Clostridium perfringens

A gram stain of Clostridium perfringens.  Note the characteristic large Gram-positive rods.    Image courtesy of the Medical Education Information Center (MEDIC TM) at The University of Texas-Houston Health Science Center.

Introduction:  Clostridium perfringens can be a bacterial cause of intestinal disease in cattle, sheep, horses, and pigs.  However, it is also part of the normal flora of the alimentary tract in many healthy animals.  C. perfringens is a large Gram-positive rod of which there are several types.  Types B and C can cause severe enteritis and diarrhea with dysentery in young calves, lambs, foals, and piglets (usually less than 10 days old), but can also affect older animals.  Morbidity and mortality depend on the type of C. perfringens encountered as well as several host factors.  Type B is not reported in the United States.

Pathophysiology:  The organism is found in the soil or feces, and when ingested, proliferates and attaches to the surface of the epithelial cells of the intestinal villi.  It is unclear how proliferation and attachment take place.  The disease reflects production of specific exotoxins by each of the pathogenic strains.  Strain types B and C produce beta-toxin, a necrotizing toxin, which is responsible for the pathology that leads to the clinical signs.  The microvilli are damaged by the toxin, which is then followed by destruction of the intestinal epithelial cells.  The result is hemorrhagic enteritis with ulceration of the intestinal mucosa.  C. perfringens tends to cause sporadic disease in individual animals, rather than outbreaks.  

Signalment:  Usually affects calves, lambs, foals, and piglets less than 10 days old, but can occur in older animals.  

Clinical Signs:  The mortality rate is high.  The clinical signs are usually acute to peracute, and may include diarrhea, dysentery, acute abdominal pain, and distention.  There may be additional nervous signs including tetany and opisthotonus.  In calves, Cl. perfringens type B/C are not typically associated with "scours", but more commonly cause sudden death.  Death can occur in as little as a few hours with no signs of diarrhea.  

Gross Pathology:  Necropsy results include severe mucosal ulceration, and discoloration in the small intestine.  Blood is frequently present within the intestine. 

Histopathology:  Epithelial cell necrosis, which is a result of the bacterial toxin, is visible and typically dramatic.  Sections of intestine can sometimes be stained to identify clostridial organisms.  In those cases, the necrotic mucosa is often lined by numerous gram-positive bacterial rods.

Diagnosis:  The age of sick animals combined with appropriate clinical signs and the quick course of the disease are suggestive of an infection with Clostridium perfringens.  Laboratory tests are needed for a definitive diagnosis.  These tests include demonstration of characteristic lesions by necropsy & histopathology, bacterial culture of feces or intestinal contents, mouse inoculation with intestinal contents, and neutralization of any exotoxin produced in culture using specific antitoxin.  More recently, the mouse inoculation/neutralization tests have been replaced by PCR.  The PCR reaction is used when C. perfringens is isolated from an animal to demonstrate whether genes encoding the required exotoxins are present in the isolated strain.

For More Information...

• Mark S. Kuhlenschmidt's lecture notes on Clostridia (Veterinary Pathobiology 331) provide an excellent overview of these organisms.