An atypical weakly haemolytic strain of Brachyspira hyodysenteriae is avirulent and can be used to protect pigs from developing swine dysentery

Table 2 Shedding of B. hyodysenteriae in the faeces of pigs in experiment 1 as detected by selective anaerobic culture

Pig group	Pig number
Pig group	Pig number	3	7	10	14	17	21	24	28	31	35	38	42	45	Median^b
A	1	0	0	0	1	1	1	2	2	2	2	1	1	1	1
	2	0	0	0	1	2	1	1	1	1	2	1	2	2	1
	3	0	0	0	0	0	1	1	2	1	0	0	0	0	0
	4	0	0	0	0	0	0	2	2	1	0	0	0	0	0
	5	0	0	0	1	1	2	2	2	1	1	0	1	1	1
	6	0	0	0	1	1	1	2	2	1	1	0	1	1	1
	7	0	0	0	0	0	1	1	1	1	1	1	1	0	0
	8	0	0	0	1	2	2	2	1	1	0	0	0	0	0
	9	0	0	1	1	1	5	5	3	3	3	3	2	2	2
	10	0	0	0	0	0	1	1	1	0	0	0	0	0	0
Median^c		0	0	0	1	1	1	2	2	1	1**	0**	1**	1**	1**
B	11	0	0	1	4	4	4	4	4	4	4	4	4	4	4
	12	0	0	0	0	1	1	1	1	1	1	1	1	1	1
	13	0	0	0	1	1	2	1	1	1	1	1	1	1	1
	14	0	0	0	0	1	1	3	4	4	4	4	4	5	3
	15	0	0	0	0	1	1	1	1	1	1	1	1	1	1
	16	0	0	0	1	1	1	1	1	1	2	2	2	2	1
	17	0	0	0	3	3	5	4	4	4	4	4	4	4	4
	18	0	0	1	1	2	4	4	4	4	4	4	5	5	4
	19	0	0	0	0	1	1	1	2	2	3	3	3	4	1
	20	0	0	4	4	4	4	4	4	4	4	4	4	4	4
Median^c		0	0	0	1	1	1.5	2	3	3	3.5**	3.5**	3.5**	4**	2**

Pigs in group A were inoculated with weakly haemolytic B. hyodysenteriae strain MU1 and those in group B were challenged with a strongly haemolytic field strain NSW54 isolated from a pig with SD.
^aCulture score: 1 to 5, extent of growth on selective agar plates; 0, no growth.
^bMedian calculated using values from day 3–35 post challenge.
^cMedians for the sampling days in groups A and B that are significantly different in a Mann–Whitney test are marked with asterisks (* p < 0.05; ** p < 0.01).

ISSN: 1297-9716