A conspicuous adaptability to antibiotics in the Escherichia coli mutator strain, dnaQ49.
By repeating the cycle of mutagenesis and selection, the Escherichia coli dnaQ49 mutator acquired high level resistance to ampicillin (30,000 micrograms ml-1), streptomycin (26,000 micrograms ml-1) and ofloxacin (3000 micrograms ml-1). Under the strong pressure of ofloxacin, dnaQ49 also followed the history of mutations in the gyrase and topoisomerase i.v. genes previously observed in clinical isolates of quinolone-resistant E. coli. The results of these in vitro experiments suggest that naturally existing mutators may participate in the rapid acquisition of resistance to various antibiotics in patients. A possible mechanism for the occurrence of this adaptability is discussed with special reference to the property of mutagenesis accompanying DNA replication.
Department of Radiological Sciences, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Japan.
K
K
Tanabe
T
T
Kondo
Y
Y
Onodera
M
M
Furusawa
D000595:Amino Acid Sequence; D000668:Ampicillin Resistance / Q000502:physiology*; D027081:DNA Gyrase; D027101:DNA Topoisomerase IV; D004250:DNA Topoisomerases, Type II / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D008969:Molecular Sequence Data; D009154:Mutation; D015242:Ofloxacin / Q000494:pharmacology; D015363:Quinolones / Q000494:pharmacology; D013307:Streptomycin / Q000494:pharmacology
D015363:Quinolones; C046819:EN 272; D015242:Ofloxacin; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase; D004250:DNA Topoisomerases, Type II; D013307:Streptomycin