Group-1 isolates alone were identified in a single blood sample from 14 cows, in combination with a group-2 isolate in 2 cows, and in combination with Bacillus spp in 4 cows with ACM. Group-2 isolates alone were identified in a
single blood sample from 8 cows and in combination with Bacillus spp in 4 cows with ACM. Bacillus spp alone were identified in a single blood sample of 14 cows with ACM. Bacteria were isolated from 30, 8, and 14 blood samples of cows with ACM taken at 0, 24, and 48 hours, respectively. Bacteria were isolated from the blood of cows with ACM at both 0 and 24 hours from 3 cows and at both 0 and 48 hours from 3 cows. Group-1 isolates were identified at time 0 in 11 cows, at 24 hours in 3 cows, at 48 hours in 4 cows, at 0 and 24 hours in 1 cow, and at 0 and 48 hours in 1 cow. Cows were classified as bacteremic if bacteria were isolated from at least 1 blood sample at any time point. Group-1 bacteremia was identified in a significantly (P < 0.001) greater percentage of cows with ACM (14%; 20/144), compared with control cows (0%; 0/156). Fifteen percent (21/144) of cows with ACM had a Bacillus spp bacteremia, which was significantly (P < 0.001) more than control cows (1.9%; 3/156). The percentage of cows with group-2 isolates was not significantly (P = 0.2) different between cows with ACM and controls