TABLE 1.

MDR pumps inhibited by the EPIs used in this study

MDR pump(s)	Organism	Substrates	EPI(s)	Reference(s)
AcrAB	E. coli	Bile salts, fatty acids, antibiotics (tetracycline, chloramphenicol, quinolones, fluoroquinolones, rifampin), dyes, detergentsa	NMP, PAβN	3, 7, 8, 21, 27, 31, 33
AcrEF	E. coli	Hydrophobic uncouplers, multiple structurally dissimilar antibiotics, basic dyes	NMP	3, 33, 38
AcrAB	K. pneumoniae	Multiple structurally dissimilar antibiotics	PAβN	4
MexAB, MexCD, MexEF	P. aeruginosa	Multiple structurally dissimilar antibiotics	NMP, PAβN	1, 23, 39, 40
NorA	S. aureus	Tetracycline, chloramphenicol, quinolones, fluoroquinolones, reserpine, plant alkaloidsa	Thioridazineb	30, 36

^aThe quinolones include nalidixic acid, levofloxacin, and ciprofloxacin.

^bIt should be noted that thioridazine has been shown to reduce vancomycin resistance in the gram-negative bacterium Enterococcus faecalis.