Multiple drug-resistant Staphylococcus aureus with resistance to oxytetracycline and minocycline, an example for the distribution of a multiresistant strain-clone.

Multiresistant S. aureus-strains with chromosomally localized determinant for resistance to oxytetracycline-minocycline (tmn) exhibit uniform characteristics, obviously they have been spread as a clone. These strains harbour two plasmids: one with MW of 18 MD for beta-lactamase and determinants for resistance to mercury and to cadmium and one with MW of 2 MD for resistance to chloramphenicol. Beside the tmn-determinant, also the determinants for resistance to macrolides and to gentamicin are not located on plasmids. The tmn-determinant is specific for defined hospital strains reacting with group-III phages; it was not found in other strains of different origin.