Comparative bactericidal activity of fluoroquinolones against clinical isolates resistant to fluoroquinolones

Increasing Resistance According to Patient's Age and Sex inEscherichia coliIsolated from Urine in Italy

The prevalence of Escherichia coli among the uropathogens routinely isolated in non-hospital laboratories (Labs) and its susceptibility profiles were investigated. Thirty-three Labs were selected throughout Italy. In vitro assays were performed by means of disk diffusion according to the CLSI. Females were prevalent (79.9%) and the mean patient age was 58.6 (sd 20.4) years. Overall, the prevalence of E. coli was 55.3% (1375 strains), with Enterococcus spp 10.2 %, Proteus mirabilis 4.8%, coagulase-negative staphylococci 4.3% and Klebsiella 3.8% being the next most frequently encountered species. High compliance with quality control program was observed. Susceptibility figures in E. coli were consistently low for many antimicrobial agents such as ampicillin (51.3%) and co-trimoxazole (74.6%) and higher for others such as gentamicin (87.9%) and ceftazidime (95.1%). Resistance rates were higher among male patients and increased according to the patient's age.

Bactericidal activity of garenoxacin tested by kill-curve methodology against wild type and QRDR mutant strains of Streptococcus pneumoniae

Kill-curve bactericidal assays over 24 hours were determined for garenoxacin, a novel des-F(6) quinolone, and levofloxacin at achievable serum drug concentrations ranging from 2 to 8 microg/mL. Tested strains included 4 wild type and 2 target quinolone resistance-determining region (QRDR) mutant Streptococcus pneumoniae. Garenoxacin was 16-fold to 32-fold more active than levofloxacin, and mutant strains (3 QRDR sites) had garenoxacin minimum inhibitory concentration (MIC) values at 1 microg/mL (levofloxacin MIC >32 microg/mL, resistant), but equal to the levofloxacin potency against wild type strains. Garenoxacin killed mutant pneumococci with comparable rapidity, as did levofloxacin versus strains without target alterations. Garenoxacin appears to be a widely usable and highly active agent against S. pneumoniae resistant to other quinolones such as levofloxacin.

Current and future perspectives for levofloxacin in severe Pseudomonas aeruginosa infections

The question of whether levofloxacin includes Pseudomonas aeruginosa in its spectrum of clinical activity is discussed by reviewing the major findings on this issue, mainly those published in Italy. The in vitro activity of levofloxacin against P. aeruginosa is now documented on thousands of strains worldwide. The pharmacodynamic properties of levofloxacin allow for the treatment of pseudomonal infections. The levofloxacin clinical results extrapolated from published studies document the efficacy of levofloxacin in the treatment of infections sustained by P. aeruginosa.