FIG. 1.

Maps of the S. aureus multiresistance plasmid pSK1 (23), its deletion derivatives pSK30 and pSK78, and the related S. epidermidis plasmid pSK105 (13) are aligned with respect to the qacA locus; in comparison to pSK1, pSK105 lacks Tn4003, and Tn4001 is located in a different position. The qacA-carrying S. epidermidis plasmids pSK107 and pSK638 are unrelated to the pSK1 family plasmids (13). Plasmid sizes are indicated on the right. The positions of the transposons are indicated above each map. White and black solid boxes denote copies of IS256 and IS257, respectively. The DNA segments deleted from pSK30 and pSK78 are denoted by broken lines, and the size of the deletion is shown below the line. Loci encoding the indicated functions are shown below the maps: aacA-aphD, resistance to the aminoglycosides, gentamicin, tobramycin, and kanamycin; dfrA, resistance to trimethoprim; qacA, multidrug resistance to antiseptics and disinfectants; and qacR, transcriptional regulation of qacA (the presence of qacR in pSK105, pSK107, and pSK638 is assumed but not proven at this time). Restriction sites: B, BglII; E, EcoRI; P, PvuII.