Multiplex PCR for aminoglycoside-modifying enzyme genes and mecA. The molecular size marker used in lanes 1 and 20 was the 1-kb Plus DNA ladder (Invitrogen, Grand Island, NY). The template DNAs used in the multiplex PCR were as follows: lanes 2 and 15, S. aureus ATCC 29213; lanes 3 and 16, S. aureus ATCC 43300; lanes 4, 17, and 19, no template DNA as a negative control; lanes 5 to 14 and 18, clinical S. pseudintermedius isolates (lane 5, isolate 13-089; lane 6, isolate 24-089, lane 7, isolate 29-086, lane 8, isolate 30-027, lane 9, isolate 30-076, lane 10, isolate 30-077, lane 11, isolate 31-094, lane 12, isolate 32-006, lane 13, isolate 32-010, lane 14, isolate 35-079; lane 18, isolate 30-077). Black arrows from top to bottom correspond to the PCR products, aac(6′)/aph(2″) (predicted 491 bp), mecA (predicted 314 bp), aph(3′)-IIIa (predicted 242 bp), and ant(4′)-Ia (predicted 135 bp), respectively.