ONE STEP RESISTANCE DEVELOPMENT TO ISONIAZID AND SODIUM- p -AMINOSALICYLATE

Abstract
The mutation rate per bacterium per generation of Bacillus megatherium to isonicotinylhydrazine resistance is 6([plus or minus] 1.5) x 10-5. The rate to Na-p-aminosalicylate resistance is 1([plus or minus] 0.3) x 10-6. The rate of mutation to double resistance is 8([plus or minus] 1.8) x 10-10, i.e., 7-8 times higher than the theoretically expected value derived as the product of the individual mutation rates. The significance of these observations is discussed.