Abstract
Efflux pumps are a key component in bacteria's ability to gain resistance to antibiotics. In addition to increasing efflux, new research has suggested that the antibiotic, tetracycline, may have larger impacts on bacterial membranes. Using second harmonic scattering, we monitor the transport of two small molecules across the membranes of different Gram-positive bacteria. By comparing our results to a simple kinetic model, we find evidence for changes in influx and efflux across both bacterial species. These changes, however, are probe-dependent, opening new questions about the localization of the drug's effects and the specificity of the efflux pumps involved.