title: In-vitro postantibiotic effect of sparfloxacin and ciprofloxacin against Pseudomonas aeruginosa and Enterococcus faecalis.
abstract: The effect of concentration and exposure time on the postantibiotic effect (PAE) of sparfloxacin and ciprofloxacin against Pseudomonas aeruginosa Psa-1 and Enterococcus faecalis SD-63 was evaluated by the colony counting method using centrifugation to remove the antibiotic. The microorganisms were exposed for 15, 30 and 60 min to drug concentrations ranging from 1 x MIC to 31 x MIC. The PAE was calculated as the difference in time required by test and control cultures to increase 1 log10 after the drug was removed. The MICs of sparfloxacin for P. aeruginosa and E. faecalis were 0.50 mg/L and 0.25 mg/L, respectively, whereas the MICs of ciprofloxacin were 0.25 mg/L for P. aeruginosa and 0.50 mg/L for E. faecalis. PAEs increased as a function of concentration and exposure time. Against E. faecalis no point of maximal response was reached. On the contrary, against P. aeruginosa this point was reached at 8 x MIC of ciprofloxacin and 16 x MIC of sparfloxacin PAE values of sparfloxacin for P. aeruginosa and E. faecalis ranged from 7 to 96 min and from 0 to 112 min, respectively, and those of ciprofloxacin from 8.5 to 82.33 min and from 0 to > 136 min, respectively. Significant PAEs for P. aeruginosa were obtained after 60 min exposure at 4 x MIC (62.6 min) and 2 x MIC (52.6 min) of ciprofloxacin and sparfloxacin, respectively, and at 8 x MIC (81.5 min) and 16 x MIC (81.6 min) for E. faecalis.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Unidad de Bacteriología Experimental, Hospital Universitario La Fe, Valencia, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Pastor
authors.forename: J
authors.initials: J
authors.lastname: Pemán
authors.forename: E
authors.initials: E
authors.lastname: Cantón
mesh_terms: D000890:Anti-Infective Agents / Q000494:pharmacology*; D002939:Ciprofloxacin / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D013293:Enterococcus faecalis / Q000187:drug effects*; D024841:Fluoroquinolones; D008826:Microbial Sensitivity Tests; D011550:Pseudomonas aeruginosa / Q000187:drug effects*; D015363:Quinolones / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D000890:Anti-Infective Agents; D024841:Fluoroquinolones; D015363:Quinolones; D002939:Ciprofloxacin; C061363:sparfloxacin