Analyses of Lipopolysaccharides Extracted from Penicillin-Resistant, Serum-Sensitive Salmonella Mutants

Abstract

SUMMARY: Serum-sensitive mutants have been derived from serum-resistant smooth virulent Salmonella typhimurium and S. enteritidis strains by selection for resistance to cephalosporin or penicillin. Chemical analyses of the lipopolysaccharides of these mutants reveal that they belong to at least three different rough or semi-rough classes. Partial or total loss from the lipopolysaccharide of the sugars responsible for O antigenicity resulted in loss of virulence, as well as increased sensitivity to the bactericidal effect of antibody plus complement. However, such loss is not necessary for serum sensitivity because two serum-sensitive mutants possessed lipopolysaccharides indistinguishable from the smooth serum-resistant parents and were nearly as virulent.