Table 2.

Main antibiotic resistance determinants encoded in S. maltophilia genome.

Gene	Product	Drug Resistance	Type of Resistance	References
L1	Class B3 Zn2+-dependent MBL	β-lactams (except monobactams)	IR *, TR ***	[208,211]
L2	Class A clavulanic acid-sensitive cephalosporinase	β-lactams	IR, TR	[209,211]
aac(6′)-Iz	N-Aminoglycoside acetyltransferase	Amikacin, tobramycin, sisomicin, netilmicin	IR	[214]
aac(6′)-Iak	N-Aminoglycoside acetyltransferase	Arbekacin, kanamycin, neomycin, sisomicin, tobramycin	IR	[213]
aph(3′)-IIc	Aminoglycoside phosphotransferase	Kanamycin, neomycin, paromycin, butirosin	IR	[215]
Smqnr	Pentapeptide repeat protein	Quinolones	IR, AR **	[218,219,240]
smeYZ	RND efflux pump	Aminoglycosides, tetracycline, leucomycin, SXT	IR, AR, TR	[247,444]
smeDEF	RND efflux pump	Fluoroquinolones, chloramphenicol tetracycline, tigecycline, macrolides, sulfamethoxazole, trimethoprim, SXT	IR, AR, TR	[207,225,229,445,446]
smeGH	RND efflux pump	β-lactams, fluoroquinolones, tetracycline, polymyxin B, ceftazidime	IR, AR	[221]
smeIJK	RND efflux pump	Aminoglycosides, tetracycline, ciprofloxacin, levofloxacin, leucomycin, minocycline	IR, AR	[222]
smeOP	RND efflux pump	Nalidixic acid, doxycycline, aminoglycosides, macrolides	IR	[223]
smeVWX	RND efflux pump	Quinolones, chloramphenicol, trimethoprim/sulfamethoxazole	AR, TR	[225,226,247,248]
smeABC	RND efflux pump	Aminoglycosides, β-lactams and fluoroquinolones	AR	[238]
smrA	ABC efflux pump	Fluoroquinolones, tetracycline, doxorubicin	ND	[230]
macABCsm	ABC efflux pump	Aminoglycosides, macrolides, polymyxins	IR	[231]
emrCABsm	MFS efflux pump	Nalidixic acid, erythromycin, CCCP, tetrachlorosalicylanilide	IR	[232]
fuaABC	Fusaric acid tripartite efflux pump	Fusaric acid	TR	[249]

* Intrinsic (IR) ** Acquired (AR) and *** Transient (TR) antibiotic resistance.