Clostridium septicum characteristics, morphology, symptoms

Abraham McLaughlin

Clostridium septicum it is a pathogenic sporulated anaerobic bacterium of mainly veterinary importance that rarely affects humans. This microorganism is among the 13 most virulent species of Clostridia and is classified within the cytotoxic clostridia, being highly resistant to adverse conditions due to the formation of spores..

The spores are widely distributed in nature, especially they are found in soils rich in organic matter. In Veterinary Medicine C. septicum is included among the causative agents of soil-related diseases.

Clostridium septicum

Clostridium septicum  it is related to cases of mortality in various species of animals with good body condition, including cattle, sheep and pigs. This generates large economic losses in the agricultural sector.

The disease it produces goes by several names: malignant edema, gas gangrene, or necrotizing fasciitis. This disease is due to the production of toxins that affect various tissues.

Although the disease is serious, it is not contagious, since the infection will depend on an exogenous predisposing factor (presence of a wound or trauma) in the animal or (to malignant processes) in humans..

Most of the time there is no opportunity to make a diagnosis and place treatment and death ensues.

Article index

  • 1 Features
  • 2 Taxonomy
  • 3 Morphology
    • 3.1 Microscopic characteristics
    • 3.2 Macroscopic characteristics
  • 4 Pathologies
    • 4.1 Gas gangrene or malignant edema in animals
    • 4.2 Gas gangrene or necrotizing fasciitis in humans
  • 5 Clinical manifestations
  • 6 Diagnosis
    • 6.1 Culture media and conditions
    • 6.2 Biochemical tests
  • 7 Treatment
  • 8 Prevention
  • 9 References


This microorganism is characterized by being anaerobic, but can withstand between 2 to 8% oxygen, therefore it is considered aerotolerant anaerobic.

Spores of Clostridium septicum are highly resistant to physical and chemical agents and are only destroyed at 121 ° C for 20 minutes.

Clostridium septicum produces 4 toxins called histotoxins due to the ability to affect and necrotize tissues.

Alpha toxin is known to cause intravascular hemolysis, extensive tissue necrosis, and increased capillary permeability.


Domain: Bacteria

Phylum: Firmicutes

Class: Clostridia

Order: Clostridiales

Family: Clostridiaceae

Genus: Clostridium

Species: septicum


Microscopic characteristics

Clostridium septicum they are long, slender, pleomorphic, and filamentous bacilli. They can form chains and do not have a capsule. They are about 0.6 μm wide and 3 to 6 μm long.

It is spore-forming. They are oval and are located in a sub-terminal position, deforming the bacillus, giving the appearance of a racket. The bacillus has peritric flagella, which makes it a mobile species.

With the Gram stain, the purple bacillus, that is, Gram positive, can be observed. If it is sporulated, a clear space can be observed within the sub-terminal oval bacillus corresponding to the spore..

With the Shaeffer-Fulton stain (staining for spores) the spores stain light green inside or outside the cell and the bacillus stain red.

Macroscopic characteristics

It grows on blood agar under anaerobic conditions, its colonies are usually bright gray and semi-translucent, surrounded by a 1 to 4 mm zone of complete hemolysis.

The colony is shaped like a jellyfish head with irregular and rhizoid edges, often surrounded by a zone of spread that can lead to the formation of a veil that covers the entire plate, similar to that of the genus Proteus.

Colonies are 2 to 8 mm in diameter.


Gas gangrene or malignant edema in animals

This disease is characterized by myonecrosis (tissue death). Produces it C. septicum but it can also be caused by C. chauvoei, C. oedemantis, C. novyi  Y C. sordelli.

Clostridium septicum it is a pathogenic and virulent species, but it does not have invasive power on healthy tissues. Therefore, the infection occurs in a similar way to other clostridia, such as C. chauvoei, C. tetani or C. perfringens; by contamination of a wound with spores of the microorganism.

The wound functions as a gateway; this is how the spore enters the tissue. Wounds from shearing, peeling, castration or injection of veterinary products are the main causes of spore contamination in animals.

The microorganism needs a trigger that provides optimal conditions of low oxygen tension in the tissues.

In this way the microorganism is able to germinate to the vegetative form and reproduce in appreciable quantity to produce the toxins that are ultimately responsible for the disease..

The infection is rapid, the microorganism affects the subcutaneous and muscular tissue, then septicemia, toxic-infectious shock and death of the animal occur..

Gas gangrene or necrotizing fasciitis in humans

It is less frequent and most of the time it is caused by the perfringens species.

However, when present C. septicum It is due to serious infections with high mortality, associated with underlying malignancies such as colon or cecum carcinoma, breast carcinoma and hematological malignancies (leukemia-lymphoma).

Because C. septicum It can be part of the intestinal microbiota of 2% of the population, if there is a tumor or metastasis at this level, a disruption of the mucosal barrier occurs, allowing the hematogenous invasion of the bacteria.

The neoplastic process itself generates an environment of hypoxia and acidosis from the anaerobic tumor glycolysis, favoring the germination of the spore and progression of the disease.

Other risk factors are surgical procedures such as endoscopies, irradiation or barium enema among others..

Clinical manifestations

After the surgical maneuver in the animal, if the wound becomes contaminated, some symptoms can be observed in 12 to 48 hours. The wound is often swollen with tight skin.

The behavior of the animal is not normal, it becomes depressed, it presents pain in the affected area and fever. There is almost never an opportunity to observe these signs, therefore it is not treated in time and the keeper simply notices when he sees the dead animal.

The diagnosis is generally made post-mortem. When performing a necropsy, a blackish, moist, gelatinous material with a characteristic putrid odor can be seen under the wound skin..


Culture media and conditions

Clostridia grow well in a laboratory-prepared medium containing thioglycollate broth, cysteine, or peptone, to which pieces of meat, liver, spleen, or brain are added. This medium is known as the Tarozzi medium.

It also grows in media enriched with vitamins, carbohydrates and amino acids. They grow well on blood agar and egg yolk agar..

Media should be neutral in pH (7.0) and incubated at 37 ° C for 1 to 2 days.

Culture media should be placed in an anaerobic jar. The seeded media with a commercial envelope (GasPak) is placed inside the jar.

This envelope catalytically reduces oxygen by hydrogen generated along with carbon dioxide..

Biochemical tests

Negative tests

Lecithinase, lipase, urease, catalase, indole, fermentation of mannitol, rhamnose and sucrose.

Positive tests

Milk coagulation, fermentation of glucose, maltose, salicin, glycerol, motility. Produces acetic and butyric acid.

Tests with variable result +/-:

Gelatin hydrolysis, esculin hydrolysis and lactose fermentation.

There are semi-automated and automated methods for the identification of clostridial species. Among them we can mention: Api 20 A®, Minitek®, Rapid ID 32 A®, Anaerobe ANI Card®, Rapid Anaerobe ID®, RapID-ANA® or Crystal Anaerobe ID®.


Clostridium septicum is sensitive to a wide variety of antibiotics.

Among them:

Ampicillin / sulbactam, cefoperazone, cefotaxime, cefotetan, cefoxitin, ceftriaxone, chloramphenicol, clindamycin, imipenem, metronidazole, penicillin G, piperacillin / tazobactam, ticarcillin / ac. clavulanic acid, Amoxicillin / ac. clavulanic.

However, there is almost never an opportunity for its administration and when the toxin is achieved it has wreaked havoc and the affected individual dies irretrievably..


A commercially available vaccine called Polibascol 10 (1 mL of injectable suspension for cattle and sheep), which protects against clostridial diseases.

It has a good immune response providing an active immunization that can last 6 months in the case of prevention against C. septicum and up to 12 months for other clostridia.

The vaccine contains:

  • Toxoid (alpha) of C. perfringens Type A
  • Toxoid (Beta) of C. perfringens Type B and C
  • Toxoid (Epsilon) of C. perfringens Type D
  • Complete culture of C. chauvoei
  • Toxoid C. novyi
  • Toxoid C. septicum
  • Toxoid C. tetani
  • Toxoid C. sordellii
  • Toxoid C. haemolyticum
  • Adjuvant: Aluminum potassium sulfate (alum)
  • Excipients: Thiomersal and formaldehyde.

There is no vaccine for humans.

Contraindicated on: sick or immunosuppressed animals.


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