PHYSIOLOGICAL ADAPTATION OF BACTERIA 

 TO ANTIBIOTICS 



W. KUNICKI-GOLDFINGER 

 Department of Microbiology , The University, Wroclaw 



Recent studies with bacteria have shown that the develop- 

 ment of drug-resistant strains in the majority of cases is 

 caused by genie changes (Demerec, 1945, 1948; Newcombe 

 and Hawirko, 1949; Bornschein, Dittrich and Hohne, 1951; 

 Cavalh-Sforza and Lederberg, 1953; Bryson and Szybalski, 

 1952; Gale, 1949; Lederberg and Lederberg, 1952). In con- 

 nexion with these observations the role of phenotypic or 

 physiological changes as a contributing factor seems to be 

 neglected. 



It is hoped, therefore, that it will not be out of place at this 

 meeting to discuss some physiological reactions of bacteria, 

 in which the observable changes seem to have a non-genic 

 character and Avhich result in increased resistance. 



An apparently total directed change in a relatively 

 stationary population 



Akiba (1955) and Szybalski (1955) have shown that in 

 Escherichia coli, when suspended in buffer solution and 

 incubated for a long period in the presence of streptomycin, 

 a characteristic change in total population may be observed. 

 Initially sensitive cells become resistant to a rather high level 

 of the drug. The role of selection may seem to be neglected, 

 because no growth during the incubation period was noted. 

 The induced streptomycin resistance has been shown by 

 recombination analysis to be genie (Szybalski, 1955). The 

 nature of this change was related by Szybalski to the selective 

 mutagenic action of the antibiotic. 



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