Serum survival and plasmid possession by strains of Salmonella enteritidis, Salm. typhimurium and Salm. virchow.

Strains of Salmonella enteritidis, Salm. typhimurium and Salm. virchow, carrying different numbers of plasmids, were examined for the ability to multiply in sera. Viable counts were performed to monitor the kinetics of growth of bacteria when in human, chicken and turkey sera. The presence of plasmids in Salm. enteritidis, Salm. typhimurium and Salm. virchow reduced considerably the ability of strains of these serotypes to multiply in serum. SDS-PAGE was used to show that growth of Salm. enteritidis in serum did not involve changes in outer membrane proteins or lipopolysaccharide. It was concluded that the carriage of plasmids may be disadvantageous for the survival in serum of certain common salmonella serotypes.