(A) Electrophoretogram of multiplex polymerase chain reaction (PCR) products of plasmid-mediated AmpC β-lactamase. M, DNA Marker (from top to bottom: 600, 500, 400, 300, 200 and 100 bp); 1, positive control; 2, negative control; 3–14, clinical isolates of Klebsiella pneumoniae carrying the blaDHA gene. (B) Electrophoretogram of multiplex PCR products amplified with full-length primer. M, DNA marker (from top to bottom: 1,200, 900, 700, 500, 300 and 100 bp); 1, positive control; 2, negative control; 3–13, clinical isolates of PCR products amplified with full-length primer.