Rhamnolipids and Tobramycin Co-Treatment on Various Bacterial Strains

Overview

Antibiotic resistance in lung and gut chronic bacterial coinfections have significantly compromised patient recovery rates. Therefore, further mechanisms are needed to improve antibiotic susceptibility to circumvent such challenges. Biosurfactants secreted by Pseudomonas aeruginosa called rhamnolipids are able to facilitate proton-motive force-independent tobramycin uptake in bacterial coinfections in cystic fibrosis. In this study, we utilize various bacterial strains to determine the extent of the rhamnolipids-tobramycin synergy. We performed minimum inhibitory concentration (MIC) assays of strains with tobramycin alone and tobramycin with rhamnolipids. In addition, biofilm experiments were conducted to determine rhamnolipids’ effect on biofilm susceptibility to tobramycin. We find that the MIC decreased for Staphylococcus aureus menD::erm, Enterococcus faecalis and Clostridium difficile with the addition of rhamnolipids, and that the rhamnolipids-tobramycin synergy resulted in a significant decrease of E. faecalis biofilm. These findings demonstrate that there is increased antibiotic susceptibility with the addition of rhamnolipids to tobramycin treatment in several pathogens. Consideration of the synergistic effect will improve bacterial infection treatment outcomes.