Table 1 Antibiotic E-test strips used to determine the antibiotic susceptibility profiles of E. coli O157:H7⁺/H7^- cattle and wastewater isolates and antibiotic resistance patterns of the isolates

Aminoglycoside

Amikacin

AK

0.016-256

≤ 16

≥ 64

102

-

-

Aminoglycoside

Streptomycin

S

0.064-1024

≤ 32

≥ 64

91

-

11

Aminoglycoside

Tobramycin

TOB

0.064-1024

≤ 4

≥ 16

98

4

-

Aminoglycoside

Gentamicin

CN

0.016-256

≤ 4

≥ 16

102

-

-

Aminoglycoside

Kanamycin

K

0.016-256

≤ 16

≥ 64

91

11

-

Penicillins

Ampicillin

AMP

0.016-256

≤ 8

≥ 32

82

5

15

β-Lactam/(ase) inhibitor

Amoxicillin/clavulanic acid

AUG

0.016-256

≤ 8/4

≥ 32/16

89

13

-

Monobactams

Aztreonam

ATM

0.016-256

≤ 8

≥ 32

98

-

4

Cephalosporin 1^st gen.

Cephalothin

KF

0.016-256

≤ 8

≥ 32

54

42

6

Cephalosporin 2^nd gen.

Cefaclor

CEC

0.016-256

≤ 8

≥ 32

98

-

4

Cephalosporin 2^nd gen.

Cefoxitin

FOX

0.016-256

≤ 8

≥ 32

85

4

13

Cephalosporin 3^rd gen.

Cefotaxime

CTX

0.016-256

≤ 8

≥ 64

102

-

-

Cephalosporin 3^rd gen.

Ceftriaxone

CRO

0.016-256

≤ 8

≥ 64

91

11

-

Fluoroquinolone 1^st gen.

Norfloxacin

NOR

0.016-256

≤ 4

≥ 16

91

11

-

Fluoroquinolone 2^nd gen.

Ciprofloxacin

CIP

0.002-32

≤ 1

≥ 4

91

11

-

Quinolone 1^st gen.

Nalidixic acid

NA

0.016-256

≤ 16

≥ 32

98

-

4

Folate Pathway Inhibitors

Sulfamethoxazole

SMX

0.064-1024

≤ 256

≥ 512

78

-

24

Folate Pathway Inhibitors

Trimethoprim

TM

0.002-32

≤ 8

≥ 16

83

-

19

Phenicols

Chloramphenicol

C

0.016-256

≤ 8

≥ 32

87

7

8

Tetracyclines

Tetracycline

TE

0.016-256

≤ 4

≥ 16

77

-

25