Some data on the character of staphylococci surviving the action of penicillin

Summary

• 1) The development of colonies originating from staphylococci surviving the influence of high and medium concentrations of penicillin, experiences a delay and the variation of their growth-rate increases as compared with untreated bacteria. Critical concentrations of penicillin have a brief growth-stimulating effect.

• 2) This delay in the development of colonies is connected with structural changes effected by penicillin. As the duration of the contact is longer and the concentrations higher, the changes become more radical.

• 3) The first degree of involution is thought to be an intermediary form; next the ‘large body’; the more drastically transformed structures are supposed to be desintegration products of the large bodies.

• 4) WithProtens mirabilis, E. coli, Streptococcus andH. influenzae also, organisms surviving the action of lethal concentrations of penicillin were found. The structural changes in these organisms are, if comparable at all, less frequent and mostly less radical than those found inStaphylococcus.