Colicine typing of Shigella sonnei using the methods of Naito et al. and Abbott and Shannon were performed in parallel on a large number of epidemic strains, the indicator strains used in both methods, and on stock strains used to test the accuracy of the indicators. The following results were obtained after typing 462 epidemic strains: by Naito's method, 18 strains were in A₁, 87 in A₂, 33 in B₁, 253 in B₂, 38 in C₁, 3 in C₂, 2 in D, and 3 in E, and 25 strains were unclassifiable; while by Abbott and Shannon's method, using the present authors' simplified designation, 189 strains were in type 6/11, 124 in type 4/14, 85 in type O, and 41 in type 8, and 23 strains were either in other types or found unclassifiable. Naito's type A was in large part, equivalent to Abbott and Shannon's type O, but included some type 6/11 and type 4/14 strains. Naito's type B consisted of types 6/11, 4/14, 3A and 13, and type E consisted of 1A, 1B, 3, 5, 9, and 10. Type C coincided with type 8 and type D with type 12. In addition, there were strains determined to be Abbott and Shannon's types 6/11, 4/14, 2, 7 and 9. The Abbott and Shannon's method revealed the possibilities of these strains to be classified in further detail. This is considered to be attributable not merely to the lack of indicators in the Naito's method corresponding to those of Abbott and Shannon's, but also to insufficient production of certain colicines in the Naito's method. Because of the type distribution found in Japan at present, further investigation should be done so that types 6 and 11, and types 4 and 14 can be separated.

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Many urinary isolates which belong to the Enterobacteriaceae and bear multiple drug resistance were shown to harbor transmissible resistance factors (R factors). The levels of resistance were almost uniform in every strain investigated. The resistance markers were usually transferred as a unit. Frequency of transfer varied from host to host even when the same recipient strain was employed. However, no remarkable differences were observed in successive transfers of R factors between substrains of Escherichia coli K-12. The role of R factors in urinary tract infection is discussed.

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The zymogram patterns of esterases and catalases of mycobacterial strains were studied using the thin layer agar electrophoresis. Though there were some variations, Myco-bacterium hominis, M. bovis, M. kansasii, M. fortuitum, M. runyonii, M. avium, M. phlei and M. smegmatis seemed to show species-specific patterns consisting of 2 to 6 esterase bands and one or more catalase bands. The patterns of scotochromogens and nonchromogens were rather variable.

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Complement fixation reaction and agar gel double diffusion test were made using as antigens, water or phosphate buffer saline extracts of liver from mice severely infected with Tyzzer's disease. The supernatant of the extract heated at 56C for 30 minutes was highly reactive with immune mouse serum in the complement fixation test, while an intense precipitate band was observed only with unheated extracts in agar gel double diffusion tests. Cross reactions were observed in both tests between liver extracts from mice infected with different strains of organisms originating from different sources and showing varied degrees of virulence. Such reactions were not shown between Tyzzerimmune serum and liver extracts from uninfected or murine hepatitis-infected mice, nor were they shown between the Tyzzer-antigen and normal or anti-murine hepatitis virus serum. The complement fixation test was used to test retired breeder mouse sera for disease contamination in mouse colonies. Positive reactions were observed in test sera collected from some breeding colonies that subsequently proved to be contaminated by the cortisone provocation test in young animals.

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Crude mannans extracted from Candida albicans and Saccharomyces cerevisiae by autoclaving yeast cells in citrate buffer (pH7.0) according to Peat's method, were fractionated repeatedly by column chromatography on DEAE-Sephadex, acetate form, yielding neutral and acidic mannans. The former fraction showed a single peak by boundary electrophoresis and ultracentrifugal analysis, while the latter contained small amounts of phosphorus and protein. Using purified mannans as controls, various serological experiments were carried out with mannan antigens extracted from C. albicans with 45% phenol water and with 3% NaOH. No remarkable differences were observed in the antigenic activity of 4 mannan antigens from C. albicans, and the purified mannan exhibited very high antigenic activity. It was found that the mannan of S. cerevisiae was antigenically less specific than that of C. albicans mannan. The difference in serological specificity between mannans of both species may reflect not only differences in mannopyranose linkages but differences in the structure of the macromolecules.

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The phage typing patterns of phage type 52/52A/80/81 staphylococcal strains were changed to type 80/81 and the non-typable group by lysogenization with phages 27 and 146. When a particular strain of Staphylococcus aureus, MS1590 phage type 52/52A/ 80/81, was lysogenized with phage 146, type 80/81 and the non-typable group strains were produced. According to the comparison of host range of the prophages, it has been concluded that the two strains with different phage typing patterns have different kinds of prophages.

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Five strains of bovine diarrhea virus were isolated from Japanese cattle using bovine tissue cultures. These are the first isolations of this virus from Japanese cattle to be reported. Of importance is the finding that the new isolates, which are non-cytopathogenic, induce an exaltation of Newcastle disease virus in bovine testicular cell culture. This finding has provided a laboratory tool whereby the assay of the virus and its neutralizing antibody can readily be performed.

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A nontransferable R₂₁ (TC) factor was obtained by transduction of R₁₀ (TC. CM. SM. SA) with phage epsilon in group E Salmonella. The R₂₁ (TC) factor acquired transmissibility by the normal conjugal process when group E Salmonella strains harboring R₂₁ (TC) factor were infected with wild-type F or R₁₀ (CM) factor. This transmissibility at high frequency was accounted for by the formation of the recombinant F TC and R₁₈ (CM) TC factors. The F TC and R₁₆ (CM) TC factors were genetically the same as the original F and R₁₆ (CM) factors, except for the ability to confer TC resistance. In the transduction of F TC factor with phage P1, a dF TC (d: defective) factor was obtained that was defective in many F properties, such as the ability to introduce host chromosome and produce male substance, but was capable of transducing TC resistance (dF TCinfection) at low frequency.

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