Table 1.

Carbapenemase Genes in Acinetobacter baumannii: Genetic Location, Horizontal Gene Transfer Mechanisms, Genetic Context and Movement of Mobile Genetic.

Carbapenemases	bla Gene Type	Resistance Origin	Location	Intercelullar Transfer (HGT) 1	Genetic Context	Intracellular Movement	References
CHDLs 2	OXA-51	Intrinsic	Mainly chromosomal;		Sometimes, ISAba1-blaoxa-51-like		[33,35]
			plasmid		Tn6080	Transposition	[34]
	OXA-23	Acquired	Chromosome and plasmid	Conjugation	Genomic islands; Transposons; Insertion sequences	Transposition	[62,63,64,65,66,67,68,69,70,71,72,73]
	OXA-40/24	Acquired	Chromosome and plasmid	Conjugation? 5	Self-transmissible plasmid belonging to replicon group GR6		[45,74,75,76,77]
					and in plasmids containing mob genes		[52,78]
					Flanked by conserved inverted repeats homologous to XerC/XerD, recombinases’ targets	Site-specific recombination	[77,78,79,80]
				OMVs 4-mediated transfer			[59]
	OXA-58	Acquired	Mostly plasmidic	Conjugation? 5	Self-conjugative plasmid belonging to replicon group GR6		[52,67,81,82,83]
					Insertion sequences		[3,50,84,85]
					Flanked by two repeated sequences, Re27	Homologous recombination	[84]
					Flanked by two IS26 leading to duplication of ISAba2/ISAba3-blaOXA-58-ISAba3	Transposition	[86]
	OXA-143	Acquired	Plasmid		Flanked by two rep genes	Homologous recombination	[45]
					XerC/XerD recognition site	Site-specific recombination	[87]
	OXA-235	Acquired	Chromosome and plasmid		Flanked by two ISAba1	Transposition	[46]
MBLs 3	IMP	Acquired	Chromosome and plasmid	Conjugation	Many inserted in class 1 integrons		[88,89,90,91,92,93]
					Gene not embedded into integrons		[94]
					Class 1 integron flanked by MITEs 6	Transposition	[95,96]
				Natural transformation	Chromosomal class 1 integron	Homologous recombination	[89,97]
	VIM	Acquired	Chromosome		Class 1 and 2 integrons		[98,99,100,101,102], GenBank Ac. nr. LC107606
	NDM	Acquired	Mostly plasmidic;	Conjugation	Associated to composite transposon Tn125	Transposition	[103,104,105,106,107,108,109,110]
			chromosome	Transduction	Flanked by ISAba125 and ISCR21		[111]
Class A β-lactamases	KPC	Acquired	Chromosome		Tn4401b embedded into KQ-like element	Transposition	[112]
					(Novel truncated version of) Tn4401e		[113]
	GES	Acquired	Chromosome and plasmid	Conjugation	Class 1 integrons		[114,115,116,117,118,119]

¹ HGT, Horizontal gene transfer; ² CHDLs, Carbapenem-hydrolysing oxacillinases; ³ MBLs, Metallo-β-lactamases; ⁴ OMVs, Outer-membrane vesicles; ⁵ Failed demonstration [50,51,76,78,120]; ⁶ MITEs, Miniature inverted repeat transposable elements.