In the antibiotic screening studies directed by Prof. Sumiki, an antifungal substance was found in a culture filtrate of a fungus, No. K-5201, which was isolated from a soil collected at Karuizawa, Nagano Prefecture. The cultural characteristics of the strain No. K-5201 were investigated by Abe and others¹⁾. The strain was designated as Paecilomyces varioti Bainier var. antibioticus, and the antibiotic produced by this strain was named variotin.

Variotin is a new antifungal antibiotic, having low toxicity and exhibiting inhibition against Trichophyton and other pathogenic fungi. This paper describes processes of production, extraction and purification of variotin and its properties.

As previously reported¹⁾, variotin is a new antifungal antibiotic, having low toxicity and exhibiting inhibiticn against Trichophyton and other pathogenic fungi. In this paper, the cultural characteristics and microscopic observations on variotin-producing strain are presented.

A fungus isolated from a soil sample collected at Karuizawa, Nagano Prefecture, was numbered as K-5201.

With the recent development of antibiotic therapy and with the frequent application of corticosteroid hormones, incidence of microbisme substitué and fungal diseases, respectively, are reported to be increasing^1,2). In these circumstances, studies on antifungal agents have been carried out by many investigators, and good many antifungal drugs were examined in dermatomycosis³⁾, though only a few antibiotics were applied to internal fungous diseases⁴⁾.

The present authors studied the antifungal activity of variotin, a new antifungal antibiotics discovered by Sumiki, Umezawa, Yonehara, etc. in the Institute of Applied Microbiology of Tokyo University, as well as certain characteristics concerning chemotherapeutic effect. The results of experiments are reported in this paper.

Variotin is a new antifungal antibiotic discovered by Yonehara, Takeuchi and others^1,2,3). It is a neutral oily substance, produced by Paecilomyces varioti Bainier var. antibioticus.

Notwithstanding its strong activity against pathogenic fungi such as Trichophyton and Blastomyces, industrial production of variotin has been difficult because of low stability. In the studies on stabilization of variotin preparations, following results were obtained.

Variotin is a new antifungal antibiotic discovered by Sumiki, et al. It is a fragrant white or yellowish oily substance produced by Paecilomyces varioti var. antibioticus. Its chemical characteristics, antibacterial spectrum and clinical effects have been reported, but, in regard to its pharmacological action, it is only reported to have low acute toxicity. Therefore, the authors examined the pharmacological action of variotin and obtained the results described in this paper.

Although comparatively good clinical results have been obtained in the treatment of fungal disases using antifungal drugs containing fatty acids, mercuric compounds and antibiotics such as aureothricin and trichomycin, still better drugs are expected. The present paper deals with experimental and clinical results of a new antibiotic, variotin, produced by Paecilomyces varioti Bainier var. antibioticus.

Variotin is white or yellowish liquid having ester-like odor. It is unstable and disintegrates gradually, but is stabilized when it is dissolved in organic solvent avoiding the contamination with heavy metals added with etylene diamine-tetra-acetic acid (EDTA). It is reported that the toxicity is extremely low. Mouse survived intraperitoneal injection of 320,000u/kg.

Trichophytia pompholyciformis and trichophytia eczematosa are comparatively difficult to cure. Many works have been published en these disease especially after the War and number of antifungal preparations have been supplied. Most of them are mercuric drugs, but recently a group of antibiotics have appeared, which include trichomycin, aureothricin, etc. The authors received a new antibiotic variotin from Nippon Kayaku Co. Ltd., and applied it clinically to several dermatomycosis with some favorable effect.

Variotin is a faintly yellowish, oily antibiotic isolated at the Institute of Applied Microbiology, Tokyo University from Paecilomyces varioti Bainier var. antibioticus. It is insoluble in water, but soluble in various organic solvents. Recent studies on variotin have shown the favorable antifungal activity against pathogenic fungi of ringworm. The present paper describes the observation on the effectiveness of variotin topical treatment in the patients with dermatomycoses.

Nowadays the treatment of dermatomycosis, especially of tinea pedis, is considered to be falling into difficulties, although various kinds of medicament for fungous diseases appear every year, and it is universally agreed that the complete cure of tinea pedis is considerably unattainable even if a clinical healing is seen by treatment.

In this paper the clinical effect of variotin on dermatomycosis, including in vitro antifungal activity and animal experiment of the antibiotic was described.

There have been many therapeutic agents against trychophytosis, and some of them have shown fairly good curative effects. Most of the agents which are still in daily clinical use because of high effective rate contain mercuric compounds, salicylic acid, undecylenic acid, pentachlorphenol, sulfur, etc. as their main ingredients. With the advance of antibiotic research, there gradually has been introduced a number of antibiotics with anti-trychophytosis activity. In Japan, aureothricin, trichomycin and nystatin have already been used, and many authors have reported clinical data with these antibiotics. Curative effects of these antibtotics, however, are not necessarily superior to those of above-mentioned chemical therapeutics, and the latters were even superior to the formers in many cases.

The present authors want to make an interim report on their experiences with variotin liquid, a new anti-trichophytosis agent supplied by Nippon Kayaku Co. Ltd., which showed quite an excellent result in comparison with old therapeutics.

Variotin is a new antifungal antibiotic isolated from Paecilomyces variotii Bainier var. antibiocticus by Sumiki, Umezawa and Yonehara in 1956. Its fungistatic activity and effect on animal and human dermatophytosis were studied.

The effect of variotin tincture to the superficial skin fungous infections has been evaluated.

Vast efforts have been expended in finding out antifungal agents by many researchers. Recently, some antibiotics such as candicidin, aureothricin, furacidin, trichomycin, nystatin, etc. which have antifungal activity have been discovered and shown clinically to be effective for fungous infections. Variotin is a new antifungal antibiotic obtained from Paecilomyces varioti Bainier var. antibioticus. In this short report, the results obtained from topical use of alcohol solution of variotin for various superficial fungous diseases of the skin are presented.

This is a preliminary report on variotin in the treatment of skin diseases caused by Trichophyton. Variotin is an antifungal antibiotic discovered at the the Department of Antibiotics, the Institute for Applied Microbiology, Tokyo University, to be produced by Paecilomyces varioti var. antibioticus.

In our laboratory, the action on Trichophyton has been studied by Koide¹⁾ using an antibiotic prcduced by an Aspergillus since 1948. In this preliminary study on variotin, on account of small number of cases, a few cases diagnosed only by clinical symptoms were included, though mycolcgical diagnosis should be established.

Antifungal antibiotics so far existent have been all isolated frcm Streptomyces, while variotin is a substance produced by a fungus and, therefore, provides many specific characteristics. As ever as the discovery of new antibiotics, variotin was investigated for antibacterial spectrum against organisms and fungi and for influence on respiration of protozoa and tumor cells. Besides, were studied emergence and speed of variotin resistance as well as antagonistic substance to variotin.

The therapeutic results of dermatomycosis with antifungal agent, variotin, has teen published by the present authors. At that time, variotin was smeared topically 2–3 times a day with brush. The effect was remarkable in 20 cases, effective in 10, ineffective in 12 out of 46, and effective rate was 76%. Clinically, variotin was characterized in its low irritability. Slight irritation was experienced only in 2 out of 46 cases of wet type of trichophytia pompholyciformis. However, smearing variotin directly to 7 wet type cases caused less irritation as compared with usual mercuric preparations. This may due to oiliness of variotin. In addition, it is of interest that variotin was remarkably effective of trichophytia interdigitalis, as reported by Tanuma.

Umezawa, et al.¹⁾ had reported a new antibiotic kanamycin and the strain producing this antibiotic was assigned to a new species, Streptomyces kanamyceticus. This strain was isolated by the present authors from a soil sample taken at Nagano Prefecture. This strain was numbered as K-2J in Department of Antibiotics, National Institute of Helath and as Ka (by the Japanese syllabary)-2J in Department of Bacteriology, Faculty of Medicine, Shinshu University. After the usefulness of kanamycin had been widely known, the present authors needed to study the origin of the soil more in detail. K-2J strain of National Institute of Health and Ka-2J of Shinshu University were recorded to have been isolated from a soil sample taken at Tobira Hot Spring Place in Nagano Prefecture. One of the present authors, Tazaki, Department of Bacteriology, Shinshu University, had also kept another strain which was numbered as K-2J in his laboratory, and which was recorded to have been isolated from a soil taken at Nagoya. Reconfirmation of record revealed that the kanamycin-producing strain was his strain of Ka-2J, but not his strain of K-2J. Thus, the origin of the kanamycin-producing strain was determined to be the soil of Tobira Hot Spring Place in Nagano Prefecture.

The strain K-2J (the present authors adopt the strain number of K-2J of National Institute of Health hereafter), S. kanamyceticus, showed originally yellow colored growth as indicated in the previous paper, but white colonies were frequently found on agar slant or plates of Czapek’s agar or Krainsky’s glucose asparagine agar. These white colonies were not contaminants. The study of mutants which are frequently obtained must be helpful for detailed characterization of the kanamycin producing strain. This kind of study is also helpful for improving the strain refering to its productivity of kanamycin and would contribute to the knowlege of variation in a species of S. kanamyceticus. In this paper, the authors describe several types of mutants of this species with reference to their productivity of the antibiotics.

Streptomycin production has been found in species of S. griseus (Krainsky) Waksman et Henrici, (A. globisporus Krassilnikov), S. bikiniensis Johnstone et Waksman, S. mashuensis Sawazaki at al¹⁾. Hydroxystreptomycin was isolated from the fermentation broth of S. griseocarneus Benedict et al. by Benedict et al.²⁾ and independently by Grundy et al.³⁾ and from that of S. reticuli-like organism by Hosoya et. al.⁴⁾ Dihydrostreptomycin was isolated from the broth of S. humidus Nakazawa at al. by Nakazawa et al. Recently, a characteristic streptomyces different from other known species was found to produce streptomycin as reported in previous paper⁸⁾ and given the name of S. galbus nov. sp. Okami et Umezawa on the basis of its characteristic yellow color of growth.

In this paper, description of S. galbus nov. sp. and some remarks on the species producing streptomycin-group antibiotics are presented.

It has been generally accepted that the selection of the most effective antibiotic for the treatment of an infection should be based on the result of in vitro sensitivity test. Of a number of methods, the serial dilution method (dilution method) has been considered to be the most reliable, because its result offers a rational information on the therapeutic effect of tested antibiotic in vivo. In addition, dilution method possesses reproducibility and accuracy in the test, when the procedure is carefully standardized and controlled. The disc-plate method (disc method), however, is the most widely used especially in routine laboratories because of its simplicity.

Two methods can be considered to be different in their modes of antibiotic action on the growth of inoculum. In dilution method, antibiotic concentration is constantly maintained in culture medium during incubation period. In disc method, however, the bacterial cells inoculated at any given portion of the surface of an agar plate are influenced by antibiotic, diffusing through from the disc put on a plate, and varying always with its own concentration within a certain time period. Two methods are also different in the manner of reading the results. In dilution method, susceptibility is expressed in terms of minimum inhibitory concentration (MIC), while in disc method, that is determined by measuring the inhibition zone around the disc. Therefore, these facts suggest that the results obtained by both methods may not coincide completely.

On the other hand, method of performing the test, reading and interpreting the results are poorly standardized in disc method, making it difficult to compare results obtained in different laboratories.

Moreover, fundamental analysis of disc method has not yet been completely discussed. In an attempt to make disc method reliable, fundamental study is present in this paper as follows:

1. Study of antibiotic diffusion in disc method, by measuring the actual antibiotic concentration in agar layer, and discussion of the principle of producing the inhibition zone.

2. Observation of various factors affecting the result of disc method.

3. Estimation of the correlation between results of disc and dilution methods.