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Table 4 Fractional inhibitory concentration (FIC) of antibiotics in combination with Hexane-soluble fraction of Ishige okamurae against antibiotic-resistant Pseudomonas aeruginosa

From: Antibacterial effect of Ishige okamurae extract against cutaneous bacterial pathogens and its synergistic antibacterial effect against Pseudomonas aeruginosa

Strains Test compound MIC (μg/mL) ∑FICmax ∑FICmin Median ∑FIC Minimum concentration for observing synergy
P. aeruginosa
KCTC 1637
Hexane 64 1.06 0.31 0.57 8
Ceftazidime 8 2
Hexane 64 1.06 0.52 0.63 8
Meropenem 16 4
P. aeruginosa
isolate 4068
Hexane 64 1.00 0.31 0.50 4
Ceftazidime 16 4
Hexane 64 1.06 0.38 0.57 8
Ciprofloxacin 16 4
Hexane 64 1.50 0.52 0.75 16
Meropenem 16 4
P. aeruginosa
isolate 4135
Hexane 128 1.13 0.38 0.63 16
Ceftazidime 8 2
Hexane 128 1.25 0.31 0.63 16
Ciprofloxacin 16 4
P. aeruginosa
isolate 4561
Hexane 128 1.00 0.38 0.52 8
Ceftazidime 16 4
Hexane 128 1.06 0.38 0.50 8
Ciprofloxacin 16 2
Hexane 128 1.13 0.50 0.75 32
Meropenem 16 8
  1. The FIC index indicated synergistic effect: < 0.5, marked synergy; 0.5 to < 1.0, weak synergy; 1.0, additive; > 1.0 to < 2.0, subadditivie; 2.0, indifferent; > 2.0, antagonistic
  2. ∑FIC max maximum FIC, ∑FIC min minimum FIC, ∑FIC med medium FIC