Intestinal colonization of different Brachyspira spp. in laying hens

Background: avian intestinal spirochetosis (ais) is caused by spiral-shaped gram-negative brachyspira spp. in poultry. it is known as a cause of diarrhea, low egg production, and increased occurrence of dirty eggs in layer hens. objectives: in this study, the presence of some brachyspira spp. was investigated in laying hens. methods: a total of 100 cloacal swab samples were individually collected from 20 laying hen flocks showing fecal egg staining in northeast of iran. results: using culture and morphologic examination, 41 samples (41%) from 20 flocks were positive; however, by using genus-specific pcr, only 37 (37%) samples were confirmed as brachyspira spp. using species-specific primers, single colonization was identified in 18 samples associated with b. pilosicoli (48.6%), while single colonization with b. intermedia was found in only two samples (5.4%). simultaneous colonization by b. intermedia and b. murdochii was detected in 3 samples (8.1%). b. pilosicoli was the most prevalent species in concurrent colonization in 11 cases (29.7%). finally, co-colonization by b. intermedia and b. innocens was identified in 3 samples (8.1%). conclusions: the results of this study showed the colonization of different species of brachyspira with dominance of b. pilosicoli in layer hens.