Transferable plasmids mediating multiple-antibiotic resistance in Streptococcus faecalis subsp. liquefaciens.

In strain HK187 (Streptococcus faecalis subsp. liquefaciens) four plasmids were isolated. The molecular weights, as analyzed in neutral sucrose gradients and by electron microscopy, were found to be about 36 x 10(6), 31 x 10(6), 26 x 10(6), and 4 x 10(6). Plasmid 3, also designated pFK14, with a molecular weight of 26 x 10(6), was found to be responsible for resistance to chloramphenicol and erythromycin and also for high-level resistance to streptomycin and lincomycin. In mixed cultures these four resistances could be transferred with high frequency to a plasmid-free recipient, S. faecalis strain JH2-2.