Activity of non-fluorinated quinolones (NFQs) against quinolone-resistant Escherichia coli and Streptococcus pneumoniae.
The newly developed 8-methoxy, non-fluorinated quinolones (NFQs) were studied to elucidate their enzyme inhibitory activity against wild-type and mutant GyrA (Ser-83-->Trp) forms of Escherichia coli DNA gyrase. Using a DNA supercoiling inhibition assay, the NFQs were found to inhibit 50% (IC50) of the E. coli DNA gyrase activity in the 1.6-3.2 mg/L concentration range and were comparable to ciprofloxacin. However, against the GyrA (Ser-83-->Trp) mutant, the NFQs were approximately 16-fold more potent than ciprofloxacin. Antibacterial potency of the NFQs was investigated using clinical isolates of E. coli and penicillin-resistant Streptococcus pneumoniae (PRSP), including strains with reduced susceptibility to quinolones. Against 20 uncharacterized clinical isolates of E. coli, the MIC90s of the NFQs were in the 0.125-0.25 mg/L range while those of ciprofloxacin, trovafloxacin, gatifloxacin and clinafloxacin were in the 0.016-0.125 mg/L range. Against clinical isolates with characterized mutations in gyrA and parC, PGE9262932, an NFQ, was two- to eight-fold more potent than ciprofloxacin. Against 23 clinical isolates of PRSP, the NFQs (MIC90 0.031-0.125 mg/L) were more potent than ciprofloxacin, trovafloxacin, and gatifloxacin (MIC90 0.25-2.0 mg/L), and at least as potent as clinafloxacin (MIC90 0.125 mg/L). Against S. pneumoniae strains with gyrA and parC mutations, the NFQs (MIC 0.125-1.0 mg/L) were more potent than ciprofloxacin, trovafloxacin and gatifloxacin (MIC 4-32 mg/L), and comparable to clinafloxacin (MIC 0.5-1 mg/L).
Roychoudhury
S
S
Procter & Gamble Pharmaceuticals, Health Care Research Center, 8700 Mason-Montgomery Road, Mason, OH 45040, USA. roychoudhury.s@pg.com
Twinem
T L
TL
Makin
K M
KM
McIntosh
E J
EJ
Ledoussal
B
B
Catrenich
C E
CE
D000890:Anti-Infective Agents / Q000494:pharmacology*; D027081:DNA Gyrase; D027101:DNA Topoisomerase IV; D004250:DNA Topoisomerases, Type II / Q000235:genetics; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects*; D024841:Fluoroquinolones; D008826:Microbial Sensitivity Tests; D013296:Streptococcus pneumoniae / Q000187:drug effects*; D059005:Topoisomerase II Inhibitors
D000890:Anti-Infective Agents; D024841:Fluoroquinolones; D059005:Topoisomerase II Inhibitors; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase; D004250:DNA Topoisomerases, Type II