Discussion 101 



the problem of seeing whether resistance is exactly proportional to the 

 rate of synthesis of penicillinase? 



Pollock: Yes, one mi«fht possibly do that. 



Hayes: What about low pH's, to which I understand penicillinase- 

 producing staph ^^lococci are sensitive, and the enzyme is not produced? 



Pollock: I admit I have not exhausted all the possibilities. 



Knox: With regard to the relation between penicillin sensitivity and 

 the type of penicillinase, have you tested all these strains at say 42° or 

 43°? 



Pollock: No, I have not, but it might be interesting. 



Knox: You might get a better correlation between penicillin sensitivity 

 and the amount of enzyme initially present. 



Hotchkiss: Does the amount of penicillinase in your unit correspond 

 approximately to the amount which could destroy an appreciable part 

 of the penicillin in the medium? In other words, I assume that when 

 you say that a strain having penicillinase has resistance to 10 units you 

 must be measuring under conditions in which penicillin is maintained at 

 approximately 10 units. This must mean that you do not destroy very 

 much by this sj^stem. 



Pollock: It is rather surprising that you can produce such a lot of 

 enzyme and still not have a very resistant organism ; also that you can 

 find a strain producing, for instance, 15 molecules of penicillinase per 

 cell and have an organism almost as sensitive as the most sensitive of 

 staphylococci. 



Hotchkiss: You can see that the question has a general bearing on the 

 survival of the cell; whether for other systems, too, the amount of 

 inducible protein can be such that it can change response to drugs. 



