Table III.

Result of challenge studies using live bacterial culture or lysate

	Days after challenge
Group	1	3	5	7	10	Total
1	—	—	—	—	2	2/12*
2	—	—	—	—	1	1/12*
3	2	10	—	—	—	12/12
4	—	6	—	—	6	12/12

^*Two-sided P-value is lower than 0.0001, which is extremely significant on Fisher’s exact test.