T. Aoki, S. Egusa, T. Arai
Apr 1, 1975
Citations
0
Influential Citations
9
Citations
Quality indicators
Journal
Japanese journal of microbiology
Abstract
Nitrofuran derivatives are among the commonly used chemotherapeutics for human urinary tract infections. These drugs are also generally used for the treatment and prevention of fish infectious diseases and the preservation of fresh fish meat in Japan. Because of the continuous use of nitrofurans in Japan, the incidence of nitrofuran resistance has been reported as high [7, 8]. Most of the nitrofuran-resistant characters were found to be coded by the bacterial chromosome with none of the R factors detected in these bacteria found to carry nitrofuran-resistant genes [8]. We have been studying the R factors which conferred nitrofuran resistance in bacteria isolated from areas where nitrofurans are commonly used. Naturally occurring bacteria and bacteria which received R factors from these natural isolates were examined concerning their minimal inhibitory concentrations (MIC) to the nitrofurans: furazolidone (Takeda), nifuriprinol (Dainippon Seiyaku) and nifurprazine-HCl (Yamanouchi). Heart infusion agar (Eiken) plates containing various concentrations of nitrofuran derivatives were used as solid media for MIC measurements. A 0.025-ml sample of a liquid culture containing 103 cells was spotted on the above plates and incubated at the proper temperature (37 C for enteric bacteria and 25 C for the other bacteria). The nitrofuran concentrations which gave less than ten colonies per plate were taken as the MIC [2]. Naturally occurring nitrofuran-resistant strains which were found to carry R factors were cultivated in Bacto-penassay broth