クロルテトラサイクリン氷を使用した魚函における耐性菌の増加ならびに魚函の殺菌について

Abstract

The aims of this paper are to study the change in total bacterial counts and number of emerged resistant strains on fish and fish container during a 1-month storage of CTC-treated Jack mackerel (Trachurus japonicus) in crushed plain ice or CTC-ice, and further to estimate the effectiveness of bactericides in reducing bacterial counts on used wooden container. The growth of bacteria on the fish was retarded by a combination of CTC-dip and CTC-icing (Fig. 1). Retardation of growth of bacteria on the fish as well as on the container by the use of CTC-ice was more marked when held in the metallic container (Figs. 1 and 2). The emergence of resistant strains (MIC > 10ppm) on the metallic container occurred 5 to 10 days later than on the wooden one. Difference in time of emergence of resistant strains on fish skin was also noted between groups stored in these containers (Fig. 3). The maximum attainable number of total bacteria and of resistant strains which occurred on the metallic container was remarkably lower than that on the wooden container irrespective of kinds of ice employed (Fig. 2). Brushing of surface of the wooden container with benzarconium chloride or sodium hypochloride solution containing a 200 ppm level was effective in reducing the bacterial count to only about 1.5% of the original count before the treatment. It is to be noted that bacterial count in a 2-mm layer from surface of a water-washed wooden container did not show any appreciable decrease even after a thorough washing with a 200-ppm solution of any one of the bactericides studied (Table 3).