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Table 3 MIC values after multi-step selection of resistance in E. coli and Klesiella spp. at plasma concentration of fluoroquinolones

From: In vitro selection of resistance in Escherichia coli and Klebsiella spp. at in vivo fluoroquinolone concentrations

Drug

MIC (mg/L): median (range)

 

Nr of strains

Pre-sel

I STEP

V STEP

X STEP

X STEP

free

E. coli (n = 20)

LVX

500 mg

7

0.5

(0.5 - 1)

2

(0.5-4)

4

(1 - 8)

8

(2 - 8)

4

(1 - 8)

LVX

750 mg

0

0.016 - 1

n.d.

n.d.

n.d.

n.d.

CIP

500 mg

8

0.25

(0.125 - 0.5)

0.5

(0.125 - 1)

2

(2 - 4)

8

(4 - 16)

4

(1 - 8)

PRU

600 mg

12

0.064

(0.016 - 0.125)

1

(0.5 - 4)

2

(2 - 4)

4

(2 - 8)

4

(2 - 8)

Klebsiella spp. (n = 20)

LVX

500 mg

0

0.03 - 1

n.d

n.d

n.d

n.d

LVX

750 mg

0

0.03 - 1

n.d

n.d

n.d

n.d

CIP

500 mg

11

0.06

(0.03 - 0.5)

0.5

(0.5 - 1)

2

(1 - 8)

8

(4 - 16)

4

(1 - 4)

PRU

600 mg

16

0.06

(0.03 - 0.25)

0.5

(0.06 - 1)

2

(0.25 - 16)

4

(0.5 - 32)

4

(0.25 - 16)

  1. LVX: Levofloxacin; CIP: Ciprofloxacin; PRU: Prulifloxacin; Pre-sel: MICs before starting multi-step selection of resistance; I Step: MICs after the first passage on antibiotic gradient agar plates; V Step: MICs after the fifth passage on antibiotic gradient agar plates; X Step: MICs after the last passage on antibiotic gradient agar plates; X step free: MICs after ten subcultures on antibiotic free agar plates.
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BMC Microbiology

ISSN: 1471-2180

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