Table 2  RFLP patterns of staphylococcal plasmids reveal three prevalent families
FamilyRestriction TypeEstimated Size (kb)aNumber of Plasmidsb20–30 kbd>20 kbe
pMW2-likeRT118–212719.6%14.7%
pIB485-likeRT225–2736c26.1%19.6%
pUSA300HOUMR-likeRT325–272719.6%14.7%
Total90c65.3%49.0%
  • a Sizes estimated by comparisons of electrophoresed undigested DNA to size ladder (see Materials and Methods).

  • b Includes all typable plasmids >20 kb (n = 184) from newly examined strains.

  • c There was one additional pIB485-like plasmid in a strain previously examined for plasmids (for a total 37 of 214 typable >20 kb plasmids from all strains).

  • d The representation of that family among the typable 20–30 kb plasmids from newly examined strains (n = 138)

  • e The representation of that family among all typable >20 kb plasmids from newly examined strains (n = 184).