Use of a clinical Escherichia coli isolate expressing lux genes to study the antimicrobial pharmacodynamics of moxifloxacin

Escherichia coli isolate 16906 expressing lux genes was used for real-time monitoring of moxifloxacin effects on bacterial metabolism compared with ef fects on cell replication. Viable counts showed concentration-dependent kil ling by moxifloxacin; real-time measurement of bioluminescence on the same cultures showed metabolic activity over 54 h, but with greater inhibition a t 1 x MIC than with higher MIC multiples. Post-antibiotic effect was longer when determined using bioluminescence than by viable counts. The control-r elated effective regrowth time was consistent with both methods. Biolumines cent bacteria provide a rapid and sensitive means for measuring antimicrobi al effects on bacterial metabolism.