In vitro selection and characterization of bacillus anthracis mutants with high-level resistance to ciprofloxacin

Lance B. Price, Amy Vogler, Talima R Pearson, Joseph D. Busch, James M. Schupp, Paul S Keim

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Mutants of attenuated Bacillus anthracis with high-level ciprofloxacin resistance were isolated using a three-step in vitro selection. Ciprofloxacin MICs were 0.5 μg/ml for first-step mutants, which had one of two gyrA quinolone resistance-determining region (QRDR) mutations. Ciprofloxacin MICs were 8 and 16 μg/ml for second-step mutants, which had one of three parC QRDR mutations. Ciprofloxacin MICs for third-step mutants were 32 and 64 μg/ml. Mutants for which MICs were 64 μg/ml had one of two additional mutations within the gyrA QRDR or one of two mutations within the gyrB QRDR. Mutants for which MICs were 32 μg/ml had no additional target modifications but showed evidence of enhanced ciprofloxacin efflux.

Original languageEnglish (US)
Pages (from-to)2362-2365
Number of pages4
JournalAntimicrobial Agents and Chemotherapy
Issue number7
StatePublished - Jul 1 2003


ASJC Scopus subject areas

  • Pharmacology (medical)

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