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Table 2 Minimal inhibitory and bactericidal concentrations of crude extract, his derived fractions and chloramphenicol

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 Tested samples and concentrations (μg/mL)
CSB CSBa CSBb CSBc Chloramphenicol
MIC MBC R MIC MBC R MIC MBC R MIC MBC R MIC MBC R
Escherichia coli
 ATCC8739 512 512 1 512 512 1 nt nd 128 128 1 2 64 32
 AG102 512 512 1 nt nd nt nd 512 512 1 32 256 8
Klebsiella pneumoniae
 ATCC11296 512 > 1 512 512 1 nt nd 512 > 1 32 256 8
 KP55 128 512 4 512 512 1 nt nd 128 512 4 64 256 4
Enterobacter aerogenes
 ATCC13048 512 512 1 nt nd nt nd 512 512 1 16 128 8
 EA27 nt nd nt nd nt nd nt nd 32 256 8
Providencia stuartii
 ATCC29916 512 512 1 nt nd 512 512 1 512 512 1 64 256 4
 PS2636 512 512 1 nt nd 512 512 1 512 512 1 64 256 4
Pseudomonas aeruginosa
 PA01 512 > 1 nt nd nt nd 512 > 1 64 > 4
 PA124 512 512 1 nt nd nt nd 512 512 1 64 > 4
 PSBS (%) 90    30    20    90    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 for crude extract and fractions and > 256 for chloramphenicol 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 CSB is crude extract of Cassia sieberiana CSBa, CSBb and CSBc are fractions from CSB