In Vitro Activities of Sitafloxacin (DU-6859a) and Six Other Fluoroquinolones against 8,796 Clinical Bacterial Isolates

Abstract

The in vitro activities of sitafloxacin, ciprofloxacin, trovafloxacin, levofloxacin, clinafloxacin, gatifloxacin, and moxifloxacin against 5,046 gram-negative bacteria, 3,344 gram-positive cocci, and 406 anaerobes were determined. Sitafloxacin was the most active agent against gram-positive cocci and anaerobes. Against Enterobacteriaceae and nonfermenters, its activity was either equivalent to or better than that of clinafloxacin.Sitafloxacin (DU-6859a) is a new fluoroquinolone active against gram-positive and gram-negative bacteria, including anaerobes (3,7,13). In the present study, the in vitro activities of sitafloxacin against a large number of contemporary and clinically relevant bacterial isolates were determined and compared with those of ciprofloxacin, clinafloxacin, gatifloxacin, levofloxacin, moxifloxacin, and trovafloxacin.A total of 8,796 bacterial strains were tested which had been isolated between April 1997 and February 1999 from patients in 24 university hospitals in 14 European countries, 1 in Israel, and 3 in South Africa. Only one isolate per patient was permitted. Strains were reidentified in our laboratory using a combination of standard methods and either the VITEK or the API system (BioMerieux, s'Hertogenbosch, The Netherlands). MICs were determined by a microdilution method described by the National Committee for Clinical Laboratory Standards (15), using cation-adjusted Mueller-Hinton broth. For testing Streptococcus spp. and Neisseria spp., 5% lysed horse blood was added. Haemophilus spp. were tested using Haemophilus test medium. The inoculum was adjusted to 5 ϫ 10 5 CFU/ml. Plates were read after 20 to 24 h of incubation at 35°C in ambient air. Anaerobic bacteria were tested with WilkinsChalgren broth and a final inoculum of 10 6 CFU/ml. Plates were read after 48 h of incubation at 35°C in an anaerobic environment (16).The results of susceptibility testing are presented as the MICs at which 50 and 90% of the isolates tested are inhibited (MIC 50 and MIC 90 ) and the ranges of MICs (Table 1). Sitafloxacin was very active against enterobacterial species, inhibiting 96.9% of the 3,129 strains at a concentration of 1 g/ml. The MIC 50 s ranged from Յ0.008 to 1 g/ml, and the MIC 90 s ranged from 0.015 to 2 g/ml. The MIC 90 for Providencia spp. was the highest (2 g/ml), followed by those for Enterobacter aerogenes and Escherichia coli (1 g/ml for each). These three species also exhibited the highest rates of ciprofloxacin resistance (51.6, 38.5, and 14.6%, respectively). The MIC 90 s of sitafloxacin for Citrobacter koseri, Klebsiella oxytoca, Pantoea agglomerans, Proteus vulgaris, salmonellae, Serratia liquefaciens, Shigella spp., and Yersinia enterocolitica ranged from 0.015 to 0.12 g/ml and were similar to those of ciprofloxacin. However, sitafloxacin was four times more active than ciprofloxacin against Citrobacter freundii, Klebsiella pneumoniae, Morganella morganii, and Serratia marcescens and at least eight times more active against E. aerogenes, Enterobacter cloacae, E. coli, and Prot...

High Incidence of Cefoxitin and Clindamycin Resistance among Anaerobes in Taiwan

“…Many new fluoroquinolones have been tested for in vitro activities against gram-positive, gram-negative, and anaerobic bacteria previously (4,9). Similarly, other studies have demonstrated the good activity of new fluoroquinolones against various anaerobic species.…”

“…Antimicrobial resistance is becoming less predictable and may fluctuate from one medical center to another, as well as from one geographic region to another (1)(2)(3)(4)(7)(8)(9). The increasing resistance among several species emphasizes the need to survey the susceptibility patterns of these organisms.…”

“…Over the past 10 years, there has been a significant problem with increasing resistance to antimicrobial agents among anaerobic bacteria (1)(2)(3)(7)(8)(9). Antimicrobial resistance is becoming less predictable and may fluctuate from one medical center to another, as well as from one geographic region to another (1)(2)(3)(4)(7)(8)(9).…”

Comparative mutant prevention concentration and mutant selection window of sitafloxacin versus other quinolones using strains of Haemophilus influenzae with decreasing susceptibility to levofloxacin

“…Additionally, the mutant selection window (MSW) is an antimicrobial concentration range extending from the minimal concentration required to block the growth of wild-type bacteria up to that required to inhibit the growth of the single-step mutant, and the upper boundary is also called the MPC 1,4 . Sitafloxacin is a new fluoroquinolone that has been reported to have a broader spectrum, and the greater activity against quinolone-resistant strains than that of other quinolones 5 . The purpose of this study was to evaluate the in vitro activity of sitafloxacin and compare its MPC and MSW to those of levofloxacin, moxifloxacin, garenoxacin, and ciprofloxacin.…”

“…NC_000907), which was used as the wild-type standard strain in this study. The MPC is defined as the fluoroquinolone concentration at which no colony was recovered when more 4 than 10 10 cells were applied to agar plates, and generally, it is also defined the lower limit of the MSW equal to the MIC 5 . The MPC methodology was adapted from the method outlined by Blondeau et al 1 .…”