Background: Carbapenems are the treatment of choice for multidrug-resistant (MDR) A. baumannii infection but are inadequate for carbapenem-resistant A.baumannii (CRAB) infections. Combination therapy came into the spotlight in the last decade. This study compares the colony count reduction after exposure to meropenem-based antibiotics in clinically achieved concentration with the time-kill test.

Results: A bactericidal effect was achieved in isolates that were intermediate to ampicillin sulbactam at the administration of meropenem and ampicillin-sulbactam with a 2 MIC + 2 MIC. The combination of meropenem and ampicillin-sulbactam showed a bacteriostatic effect in isolates resistant to both antibiotics. The bactericidal effect was not achieved when meropenem and amikacin were administered to isolates that were intermediate or resistant to meropenem and amikacin.

Conclusion: There is a significant difference in the colony count reduction between groups of A. baumannii isolates after exposure to antibiotic combinations.

These data represent the turbidity and colony count data of the Acinetobacter baumannii test suspension after being subjected to the combination antibiotic meropenem + ampicillin-sulbactam and meropenem + amikacin. Data were obtained from six replications formatted in Microsoft Excel and then processed with IBM SPSS Statistics 23.

This experimental laboratory study was conducted on ATCC 19606 isolate and three clinical isolates with different antibiotic susceptibility types. Meropenem and ampicillin-sulbactam as well as meropenem and amikacin in concentrations of ½ MIC + ½ MIC, 1 MIC + 1 MIC, 2 MIC + 2 MIC, and 2 MIC + ½ MIC were tested against isolates. Turbidity measurements were made at the predetermined time point of 0, 1, 2, 4, 6, 8, and 24 hours after exposure; bacterial concentration was enumerated using the agar plate method. Six replications were performed, and the results were plotted in a time-kill curve.

Data formatted in Microsoft Excel and then analysed with IBM SPSS Statistics 23. Images created with the GraphPad Prism 9 App.