TABLE 6.

Antibiotic resistance genes (ARGs).

			Distribution			Protein
			ZnCl2-MICs (μg/ml)							REF
Factor	Symbol	Gene	128	256	512
			n = 7a	n = 136a	n = 36a	L	AV	C	I
			%	%	%	AA	n	%	%
Streptomycin 3′′-adenyltransferase	AadA1	aadA1	28.6	18.4	52.8	263	2	100	99.2	[1]
Aph(3′′)-Ib PT	APH(3′′)-Ib	strA	14.3	38.2	0	267	2	100	99.9	[2]
Aph(6)-Id PT	APH(6)-Id	strB	14.3	38.2	0	287	1	100	100	[2]
Tetracycline resistance protein	Tet(A)	tet(A)	0	11.0	52.8	399	2	100	99.9	[3]
Tetracycline resistance protein	Tet(B)	tet(B)	14.3	29.4	0	401	1	100	99.9	[4]
Macrolide 2′-PT II	MPH(2‘)-II	mph(B)	0	2.2	0	302	1	100	100	[5]
β-lactamases	BlaTEM-1b	blaTEM-1b	0	30.9	0	286	1	100	98.6	[6]
Dehydrofolate reductase	DfrA1	dfrA1	0	11.8	52.8	157	2	100	99.9	[7]
Dihydropteroate synthase-type 1	DHPS-1	sul1	0	8.1	52.8	279	2	100	99.9	[8]
Dihydropteroate synthase-type 2	DHPS-2	sul2	0	0.7	0	271	1	100	99.4	[8]
Dihydropteroate synthase-type 3	DHPS-3	sul3	0	9.6	52.8	263	1	100	99.9	[8]

Whole genome sequencing data of 179 porcine commensal E. coli were screened with respect to antibiotic resistance genes (ARGs). Predicted amino acid sequence lengths were compared to those of the ResFinder 3.1 data base (Zankari et al., 2012) in order to check for putative premature stop codons or deletions affecting the putative function of the protein. None of the amino acid sequence variations (AV) was solely associated with a particular ZnCl₂ MIC. Isolates with the 512 μg/ml ZnCl₂ MIC which were positive for plasmid-associated ARGs exclusively belonged to ST10 O182:H19 (Figure 4). n, number of isolates; ^a, number of isolates with particular ZnCl₂ MIC; L, length; AA, amino acid; AV, number of amino acid sequence variants; C, amino acid sequence coverage with respect to ResFinder 3.1 data base (Zankari et al., 2012); I, maximum amino acid sequence identity among the 179 isolates; REF, references. [1] Hollingshead and Vapnek, 1985; [2] Scholz et al., 1989; [3] Aldema et al., 1996; [4] Roberts, 2005; [5] Pawlowski et al., 2018; [6] Salverda et al., 2010; [7] Sköld, 2001; [8] Antunes et al., 2005.