The impact of therapeutic-dose induced intestinal enrofloxacin concentrations in healthy pigs on fecal Escherichia coli populations

Table 3 Results of the gene mutations of gyrA and parC for selected strains from the different treatment groups, the minimal inhibitory concentration (MIC) values are also provided for these isolates with wild-type cut-off of 0.125 μg/mL. The silent mutations, i.e. polymorphisms in codon sequence resulting in the same amino acid, in gyrA and parC are given, with the reference sequences indicated in grey. Escherichia coli K12 MG1655 was used for reference

Isolate	MIC (μg/mL)	*gyr*A mutations	*par*C mutations	Silent mutations (gyrA/ parC) and additional resistance mechanisms
*E. coli* K12 MG1655	NA	None	None	REFERENCE gyrA: 85GTC, 91CGC, 100TAT, 110TCT /parC: 91CAA
ATCC 25922™	0.064	None	None
Y01.V2 – Group 1 – 0 h	0.064	None	None
Y08.V3 – Group 2 – 0 h	0.032	None	None
Y11.V2 – Group 3 – 0 h	0.016	None	None
Y12.V2 – Group 4 – 0 h	0.064	None	None
X02.V2 – Group 1 – 0 h	2.00	None	None	gyrA: 85GTT, 91CGT, 100TAC, 110TCC/ parC: 91CAG and qnrS1 positive
Y02.V2 – Group 2 – 0 h	4.00	None	None	gyrA: 85GTT, 91CGT, 100TAC, 110TCC/ parC: 91CAG and qnrS1 positive
X06.V2 – Group 2 – 0 h	4.00	None	None	gyrA: 85GTT, 91CGT, 100TAC, 110TCC/ parC: 91CAG and qnrS1 positive
Y09.V2 – Group 3 – 0 h	2.00	None	None	gyrA: 85GTT, 91CGT, 100TAC, 110TCC/ parC: 91CAG and qnrS1 positive
X12.V2 – Group 4 – 0 h	1.00	None	None	gyrA: 85GTT, 91CGT, 100TAC, 110TCC/ parC: 91CAG and qnrS1 positive
X04.V2 – Group 1 – 58 h	> 32.00	83Leu, 87Asn	80Ile
X07.V3 – Group 2 – 58 h	> 32.00	None	None
X08.V4 – Group 2 – 58 h	> 32.00	83Leu, 87Asn	80Ile
X09. V4 – Group 2 – 58 h	> 32.00	83Leu, 87Asn	80Ile
X11.V6 – Group 3 – 58 h	> 32.00	83Leu, 87Asn	80Ile
X13.V1 – Group 4 – 58 h	> 32.00	83Leu, 87Asn	80Ile
X14.V1 – Group 4 – 58 h	> 32.00	83Leu, 87Asn	80Ile
X15. V1 – Group 4 – 58 h	> 32.00	83Leu, 87Asn	80Ile

ISSN: 1746-6148