Fig. 3.

(A) Histograms of the fluorescence intensity detected from positive droplets normalized to their respective average negative droplet fluorescence are plotted for a reference strain of E. coli without and with the antibiotic gentamicin. In the presence of 4 μg/mL of gentamicin, a smaller positive droplet population is observed. The positive droplet population is then normalized to the average positive droplet population from the no-antibiotic control and plotted side-by-side for comparison. There is a significant reduction in percentage of positive droplets (p < 0.05) for the reference strain of E. coli when subject to gentamicin; (B) For a multi-drug resistant strain of E. coli subject to the same antibiotic conditions, histograms of positive droplet fluorescence looks very similar without and with gentamicin. Moreover, from triplicate experiments for each condition, the positive droplet population without and with gentamicin stayed approximately equal. 30000 droplets are interrogated in each experiment, and error bars correspond to triplicate measurements.