Effect of penicillin series antibiotics on the properties of Brucella]

Investigation of the properties of antibiotic-resistant variants obtained experimentally from various species of Brucella indicated that benzylpenicillin, ampicillin and ceporin induced significant changes in the main properties of Brucella, i.e. phagolysability, agglutinability, production of brucellacin and hydrogen sulfate, attitude to dyes. Only the nutrient requirements of Brucella did not change when it was grown on synthetic media which is of great importance for investigation of changed Brucella strains.     

Method of membrane filtration for determining the sterility and microbial contamination of antibiotics]

During membrane filtration antibiotics belonging to different chemical groups are strictly absorbed on the filters. When the filters are put into liquid thioglycol medium, the residual amounts of the antibiotics on the filters did not prevent the growth of sensitive microflora experimentally added to the drug. When the filter was put onto solid nutrient medium, only resistant forms of the microbes grew as a rule on its surface, the amount of the grown microbes being 26--43 per cent of the added one. The sensitive microbes grew only in the amount of 0.3--1.3 per cent. Subsequently the residues of the antibiotic adsorbed on the filter inhibited the growth of the sensitive and partially resistant microflora.     

Determination of the microbial contamination of tablets of tetracycline series antibiotics]

The experiments showed that the method of direct plating of tetracycline tablet suspensions on solid nutrient media containing magnesium sulfate may be used for determination of microbial contamination. The method provided determination of both the antibiotic resistant and the antibiotic sensitive organisms which may be present in the drug. Dilution of the basic suspensions increased the probability of the microbe detection in the tablets.     

Effect of some antibiotics and chemotherapeutic preparations on Leptospira in vitro]

It was shown in vitro with the method of successive serial dilutions that polymyxin M, thilan, streptomycin, neomycin, sodium levomycetin succinate, brilliant green, tripaphlavin, azidin, aminoacrichin, and novarsenol had the most pronounced bactericidal effect on Leptospira. Combination of the antibiotics or the chemotherapeutics apart from azidin and tripaphlavin did not increase the bactericidal effect as compared to their use alone. The clinical and collection strains of Leptospira had the same sensitivity to the substances tested. The above drugs should be tested on animals with leptospirosis.     

Functional state of the testis after the use of certain antibiotics and nitrofuran preparations]

The functional state of the testis due to the effect of antibacterial therapy was studied in 50 patients suffering from chronic inflammatory diseases of the urinary-genital system and treated with neomycin, streptomycin, tetracycline, furadonin and furagin. It was shown that the above nitrofurans and neomycin had a negative effect on the testis function lowering the number of the spermatozoa in 1 ml and the whole ejaculate and their mobility. Contrary to it tetracycline therapy had no significant effect on the spermatozoa number, while the use of streptomycin was accompanied by a certain tendency to an increase in their number. The data were to some extent in certain accordance with the results of the experimental studies.     

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.     

Long-term analysis of sterility testing of immunobiological preparations

The data for sterility testing for 16 years show a high stability from different points of view. The summarized and compared results after 10 and 16 years are similar, so we can assume a fixed methodological, technological and biological balance. The necessity of changes in these methods and the achieved balance is discussed.     

Early discoveries in the penicillin series.

It is now 50 years since the therapeutic potential of penicillin was first demonstrated. This first antibiotic and the series of compounds derived from it have been of immense importance in modern medicine. This article describes the early search for more potent penicillin derivatives, culminating with the discovery of an intermediate of penicillin biosynthesis, 6-beta-amino penicillanic acid (6-APA). A companion article in next month's TIBS will chart the subsequent exploitation of 6-APA and the preparation of a range of clinically important semi-synthetic penicillins.     

Lysozyme activity in the leukocytes and blood serum of white rats administered massive doses of penicillin preparations]

Activity of lysozyme in the blood serum and leucocytes was determined. The experiments were carried out on albino unbred rats weighing 170 to 200 gm. Benzylpenicillin and oxacillin were administered intramuscularly in doses of 500000 Units/kg or 20000 gamma/kg once every 24 hours for 2, 4 and 6 days. The activity of lysozyme was determined by the turbidimetric and agar-diffusion methods. It was found that the activity of lysozyme in the leucocytes increased by the 5th day accompanied by a simultaneous decrease in its level in the serum followed by reaching the initial values. The data are indicative of the fact that the use of antibiotics in mega-doses is not contraindicated from the point of view of their effect on lysozyme activity.     

Evolution of resistance to penicillin and cephalosporin antibiotics

Microorganisms belong to the main regulators of insect populations under natural conditions. They perform this function in several ways. In the first place, bacterial metabolites exist which are as potent as chemical insecticides. In the second, entomopathogenic fungi and viruses spread deadly infections among insect populations. The use of advanced techniques in molecular biology, genetic engineering and biotechnology is increasingly expanding the potential of microorganisms as agents of insect pest control.