152 ANTISEPTICS 



amounts of sulfanilamide. While the concentration of the 

 latter needed to retard by 85% the growth of B.coli is 

 0.005M, they use 8 times .^s much (0.04M or 0.69%) for 

 the much more sensitive streptococcus. 



Wyss, Strandskov and Schmelkes (1942), following 

 the Sevag technique, obtained a decrease of 20-28% in 

 the oxygen uptake of Strep, pyogenes with 0.04 M sul- 

 fanilamide, but the same or larger decreases were ob- 

 tained with the ortho and meta derivatives which are 

 chemotherapeutically inactive. The results with Bad. 

 coli and Staph, aureus were similar. If these compounds 

 retard respiration without producing the true sulfona- 

 mide action, we cannot very well explain the sulfonamide 

 action as the result of retarded respiration. The same 

 conclusion must be reached from the findings of Sevag^ 

 that ''approximately 65% inhibition of aerobic respira- 

 tion or approximately 45% inhibition of anaerobic respir- 

 ation results in (or accompanies) complete bacterio- 

 stasis." 



This checks with Ely's result (1939) that the respira- 

 tion of Bad. coli is decreased about 50% by 0.8% sulfan- 

 ilamide, "with little or no killing of bacteria". In other 

 words, multiplication ceases completely when the cells 

 are capable of producing 35 to 55% of their energy by 

 respiration or fermentation. 



However, bacteria do not cease growing under such 

 circumstances. Foter and Eahn (1936) have shown that 

 at low temperatures, streptococci and lactobacilli need 

 only half as much energy for doubling their number as 

 at the optimum temperature, but are capable of multi- 

 plying slowly and continuously with only 5% of the 

 energy output observed at the optimal temperature. The 

 complete inhibition of multiplication of cells which still 

 show respiration or fermentation can be due only to a 



1. Quoted from Henry (1943), p. 226. 



