Antibrucella Activity of Quinolone Sparfloxacin

Background: Sparfloxacin is a new fluoroquinolone with excellent in vitro activity against a variety of Gram-positive and Gram-negative bacteria. Methods: In vitro antibacterial activity of this new drug was tested against 139 strains of Brucella melitensis. These strains were isolated from 138 patients at a major tertiary care referral center in Riyadh, Saudi Arabia. Results: Seven percent of the strains were inhibited by 0.06 mg per L and 99% by 0.12 mg per L of sparfloxacin. Of the five other fluoroquinolones tested, ciprofloxacin, norfloxacin, pefloxacin, and fleroxacin exhibited comparable or slightly higher minimal inhibitory concentrations values. They inhibited the growth of 138 of the 139 isolates at 0.25-0.5 mg per L. Rufloxacin required 2-8 mg per L to inhibit 138 of the 139 strains tested. One of the isolates, which had previously developed resistance to ciprofloxacin during therapy with this drug, with a rise in MIC from 0.06 mg per L to >5.0 mg per L, exhibited cross-resistance to sparfloxacin and other fluoroquinolones. Conclusion: Sparfloxacin exhibited excellent in vitro activity against clinical isolates of Brucella. Clinical trials are warranted to determine its potential in the treatment of brucellosis.