Proteus mirabilis is an opportunistic pathogen associated with nosocomial infections and foodborne diseases. The resistance and biofilm formation of P. mirabilis have been a great concern. In this study a multidrug-resistant P. mirabilis strain 012 was exposed to a lethal dose of ampicillin (10 mg/mL, 2.5-fold minimal bactericidal concentration) for 24 h at 37°C. After resuscitation and isolation, five variant isolates were selected and subjected to ampicillin induction by repeatedly streaking on ampicillin-containing plates (10 mg/mL) for at ...
