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Table 2 Reduction of MICs of β-lactam antibiotics combined with Monolaurin (250 µg/ml) against MRSA (n = 103)

From: Novel synergistic interactions between monolaurin, a mono-acyl glycerol and β lactam antibiotics against Staphylococcus aureus: an in vitro study

MIC (µg/mL)

FICA/FICB

FIC index

Interpretation

No. of isolates

P value

Alone

In combination

Ampicillin /Monolaurin

Ampicillin /Monolaurin

8/1000

1/250

0.125/0.25

0.375

Synergistic

15

 < 0.001

8/250

1/250

0.125/1

1.125

Indifference

3

8/1000

2/250

0.25/0.25

0.5

Synergistic

20

16/500

1/250

0.0625/0.5

0.5625

Partial synergy

9

16/1000

4/250

0.25/0.25

0.5

Synergistic

7

32/1000

1/250

0.03125/0.25

0.281

Synergistic

16

32/1000

4/250

0.125/0.25

0.375

Synergistic

22

32/2000

1/250

0.03125/0.125

0.1562

Synergistic

3

32/2000

4/250

0.125/0.125

0.25

Synergistic

8

 

Amoxicillin (A) /Monolaurin (B)

Amoxicillin (A) /Monolaurin (B)

FIC (A) / FIC (B)

FIC index

Interpretation

No. of isolates

P value

32/250

0.5/250

0.015625/1

1.015

Indifference

3

 < 0.001

32/1000

0.5/250

0.015625/0.25

0.265

Synergistic

3

32/1000

4/250

0.125/0.25

0.375

Synergistic

2

32/500

4/250

0.125/0.5

0.625

Partial synergy

9

32/1000

8/250

0.25/0.25

0.5

Synergistic

12

64/1000

0.5/250

0.0078/0.25

0.2578

Synergistic

32

64/1000

2/250

0.03125/0.25

0.281

Synergistic

5

64/1000

4/250

0.0625/0.25

0.3125

Synergistic

16

64/1000

8/250

0.125/0.25

0.375

Synergistic

11

128/1000

1/250

0.0078/0.25

0.2578

Synergistic

2

128/2000

1/250

0.0078/0.125

0.1328

Synergistic

4

128/2000

8/250

0.0625/0.125

0.1875

Synergistic

4

Piperacillin /Monolaurin

Piperacillin /Monolaurin

FIC (A) / FIC (B)

FIC index

Interpretation

No. of isolates

P value

16/250

4

0.25/1

1.25

Indifference

2

 < 0.001

16/250

8

0.5/1

1.5

Indifference

1

16/1000

8

0.5/0.25

0.75

Partial synergy

17

64/1000

16

0.25/0.25

0.5

Synergistic

12

64/500

8/250

0.0625/0.5

0.5625

Partial synergy

9

128/1000

16

0.125/0.25

0.375

Synergistic

20

128/1000

32

0.25/0.25

0.5

Synergistic

16

256/1000

32/250

0.125/0.25

0.375

Synergistic

14

256/1000

8/250

0.03125/0.25

0.28125

Synergistic

4

256/2000

8/250

0.03125/0.125

0.15625

Synergistic

8

  1. *total synergistic (FICI≤0.5), partial synergistic (0.5 < FICI < 1), additive FICI=1 or indifferent (1 < FICI < 4 and antagonistic (FICI≥4)
  2. **significant difference at P value < 0.05
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BMC Infectious Diseases

ISSN: 1471-2334

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