Antimicrobial susceptibility, phylotypes, and virulence genes of Escherichia coli from clinical bovine mastitis in five provinces of China

Figures & data

Figure 1. Antibiotic resistance of E. coli isolates from bovine mastitis in five major dairy-producing regions of China.

Table 1. Antibiotic resistance (%) of E. coli isolates from raw milk of mastitic cows in China.

Antibiotics	No. (%) of positive strains
	Shanghai	Inner Mongolia	Hebei	Heilongjiang	Shandong	Total
	(n = 24)	(n = 19)	(n = 19)	(n = 18)	(n = 12)	(n = 92)
AMP^a	15 (62.5)	4 (21.0)	7 (36.8)	8 (44.4)	4 (33.3)	38 (41.3)
PIP^a	11 (45.8)	3 (15.8)	6 (31.6)	10 (55.6)	4 (33.3)	34 (36.9)
TET^ab	12 (50.0)	4 (21.1)	6 (31.6)	6 (33.3)	4 (33.3)	32 (34.8)
SXT^ab	10 (41.7)	4 (21.1)	7 (36.8)	9 (50.0)	1 (8.3)	31 (33.7)
CHI	9 (37.5%)	4 (21.1)	2 (10.5)	4 (22.2)	4 (33.3)	23 (28.3)
ATM	3 (12.5)	1 (5.3)	5 (26.3)	5 (27.8)	4 (33.3)	18 (19.6)
GEN	9 (37.5)	1 (5.3)	2 (10.5)	3 (16.7)	2 (16.7)	17 (18.5)
OFLX^bd	4 (16.7)	1 (5.3)	2 (10.5)	2 (11.1)	3 (25.0)	12 (13.0)
CIP^bc	3 (12.5)	0 (0)	2 (10.5)	1 (5.5)	2 (16.7)	8 (8.7)
FOX	2 (8.3)	0 (0)	1 (5.3)	2 (11.1)	1 (8.3)	6 (6.5)
AMC^cd	1 (4.2)	2 (10.5)	1 (5.3)	0 (0)	0 (0)	4 (4.3)
MEM^e	0 (0)	0 (0)	0 (0)	0 (0)	0 (0)	0 (0)
KAN^e	0 (0)	0 (0)	0 (0)	0 (0)	0 (0)	0 (0)

Note: No. (%): (numbers of positive strains)/n. Antimicrobials: AMP, ampicillin; FOX, cefoxitin; AMC, amoxicillin-clavulanic acid; SXT, sulfamethoxazole-trimethoprim; PIP: piperacillin; CIP, ciprofloxacin; ATM: aztreonam; MEM: meropenem; OFLX: ofloxacin; CHL, chloramphenicol; KAN, kanamycin; GEN, gentamicin; TET, tetracycline. (P ≤ 0.05).

Table 2. Antimicrobial resistance patterns of E. coli isolates.

Resistance pattern	No. of isolates
AMP	1
AMP + PIP	2
AMP + TET	1
AMP + SXT	1
OFLX + SXT	1
SXT + PIP	1
TET	1
PIP	3
AMC	1
OFLX	1
SXT	1
AMP + CIP + TET	1
AMP + PIP_ATM	1
AMP + AMC + TET	1
AMP + SXT + PIP	1
AMP + SXT + PIP + ATM	1
PIP + ATM + OFLX + CHI	1
AMP + SXT + CHI + TET	1
AMP + FOX + CHI + TET	1
AMP + SXT + PIP + GEN + TET	1
AMP + SXT + PIP + CHI + TET	2
AMP + SXT + CHI + GEN + TET	2
AMP + PIP + ATM + CHI + TET	1
AMP + SXT + ATM + GEN + TET	1
AMP + SXT + ATM + CHI + TET	1
AMP + SXT + PIP + ATM + TET	1
AMP + SXT + PIP + CHI++GEN + TET	2
AMP + SXT + PIP + CHI++ATM + TET	1
AMP + OFLX + PIP + CIP + ATM + SXT + TET	2
AMP + OFLX + PIP + CHI + ATM + SXT + TET	1
AMP + SXT + PIP + ATM + CHI + GEN + TET	4
AMP + AMC + FOX + AXT + PIP + CHI + GEN + TET	1
AMP + SXT + PIP + CIP + OFLX + CHI + GEN + TET	1
AMP + FOX + SXT + PIP + ATM + OFLX + CHI + GEN + TET	1
AMP + FOX + AMC + SXT + PIP + CIP + ATM + GEN + TET	1
AMP + SXT + PIP + CIP + ATM + OFLX + CHI + GEN + TET	2
AMP + FOX + PIP + CIP + ATM + OFLX + CHI + GEN + TET	1
Total	48

Table 3. Percentage of resistant strains based on phylogenetic group.

Phylogroup	Total (n)	Isolates (n)	AMP	PIP	TET	SXT	CHI	ATM	GEN	OFLX	CIP	FOX	AMC	MEM	KAN
A	29	12	27.6	27.6	24.1	31	20.7	6.9	20.7	0	3.4	0	0	0	0
B1	33	15	39.4	33.3	27.3	18.2	9.1	18.2	9.1	9.1	9.1	6.1	3.0	0	0
C	21	13	42.9	42.9	47.6	42.9	28.6	28.6	28.6	23.8	14.3	4.8	9.5	0	0
E	4	2	0	50.0	50.0	0	25.0	50.0	25.0	50.0	25.0	25.0	0	0	0

Note: Antimicrobials: AMP, ampicillin; FOX, cefoxitin; AMC, amoxicillin-clavulanic acid; SXT, sulfamethoxazole-trimethoprim; PIP: piperacillin; CIP, ciprofloxacin; ATM: aztreonam; MEM: meropenem; OFLX: ofloxacin; CHL, chloramphenicol; KAN, kanamycin; GEN, gentamicin; TET, tetracycline; n, number of strains.

Table 4. Antimicrobial resistance genes identified in E. coli isolates from raw milk of mastitic cows.

Antibiotic class	Antibiotic	resistance gens	positive strains
			No.	(%)
β-Lactam	AMP	blaTEM	19	20.6
		blaCTX-M	16	17.3
		blaTEM+blaCTX-M	10	10.9
	FOX	blaFOX	0	0
	AMC	blaNDM	0	0
		blaKPC	0	0
	SXT	blaOXA	0	0
Tetracyclines	TET	TetA	24	26
		TetB	0	0
Quinolones	CIP	gyrA	90	97.8
		gyrB	84	95.6
Aminoglycosides	GEN	aac4A	13	14.1
		aac6	9	9.7
		aac4A + aac6	8	8.7
		aac3	0	0
Chloramphenicol	CHI	floR	18	19.5

Table 5. Prevalence of virulence genes in E. coli isolates.

	Virulence gene	No. of isolates	% isolates
EPEC	eae	75	81.5
EAEC	aggR	0	0
STEC	Stx1	0	0
	Stx2	0	0
EIEC	ipaH	57	61.9
ETEC	elt	6	6.5

Table 6. Distribution of O serogroups among different phylogenetic groups.

phylogenetic group	Strains (No.)	Data for O serotype/strains in:					Total
		HLJ	SH	HB	SD	NM
A	29	4(13.8),O121,UT(3)	9(31.0),O111(2),O121(2),O128(3),O91,UT	5(17.2),O121(2),O91,UT(2)	5(17.2),O121(2),O91,UT(2)	6(20.7),O121,O91,UT(4)	O121(8),O91(4),O128(3),O111(2),UT(12)
B1	33	7(21.2),O121(2),O128,O91,UT(3)	11(33.3),O121(6),O128(3),O22,UT	8(24.2),O121,O91(2),O22(3),O113,UT	4(12.1),O91,UT(3)	3(9.1),O121(2),UT	O121(11),O91(4),O113,O22(4),O128(4),UT(9)
B2	ND
C	21	3(14.3),O121(3)	3(14.3),O121(3)	4(12.1),O113,O26,O91,O121	3(14.3),O91(2),UT	8(24.2),O121(3),O91(3),UT(2)	O91(6),O121(10),O113,O26,UT(3)
D	ND
E	4	1(25.0),O121		2(50.0),O121(2)		1(25.0),O22	O121(3),O22
F	ND
UNKNOWN	5	2(40.0),UT(2)	1(20.0),O121			2(40.0),O91,UT	O91,O121,UT(3)
Total	92	17(18.5)	24(26.1)	19(20.7)	12(13.0)	20(21.7)

Note: ND: not detected.

Figure 2. Distribution of intimin types among phylogroups in E. coli isolates from bovine mastitis in China.

Table 7. Distribution of O serogroups among different intimin types.

Intimin type	Strains (No.)	O serotype(s) in:					Total
		HLJ	HB	SD	NM	SH
eae-μR-ι2	45	O121(5),O128,UT(6)	O121(2),O113(2),O91,UT(2)	O121,O91(3),UT	O121(5),O91(2),UT(3)	O121(6),O128(2),O22,O111(2)	O121(19),O113(2),O91(6),O128(3),O22,O111(2),UT(12)
eae-λ	15	O121	O91,O121,O22(2),UT	O121	O91,UT(2)	O121(2),O128,O91,UT	O91(3),O121(5),O22(2),O128,UT(4)
eae-ξR/β2	10		O26,O121	UT	O91(2),UT(3)	O121(2)	O26,O121(3),O91(2),UT(4)
eae-νR-ε2	3	O121	O91			O128	O91,O121,O128
eae-η	2			UT	O121		O121,UT
ND	17	O91,UT(2)	O121(2),O91,O22	O91,UT(3)	O22	O121(2),O128(2),UT	O22(2),O91(3),O121(4),O128(2),UT(6)

Note: UT: untypeable; ND: not detected.