In vitro pharmacodynamics of ofloxacin and ciprofloxacin against common ocular pathogens

Citation
Mc. Callegan et al., In vitro pharmacodynamics of ofloxacin and ciprofloxacin against common ocular pathogens, CORNEA, 19(4), 2000, pp. 539-545
Citations number
21
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Optalmology
Journal title
CORNEA
ISSN journal
0277-3740 → ACNP
Volume
19
Issue
4
Year of publication
2000
Pages
539 - 545
Database
ISI
SICI code
0277-3740(200007)19:4<539:IVPOOA>2.0.ZU;2-C
Abstract
Purpose. Time-kill curve methodology was used to assess the pharmacodynamic s of two fluoroquinolones, ofloxacin and ciprofloxacin, against six strains representing the most common ocular pathogens: Pseudomonas aeruginosa, Sta phylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, S erratia marcescens, and Haemophilus influenzae. Methods. For time-kill stud ies, ofloxacin and ciprofloxacin solutions were prepared at concentrations of 0.5 x, 1.0 x, 2.0 x, and 3.0 x the MIC (minimal inhibitory concentration ) for each respective strain. Inocula were prepared by diluting overnight c ultures to final concentrations of 10(2), 10(3), 10(4), and 10(5) cfu (colo ny-forming units)/mL in each antibiotic solution. Growth controls were incl uded. Viability counts of antibiotic-containing and control bacterial suspe nsions were performed at 0, 10, 20, 30, 60, 90, 120, and 180 minutes. Resul ts. In general, the kill rates of ofloxacin at 1.0 x, 2.0 x, and 3.0 x the MIC were significantly faster than the kill rates of ciprofloxacin by appro ximately 30 minutes, regardless of the bacterial concentration tested. At 0 .5 x MIC, the kill kinetics of ciprofloxacin and ofloxacin were similar, re gardless of the strain tested. At 1.0 x MIC, ofloxacin achieved 99.9% killi ng of P. aeruginosa and S. aureus within 30 minutes, and S. epidermidis and S. marcescens within 90 minutes. Overall, the kill kinetics of both quinol ones for H. influenzae were similar, while neither quinolone achieved 99.9% killing of S. pneumoniae, regardless of the antibiotic concentration teste d. Conclusion. Time-kill curve analyses in the present study demonstrate th at ofloxacin achieved killing of the majority of ocular pathogens tested at rates equivalent to or faster than that of ciprofloxacin. Both fluoroquino lones were more effective against nonencapsulated bacteria than against enc apsulated bacteria.