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Table 4 Minimal inhibitory and bactericidal concentrations of different compounds

From: Bark extract of Cassia sieberiana DC. (Caesalpiniaceae) displayed good antibacterial activity against MDR gram-negative phenotypes in the presence of phenylalanine-arginine β-naphthylamide

Bacterial strains Compounds and concentrations (μg/mL)
1 2 6 Chloramphenicol
MIC MBC R MIC MBC R MIC MBC R MIC MBC R
Escherichia coli
 ATCC8739 128 512 4 256 > 1 256 > 2 2 64 32
 AG102 256 > 1 nt nd nt nd 32 256 8
Klebsiella pneumoniae
 ATCC11296 128 nt nd 256 512 2 nt nd 32 256 8
 KP55 > 1 512 > 1 nt nd 64 256 4
Enterobacter aerogenes
 ATCC13048 128 > 1 nt nd nt nd 16 128 8
 EA27 128 512 4 nt nd nt nd 32 256 8
Providencia stuartii
 ATCC29916 128 > 1 256 > 2 nt nd 64 256 4
 PS2636 nt nd nt nd nt nd 64 256 4
Pseudomonas aeruginosa
 PA01 512 > 1 512 > 1 512 nt nd 64 > 4
 PA124 nt nd 512 > 1 nt nd 64 > 4
 PSBS (%) 70    60    20    100   
  1. MIC minimal inhibitory concentration, MBC minimal bactericidal concentration R: MBC / MIC ratio (a sample is considered as bacteriostatic or bactericidal when this ratio is > 4 or ≤ 4 respectively) (−): MIC or MBC > 512 μg/mL nt: not tested nd: not determined (as no MIC and MBC values were not observed till 512 μg/mL) PBSS: percentage of susceptible bacteria to substances Compounds 1, 2 and 6 were obtained from fraction CSBc Compounds 3 isolated from the residual extract and compounds 4 and 5 isolated from fraction CSBb did not showed any activity against all studied bacterial