Detection of Clostridium botulinum type C cells in the gastrointestinal tracts of Mozambique tilapia (Oreochromis mossambicus) by polymerase chain reaction

We established a method of directly detecting Clostridium botulinum type C cells, while minimizing spore detection, in the intestinal contents of Mozambique tilapia (Oreochromis mossambicus). This technique involved extraction of predominantly cellular DNA from tilapia intestinal tracts and used a polymerase chain reaction assay to detect presence of type C₁ toxin gene. We consistently detected C. botulinum type C cells in tilapia gastrointestinal contents at a level of 7.5×10⁴ cells per 0.25 g material or 1.9×10³ cells. This technique is useful for determining prevalence of the potentially active organisms within a given population of fish and may be adapted to other types of C. botulinum and vertebrate populations as well.