[in Japanese]

View full abstract

The double-layer cylinder-plate method or so-called FDA cup method has been widely used for the assay of antibiotics. The basal layer of the assay plate in this system prevents irregularities of inhibition circles otherwise caused by uneven bottom surface of a glass Petri dish. Smooth-bottomed plastic dishes have recently replaced glass dishes and the time appears ripe now for exploring the possibility if this basal agar layer could be omitted without affecting the accuracy of ssay.
Employing 4 serial two-fold dilutions of 4 antibiotics (benzylpenicillin, tetracycline, erythromycin and streptomycin) comparative studies were made between the conventional double-layer cylinder-plate method and the thin-layer cylinder-plate method with 5ml seed layer in a plastic Petri dish.
The results obtained are summarized as follows:
1) No statistically significant difference (P at 5% level) could be found in variations of measured values for each antibiotic between the two assay systems.
2) Variations in values obtained by these 2 methods in quadruplicate gave standard errors to range 130-77% at maximum and 119-84% at minimum with the double-layer method, and 128-78% at maximum and 120-83% at minimum with the thin-layer method, respectively.
The foregoing results indicate that the thin-layer system using a plastic Petri dish with smoothsurfaced bottom can be a reliable and simple assay system for antibiotic assay comparable to the conventional double-layer technique.

View full abstract

Body fluid concentrations of cephalosporin antibiotics are influenced by factors of route of administration, dosage, assay method, degree of protein binding, degree of renal clearance, metabolism in the body, etc. Blood and urine concentrations of cephalothin, cephaloridine and cefazolin were determined in adult volunteers by injectable administration to find out the correlationship of the above factors, and the following results were obtained:
1. A remarkable dose-response relationship was observed in blood levels of cephalothin, cephaloridine and cefazolin by single injection of the dose of 0.25g-1.0g.
2. The changing pattern of blood levels of three antibiotics showed a similar pattern on intramuscular and intravenous (one shot and drip) injection.
3. A remarkable difference of assay values of cephalothin and cefazolin was observed when the blood samples were diluted with phosphate buffer or serum.
4. A peculiar difference of the blood level and urinary excretion correlationship was observed between the three antibiotics of cephalosporin derivatives.
5. No tendency of accumulation of the antibiotics in the blood was observed when usual clinical doses were administered to volunteers with normal renal function.
6. The above-mentioned results seem to indicate an important role of serum-protein binding of the antibiotics. This problem will be elucidated in future.

View full abstract

Absorption, excretion and distribution of colistin sulfate (CLS) was examined in chickens and pigs.
(1) After oral administration of CLS in chicken, the serum and bile levels reached maximum of 10.2 and 5.7mcg potency/ml at 2 hours with a dose of 50mg potency/kg, and were greatly reduced after 6 hours. The concentration of CLS in other organs were lower or almost undetectable. With 25mg potency/kg, the concentration in organs were nil.
(2) In pigs, the serum and bile levels of CLS following oral administration were 1.0 and 4.0 mcg potency/ml with 25mg potency/kg, 8.3 and 9.0 mcg potency/ml with 50 mg potency/kg respectively. In other organs, the levels were lower or almost undetectable.
(3) When feeds containing 1, 3 and 9 ppm of CLS were given to pigs for 16 weeks, lower concentrations of CLS distributed in serum and bile, and almost undetecable levels in other organs.

View full abstract

We studied on the isolation rates of enterococci from various clinical materials and their susceptibility to antibiotics during ten years since 1961.
Enterococci were isolated from urine, pleural and abdominal exudates, pus and secretes in high rate, but the isolation rate from blood or spinal fluid was low. Since 1963 the isolation rates of enterococci from various materials became slightly high.
Enterococci were resistant to various antibiotics, but almost all strains were sensitive to ampicillin and carbenicillin. Strains isolated from bilewere more sensitive to antibiotics than those from other materials. No changes were observed in susceptibility during ten years.

View full abstract