Antibiotic resistance mechanisms render current antibiotics ineffective, requiring higher concentrations of existing drugs or the development of more powerful drugs for infection treatment. This study demonstrates the synergistic inactivation of a gram-positive (Staphylococcus aureus) and a gram-negative (Escherichia coli) bacteria by combining either tobramycin or rifampicin with 300-ns electric pulses (EPs). For EPs depositing the same total energy density into the sample with no drug, higher electric fields induced greater inactivation, indicating a threshold for irreversible electroporation at these fields and membrane recovery in between lower intensity EPs. Synergistic inactivation generally increased with increasing drug concentration up to 20 mu g/mL compared to strictly EP treatment. Combining even 1/20 of the clinical dose of tobramycin with a train of EPs induced between 2.5 and 3.5 log inactivation after only 10 min of exposure compared to hours to induce inactivation with a clinical dose with no EPs. Similarly, combining a train of EPs with a clinically relevant dose of rifampicin induced 7 to 9 log inactivation over the same time of exposure. These results indicate the promise of combining EPs with antibiotics to rapidly inactivate antibiotic-resistant bacteria in localized treatment areas.