Taxonomy
- Domain: Bacteria
- Phylum: Firmicutes
- Class: Clostridia
- Order: Clostridiales
- Family: Clostridiaceae
- Genus: Clostridium
- Species: Clostridium cadaveris
- Authority: (Koch 1880) Collins et al. 1994
Morphology and Physiology
Clostridium cadaveris is an obligate anaerobic, Gram‑positive, rod‑shaped bacterium. Cells are typically 0.5–1 µm in width and 2–10 µm in length, occurring singly or in short chains. Like other members of the genus, it forms endospores, which are centrally or subterminally positioned and confer resistance to adverse conditions. The organism is motile, possessing peritrichous flagella. Metabolically, it is a fermentative organism that utilizes a variety of carbohydrates, producing acids such as acetate, butyrate, and propionate, as well as gases (hydrogen and carbon dioxide). It does not produce catalase or oxidase.
Habitat and Ecology
Clostridium cadaveris is most commonly isolated from decomposing animal tissue and is therefore considered part of the normal post‑mortem microbial succession. It is also present in the gastrointestinal tracts of humans and animals, where it exists as a minor component of the anaerobic flora. Because of its strong association with cadaveric material, the species name “cadaveris” reflects its frequent recovery from corpses.
Clinical Significance
In most healthy individuals, C. cadaveris is non‑pathogenic. However, opportunistic infections have been reported, particularly in immunocompromised patients or those with disrupted gastrointestinal barriers. Documented clinical manifestations include:
- Bacteremia: Rare cases of bloodstream infection, often associated with underlying abdominal pathology or invasive procedures.
- Soft‑tissue and wound infections: Occasionally isolated from necrotic or anaerobic wound sites.
- Intra‑abdominal infections: Reported in polymicrobial infections following perforated viscera or peritonitis.
Therapeutic management typically follows standard anaerobic coverage, with susceptibility patterns indicating sensitivity to metronidazole, clindamycin, and carbapenems. Resistance to penicillin has been noted in some isolates, emphasizing the importance of susceptibility testing.
Laboratory Identification
Isolation requires strict anaerobic conditions. Colonies on blood agar are usually circular, convex, and may display a slight hemolysis. Identification methods include:
- Phenotypic tests: Gram stain, catalase negativity, motility, and carbohydrate fermentation profiles.
- Molecular techniques: 16S rRNA gene sequencing provides definitive species‑level identification and is increasingly employed in clinical microbiology laboratories.
Historical Notes
The organism was first described in the late 19th century by Koch, who isolated it from decaying cadavers, leading to its nomenclature. Subsequent taxonomic revisions placed it firmly within the genus Clostridium based on spore morphology and anaerobic growth characteristics. Modern phylogenetic analyses using ribosomal RNA genes have confirmed its placement within the Clostridiaceae family.
References
(References are omitted in this summary but are available in standard microbiology and clinical infectious disease literature.)