Finding a new bacterial species

Clostridium neonatale sp. nov. linked to necrotizing enterocolitis in neonates and a clarification of species assignable to the genus Clostridium (Prazmowski 1880) emend. Lawson and Rainey 2016. Bernard K*, Burdz T*, Wiebe D*, Alfa M, Bernier AM. Int J Syst Evol Microbiol 2018 Aug; 68(8):2416-23. doi:

This science story explains the collaborative work and publication that formally describes and names Clostridium neonatale. The work highlights the use of both traditional and cutting-edge molecular tools to characterize bacterial species.

What was known about this area prior to your work, and why was the research done?

In 1999, the NML’s Special Bacteriology (SB) unit assisted with an outbreak investigation of necrotizing enterocolitis (NEC) among newborn babies at a Winnipeg hospital. NEC is a gastrointestinal disease that causes necrosis in a portion of the human bowel. SB’s role in the investigation was the characterization of anaerobic strains of the NEC bacteria. In doing so, it was discovered that the bacterial strains represented a species that was unidentifiable in the contemporary literature. Nonetheless, the strains best fit the genus Clostridium, which is a grouping that includes a number of pathogens such as those causing botulism and tetanus. Based on this information the species was provisionally named ‘Clostridium neonatale’ in the publication of the findings of this outbreak [1]. Upon recent re-evaluation of this organism, an article was published to formally describe and name Clostridium neonatale.

What are your most significant findings from this work?

The re-evaluation ‘Clostridium neonatale’ to confirm if it still fit classification as a ‘true’ Clostridium [2] commenced in 2017. During this process, it was discovered that 24 validly named Clostridium species, and 3 species from another genus, had been overlooked in recent reviews [3]. Therefore, these findings served to both formally describe and name Clostridium neonatale, as well as provide a list of species that should be included in an updated description of the genus Clostridium. The overall findings of this study provided important new information for public health professionals in identifying anaerobic bacteria of this genus.

What are the implications or impact of the research?

For over 100 years, a new species was generally eligible to be included in the genus Clostridium if it fit the broad category of a “strictly-anaerobic, Gram-positive, spore-forming bacillus”. However, modern molecular typing and characterization tools have led to the re-assignment of nearly half of the species away from the genus Clostridium (e.g., Clostridium difficile is re-assigned as Clostridioides difficile). These discoveries can have implications on infectious disease surveillance systems. As of 2018, there are over 200 Clostridium species.

This evaluation confirmed that this new species can be reported C. neonatale using italicized text reserved for validly-named species described in a publication. Now that this pathogen has been formally described, it will also undergo standard biosafety risk assessment, a critical step to assess any potential impacts it could have on laboratory staff working with it.

Additional References of Significance:

  • Alfa MJ, Robson D, Davi M, Bernard K*, Van Caeseele P, et al. An outbreak of necrotizing enterocolitis associated with a novel Clostridium species in a neonatal intensive care unit. Clin Infect Dis 2002 Sep 1; 35(Suppl 1):S101-5. doi:
  • Lawson PA, Rainey FA. Proposal to restrict the genus Clostridium (Prazmowski) to Clostridium butyricum and related species. Int J Syst Evol Microbiol 2016 Feb; 66(2):1009-16. doi:
  • Lawson PA, Citron DM, Tyrrell KL, Finegold SM. Reclassification of Clostridium difficile as Clostridioides difficile (Hall and O'Toole 1935) Prévot 1938. Anaerobe 2016 Aug; 40:95-9. doi:

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