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Table 1 Guidelines for antibiotic discs used for antimicrobial susceptibility test of E. coli with their respective concentrations

From: RETRACTED ARTICLE: Occurrence and antimicrobial susceptibility profile of Escherichia coli O157:H7 from food of animal origin in Bishoftu town, Central Ethiopia

Antimicrobial agent

Symbol

Disc content

Zone of inhibition in millimeters (mm) with its interpretation

Susceptible

Intermediate

Resistant

Ceftriaxone

CRO

30 μg

≥ 23

20–22

≤ 19

Streptomycin

S

10 μg

≥ 15

12–14

≤ 11

Tetracycline

TTC

30 μg

≥ 15

12–14

≤ 11

Gentamycin

GN

10 μg

≥ 15

13–14

≤ 12

Ciprofloxacilin

CIP

5 μg

≥ 21

16–20

≤ 15

Vancomycin

VA

30 μg

≥ 12

10–11

≤ 9

Chloramphenicol

C

30 μg

≥ 18

13–17

≤ 12

Ampicillin

AMP

10 μg

≥ 14

12–13

≤ 11

  1. Source: (CLSI (clinical and laboratory standards institute), 2012)