Table 1.

Characterization of the tet(X4)-positive Escherichia coli.

Strain	Species	Source	Sequence type	Antimicrobial agents (mg/L) 1
				TGC	CPL	NAL	FFC	STX	CTX	COL	MEM	AMK
e6cp	E. coli	Duck feces	ST10776	8	> 512	> 16	256	> 16	< 0.125	0.125	0.03	2

¹ Abbreviations and antibiotic resistance break-points according to the Clinical and Laboratory Standards Institute (CLSI) 2020 guidelines: TGC: tigecycline (R > 2 mg/L), CPL, chloramphenicol (R > 8 mg/L); NAL, nalidixic acid (R > 4 mg/L); FFC, florfenicol (R > 16 mg/L); SXT, trimethoprim–sulfamethoxazole (R > 4 mg/L); CTX, cefotaxime (R > 2 mg/L); COL, colistin (R > 2 mg/L); MEM, meropenem (R > 8 mg/L;, AMK, amikacin (R >16 mg/L). Bold underlined numbers indicate resistance to the corresponding antimicrobial agents.