Levels of persisters influenced by aeration in Acinetobacter calcoaceticus-baumannii.

Aim: To evaluate the influence of aeration on persister levels from Acinetobacter calcoaceticus-baumannii isolates exposed to meropenem or tobramycin, as well as analyze morphological and structural changes in persisters.

Materials & Methods: Levels of persisters were determined after a 48-h exposure to tobramycin or meropenem under aerated or static conditions, and persisters were analyzed by scanning and transmission electron microscopy.

Results: The fractions of persisters varied between isolates. Aeration reduced cell survival under each antibiotic treatment, and cell survival decreased as the tobramycin concentration was increased. Interestingly, division septa were observed in persisters by electron microscopy.

Conclusion: Aeration may have stimulated bacterial growth, providing more targets for antibiotic action and leading to increased production of reactive oxygen species, which decreased levels of persisters.