The application of antimicrobial combinations on multidrug-resistant
Pseudomonas aeruginosa might be of clinical relevance if they possess a
significant postantibiotic effect (PAE). Twenty-two nosocomial isolates
were exposed over time to ceftazidime, imipenem, or ciprofloxacin, and
to their interaction with amikacin; all were applied at concentrations
equal to their average serum level. After 24 h of exposure, live cells
were washed and resuspended into fresh broth, and bacterial growth was
monitored. PAE was found only for isolates subjected to the synergistic
effect of the applied interactions. For these isolates, the mean PAEs
(+/- SE) were 3.10 +/- 0.71 h for ceftazidime and amikacin, 4.38 +/-
0.83 h for imipenem and amikacin, and 3.33 +/- 2.83 h for ciprofloxacin
and amikacin. The prolonged PAE documented after exposure to the
interactions of the studied drugs strengthens the application of their
combination for the management of infections by multidrug-resistant P.
aeruginosa. (c) 2005 Elsevier Inc. All rights reserved
