Gemifloxacin: effects of sub-inhibitory concentrations on various factors affecting bacterial virulence.
This study investigated the ability of sub-MICs of gemifloxacin to interfere with the bacterial virulence parameters of adhesiveness, haemagglutination, hydrophobicity and motility, as well as their interactions with host neutrophilic defences such as phagocytosis, killing and respiratory bursts. The adhesiveness of both Escherichia coli and Staphylococcus aureus was significantly reduced to a subinhibitory concentration of 1/32 MIC. Indirect fimbriation parameters, such as hydrophobicity and haemagglutination were significantly reduced at a concentration of 1/8 MIC, as was migration (swarming). Phagocytosis and the respiratory burst measured by means of chemiluminescence were not affected, but killing was significantly increased from 1/2 to 1/8 MIC. The interpolation of these pharmacodynamic findings with pharmacokinetic curves indicates that sub-MIC concentrations of gemifloxacin can prolong antimicrobial effects on virulence determinants up to 27 h after the antimicrobial concentration has fallen below the MIC value.
Dal Sasso
M
M
Department of Pharmacology, Center of Respiratory Pharmacology, School of Medicine, University of Milan, Via Vanvitelli 32, 20129 Milan, Italy.
Culici
M
M
Bovio
C
C
Braga
P C
PC
D001422:Bacterial Adhesion / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells; D004926:Escherichia coli / Q000187:drug effects* / Q000472:pathogenicity; D024841:Fluoroquinolones / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology*; D000077735:Gemifloxacin; D006384:Hemagglutination / Q000187:drug effects; D006801:Humans; D008826:Microbial Sensitivity Tests; D009061:Mouth Mucosa / Q000166:cytology / Q000382:microbiology; D009287:Naphthyridines / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology*; D010587:Phagocytosis / Q000187:drug effects; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000472:pathogenicity; D014774:Virulence / Q000187:drug effects
D024841:Fluoroquinolones; D009287:Naphthyridines; D000077735:Gemifloxacin