Effects of meropenem exposure in persister cells of Acinetobacter calcoaceticus-baumannii.

Aim: To evaluate the influence of meropenem in the Acinetobacter calcoaceticus-baumannii (ACB) persister levels.

Methods: Persister levels in planktonic and biofilm cultures from ACB isolates were evaluated after exposure to different meropenem concentrations.

Results: A high variability of persister fractions was observed among the isolates cultured under planktonic and biofilm conditions. Meropenem concentration did not influence persister fractions, even when far above the MIC. No correlation was found between persister levels and biofilm biomass.

Conclusion: The magnitude of persister levels from ACB planktonic and, particularly, biofilm cultures exposed to meropenem was independent of the antibiotic concentration, dosing regimen and biofilm biomass. These findings, in a context of meropenem failure to treat chronic infections, strengthen the importance of understanding persister behavior.