ANALYSIS OF 2 STAPHYLOCOCCUS-EPIDERMIDIS PLASMIDS CODING FOR RESISTANCE TO STREPTOGRAMIN-A

The two Staphylococcus epidermidis plasmids pIP1629 (7.5 kb) and pIP16 30 (14.4 kb) contain the vga gene conferring resistance to streptogram in A. All the sequences of pIP1629, except two of the four 22-nt itero ns preceding the replication gene were found in pIP1630. The additiona l 6.9-kb fragment of pIP1630 is similar to the mobilizable S. epidermi dis plasmid pSK639, carrying the dfrA-thyE-orf140 operon and thought t o replicate by an iteron controlled theta-type replication mechanism. The replication-mobilization elements of pIP1629 and pSK639 are very s imilar despite having been isolated in France and in Australia, respec tively, showing that they are geographically widely dispersed in S. ep idermidis. The gene thyE encoding thymidylate synthetase carried by pS K639 is not present in pIP1630. pIP1630 probably arose by the recombin ation of two homologous plasmids carrying distinct resistance determin ants. (C) 1998 Academic Press.