SUMMARY. Plasmid-mediated resistance to chloramphenicol (Chl), erythromycin (Ery), tetracycline (Tet) and clindamycin (Clind) was transferred from three clinical isolates of and one faecal isolate of to strains of and , and subsequently to and second-and third-stage recipients in series. Successful transfer was achieved by membrane-filter and centrifugation techniques that provide stable cell-to-cell contact but not by simple mixed broth culture. Chl Ery Tet and Clind Ery were transferred at high frequency (1·9 × 10 -1·8 × 10) but Tet was transferred at low frequencies (1–1·6 × 10). Segregation of resistance markers was observed with selection for Tet when donors were Chl Ery Tet and Chl Tet. All transcipients were identical with the parent recipient strains but had the resistance markers of the donor strains. Resistance to antibiotics other than tetracycline was cured by growth with subinhibitory concentrations of aminoacri-dines and ethidium bromide for 24 h; cure of solitary Tet required longer incubation (21 days). Identical plasmid DNA bands were demonstrated by agarose-gel electrophoresis in all the donor and corresponding transcipient strains but plasmids were not found in the recipient strains or in strains cured of resistance. Plasmid-mediated transferable antiobiotic resistance in spp. may compromise the treatment of infections and may provide a reservoir of antibiotic resistance in the intestinal flora.


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error