Plasmid-encoded functions compensate for the biological cost of AmpC overexpression in a clinical isolate of Salmonella typhimurium

In a previous study with a Salmonella typhimurium strain containing cloned ampC-ampR from Enterobacter cloacae, it was suggested that ampC expression must be kept at low levels by AmpR to maintain normal growth and virulent phenotype. The purpose of this study was to determine whether findings obtained with a laboratory model can be extended to a virulent clinical isolate of S. typhimurium expressing the plasmid-encoded bla(CMY-7).