In vitro activity of gemifloxacin and other antimicrobial agents against isolates of Bordetella pertussis and Bordetella parapertussis

We investigated the activity of the novel quinolone agent gemifloxacin (SB-265805) and a panel of comparator agents against Bordetella pertussis and Bordetella parapertussis. Erythromycin, azithromycin, ciprofloxacin and gemifloxacin were consistently active against both species. An azithromycin- and erythromycin-resistant B. pertussis isolate was not resistant to any of the other agents tested (gemifloxacin MIC less than or equal to 0.008 mg/L; ciprofloxacin,,less than or equal to 0.015 mg/L; ampicillin, 2.0 mg/L; trimethoprim-sulphamethoxazole, 4.0 mg/L). The potency of ampicillin, azithromycin, erythromycin, ciprofloxacin and trimethoprim-sulphamethoxazole recorded against B. pertussis and B. parapertussis in this study was comparable to that noted in previous studies. However, MICs were generally higher than those noted in other trials; this may reflect the different methods used. Although in vitro data on the potency of gemifloxacin against B. pertussis and B. parapertussis have not previously been reported, these results are comparable to the potency of other quinolones against these pathogens. Should gemifloxacin achieve similar concentrations within the respiratory tract as other quinolones, this, coupled with its high in vitro potency, suggests that gemifloxacin has potential clinical efficacy in pertussis.