Table 2.

Antibacterial activity of fatty acids against C. difficile strain R20291.

	Number of carbon backbone	General name	MIC (mg/ml)	MBC (mg/ml)	pH (in BHIS)
SCFAs	C3	Propionic acid	1.25	5	3.91
	C4	Butyric acid	25	50	7.11
	C4	Isobutyric acid	1.25	5	4.97
	C5	Valeric acid	1.25	2.5	5.78
	C5	Isovaleric acid	2.5	2.5	5.76
MCFAs	C6	Hexanoic acid	1.25	2.5	5.94
	C8	Octanoic acid	2.5	5	5.51
	C10	Capric acid	0.63	1.25	6.81
	C12	Lauric acid	0.31	0.31	6.91
LCFAs	C14	Myristic acid	>10	>10	6.51
	C16	Palmitic acid	10	10	6.77

Clostridium difficile strain R20291 was exposed to various dilutions of different fatty acids for 24 h, and MBC was determined as the concentration of fatty acids at which no visible growth was observed. Results are expressed as average of at least three independent replicates. SCFA, short-chain fatty acids; MCFA, medium-chain fatty acids; LCFA, long-chain fatty acids.