Agglutinating and opsonic activities of the commercially available human immunoglobulin as well as a healthy human volunteer serum against various bacteria were examined. The opsonin titers of both serum materials against most of the rare resident bacteria were found to be almost same as their agglutinin titers, suggesting that opsonins in the serum materials were specific agglutinating antibodies. Therefore, the protective activities of the serum materials against various opportunistic pathogens could be judged by their contents of specific antibodies. But it was also observed that the opsonin titers against the major resident bacteria, such as Escherichia coli, Streptococcus faecalis and Lactobacillus spp. were higher than the agglutinin titers, suggest-ing that the circulating antibodies specific for major resident bacteria were small, because of the frequent consumptions by the invaded bacteria into cir-culation.
A plasmid-mediated surface antigen of naturally occurring Escherichia coli strains were demonstrated. This antigen was classified into L type (heat-labile K) antigens but was suggested not to be a pilus antigen, because no pilus was found on the surface of those common pili-free E. coli C strains carrying the responsible plasmids and also because the strains did not hemag-glutinate red blood cells of any animal species so far studied. Incidences of such antigen-forming strains were higher in the strains isolated from feces and respiratory tract secretions than in those from other sources. Plasmid DNAs from these strains were different from one another in their molecular sizes, but they had a common size band after digestion by EcoRI endonuclease, suggesting that they had a similar or the same origin(s).
We surveyed antibiotic resistances of fecal Escherichia coli strains from healthy human in Tokyo in 1978 and their conjugative R plasmids. Approxi-mately 50% of healthy human had streptomycin/tetracycline resistant E. coli strains in their intestines. In addition, 34%, 28% and 17% of them had ampicillin, kanamycin, and chloramphenicol resistant strains, respectively. Coincidences of various resistance markers of these isolated strains were higher in the closer markers in the linear order of Km-Sm-Tc-Ap-Cm. Incidences of the single drug resistant conjugative R plasmids in the strains selected by tetracycline, streptomycin, kanamycin and ampicillin were found to be high in these years, but the multiple drug resistant conjugative R plasmids were found to be still predominant in the strains selected by chloramphenicol even though the incidences of these strains had been decreasing. These results might be caused by the present selective chemotherapeutic environments.
Incidences of colicinogenic strains in the Escherichia coli strains isolated from various clinical materials were examined. The incidences were higher in the order in the strains isolated from pustular materials, feces, sputa and urine. Approximately 32% of the pustular strains were found to be colicino-genic. Heat stability of these colicins were examined and incidences of the heat stable colicins were found to be higher in the strains from pustular mate-rials than the strains from any other materials. Some of the colicins which retained their activity after treatment at 100°C for 30 minutes were con-centrated and tested for the cellophane membrane permeability and the re-sistance to methanol, acid and alkaline. They were all found to be permeable through cellophane membrane and resistant to all the chemicals.
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