the mutagenic potential of drugs employed as food additives. For that purpose we first selected a microbiological system for performing this assay. The method assayed consisted of investigating the effect exerted on genetic recombination by the following chemical agents: Chloroacetic Acid, Iodoacetic Acid, Sorbic Acid, Potassium Metabisulfite, Sodium Nitrite, Auramine and Erythrossine. The activity of these agents was detected though their effect on the transformation of an auxotrophic strain of Bacillus subtilis. Comparative assays of reversion of characters have been made with strains of Salmonella typimurium already used by other authors. These assays have also been repeated with several auxotrophic strains of Bacillus subtilis and different genetic characters have been studied. Most results suggest that changes in the recombination process should have occured at different levels according with the drugs assayed. On the other hand, the results of reversion have not been significant enough. We think that more accuracy is afforded by both the recombination and the reversion assay developed to other for this kind of detection.

Animals↗
PubMed2005

Semi-automated genetic analyses of soil microbial communities: comparison of T-RFLP and RISA based on descriptive and discriminative statistical approaches.

Cultivation independent analyses of soil microbial community structures are frequently used to describe microbiological soil characteristics. This approach is based on direct extraction of total soil DNA followed by PCR amplification of selected marker genes and subsequent genetic fingerprint analyses. Semi-automated genetic fingerprinting techniques such as terminal restriction fragment length polymorphism (T-RFLP) and ribosomal intergenic spacer analysis (RISA) yield high-resolution patterns of highly diverse soil microbial communities and hold great potential for use in routine soil quality monitoring, when rapid high throughput screening for differences or changes is more important than phylogenetic identification of organisms affected. Our objective was to perform profound statistical analysis to evaluate the cultivation independent approach and the consistency of results from T-RFLP and RISA. As a model system, we used two different heavy metal treated soils from an open top chamber experiment. Bacterial T-RFLP and RISA profiles of 16S rDNA were converted into numeric data matrices in order to allow for detailed statistical analyses with cluster analysis, Mantel test statistics, Monte Carlo permutation tests and ANOVA. Analyses revealed that soil DNA-contents were significantly correlated with soil microbial biomass in our system. T-RFLP and RISA yielded highly consistent and correlating results and both allowed to distinguish the four treatments with equal significance. While RISA represents a fast and general fingerprinting method of moderate cost and labor intensity, T-RFLP is technically more demanding but offers the advantage of phylogenetic identification of detected soil microorganisms. Therefore, selection of either of these methods should be based on the specific research question under investigation.

Bacteria↗