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Table 2 The minimum inhibitory concentration (MIC) range and resistance rates among Escherichia coli isolates from pups originating from two kennels (A and B).

From: Clonal spread of antimicrobial-resistant Escherichia coli isolates among pups in two kennels

Substancea

MIC range (μg/mL)

MIC50

MIC90

Resistance breakpoints (μg/mL)b

No. of resistant isolates (%)/No. of pups that harboured resistant isolate(s) (%)

     

Total

Kennel A

Kennel B

     

(n = 86/43)

(n = 50/25)

(n = 36/18)

AMP

2 - >512

>512

>512

≥32

52 (60.5)/30 (69.8)

29 (58.0)/17 (68.0)

23 (63.9)/13 (72.2)

CFZ

8 - 128

4

8

≥32

5 (5.8)/3 (7.0)

0 (0)/0 (0)

5 (13.9)*/3 (16.7)

CEF

≤0.125 - 32

0.5

1

≥8

5 (5.8)/3 (7.0)

0 (0)/0 (0)

5 (13.9)*/3 (16.7)

DHS

2 - >512

512

>512

≥32

57 (66.3)/32 (74.4)

35 (70.0)/19 (76.0)

22 (61.1)/13 (72.2)

GEN

0.5 - 256

1

128

≥16

16 (18.6)/12 (27.9)

16 (32.0)*/12 (48.0)*

0 (0)/0 (0)

KAN

2 - >512

4

16

≥64

3 (3.5)/2 (4.7)

3 (6.0)/2 (8.0)

0 (0)/0 (0)

OTC

1 - 512

2

512

≥16

23 (26.7)/17 (39.5)

18 (36.0)*/14 (56.0)*

5 (13.9)/3 (16.7)

CHL

4 - >512

8

512

≥32

23 (26.7)/17 (39.5)

18 (36.0)*/14 (56.0)*

5 (13.9)/3 (16.7)

NAL

2 - >512

4

16

≥32

7 (8.1)/5 (11.6)

2 (4.0)/2 (8.0)

5 (13.9)/3 (16.7)

ENR

≤0.03 - 256

0.06

1

≥4

5 (5.8)/3 (7.0)

0 (0)/0 (0)

5 (13.9)*/3 (16.7)

SXT

≤0.25/4.75 - >64/1216

1/19

>64/1216

≥16/304

36 (41.9)/21 (48.8)

27 (54.0)*/16 (64.0)*

9 (25.0)/5 (27.8)

  1. aAMP, ampicillin; CFZ, cefazolin; CEF, ceftiofur; DHS, dihydrostreptomycin; GEN, gentamicin; KAN, kanamycin; OTC, oxytetracycline; CHL, chloramphenicol; NAL, nalidixic acid; ENR, enrofloxacin; SXT, trimethoprim-sulfamethoxazole.
  2. bThe breakpoints for AMP, CFZ, CEF, GEN, KAN, OTC, CHL, ENR and SXT, and that for NAL were based on CLSI document M31-A3 [9] and M100-S20 [8], respectively, whereas the breakpoint of DHS was based on an epidemiological cut-off value according to another report [10]