An actinomycete, isolated from soil, was selected for investigation on the basis of its ability to produce an agent inhibiting WALKER 256 tumors in rats. This agent is a new antibiotic that has been designated "kundrymycin". Increased kundrymycin yield was obtained with media development and strain selection. Improvement was based on results obtained in in vivo tumor inhibition tests. Antibiotic yield in an 800-gallon (3, 000-liter) tank fermentation was 4.2mg/ml.
Kundrymycin, a new antibiotic, was isolated from fermentations of Streptomyces metachromogenes, sp. n., ATCC 21, 440, by methylene chloride extraction. It is an acid-base indicator with a molecular weight of 878.9. Biologically it is inhibitory to gram-positive bacteria, moderately cytotoxic to HeLa cells and inhibitory in vivo to WALKER 256 tumors in rats.
The frequencies of multiple-drug-resistant strains were investigated in Staphylococcus aureus from 1965 through 1968 and in Escherichia coli from 1966 through 1968 classifying them with each of the corresponding drugs. The following changes were found during the periods of investigation. S. aureus (7 drugs tested) : (1) In PC-G-resistant strains, there was a tendency for 5-drug-resistant and 6-drug-resistant strains to increase. (2) In SM-resistant strains, a tendency was noted for 5-drug-resistant strains to increase markedly. (3) In EM-resistant strains, for 4-drug-resistant strains showeda tendency to increase. (4) Almost no change was observed in the frequencies of multiple-drug-resistant strains comprising CP resistance. (5) In KM-resistant strains, a tendency was observed for 6-drug-resistant and 7- drug-resistant strains to increase. (6) No change was found in the frequencies, of multiple-drug-resistant strains comprising TC resistance. (7) In SIM-resistant strains, there was a tendency for 5-drug-resistant strains to increase. E. coli (6 drugs tested) : (1) In SM-resistant strains, there was a tendency for 4-drug-resistant strains to decrease, while 5-drug-resistant strains increased. (2) In CP-resistant strains, a tendency was noted for 4-drug-resistant strains to decrease. (3) No change was found in the frequencies of multiple-drugresistant strains comprising KMresistance. (4) No change was found in the frequencies of multiple-drug-resistant strains comprising CET resistance. (5) In TC-resistant strains, there was a tendency for 5-drug-resistant strains toincrease. (6) In SIM-resistant strains, 3-drug-resistant strains showed a tendency to increase. The possible processes for the development of the main types of multiple-drug-resistant strains were examined in light of their frequencies. The resultssuggest that the markers of resistance to TC, PC-G and SIM form a common basis of the various drug-resistance patterns in S. aureus. It is inferred that various types of multiple-drug-resistant strains may be formed by the successive addition of SM, EM, CP and KM markers in this order to the TC, PC-G and SIM markers. It is similarly inferred that in E. coli TC, SM and SIM markers form a commonbasis of various drug-resistance patterns and that various types of multiple-drug-resistant strains may be formed by the successive addition of CP and KM or CET markers in this order to the TC, SM and SIM markers. The pattern of KM resistance of various multiple-drug-resistant strains of S. aureus and E. coli was quite unique among the various drug resistances investigated. In the preceding paper1) the general tendency of drug-resistances of Staphylococcus aureus (coagulase-positive) and Escherichia coli. was reported on the strains clinically isolated in Japan during the past four years, 1965-1968. The purpose of this paper is to describe multiple-drug resistance in strains of the two species. With regard to multiple-drug resistance, a number of studies have been already reported2-5). However, few of these reports investigated annually and analysed statistically. In view of previous results showing that the degrees of drug sensitivity are very different depending on the sources of isolation, we here used only the strains from the same source of isolation : S. aureus strains were the isolates from pus specimens and E. coli from urine. Also sulfamethoxazole was newly added to the drugs tested. The details of the investigations are described hereunder; first on S. aureus and then on E. coli.
A new polyene antibiotic was isolated from the culture broth of a new Streptomyces, designated as Streptomyces noursei HAZEN et BROWN, 1950 var. jenensis nov. var. JA 3789. This antibiotic is a tetraene and was named tetramycin. The morphological and physiological characteristics of Streptomyces JA 3789 and the isolation, purification, physiochemical, and biological properties of the antibiotic are described. Tetramycin was differentiated from related antibiotics by physical and chemical data.
Bleomycin A2 caused degradation of DNA in the intact cells of E. coli 15T- and stimulated breakdown of DNA by DNase in the crude extract of E. coli B. On the other hand, the incorporation of dGMP into acid-insoluble fraction by partially purified E. coli B DNA polymerase was stimulated by bleomycin A2 for a short period after the addition of the antibiotic, and thereafter degradation of the product was observed. Digestion of salmon sperm DNA by pancreatic DNase was also stimulated by the antibiotic. An inhibitory effect of bleomycin A2 on polynucleotide ligase prepared from T4 phage-infected E. coli B was observed. The above in vivo and in vitro effects of bleomycin A2 can be explained if it causes strand scission of DNA. The stimulation of DNase reaction may also be related to the DNA strand scission by bleomycin.
Polyuridylic acid directed protein synthesis by ribosomes from tetracyclinesensitive and tetracycline-resistant cells of Mycoplasma laidlawii B was found to be sensitive to tetracycline. The ribosomal preparations were somewhat more sensitive to tetracycline than mixtures of ribosomes and cell membrane fragments. No requirement for an exogenous m-RNA could be demonstrated with the latter preparations.
A new antitumor antibiotic neopluramycin (NPM) exerts its effect on YOSHIDA rat sarcoma cells primarily by inhibiting cellular nucleic acid synthesis. The mechanism of action of NPM was studied in various in vitro systems. It is suggested that at low concentrations, NPM intercalates into DNA double strands, resulting in a decrease in S-value of DNA and a metachromatic change of UV spectra of NPM-DNA solutions. Besides these effects, interaction of NPM with single-stranded polynucleotide chains is suggested by shifts of the UV absorption profiles of NPM in the presence of RNA or denatured DNA. At high concentrations, NPM causes an increase in the S-value of native DNA, the elevation of Tm of DNA and the acceleration of renaturation of heatdenatured DNA. From these observations, we presume that NPM at high concentrations makes the double-stranded structure of DNA somewhat tighter. Wefind that dinucleotides are the minimum-required structure for interaction with NPM, suggesting that the two neighbouring bases which are adjacent on a polynucleotide chain would sandwich a NPM molecule. Dinucleotides containing guanylyl residues did not show this effect; therefore, there must be somebase specificity for the interaction.