Bacterial efflux pumps excrete SYTO™ dyes and lead to false-negative staining results

Multidrug efflux pumps excrete a range of small molecules from bacterial cells. In this study, we show that bacterial efflux pumps have affinity for a range of SYTO™ dyes that are commonly used to label bacteria. Efflux pump activity will there lead to false negative results from bacterial staining and SYTO™ dyes should be used with caution on live samples. Multidrug efflux pumps remove a range of fluorescent SYTO stains from bacterial cells.