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Postantibiotic effect of imipenem, alone and in combination with amikacin, on Pseudomonas aeruginosa
1Department of Pharmaceutical Microbiology, Faculty of Pharmacy, University of Istanbul, Turkey.
Abstract:
Imipenem and amikacin, alone and in combination, were investigated for their postantibiotic effect (PAE) on Pseudomonas aeruginosa. Four clinical strains of P. aeruginosa in the logarithmic phase of growth were exposed for 1 h to antibiotics, alone and in combination. Recovery periods of test cultures were evaluated after dilution using viable counting. Imipenem produced a PAE ranging from 0.7 to 1.55 h. Similar PAEs were induced by amikacin (ranging from 0.65 to 2 h). In combination, imipenem and amikacin produced as a final PAE (ranging from 1.6 to 2.65 h), a rough mathematical sum of the individual effects. The finding of this study may have important implications for the timing of doses during therapy with antimicrobial combinations.
Insights
This study examined the postantibiotic effect (PAE) of imipenem and amikacin on Pseudomonas aeruginosa. Combining these antibiotics resulted in a PAE that was roughly the sum of their individual effects, suggesting implications for dosing strategies.
Area of Science:
- Microbiology
- Pharmacology
- Infectious Diseases
Background:
- Pseudomonas aeruginosa is an opportunistic pathogen often associated with hospital-acquired infections.
- Antimicrobial resistance in P. aeruginosa necessitates understanding drug efficacy and synergistic effects.
- Postantibiotic effect (PAE) describes the delay in bacterial regrowth after antibiotic exposure.
Purpose of the Study:
- To investigate the postantibiotic effect (PAE) of imipenem and amikacin, both alone and in combination, against clinical strains of Pseudomonas aeruginosa.
- To determine if the combined PAE of imipenem and amikacin exhibits synergy or additivity.
- To provide insights into optimizing antimicrobial dosing regimens for P. aeruginosa infections.
Main Methods:
- Exposure of four clinical P. aeruginosa strains to imipenem and amikacin (individually and combined) for 1 hour during logarithmic growth.
- Evaluation of bacterial regrowth following antibiotic exposure using viable counting after serial dilution.
- Quantification of the postantibiotic effect (PAE) for each treatment condition.
Main Results:
- Imipenem alone induced a PAE ranging from 0.7 to 1.55 hours.
- Amikacin alone induced a PAE ranging from 0.65 to 2 hours.
- The combination of imipenem and amikacin resulted in a PAE ranging from 1.6 to 2.65 hours, approximating the sum of individual effects.
Conclusions:
- The combined postantibiotic effect of imipenem and amikacin against P. aeruginosa is roughly additive.
- These findings suggest that the timing of drug administration in combination therapy may be crucial for maximizing therapeutic outcomes.
- Understanding PAE in combination therapy can inform clinical strategies for treating P. aeruginosa infections.