Interaction of Nanoparticles with Multidrug-Resistant Bacteria

Infections due to drug-resistant bacteria have emerged as a global health risk and are expected to grow at an alarming rate in the coming decades. The number of new antibacterial compounds under preclinical and clinical development is dismayingly low; thus, efforts are underway to either increase the activity of existing compounds or identify other alternatives. Nanoparticles (NPs) have been shown to possess antimicrobial properties along with the ability to improve the activity of existing antimicrobial drugs, including against bacteria. The present study evaluated the effects of carbon nanotubes, graphene, and silver NPs against drug-resistant Escherichia coli and Staphylococcus aureus. NPs increased nucleic acid and protein leakage, along with increased crystal violet dye uptake, suggesting damage to the cell envelope. Scanning electron microscopy revealed morphological changes in both bacteria, which are reminiscent of stress and cell envelope damage. An increase in the leakage of intracellular components and a decrease in the minimum inhibitory concentration (MIC) were observed in the drug-NP combinations. Coarse-grained molecular dynamics studies revealed interactions between NPs and bacterial membranes as well as peptidoglycan. These findings suggest that NPs enhance the activity of drugs, particularly those inhibiting cell wall biosynthesis, and that drug-NP combinations could aid in combating drug-resistant bacteria.