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Biomedical subjects

E Semenitz

Publications and source records attributed to E Semenitz.

At least 37 records · Page 2Linked to original sources
PubMed1985

Kill kinetics and regrowth pattern of bacteria exposed to antibiotic concentrations simulating those observed in vivo.

Antibiotic concentrations observed in vivo were simulated in an in vitro two compartment model with a dialyser interconnection. Kill kinetics and regrowth pattern of bacteria were investigated under these fluctuating antibiotic concentrations. There were large differences in the rate of reduction of viable organisms by various antibiotics not reflected in small differences in initial MIC values. Data suggested that the area under the concentration curve might be of importance in determining the antimicrobial activity of substances rather than the initial concentration. The inclusion of pharmacokinetic parameters in antimicrobial susceptibility testing might add a new dimension to the appreciation of the activity of antimicrobial substances.

Anti-Bacterial Agents↗
PubMed1983

[Mechanism of action of beta-lactam antibiotics and problems concerning the development of resistance in antibacterial chemotherapy].

Beta-lactam antibiotics influence the metabolism of bacteria in very low concentrations by blocking the activity of penicillin binding proteins of gram-negative rods. Dependent on the type of binding protein affected bacteria form filaments or sphaeroblasts. The most important resistance mechanism is the formation of beta lactamases, which cleave the beta-lactam ring and inactivate the antimicrobially active molecule. Gram-positive bacteria like Staphylococci excrete the enzymes into the environment; as long as the antibiotic is not destroyed by the enzyme, activity antimicrobial effectiveness is present and prevents bacterial proliferation. In gram-negative bacteria the beta lactamases are formed in the periplasmic space and inactivate the antibiotic after penetration into the bacterial organism. This type of beta-lactamase formation is transferred to the organism by transduction, transformation or conjugation. Bacterial resistance against beta-lactam antibiotics need not only be due to inactivation of the antimicrobial substance by beta lactamases, but can also be due to mechanisms independent of enzyme activity. We call this intrinsic resistance. Prior to clinical application of beta-lactam antibiotics the susceptibility of the organism should be determined by an antibiogram.

Anti-Bacterial Agents↗
PubMed1982

[Comparative analysis of tetracycline, doxycycline and minocycline on chromosomal and plasmid tetracycline-resistant and -sensitive strains of Staphylococcus aureus using MIC, microcalorimetric effect and ultrastructural alterations].

A staphylococcus aureus strain of a patient with plasmidical tetracyclinresistance has first been cured from the plasmid and after that selected in nutritive broth by increasing the concentrations of tetracyclin. By this way we found three variants of the same strain: a tetracyclin-sensitive and two tetracyclin-resistant: an R-plasmid-mediated and the other as a result of mutation. These three variants have been tested against tetracyclin, minocyclin and doxycyclin on an agarmedium. Under influence of these three substances a microcalorimetrical investigation of the strains has taken place. We then tested the strains with the electronic microscope for alterations in the ultra-structure by the three substances. Following results have been obtained: 1. The sensitive strains were inhibited in the same extent by all of the three substances. Plasmidical resistant strains were only resistant against tetracyclin but not against minocyclin and even less against doxycyclin. 2. The microcalorimetrical tests confirmed the conclusions from the cultural test. 3. Alterations in ultra-structure were only found under tetracyclin-influence by strains in division. Comparing the three tetracyclines we did not find any significant difference in quality. 4. With all of the three investigation-methods we proved that R-plasmid-mediated tetracyclin-resistance of staphylococci is not effective for minocyclin and even less for doxycyclin.

Calorimetry↗
PubMed1979

[Microcalorimetric testing of the antibacterial activity of doxycycline, gentamicin and their combination (author's transl)].

The antibacterial activity of doxycycline and gentamicin was tested by microcalorimetric methods and by finding out the MIC of these substances, the test organisms being Staph. aur. haem. (13.665) and E. coli (3.579). The investigations were carried out with the above mentioned substances both alone and in combination. A synergistic effect was found with both methods applied, but microcalorimetry showed that the combination influences the cell metabolism in another way than the individual substances. Another remarkable finding is that doxycycline inhibits the microcalorimetric activity of our bacterial strains in doses 10 to 100 times lower than found with the standard MIC finding methods.

Calorimetry↗
PubMed1978

[The antibacterial activity of diphenhydramine (author's transl)].

Diphenhydramine (N,N-dimethyl-2-diphenyl-methoxy-ethylamine) [N,N-dimethyl-2-(diphenylmethoxy)-ethylamin] (DPH) is a well-known local anaesthetic and an antagonist of both acetylcholine and histamine. We tested its antibacterial efficacy by means of three different investigation methods, i.e. microcalorimetry, continuous density measurement and the microdilution test to find out the MIC of this compound against various bacteria. DPH inhibits the growth of E. coli and Klebsiella strains at a concentration of 0.18% of Staphylococcus aureus haemolyticus at 0.37%, of Pseudomonas aeruginosa at 0.75% and Streptococcus faecalis strains at 1.5%. The results of microcalorimetry and continous density measurements showed that the addition of 0.2% DPH to a broth with growing bacteria interferes very quickly with cell metabolism and stops further reproduction. The microcalorimetric findings were carried out with Staphylococcus aureus haemolyticus strain No. 13,665 an- the E. coli strain No. 3579.

Anti-Bacterial Agents↗
PubMed1978

[The problem of endotoxin shock after antibiotic therapy in surgery (author's transl)].

2 fatal cases of endotoxin shock after antibiotic therapy due to massive Escherichia coli infection after surgery are described to emphasize this rare possibility of complication. In cases of major infections with Gram-negative bacterais antibiotics should therefore prophylactically be given initially in low doses and only after observation in increasing amounts.

Appendicitis↗
PubMed1978

[Microcalorimetric Investigations, regarding the antibacterial efficiency of chemotherapeutics (author's transl)].

An investigation method is described by which microcalorimetry and continuous density measurement are used to show the antibacterial efficiency of chemotherapeutics. Oleandomycin, erythromycin, both macrolide antibiotics, and doxycycline, a tetracycline, blockers of the protein synthesis, have the same effect on the microcalorimetric curve of a staphylococcus strain. Among the aminoglycosides tobramycin and gentamicin influenced the microcalorimetric activity of a growing E. coli strain in the same way, spectinomycin produced different curves. Penicillins interfere with the synthesis of the cell membrane by blocking the enzyme transpeptidase. Epicillin, penicillin, ampicillin, oxacillin, carbenicillin, and azlocillin influence the microcalorimetric activity of staphylococci in a typical way which is different from that of the blockers of the protein synthesis.

Aminoglycosides↗
PubMed1977

[Comparison of the antibacterial efficacy of doxycycline and tetracycline (author's transl)].

In order to explain the mechanism of resistance within the tetracycline group, the minimal inhibitory concentration of tetracycline HCl was compared with that of doxycycline in the micro dilution test for bacterial collectives of 48 strains each from the groups of gram-negative and gram-positive cocci, resp. There was no significant difference between the inhibitory effect of doxycycline and tetracycline HCl for the bacterial collectives of E. coli, Klebsiella, Proteus and Staphylococcus aureus heamolyticus strains which were inhibited by a relatively low concentration of tetracycline HCl and doxycycline, respectively. On the other hand a significant difference in inhibitory effect was observed the calculation was made according to the Kolmogoroff-Smirnov test for the bacterial collectives of Enterococci and Staphylococcus aureus haemolyticus strains which were tetracycline resistant or only inhibited by higher concentrations. These results also have a practical importance, because a further testing against doxycycline can bring about a sensitivity to this substance in case of tetracycline resistant grampositive cocci. Possible explanations for the higher efficacy of doxycycline on these bacterial collectives will be discussed.

Bacteria↗
PubMed1975

[Napkin thrush clinical picture, mycology, histology, therapy (author's transl)].

A well-defined, characteristic disease has been observed in babies at the Department of Dermatology, Innsbruck University, over the past 7 years. On account of the localisation and probable pathogenesis of the condition the term "Windelsoor" (napkin thrush) has been coined by us for it. The clinical picture, the mycological and histological findings, the therapeutic results and the follow up are reported and the aetiology and pathogenesis of this disease discussed.

Antibodies, Fungal↗
PubMed1975

[On the morphology of flagella and fimbriae of Escherichia strains (author's transl)].

100 Escherichia-strains, isolated from urine and faeces, were investigated with regard to flagella and fimbriae by electron-microskopy. The flagella had a length of 3-6 mu and a diameter of ca 0.02 mu. The flagellation was different not only between to the single bacteria of the same strain, but also in the separated isolates. Of 50 strains from urine had 27 and of 50 strains from feces had 28 no flagella. Different Escherichia-strains contained fimbriae, the number of which was much higher with regard to the flagella. The length of the fimbriae differed between 0.25 and 2 mu, the diameter was constantly ca 8 nm. 21 strains of 100 (4 from 50 urine strains and 17 from 50 faeces strains) had no fimbriae.

Cell Wall↗
PubMed1975

[On the biological activity of Escherichia strains, with special reference to fimbriae (author's transl)].

According to the results of earlier investigations of other authors, there are differences between Escherichia-strains fron urinary tract infections and fron the feces of healthy persons with regard to their biochemical, hemolytic, necrotizing and pathogenic properties in mice experiments. Hemolytic Escherichia cultures are very different from non - hemolytic cultures in their necrotizing and pathogenic behaviour. In contrast to Escherichia-strains from the feces of healthy persons strains from urinary tract infections have fimbriae to a much greater extent and hemolytic strains up to 100%.

Animals↗
PubMed1975

[Diaper thrush. Clinical picture, mycology, histology, therapy (author's transl)].

During the last 7 years a well defined, characteristic disease has been observed in babies of the department of dermatology of the university clinic of Innsbruck. Because of the localisation and probable pathogenesis we have coined the term "Windelsoor" (diaper thrush) for it. Clinical picture, mycological and histological findings, therapeutical experience with therapy and follow-up results are reported. With reference to the anglo-american literature on this subject the pathogenesis of this disease is discussed.

Adrenal Cortex Hormones↗