Pseudomonas aeruginosa carrying an inducible AmpC gene that is usually silent, but when imipenem is present it acts as a strong inducer, triggering overproduction of AmpC, which results in a D-zone effect toward ceftazidime and piperacillin–tazobactam, making these antibiotics appear susceptible initially but prone to failure after induction Cefepime remains susceptible because it is structurally stable against AmpC and less affected by induction. This AST pattern indicates inducible AmpC produc