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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