Sequence-Specific Targeting of Bacterial Resistance Genes Increases Antibiotic Efficacy
(A) Sample antibiotic dose-response curves of E. coli in the absence of acrA-PPMO (black lines), in the presence of 10 μM acrA-PPMO (blue lines), and E. coli with acrA deletion (cyan lines). The MIC for each treatment is defined as the lowest concentration of antibiotic that results in a 95% reduction in the growth relative to the wild type E. coli in the presence of antibiotics (black lines). (B) Bar graphs of the measured fold changes in MIC values for wild-type E. coli in the absence of acrA-PPMO (black), 10 μM acrA-PPMO (blue), and with the acrA deletion (cyan). Abbreviations: CFT, cefotaxime; CHL, chloramphenicol; CLI, clindamycin; DOX, doxycycline; FUS, fusidic acid; GEN, gentamycin; MER, meropenem; NIT, nitrofurantoin; RIF, rifampicin; VAN, vancomycin. Every measurement was completed with four replicates, and error bars represent standard deviation. Phenotypic effects of acrA deletion and acrA silencing with acrA-PPMO are highly correlated (r = 0.94, p < 0.001, Pearson correlation test). (C) Killing of E. coli (BW25113), K. pneumoniae (F45153), S. enterica (14028S), Acinetobacter baumannii (AYE), Pseudomonas aeruginosa (PAO1), and Burkholderia cenocepacia (K56-2) by piperacillin-tazobactam alone (black line) or in combination with 10 μM control-PPMO (grey dashed line), or acrA-PPMO (blue dashed line) after 18 h incubation. The horizontal dashed line represents the inoculum (5 x 105 CFU/mL) prior to incubation. The x-axis represents the normalized MIC concentration of piperacillin-tazobactam, corresponding to different MIC values for each pathogen. Error bars represent the standard deviations of the colony forming unit (CFU) counts obtained from at least four replicate measurements.