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