When you discover a new species of Clostridium as a microbiologist, the most accurate conclusion is that it is most likely disease-causing. Many known species within the Clostridium genus, such as Clostridium botulinum and Clostridium tetani, are pathogenic and associated with serious diseases in humans. While some species might be harmless, the genus is generally known for its pathogenic members, hence a new species is more likely to be disease- causing rather than harmless.

Additional context is that Clostridium species are anaerobic, spore-forming bacteria and many have significant clinical importance due to their ability to cause diseases. Modern genomic and molecular typing tools help classify and understand new species including their pathogenic potential.