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 speciesspecific
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, cocolonization
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.