          |
 |
OMIG Main Page | 2002 Abstracts | < Previous | Next> Postantibiotic
Effect of Ciprofloxacin and Ofloxacin on Pseudomonas aeruginosa To investigate the postantibiotic effect (PAE) of commercial ophthalmic solutions of ciprofloxacin and ofloxacin, three human ocular isolates of ciprofloxacin- and ofloxacin-susceptible P. aeruginosa were exposed to 3.0 µg/ml and 30.0 µg/ml of the two fluoroquinolones for 15, 30, and 60 min. time periods. Suspensions of bacteria in logarithmic growth (approx. 108 org/ml) were incubated in a shaking water bath at 37°C in the presence of antibiotics for specific time periods. Control suspensions without antibiotics were treated in a similar manner. After incubation, bacteria were removed from broth by filtration and resuspended in media. Again, cultures were incubated in a shaking water bath at 37°C. Colony counts were performed immediately after resuspension (time 0) and hourly thereafter. The PAE was calculated as the difference in time (hours) required for the test culture concentration to increase one log above that observed immediately after drug removal, compared to the time required for the control culture to increase one log from time 0. The average
ciprofloxacin PAEs for 15, 30 and 60 min. exposures at 3.0 µg/ml
were 1.3, 2.4 and 1.9 hours, respectively and at 30.0 µg/ml
were 0.8, 2.5 and 1.8 hours, respectively. Average ofloxacin PAE
results for 15, 30 and 60 min. exposures at 3.0 µg/ml were
1.1, 2.8 and 1.8 hours, respectively and at 30.0 µg/ml were
0.9, 1.2 and 1.6, respectively. With one exception, PAEs peaked
at 30 min. exposures times. The PAE results were similar for 3.0
and 30.0 µg/ml concentrations of the antibiotics. Bacterial
strain variations in PAE results were seen, but no notable differences
in the PAEs of ciprofloxacin and ofloxacin were observed. OMIG Main Page | 2002 Abstracts | < Previous | Next>
|
|
