家鼠およびブタから分離されたブドウ球菌の生物学的性状薬剤感受性およびファージ型について

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In order to search for the source of staphylococci responsible for food poisoning, studies were made on some properties of staphylococci isolated from rats (Rattus norvegicus) and swine, both of which had close relations with human beings. These staphylococci had been isolated from the nose of swine and the skin of rats. Coagulase-positive staphylococci were derived from 65 (50%) of 130 rats and 58 (85%) of 68 swine. These isolates were proved to have the following biological characters, drug sensitivity, and phage type.1. All the strains of coagulase-positive staphylococci isolated from rats and swine produced DNase, phosphatase and lysozyme, and reduced nitrate.2. Only 34 percent of the coagulase-positive strains isolated from rats showed β hemolysis, while almost all the strains (97%) isolated from swine were β hemolytic.3. The biological properties of the strains of rat origin were not always the same as those of swine origin. There were differences between the two in such respects as colonial color, lipase production, gelatin liquefaction, coagulation and later peptonization of litmus milk, hydrolysis of esculin, and egg reaction.4. Forty percent of the strains of rat origin were relatively resistant to penicillin, showing a susceptibility higher than 25u/ml. Thirty-five percent of the strains of rat origin and 83 percent of those of swine origin were relatively resistant to streptomycin (susceptibility higher than 12.5mcg/ml). Only 13 percent of the strains of swine origin were relatively resistant to tetracycline (higher than 12.5mcg/ml). About 80 percent of the strains isolated from both animal species were resistant to sulfathiazole (higher than 100mcg/ml). All the strains tested, however, were sensitive to chloramphenicol, oleandomycin, and erythromycin (less than 6.3mcg/ml). All the strains that were relatively resistant to penicillin and streptomycin formed yellow colonies on solid medium and were proved to be α hemolytic.5. Typing was carried out on these isolates using the basic set of typing phages which has been selected by the International Committee. Eighty-one percent of 58 strains of swine origin were successfully typed. Three-fourths of the strains which had been typed by this set of phages showed susceptibility to group II, and the rest of them belonged to the mixed group. On the other hand, only 17 percent of the strains of rat origin was found to be typable and belong to group III without exception.6. It can generally be mentioned that the properties of some of the strains of rat origin were closely related to those of the strains isolated from the cases of staphylococcal food poisoning, while the strains isolated from swine were considerably different from those from human beings.From these results, it is quite probable that the rat is playing an important role as a source of contamination in the case of staphylococcal food poisoning.
日本細菌学会の論文

家鼠およびブタから分離されたブドウ球菌の生物学的性状薬剤感受性およびファージ型について

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