TABLE 1.

Genotype summary, in vitro antimicrobial susceptibility profiles, and MICs of colistin in the absence and presence of tigecycline at 0.13, 0.25, and 0.5 mg/L against study E. coli strains^a.

E. coli strain	Relevant genotype	MIC (mg/L)								CST MIC (mg/L)				FIC index
		AMP	CTX	MEM	GEN	CIP	RIF	TET	TGC	CST alone	TGC 0.13	TGC 0.25	TGC 0.5
25922	ST73; ATCC strain	4	0.06	0.03	0.5	0.008	4	1	0.13	1	NA	NA	NA	0.5
2630	ST3902; blaNDM–5	256	256	64	16	256	32	128	1	0.5	0.5	0.25	0.13	0.75
3112	ST1011; mcr-1	256	128	0.13	256	128	256	64	1	8	2	2	1	0.37
1320	ST648; blaNDM–5/mcr-1	128	64	16	32	128	8	128	2	4	2	0.5	0.5	0.37
2610	ST101; blaNDM–5/mcr-1	256	256	16	64	256	256	64	1	4	2	1	1	0.5
2121	ST156; blaNDM–5/mcr-1	256	256	16	128	128	4	128	1	8	4	2	0.5	0.5

^aAMP, ampicillin; CTX, cefotaxime; MEM, meropenem; GEN, gentamicin; CIP, ciprofloxacin; RIF, rifampicin; TET, tetracycline; TGC, tigecycline; CST, colistin; NA, not applicable.