Table 1.

Multidrug Efflux Pumps Described for Staphylococcus aureus

Efflux Pump	Familya	Regulator(s)b	Substrate Specificity	References
Chromosomally-encoded Efflux Systems
NorA	MFS	MgrA, NorG(?)	Hydrophilic fluoroquinolones (ciprofloxacin, norfloxacin) QACs (tetraphenylphosphonium, benzalkonium chloride) Dyes (e.g. ethidium bromide, rhodamine)	[16,18,19]
NorB	MFS	MgrA, NorG	Fluoroquinolones (e.g. hydrophilic: ciprofloxacin, norfloxacin and hydrophobic: moxifloxacin, sparfloxacin) Tetracycline QACs (e.g. tetraphenylphosphonium, cetrimide) Dyes (e.g. ethidium bromide)	[31]
NorC	MFS	MgrA(?), NorG	Fluoroquinolones (e.g. hydrophilic: ciprofloxacin and hydrophobic: moxifloxacin) Dyes (e.g. rhodamine)	[35,36]
MepA	MATE	MepR	Fluoroquinolones (e.g. hydrophilic: ciprofloxacin, norfloxacin and hydrophobic: moxifloxacin, sparfloxacin) Glycylcyclines (e.g. tigecycline) QACs (e.g. tetraphenylphosphonium, cetrimide, benzalkonium chloride) Dyes (e.g. ethidium bromide)	[37,38]
MdeA	MFS	n.i.	Hydrophilic fluoroquinolones (e.g. ciprofloxacin, norfloxacin) Virginiamycin, novobiocin, mupirocin, fusidic acid QACs (e.g. tetraphenylphosphonium, benzalkonium chloride, dequalinium) Dyes (e.g. ethidium bromide)	[39,40]
SepA	n.d.	n.i.	QACs (e.g. benzalkonium chloride) Biguanidines (e.g. chlorhexidine) Dyes (e.g. acriflavine)	[41]
SdrM	MFS	n.i.	Hydrophilic fluoroquinolones (e.g. norfloxacin) Dyes (e.g. ethidium bromide, acriflavine)	[42]
LmrS	MFS	n.i.	Oxazolidinone (linezolid) Phenicols (e.g. choramphenicol, florfenicol) Trimethoprim, erythromycin, kanamycin, fusidic acid QACs (e.g. tetraphenylphosphonium) Detergents (e.g. sodium docecyl sulphate) Dyes (e.g. ethidium bromide)	[43]
Plasmid-encoded Efflux Systems
QacA	MFS	QacR	QACs (e.g. tetraphenylphosphonium, benzalkonium chloride, dequalinium) Biguanidines (e.g. chlorhexidine) Diamidines (e.g. pentamidine) Dyes (e.g. ethidium bromide, rhodamine, acriflavine)	[45,49]
QacB	MFS	QacR	QACs (e.g. tetraphenylphosphonium, benzalkonium chloride) Dyes (e.g. ethidium bromide, rhodamine, acriflavine)	[53]
Smr	SMR	n.i.	QACs (e.g. benzalkonium chloride, cetrimide) Dyes (e.g. ethidium bromide)	[58,61]
QacG	SMR	n.i.	QACs (e.g. benzalkonium chloride, cetyltrymethylammonium) Dyes (e.g. ethidium bromide)	[67]
QacH	SMR	n.i.	QACs (e.g. benzalkonium chloride, cetyltrymethylammonium) Dyes (e.g. ethidium bromide)	[68]
QacJ	SMR	n.i.	QACs (e.g. benzalkonium chloride, cetyltrymethylammonium) Dyes (e.g. ethidium bromide)	[69]

^an.d.: The family of transporters to which SepA belongs is not elucidated to date.

^bn.i.: The transporter has no regulator identified to date.

QACs: quaternary ammonium compounds