Rainbow trout gastroenteritis has been related to the accumulation of segmented
filamentous bacteria in the digestive tract of fish, which presents lethargy, reduced
appetite and accumulation of mucoid faeces. Some authors associate the comparison
of illness with the presence of viable filaments, which produce and release
strings of endospores in the lumen of the gut. The segmented filamentous bacteria
that could not be cultured in vitro have been related to Clostridium group I, and
they have been named Candidatus arthromitus. Despite the various strategies that
have been used to detect unculturable microorganisms, molecular methods have
facilitated studies on culture-independent microorganisms. Direct DNA extraction
from samples and subsequent study of 16S rRNA genes represent a tool for
studying unculturable microbial flora. As direct detection of specific microorganisms
is possible through the utilization of primers or probes annealing specific
DNA sequences, the aim of this work was to design specific primers for the direct
detection of C. arthromitus in fish using a nested PCR.
