The Scientific World Journal / 2012 / Article / Tab 2

Research Article

In Vitro Synergistic Effect of Psidium guineense (Swartz) in Combination with Antimicrobial Agents against Methicillin-Resistant Staphylococcus aureus Strains

Table 2

Combination testing of the aqueous extract of Psidium guineense with antimicrobial agents against MRSA strains.

Staphylococcus aureusCombinationIndividual MIC (μg/mL)Combination MIC (μg/mL)Individual FICFIC index (FICI)Interpretation% MIC reduced% reduction of viable cells1

LFBM 01AE + AMC250/25125/0.0480.5/0.0020.5Synergistic50.0/99.880.21
AE + AMP250/400125/0.780,5/0.0020.5Synergistic50.0/99.884.43
AE + CFO250/400125/0.780.5/0.0020.5Synergistic50.0/99.887.04
AE + CIP250/50125/0.090.5/0.0020.5Synergistic50.0/99.893.49
AE + MER250/25125/0.0480.5/0.0020.5Synergistic50.0/99.884.24

LFBM 26AE + AMC250/50.0125/0.780.5/0.0020.5Synergistic50.0/99.888.82
AE + AMP250/400125/0.780.5/0.0020.5Synergistic50.0/99.883.58
AE + CFO250/40031.25/0.780.125/0.0020.125Synergistic87.5/99.880.90
AE + CIP250/50.0125/0.090.5/0.0020.5Synergistic50.0/99.894.59
AE + MER250/25125/0.0480.5/0.0020.5Synergistic50.0/99.880.76

LFBM 28AE + AMC250/12.5125/0.0240.5/0.0020.5Synergistic50.0/99.883.38
AE + AMP250/400125/0.780.5/0.0020.5Synergistic50.0/99.889.71
AE + CFO250/100125/0.190.5/0.0020.5Synergistic50.0/99.886.91
AE + CIP250/50.0125/0.090.5/0.0020.5Synergistic50.0/99.894.45
AE + MER250/25.062.5/0.0480.25/0.0020.25Synergistic75.0/99.889.08

LFBM 33AE + AMC250/12.5125/0.0240.5/0.0020.5Synergistic50.0/99.878.89
AE + AMP250/200125/0.390.5/0.0020.5Synergistic50.0/99.876.72
AE + CFO250/20062.5/0.390.25/0.0020.25Synergistic75.0/99.881.53
AE + CIP250/50.062.5/0.780.25/0.0020.25Synergistic75.0/99.894.09
AE + MER250/12.5125/0.0240.5/0.0020.5Synergistic50.0/99.881.84

MIC: minimal inhibitory concentration; FIC: fractional inhibitory concentration; AMC: amoxicillin/clavulanic acid; AMP: ampicillin; CFO: cefoxitin; CIP: ciprofloxacin; MER: meropenem; AE: aqueous extract of P. guineense; LFBM: Laboratório de Fisiologia e Bioquímica de Microorganismos.
% o f M I C r e d u c e d = ( M I C a l o n e M I C c o m b i n e d ) × 1 0 0 / M I C a l o n e .
1%reduction of viable cells in wells containing the combination aqueous extract of P. guineense (1/2 MIC) and antimicrobials agents (1/512 MIC).