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G Lebek

Publications and source records attributed to G Lebek.

At least 37 records · Page 2Linked to original sources
PubMed1982

[Classification of R-factors. Possible errors and their elimination].

The necessity for classifying plasmids is emphasized. From our results the uniformity of a nosocomial infectious outbreak is only given by the R-factor and not by the infectious agent. Determination of the appropriate pilus groups by sexphages using the HFRT-system and identification of incompatibility as a further means of subdividing the pilus groups into incompatibility groups is described. A distinction is made between incoming- and resident incompatibility. To eliminate possible errors in plasmid classification the following points are considered: 1. Testing in recombination deficient rec A- -strains of E. coli K12 to avoid any recombination of the plasmids. 2. Trypsin addition to remove the possibility of plasmid coded colicin production. 3. A proper choice of the indicator plasmids. 4. Consideration of the spontaneous loss of the indicator plasmid and also an occurrence of transposons coding for an additional pilus type.

Anti-Bacterial Agents↗
PubMed1982

Quality of breast milk: its control and preservation.

The numerous problems of bacterial contamination and proper preservation of breast milk have been examined. Both the many advantages of human milk as the optimal nourishment for the newborn baby and the extensive experiences of veterinary medicine in the handling of milk have been carefully considered. Bacterial multiplication has been studied under various storage conditions. Out of several possible procedures a simple, inexpensive, rapid and reliable dip-slide screening method for determining total bacterial colony counts is described. A clear-cut procedure for the optimal collection of breast milk is presented.

Humans↗
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↗
PubMed1981

Estimation of the biliary excretion of different cephalosporins utilizing retrograde cholangio-pancreatography (ERCP).

In the present study 21 patients undergoing retrograde cholangio-pancreatography (ERCP) were given cefamandole, cefazolin or cefaclor, and plasma and bile concentrations were measured. The cannulation of the common bile duct was possible in most of the patients investigated, but no bile could be obtained in 7 of them. In the patients in whom bile was obtained, concentrations comparable to other studies were estimated, despite a wide variation in the individual patients. In addition, cefaclor, which is not known to be excreted in the bile, showed sufficiently high inhibitory bile concentrations. Using ERCP for the estimation of bile concentrations of different drugs useful information can be obtained about the excretion of certain substances. However, for sophisticated pharmacokinetic studies, the method has certain limitations as compared with classical T-tube sampling.

Adult↗
PubMed1981

[Pyocine typing of Pseudomonas aeruginosa strains from nosocomial outbreaks - after the elimination of possible sources of mistakes by heat-treatment (author's transl)].

In 25% of the freshly cultivated Pseudomonas aeruginosa strains (isolated from nosocomial infections) a change of the pyocine type determined according to the method of Gillies and Govan results from passages on selective or non-selective media or from several days' storage at room temperature (Tab. 1 and 2). This inconstancy of the pyocine type can be avoided by exposure of the strains to 56 degrees C for 5-75 min. After this heat treatment the agarose-gel-electrophoresis of the strains shows the loss of all non-conjugative plasmids smaller than 25 kbp (Fig. 2). By typing more than 1,000 strains from nosocomial Pyocyaneus outbreaks we could demonstrate the reliability of the pyocine typing after having cured the strains by heat. Further we propose a binary numbering system for the pyocine types using the results of the 8 indicator strains (Tab. 3).

Bacteriocins↗
PubMed1981

Transduction of amikacin, gentamicin and tobramycin resistance in Pseudomonas aeruginosa with phage F 116 and AP 19, a new wildtype phage.

Amikacin-, tobramycin-, gentamicin- as well as carbenicillin-resistance has been found to be transducible, in various combinations of spectra both with the phage F 116 propagated on an Amikacin-resistant wild-type strain of Pseudomonas aeruginosa (No. BE 11) and with the phage AP 19 isolated from a different Amikacin-resistant strain (No. 578). Both strains were found to transfer Amikacin-resistance genes presumably by conjugation thus possessing an R plasmid coding for multiple antibiotic resistance. Evidence is presented that classical as well as wild-type phages may acquire and transmit antibiotic resistance genes among pseudomonads. This is particularly significant in view of the importance to preserve Amikacin as an effective reserve antibiotic for treatment of poly-resistant infections including those caused by P. aeruginosa.

Amikacin↗
PubMed1979

[In vitro study on the problem of optimal gentamicin therapy in leukopenic patients: short injections or parenteral infusions?].

Killing curves of Pseudomonas aeruginosa were performed in an in vitro system simulating in-vivo gentamicin kinetics, i.e. decay of the antibiotic concentration with a 2.1 h halflife time. Minimal inhibitory concentrations (MIC) of gentamicin killed 99.999% of the initial Pseudomonas inoculum whereas 99.99% were killed at a continuously falling gentamicin concentration (starting from the MIC level) in the same period of time. Regrowth of persistent germs occurred only after 6 hours in cultures exposed to falling gentamicin concentrations, and after 8 hours in cultures kept at the MIC. Thus, a postulated superiority of gentamicin infusions over intermittent gentamicin therapy could not be demonstrated in vitro. Intervals between bolus injections of gentamicin should probably not be longer than 6 hours.

Colony-Forming Units Assay↗
PubMed1979

[Verification of nosocomial infection chains with Pseudomonas aeruginosa (author's transl)].

With all 3 typing methods (sero, lyso, pyocin type) errors can arise. The pyocin test following heat curing can be expected to give the least erroneous results. This was demonstrated by a test of 200 non-selected strains which were grown within 4 weeks. The possibility exists that a single patient discharges several different strains simultaneously or in succession. These results must be considered when efforts are made to detect infection chains in a hospital.

Bacteriophage Typing↗
PubMed1979

[Nutritive antibiotic additives in animal feeding stuffs--a further form of environmental pollution (author's transl)].

Feeding domestic animals with mycelia, a by-product of vitamine production, gave rise to the side effect of markedly improved utilization of the fodder. This effect is not due to the vitamine and protein content but to the antibiotic content of this waste product. The nutritive effect was brought about by a larger number of different antibiotics in concentrations which were considerably lower than the therapeutically required doses. Therefore we speak, in this connection, of a nutritive addition of antibiotics to animal fodder. Since at the time of introducing this feeding method only the mutational resistance to antibiotics of pathogens was known and since the nutritive dosaging cannot select such therapeutically relevant degrees of resistance of the germs, no importance was attached to the development of the resistance and its effect on human medicine. However, during the last decade it has been found that the feeding of antibiotics is indeed capable of selecting the plasmidic resistance to antibiotics of the gram-negative intestinal bacteria in the faeces of the animals. For pigs, calves and hens--to quote only the most important animals--now contain a coliflora almost completely studded with R-factors. Owing to the transmissibility of the plasmids and the epidemiologically short path from animal to man, dangers emerge for the human medicine from this nutritive selection. Therefore the use of all antibiotics which select resistance plasmids, should be avoided in animal feed stuffs. It would be best, if antibiotics used in human medicine were not used in veterinary practice.

Animal Feed↗
PubMed1976

[Hygiene at the treatment area in the dental office].

The state of hygiene in a dental office in the canton of Bern was examined. 22 bacteriological tests were made on the surfaces around the treatment area. Also, the water from the sprays and the most important instruments were tested. Before cleaning and disinfection the test objects showed an average of 110 microorganisms per 100 cm2. The species are enumerated. Particularly infected were polishing brushes, "slurry-water", dentures polished and cleaned with water, also the water from the dental unit. The results show that improvement is badly in need. Also a warning is given for the possible transmission of hepatitis. Female dentists and dental assistants are cautioned to get a german measles vaccination.

Bacteriological Techniques↗