146 AXTISEPTICS 



phenols and methylene blue were bacteriostatic for Pneu- 

 7nococcus and most hemolytic streptococci, while the in- 

 digoes, malachite green and the indophenols were not 

 toxic. In the reduced state, methylene blue and the in- 

 dophenols were not toxic either. 



VI. MODE OF ACTION OF THE SULFONAMIDES 



The antiseptic properties of sulfanilamide and its de- 

 rivatives have probably been studied more intensely than 

 those of all other antiseptics combined. The review by 

 Henry (1943) lists 291 references. The sulfonamides are 

 not strong disinfectants, but owe their fame to their 

 ability to prevent, in concentrations which do no great 

 damage to blood or tissues, multiplication of many spe- 

 cies of bacteria. 



The sulfonamides differ from all other antiseptics in 

 that they do not affect the bacteria at once, but require 

 a measurable amount of time before bacterial gro^vth is 

 retarded. The delay varies greatly, usually from 2 to 6 

 hours, according to Henri's compilation of data from 

 seven authors. With all other antiseptics, the degree of 

 growth retardation is uniform as long as the culture 

 grows, or if the rate of multiplication occasionally va- 

 ries, it may increase, as with crystal violet, but it never 

 is normal at the start and decreases later. The writer 

 has checked all his plate count and turbidity rec- 

 ords of the early stages of antisepsis by phenol, formal- 

 dehyde, benzoic and sulfurous acid, and in every case 

 multiplication was promptly retarded even by small doses. 

 A picture like that of Figure 30, which was obtained by 

 Muir, Shamleffer and Jones (1942) in their study of the 

 effect of sulfathiazole on Bact. enteritidis is characteris- 

 tic only of sulfonamides. These authors observed that 

 Bact. enteritidis treated with sulfathiazole multiplies for 

 a short time quite normally, but after about 3 genera- 



