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Table 3 MIC of antibiotics in association of bark and leaves extracts of Nauclea pobeguinii at MIC/2 and MIC/4 against selected MDR bacteria

From: Antibacterial and antibiotic-resistance modifying activity of the extracts and compounds from Nauclea pobeguinii against Gram-negative multi-drug resistant phenotypes

Antibioticsa

Extract and concentration

Bacterial strainsb, MIC (μg/mL ) of antibiotics in the absence and presence of the extract and FIC (in brackets)

PBSS (%)

PA124

CM64

NAE16

BM47

KP55

KP63

AG100Atet

CHL

 

0

256

128

256

256

32

128

64

 
 

B

MIC/2

128(0.5)S

64(0.5)S

32(0.125)S

16(0.06)S

16(0.5)S

8(0.06)S

32(0.5)S

7/7 (100 %)

  

MIC/4

128(0.5)S

64(0.5)S

32(0.13)S

16(0.06)S

32(1)I

8(0.06)S

32(0.5)S

6/7 (85.7 %)

 

L

MIC/2

256(1)I

128(1)I

16(0.06)S

32(0.13)S

32(1)I

8(0.06)S

16(0.25)S

4/7 (57.1)

  

MIC/4

256(1)I

128(1)I

16(0.06)S

64(0.25)S

32(1)I

8(0.06)S

16(0.25)S

4/7 (57.1)

KAN

 

0

128

64

64

32

64

64

32

 
 

B

MIC/2

64(0.5)S

4(0.06)S

8(0.13)S

4(0.13)S

32(0.5)S

8(0.13)S

16(0.5)S

7/7 (100 %)

  

MIC/4

64(0.5)S

4(0.06)S

8(0.13)S

4(0.13)S

32(0.5)S

8(0.13)S

16(0.5)S

7/7 (100 %)

 

L

MIC/2

64(0.5)S

4(0.06)S

8(0.13)S

4(0.13)S

64(1)I

16(0.25)S

16(0.5)S

6/7 (85.7 %)

  

MIC/4

64(0.5)S

4(0.06)S

8(0.13)S

4(0.13)S

64(1)I

16(0.25)S

16(0.5)S

6/7 (85.7 %)

STR

 

0

64

64

32

16

64

16

128

 
 

B

MIC/2

64(1)I

4(0.06)S

16(0.5)S

4(0.25)S

32(0.5)S

2(0.13)S

−(≥2)na

5/6 (83.3 %)

  

MIC/4

256(4)A

4(0.06)S

16(0.5)S

4(0.25)S

32(0.5)S

8(0.5)S

−(≥2)na

5/6 (83.3 %)

 

L

MIC/2

256(4)A

2(0.03)S

8(0.25)S

2(0.13)S

16(0.25)S

4(0.25)S

128(1)I

5/7 (71.4 %)

  

MIC/4

256(4)A

4(0.06)S

16(0.5)S

4(0.25)S

64(1)I

4(0.25)S

−(≥2)na

4/6 (66.7 %)

CIP

 

0

64

16

8

16

16

8

64

 
 

B

MIC/2

32(0.5)S

64(4)A

8(1)I

8(0.5)S

16(1)I

4(0.5)S

64(1)I

3/7 (42.9 %)

  

MIC/4

32(0.5)S

64(4)A

8(1)I

16(1)I

32(2)A

8(1)I

64(1)I

1/7 (14.3 %)

 

L

MIC/2

64(1)I

64(4)A

16(2)A

16(1)I

16(1)I

4(0.5)S

64(1)I

1/7 (14.3 %)

  

MIC/4

64(1)I

64(4)A

16(2)A

16(1)I

16(1)I

4(0.5)S

64(1)I

1/7 (14.3 %)

TET

 

0

64

64

128

32

32

64

256

 
 

B

MIC/2

32(0.5)S

4(0.06)S

32(0.25)S

16(0.5)S

64(2)I

32(0.5)S

4(0.02)S

6/7 (85.7 %)

  

MIC/4

32(0.5)S

2(0.03)S

32(0.25)S

16(0.5)S

64(2)I

64(1)I

4(0.02)S

5/7 (71.4 %)

 

L

MIC/2

64(1)I

2(0.03)S

128(1)I

32(1)I

−(≥8)A

64(1)I

4(0.02)S

2/7 (28.6 %)

  

MIC/4

64(1)I

2(0.03)S

128(1)I

32(1)I

−(≥8)A

64(1)I

4(0.02)S

2/7 (28.6 %)

  1. (−): >256 μg/mL; 0: no extract (only antibiotic tested); na: non-applicable; Values in bold: MIC of antibiotic alone and significant synergistic effects
  2. S Synergy; I Indifference, A Antagonism, B bark extract, L Leaves extract, FIC fractional inhibitory concentration
  3. aAntibiotics [CHL: chloramphenicol, AMP : ampicillin, CEF: cefepime, KAN : kanamycin, STR: streptomycin, CIP : ciprofloxacin, TET : tetracycline]
  4. bBacterial strains: Escherichia coli [ AG100Atet], Pseudomonas aeruginosa [PA124], Enterobacter aerogenes [CM64], Enterobacter cloacae [BM47], Klebsiella pneumoniae [KP55, KP63], Providencia stuartii [NAE16]
  5. cPBSS: percentage of bacteria strain on which synergism has been observed; (): fold increase in MIC values of the antibiotics after association with plants extract