Table 1. Summary of MIC₅₀ values of cefazolin (CEZ) and nisin A, alone and in combination, against bovine mastitis pathogens.

Organism	n	MIC50 (range) of compound (µg/ml)
		Alone				In combination
		CEZ		Nisin A		CEZ		Nisin A
Staphylococcus aureus	20	0.5	(0.25–1)	1	(0.25–16)	0.06	(0.03–0.13)	0.25	(0.03–1)
Staphylococcus intermedius	20	0.5	(0.25–4)	0.06	(0.02–4)	0.13	(0.03–0.5)	0.03	(0.002–2)
Streptococcus agalactiae	10	0.13	(0.06–0.25)	0.25	(0.03–0.25)	0.06	(0.02–0.13)	0.13	(0.008–0.13)
Streptococcus dysgalactiae	18	0.13	(0.03–1)	1	(0.06–32)	0.06	(0.02–0.13)	0.5	(0.03–4)
Enterococcus faecalis	18	32	(1–64)	4	(0.5–8)	8	(0.25–16)	0.5	(0.02–4)
Escherichia coli	18	2	(1–8)	128	(64–128)	1	(0.06–2)	32	(4–64)

MIC₅₀ values were defined as the lowest concentration of the antimicrobial substance at which 50% of the each mastitis pathogens were inhibited.