Table 2 MIC distribution and percentage of resistance to antibiotics.

From: In vitro activity of antibiotics potentially effective against difficult-to-treat strains of Gram-negative rods: retrospective study

 

Acinetobacter baumannii

Enterobacterales

Pseudomonas aeruginosa

S (n = 20)

DTR (n = 20)

total (n = 40)

S (n = 10)

DTR (n = 10)

total (n = 20)

S (n = 15)

DTR (n = 15)

total (n = 30)

AMS

MIC50 (mg/l)

0.016

 > 256

1

NT

NT

NT

NT

NT

NT

MIC90 (mg/l)

0.016

 > 256

 > 256

NT

NT

NT

NT

NT

NT

range (mg/l)

0.016 to 1

 > 256

0.016 to > 256

NT

NT

NT

NT

NT

NT

% resistant (n)

   

NT

NT

NT

NT

NT

NT

A/A

MIC50 (mg/l)

NT

NT

NT

0.032

0.25

0.064

4

16

4

MIC90 (mg/l)

NT

NT

NT

0.064

0.5

0.5

4

32

32

range (mg/l)

NT

NT

NT

0.032 to 0.064

0.064 to 1

0.032 to 1

2 to 8

4 to 64

2 to 64

% resistant (n)

NT

NT

NT

      

FCR

MIC50 (mg/l)

0.125

0.25

0.25

0.016

0.125

0.032

0.25

0.25

0.25

MIC90 (mg/l)

0.25

0.5

0.5

0.032

4

1

1

2

1

range (mg/l)

0.064 to 0.5

0.125 to 1

0.064 to 1

0.016 to 0.125

0.032 to 8

0.016 to 8

0.016 to 1

0.064 to 4

0.016 to 4

% resistant (n)

   

0 (0)

20 (2)

10 (2)

0 (0)

6.7 (1)

3.3 (1)

CAT

MIC50 (mg/l)

NT

NT

NT

0.125

2

0.25

1

8

4

MIC90 (mg/l)

NT

NT

NT

0.25

 > 256

16

2

 > 256

32

range (mg/l)

NT

NT

NT

0.125 to 0.25

0.25 to > 256

0.125 to > 256

0.5 to 4

4 to > 256

0.5 to > 256

% resistant (n)

NT

NT

NT

0 (0)

30 (3)

15 (3)

0 (0)

33.3 (5)

16.7 (5)

CTL

MIC50 (mg/l)

NT

NT

NT

NT

NT

NT

0.5

2

1

MIC90 (mg/l)

NT

NT

NT

NT

NT

NT

1

 > 256

32

range (mg/l)

NT

NT

NT

NT

NT

NT

0.25 to 1

1 to > 256

0.25 to > 256

% resistant (n)

NT

NT

NT

NT

NT

NT

0 (0)

33.3 (5)

16.7 (5)

COL

MIC50 (mg/l)

1

1

1

0.5

0.5

0.5

2

1

2

MIC90 (mg/l)

1

1

1

1

8

8

8

 > 16

16

range (mg/l)

0.5 to 2

0.5 to 1

0.5 to 2

0.25 to > 16

0.5 to 16

0.25 to > 16

1 to 16

0.5 to > 16

0.5 to > 16

% resistant (n)

0 (0)

0 (0)

0 (0)

10 (1)

20 (2)

15 (3)

20 (3)

13.3 (2)

16.7 (5)

FOS

MIC50 (mg/l)

NT

NT

NT

16

32

16

64

32

32

MIC90 (mg/l)

NT

NT

NT

32

128

128

128

 > 256

 > 256

range (mg/l)

NT

NT

NT

0.5 to 64

8 to 256

0.5 to 256

4 to > 256

4 to > 256

4 to > 256

% resistant (n)

NT

NT

NT

10 (1)

50 (5)

30 (6)

   

I/R

MIC50 (mg/l)

0.25

64

0.5

0.25

32

0.5

1

8

1

MIC90 (mg/l)

0.5

64

64

0.5

64

64

1

64

64

range (mg/l)

0.25 to 0.5

64

0.25 to 64

0.25 to 0.5

0.25 to 64

0.25 to 64

0.5 to 2

1 to 64

0.5 to 64

% resistant (n)

0 (0)

100 (20)

50 (20)

0 (0)

70 (7)

35 (7)

0 (0)

86.7 (13)

43.3 (13)

  1. AMS ampicillin/sulbactam; A/A aztreonam/avibactam; FCR cefiderocol; CAT ceftazidime/avibactam; COL colistin; CTL ceftolozane/tazobactam; DTR difficult-to-treat; FOS fosfomycin; I/R imipenem/cilastatin/relebactam; MIC minimum inhibitory concentration; NT not tested; S susceptible isolates.
  2. Imipenem/cilastatin/relebactam, ceftazidime/avibactam and ceftolozane/tazobactam were tested with a fixed concentration of 4 mg/l of relebactam, avibactam and tazobactam.
  3. Empty fields illustrate nonavailability of clinical breakpoints.
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