(A) Analysis of PCR-amplified DNA with primers specific for amplification of aph(3′)-VIa. Lanes: 1, E. coli carrying the gene for APH(3′)-I; 2, E. coli carrying the gene for APH(3′)-II; 3, E. cloacae carrying the gene for APH(3′)-II; 4, S. epidermidis carrying the gene for APH(3′)-II; 5, E. cloacae carrying the gene for APH(3′)-III; 6, S. aureus carrying the gene for APH(3′)-IV; 7, E. faecalis carrying the gene for APH(3′)-IV; 8, A. baumannii carrying the gene for APH(3′)-VIa; and M, DNA molecular mass marker VI (Boehringer Mannheim, Mannheim, Germany). (B) PCR analysis of the aph(3′)-VIa gene of the amikacin-resistant clinical A. baumannii isolates studied. Control indicates an amikacin-susceptible A. baumannii strain used as a negative control. Lane M, DNA molecular size marker (100-bp DNA Ladder; Life Technologies Inc.).