The incidence of conjugative R plasmids in multiple drug-resistant strains of gram-negative bacteria isolated in 1973 from patients in a 700-bed general hospital in Tokyo and some properties of the R plasmids isolated are described. Conjugative R plasmids were found in 52 of the 96 strains (54%), from which 74 R plasmids were demonstrated. It is remarkable that the isolation frequency of R plasmids mediating quadruple- or five-drug resistance was rather low, and the complete pattern of multiple resistance of the original isolates was only rarely transferred by conjugation. These results revealed the existing state of the distribution of R plasmids among hospital strains with multiple drug-resistance.

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Two strains of Staphylococcus aureus were examined for behavior in the cutaneous tissue of mice by the fluorescent antibody technique, hematoxylin and eosin staining. When about 10⁸ viable cells of an α-hemolysin-producing strain (Wood 46) were inoculated subcutaneously into a mouse, they multiplied in the subcutaneous tissue of the mouse and gradually entered the corium to produce α-hemolysin and nuclease. Edematous and necrotic lesions were observed in the cutaneous tissue where the organisms had multiplied. When 108 viable cells of a β-hemolysin-producing strain (Kitami 3-9D) were inoculated into a mouse, they multiplied within a narrow extent surrounded mainly by infiltrating leukocytes and produced mainly β-hemolysin. The changes of cutaneous tissue were weaker in mice inoculated with Kitami 3-9D strain than in mice inoculated with strain Wood 46. When 106 viable cells of both strains were inoculated into mice, they were phagocytized by leukocytes. Neither multiplication of organisms nor production of any active extracellular substance was observed in these mice. Edema, degeneration, and necrosis were also noticed in the cutaneous tissue of mice inoculated with α- and β-hemolysin. In addition, the infiltration of leukocytes was inhibited mainly by α-hemolysin.

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An inter-Group common antigen was detected between Group A type 28 (Small) - and Group F (21/58/O'Mahoney, Colindale) -streptococcal cells by the T-typing agglutination reaction. The characteristics of this antigen coincide with those of the 28R-antigen, which was first detected in the Group A type 28 (Small) cell's by Lancefield in 1943, in the following points : 1) It can beextract ed from the cells with HC1 at pH 2.0 at 100 C in a stable state; 2) It can be kept in a stable state by heating in an alkaline solution at pH 7.8; 3) The antigen on the heat-killed cells was not affected by trypsin digestion at pH 7.8 but was destroyed by pepsin digestion at pH 2.0.

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Embryonic chickens were rendered immunodeficient by in ovo injection of homologous IgM on the 10th embryonic day. The immunodeficient embryos were intravenously given lymphoid cells taken from normal embryonic bursa, spleen or thymus on the 15th embryonic day. Gain of splenic or bursal weight, natural antibodies to sheep red blood cells (SRBC), frequencies of rosette forming cells (RFC) binding to SRBC or dinitrophenyl-SRBC (DNP-SRBC) and of immuno-globulin bearing cells (IBC) in the bursa and the spleen were investigated to assess the effect of transferred cells during the embryonic stage. Transferred bursal and splenic cells showed an ability to restore the frequency of RFC or IBC in the recipients. However, reversion from the immunodeficient state was not observed in the thymic cell transfer. These findings suggested that the cells derived from embryonic bursa and spleen contained stem cells which developed into RFC and also into precursors of IBC.

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