Effects of temperature on the bactericidal activities of ciprofloxacin and levofloxacin against Escherichia coli and Pseudomonas aeruginosa.
The bactericidal activities of the 4-quinolones ciprofloxacin and levofloxacin against Escherichia coli and Pseudomonas aeruginosa in nutrient broth were drastically reduced as the temperature of incubation was decreased from 37 to 30 to 25 to 20 degrees C. With E. coli a biphasic response was observed with either 4-quinolone at any one of the four temperatures tested. At the optimum bactericidal concentrations (OBCs) of ciprofloxacin or levofloxacin against E. coli the activity at 20 degrees C was 68- and 56-fold less than at 37 degrees C, respectively. As expected, with P. aeruginosa biphasic responses were not observed so OBC values could not be estimated. At the peak serum concentrations of ciprofloxacin or levofloxacin the bactericidal activity against P. aeruginosa was reduced by 61- or 50-fold, respectively, as temperature was decreased from 37 to 20 degrees C. This was similar in scale to the reductions in bactericidal activity observed with E. coli at its OBC values.
Department of Pharmaceutics, School of Pharmacy, University of London, Great Britain.
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D002939:Ciprofloxacin / Q000494:pharmacology*; D003470:Culture Media; D004926:Escherichia coli / Q000187:drug effects* / Q000254:growth & development; D064704:Levofloxacin; D008826:Microbial Sensitivity Tests; D015242:Ofloxacin / Q000494:pharmacology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000254:growth & development; D013237:Stereoisomerism; D013696:Temperature
D003470:Culture Media; D002939:Ciprofloxacin; D064704:Levofloxacin; D015242:Ofloxacin