Tristemma hirtum and Five Other Cameroonian Edible Plants with Weak or No Antibacterial Effects Modulate the Activities of Antibiotics against Gram-Negative Multidrug-Resistant Phenotypes

Table 4

Preliminary evaluation of antibiotic-resistance modulatory activity of selected extracts at subinhibitory concentrations against Pseudomonas aeruginosa PA124.

Plant extracts	Extract concentration	MIC of antibiotic (μg/mL) alone and in combination with extracts^a and fold increase of activity (in brackets)
		CHL	KAN	CEF	CIP	TET	ERY
	0	128	128	128	64	16	128
AAL	MIC/2	32 (4)	64 (2)	128 (1)	64 (1)	8 (2)	128 (1)
	MIC/4	64 (2)	64 (2)	128 (1)	64 (1)	8 (2)	256 (0.5)
	MIC/8	64 (2)	128 (1)	128 (1)	64 (1)	16 (1)	256 (0.5)
	MIC/16	128 (1)	128 (1)	128 (1)	64 (1)	16 (1)	256 (0.5)
ALL	MIC/2	128 (1)	64 (2)	128 (1)	64 (1)	8 (2)	256 (0.5)
	MIC/4	128 (1)	64 (2)	128 (1)	64 (1)	8 (2)	256 (0.5)
	MIC/8	128 (1)	128 (1)	128 (1)	64 (1)	16 (1)	256 (0.5)
	MIC/16	128 (1)	128 (1)	128 (1)	64 (1)	16 (1)	256 (0.5)
RHP	MIC/2	32 (4)	32 (4)	64 (2)	32 (2)	8 (2)	64 (2)
	MIC/4	64 (2)	64 (2)	128 (1)	64 (1)	16 (1)	128 (1)
	MIC/8	128 (1)	64 (2)	256 (0.5)	64 (1)	16 (1)	128 (1)
	MIC/16	128 (1)	64 (2)	256 (0.5)	64 (1)	16 (1)	128 (1)
THL	MIC/2	8 (16)	64 (2)	128 (1)	32 (2)	8 (2)	128 (1)
	MIC/4	8 (16)	64 (2)	256 (0.5)	32 (2)	8 (2)	256 (0.5)
	MIC/8	32 (4)	64 (2)	256 (0.5)	32 (2)	8 (2)	256 (0.5)
	MIC/16	32 (4)	64 (2)	256 (0.5)	32 (2)	8 (2)	256 (0.5)

Samples [AAL: Aframomum alboviolaceum (leaves), ALL: Aframomum letestuanum (leaves), RHP: Raphia hookeri (pericarps), THL: Tristemma hirtum (leaves), CHL: chloramphenicol, CEF: ceftriaxone, CIP: ciprofloxacin, ERY: erythromycin, KAN: kanamycin, STR: streptomycin, and TET: tetracycline]; in brackets: modulating factor; MIC: minimal inhibitory concentration. Values in bold represent modulating factor ≥ 2.