THE SLOW RECOVERY OF BACTERIA FROM THE TOXIC EFFECTS OF PENICILLIN

Abstract

A bacteriostatic effect on staphylococci that persists for a no. of hrs. after the removal of penicillin is not peculiar to staphylococci, but is observed with beta-hemolytic streptococci of groups A and B, alpha-hemolytic streptococci, Streptococcus fecalis, Diplococcus pneumoniae, Staphylococcus aureus, and S. albus. The bacteriostatic effect of penicillin was followed by the death of a significant proportion of the organisms. Both phenomena were observed only under conditions favorable to the growth of the organisms. The recovery of the damaged bacteria required a similarly favorable environment. The time required for this sublethal toxic effect to become manifest varied with the concn. of penicillin to which the organisms had been exposed and was correlated with the rate at which the bacteria were subsequently killed by the drug. With some strains rapidly killed by penicillin, its initial bacteriostatic effect was apparent within less than 5 min. after the addition of penicillin. There was no demonstrable correlation between the sensitivity of the several organisms to penicillin and the rate at which these toxic effects were manifested. The time required for the bacteria to recover from the toxic effects of penicillin and resume multiplication increased with the time for which they had previously been exposed to the drug. The maximum duration of this recovery period varied from 3 to 8 hrs. The implications of these observations with respect to the mode of action of penicillin, and the therapeutic significance of the recovery period; are discussed.