Mutations to Penicillin Resistance in the Enterobacteriaceae That Affect Sensitivity to Serum and Virulence for the Mouse

Publisher Website
Google Scholar
Abstract
Roantree, RobertJ. (Stanford University School of Medicine, Stanford, Calif.),and John P. Steward. Mutations to penicillin resistance in the Enterobacteriaceae that affect sensitivity to serum and virulence for the mouse. J. Bacteriol89:630–639. 1965.—Series of mutants resistant to benzylpenicillin or α-aminobenzylpenicillin were derived from serum-resistant strains ofEscherichia coliandSalmonellaby the gradientplate technique. Serum-sensitive mutants were detected in series derived from 16 of the 19 strains used, and these retained the parental O type. Most series were characterized by a mutational step to a high degree of sensitivity to serum. Penicillin-resistant mutants of virulentS. typhimuriumandS. enteritidiswere less virulent than the parent strains; those which were very sensitive to serum usually showed the greatest loss of virulence. One class of mutants fromS. enteritidiswas sensitive to human serum but virulent for mice. We found that the mice lack bactericidal antibody against this strain and that immunization with it leads to a high degree of protection.