[Clinico-laboratory testing of a new medium for determining the antibiotic resistance of microorganisms].
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Bacteria↗
Biomedical subjects
S M Chaĭkovskaia
Publications and source records attributed to S M Chaĭkovskaia.
[Use of antibioticograms for individual programs of antibacterial therapy].
The increasing role of antibiotic-resistant microorganisms in etiology of bacterial infections and the increased number of the antibiotics used for the treatment of patients with purulent infections require a rational approach to the choice of the optimal drug. Antibiotic sensitivity of the causative agents of bacterial infections is considered at present as one of the main indices determining the efficacy of antibacterial therapy. Determination of antibiotic sensitivity by the disk diffusion method with quantitative and semi-quantitative interpretation of the results provides information for choosing the most effective drug and calculating its optimal dose in control therapy. Equations for calculating the MICs antibiotics by the inhibition growth zones and the drug levels in blood and urine attained with the use of different doses and administration routes are presented.
Anti-Bacterial Agents↗
[Standardization of methods of determining microbial sensitivity to antibiotics].
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Anti-Bacterial Agents↗
[Stability of antibiotics in disks as one of the indicators of their quality].
In connection with the new requirements to the content of antibiotics in discs and a new procedure for the disc labeling stability of antibiotics in discs was studied with the methods of storage under natural conditions and under conditions of accelerated ageing. It was shown that the method of accelerated ageing was not applicable to testing antibiotic stability in discs, since with the use of this method a significant decrease in the antibiotic activity was observed which did not correspond to the real decrease in activity determined with the method of storage under natural conditions. The expiry date of the discs with benzylpenicillin or semisynthetic penicillins was determined to be equal to 1.5 years when stored at 10 degrees C. The expiry date of the discs with thermostable antibiotics was determined to be equal to 3 years when stored at 10 degrees C. Though certain inactivation of the antibiotics was observed, their content in the discs remained within the required limits, i.e. 75-135 per cent of the activity indicated on the label.
Anti-Bacterial Agents↗
[Preparation of bioindicators for controlling the efficacy of sterilization processes].
A test microbe for the control of the efficacy of vacuum steam sterilization was selected. Conditions for the spore cultivation were developed. The optimal bioindicator composition, test microbe loading, nutrient medium, pH indicator, carbohydrates and a carrier were defined.
Biological Assay↗
[Use of agar diffusion method for separate determination of concentration of streptomycin and rifampicin in the blood in the presence of isoniazid].
Conditions for determination of streptomycin and rifampicin in the blood serum on their combined use, as well as in the presence of isoniazid are described. For determination of the blood levels of streptomycin administered in combination with rifampicin it is recommended tat a variant of Bac. mycoides 537 resistant to rifampicin be used. When the rifampicin levels are determined in undiluted serum, the value obtained should be multiplied by 1.4. When a 2-fold dilution of the serum is used, the value is multiplied by 1.15. This provides an indicator maximally close to the real content of the antibiotic in the blood serum.
Bacillus↗
[Thermal resistance of the spores of a Bac. stearothermophilus culture used for the preparation of bioindicators].
Thermostability of the spores of Bac. stearothermophilus in ampoules and capillaries in concentrations of 10(9), 10(8) and 10(6) cells per 1 ml of sodium chloride isotonic solution was determined at 119 to 124 degrees C with an interval of 1 degree C and an exposure time of 5, 10, 15, 20, 25, 30, 35 and 40 minutes. The results were used for plotting the survival curves. The time of the microbial death in the ampoules and capillaries at all the temperatures was the same and the ampoules were chosen as the bioindicator vehicle because of their availability and convenience in exploitation. The survival curves may be used for determination of the optimal sterilization conditions. The spore concentration of the thermostable culture in the bioindicator should be equal or exceed the level of the object microbial contamination. In the present study the concentration of the test microbe spores in the bioindicator was 10(6)--10(8) cells/ml.
Culture Media↗
[Changes in microorganism sensitivity to antibiotics as affected by divalent metal ions].
Ca+ and Mg+ in nutrient media significantly influence the results of antibiotic sensitivity determination in microorganisms. The data of the study are indicative of a necessity for the media standardization with respect to the content of bivalent metal ions. It is recommended that agar-agar manufactured by the South Sea Factory (tafuinsky) be used for preparation of nutrient media for determination of microbial sensitivity to antibiotics and Hottinger meat pancreatic digest as the nitrogen source providing the content of 120 mg per cent of amine nitrogen in the medium.
Anti-Bacterial Agents↗
[Increase in the sensitivity and a simplification of the method for the separate determination of antibiotic activities in combined preparations (oletetrin) by using media with a varying pH value].
An agar-diffusion method for determination of oleandomycin and tetracycline low levels in solutions of the drug combination was developed. The medhod may be used for investigation of oletetrin absorption and distribution in humans and animals. It provides high accuracy in separate determination of oleandomycin and tetracycline activity in solutions of the drugs at a ratio of 1 : 2. The same test-culture, Bac. subtilis, variant L2 is used for the assay of tetracycline and oleandomycin activity. The only differences are in the values of pH and the buffer solution and the standards.
Bacillus subtilis↗
[Development of a method for the quantitative evaluation of microorganism sensitivity to antibiotics utilizing disks. The determination of the minimal doxycycline concentration that depresses microorganism growth using disks containing this antibiotic].
A quantitative method for estimation of microbial sensitivity to doxycycline with the use of discs containing 10 gamma of the antibiotic was developed. The antibiotic concentrations in the agar were determined at a distance equal to the radius of the growth inhibition zone with the help of a curve of the dependence of the logarithm of the doxycycline concentration in agar at the period of the average critical time of the zone formation equal to 5 hours and the distance from the disc center. The antibiotic concentration in the agar at the zone edges was almost the same as the MIC of doxycycline against the test-cultures determined with the method of serial dilutions in agar.
Anti-Bacterial Agents↗
[Testing the sterility of injection preparations of penicillin series antibiotics].
The efficiency of 3 variants of the method for determination of microbial flora was compared on the injection preparation of potassium benzylpenicillin artificially infected with Staph. aureus 209P and the spores of Bac. subtilis ATCC 6633 in different doses and with different amounts of the preparation in the vials. The procedure of the preparation dissolution in the vial with the thioglycol medium containing penicillinase proved to be most effective. The microbe detection amounted to 100 per cent. The procedure was less labour- and time-consuming since addition of penicillinase to each vial with the thioglycol medium was excluded. The risk of the medium occasional infection with microbial flora during the assay was decreased.
Bacillus subtilis↗
[Development of a method for the quantitative assessment of microorganism sensitivity to antibiotics using discs. The study of different nutrient media for determining microorganism sensitivity to antibiotics].
Five nutrient media used for determination of microbial sensitivity to antibiotics, i.e. beaf-peptone agar, Hottinger pancreatic beaf infusion agar, sprat hydrolysate nutrient agar of the Dagestan Research Institute of Nutrient Media, Muller-Chintone agar from Bulgaria and "Oxoid" agar for determination of microbial sensitivity were studied comparatively. The media were compared with respect to the growth density with the use of different test-cultures and the clearance of the inhibition growth zones around the discs containing different antibiotics. The best results were obtained with the use of sprat hydrolysate nutrient agar. Further studies on the medium standardization are necessary.
Anti-Bacterial Agents↗
[Biological method of identifying antibiotic substances at an early screening stage].
A biological method was used in addition to the chemical methods of identification in the screening programme of new antibiotics. The method consists of evaluation of the effect of the crude antibiotic preparations on microbial forms resistant to various antibiotics. The efficiency of the biological method is shown. It provides more complete and rapid characterization of the properties of the new antibiotics and their rough identification at early screening stages.
Anti-Bacterial Agents↗
[Use of the "Steritest" apparatus for testing the sterility of antibiotic preparations].
The efficiency of determining microbial contamination of artificially infected preparations of 8 antibiotics in ampoules and bottles and erythromycin eye ointment with the use of apparatus "Steritest" and "Millipore" was compared. It was found that "Steritest" had a number of advantages as compared to "Millipore" because of elimination of operations for preparing the apparatus for the assay, which prevented contamination of the apparatus with microorganisms from the environment. The time required for the assay with the use of "Steritest" was 2 times shorter and the amount of the tioglycol medium was 2 times lower.
Anti-Bacterial Agents↗
[Effect of different grades of agar-agar on the nature of the test microbe growth inhibition zones in controlling antibiotic activity by means of agar diffusion].
The effect of various agar grades on the size and margin character of the inhibition growth zones in assay of antibiotic activity by the agar diffusion method was studied. It was shown that not all the agar grades could be used in antibiotic activity assay. Depending on the agar type the size of the inhibition growth zones produced by the same antibiotic concentration significantly varied. The variations in the size of the inhibition growth zones depended on the agar ability to bind antibiotics and were mainly defined by the agar purity. The agars with low content of nitrogen admixtures bound the antibiotics to a low extent. The commerical grades of the agars of the South-Sea and Korsakov Plants, the experimental grade of the TINRO agar with additional purification, as well as the agars imported from Argentina and France proved to be most useful for determination of the antibiotic activity by the agar diffusion method.
Agar↗
[Development of a method for the quantitative assessment of the microorganism sensitivity to antibiotics by using discs. A study of the patterns of doxycycline diffusion from discs into the nutrient agar].
Doxycycline concentrations provided by the antibiotic diffusion from paper discs into sterile agarized medium and the medium plated with staphylococci and Coli bacteria were studied at different distances from the disc center. Infection of the nutrient medium with the test cultures had no effect on the antibiotic diffusion rate. A linear relation between the logarithm of the antibiotic concentration in the agar and distance from the disc centre were found. Probably it is possible to determine the MIC of the antibiotic with respect to various microorganisms by the value of the radius of the growth inhibition zone around the disc using diagrams expressing such a relation.
Agar↗
[Characteristics of determining the microbial contamination of penicillin series antibiotic powders and tablets].
Optimal conditions for determination of microbial contamination of drugs were studied on artificially contaminated powders and tablets of phenoxymethylpenicillin, ampicillin, oxacillin and dicloxacillin. The method of membrane filtration was the best for determination of the microbial contamination of the powders. However, it was not possible to wash out completely the antibiotic from the membrane filter. To prevent this it was necessary to add penicillinase into the nutrient medium onto which the filter was put for providing the microbial growth. For determination of microbial contamination of tablets direct plating of 3 per cent suspension of the tablet mass onto the surface of the nutrient medium with penicillinase was the best.
Ampicillin↗
[Determination of rifamycin B activity in culture liquids and in preparations with varying degrees of purity].
A possibility of using the biological method of rifamycin B activity determination in the fermentation broth and dry preparations of various purity levels was studied. It was found that the biological method was useful only for determination of rifamycin B activity in preparations containing not less than 850 gamma/mg of the main product. When the activity of rifamycin B was determined in the fermentation broth and crude preparations containing less than 800 gamma/mg of the main product, the results of the biological assay were always higher as compared to those of spectrophotometrical estimation. It was accounted for the effect of other rifamycin types possessing high biological activity.
Agar↗