Heterogeneity of susceptibility to fluoroquinolones in Bartonella isolates from Australia reveals a natural mutation in gyrA

摘要: OBJECTIVES Bartonella sp. are intracellular bacteria associated with an increasing number of clinical manifestations but few published data on in vitro susceptibility testing antibiotics. Our objective was to evaluate antibiotic susceptibilities 20 new isolates from animals Australia. METHODS MICs were determined using Etest assay Columbia agar supplemented 5% horse blood. The presence mutations the quinolone-resistance-determining region (QRDR) gyrA searched for after PCR amplification and DNA sequencing specific oligonucleotide primers. RESULTS Australia susceptible rifampicin, tetracyclines, beta-lactam macrolide compounds resistant vancomycin. We found heterogeneity fluoroquinolones ciprofloxacin being more effective (MICs 0.06 0.5 mg/L) than ofloxacin 4 mg/L). This linked a natural mutation Ser-83-->Ala (Escherichia coli numbering) QRDR. Surprisingly, this also present QRDR henselae, quintana bacilliformis. CONCLUSIONS is sensitive reliable evaluation genus Bartonella. higher sensitivity method allowed us detect among that gyrase. Because high level resistance due second may be obtained easily vitro, we believe fluoroquinolone should avoided treatment any Bartonella-related diseases.