Transfer of Antibiotic Resistance (R factor) in the Mouse Intestine ∗

Summary

An antibiotic resistant Klebsiella pneumoniae containing an R factor was fed to germ-free mice previously colonized with an antibiotic susceptible E. coli. Within a month, 21% of the E. coli acquired multiple drug resistance without the selective pressure of antibiotic therapy. However, the rate of spread of the R factor was significantly slower than in vitro.