SUMMARY. Of 3952 clinical isolates of Enterobacteriaceae, 246 exhibited resistance to at least carbenicillin, gentamicin and tobramycin. All these isolates, representing eight genera, were resistant to at least nine antimicrobial agents in common, including the three key antibiotics and streptomycin, kanamycin, sisomycin, ampicillin, cephalothin and sul-phonamide. The strains could be subdivided into seven groups depending upon additional resistance traits and some were resistant to as many as 15 antibiotics. When mated with a standard strain of , 85% of 123 randomly selected donors transferred resistance to at least the nine core antibiotics. Some donors occasionally transferred resistance to two additional antibiotics, neomycin and tetracycline, while one donor always transferred linked resistance to all 11 drugs. Although many donors were found to harbour more than one species of plasmid DNA, all except a strain of contained at least a plasmid of mol. wt 89 × 10. Analysis of transconjugants showed this plasmid to be responsible for transferable resistance to the nine core antibiotics. Restriction-endonuclease analysis indicates that the 89 × 10 plasmids originating from different isolates were essentially identical with each other. These results show that a particular R plasmid has established itself among the Enterobacteriaceae at Hines VA Hospital. This R plasmid appears to be the predominant genetic element responsible for linked resistance to carbenicillin, gentamicin and tobramycin among these hospital-associated bacteria.


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