Clostridium perfringens Infection

Etiology

Clostridium perfringens was first discovered by William H. Welch, MD, in 1891 at The Johns Hopkins Hospital after an autopsy on a 38-year-old man and was initially named Bacillus aerogenes capsulatus.[1] Later, it was known as Bacillus welchii before finally being renamed Clostridium perfringens, derived from Latin for “burst through.”

Classification is based on the production of the six major toxins: alpha-toxin (CPA), beta-toxin (CPB), epsilon-toxin (ETX), iota-toxin (ITX), enterotoxin (CPE), and necrotic enteritis B-like toxin (NetB).[2]

• A: CPA only
• B: CPA, CPB, ETX
• C: CPA, CPB, CPE (+/-)
• D: CPA, ETX, CPE (+/-)
• E: CPA, ITX, CPE (+/-)
• F: CPA, CPE
• G: CPA, NetB

C. perfringens spores can survive normal cooking temperatures. Therefore, it can proliferate in foods that are improperly stored. Outbreaks are most commonly associated with improperly heated or reheated gravy, poultry, or meats.[3]

Epidemiology

Type A and Type C toxins are known to cause human disease. Type A is responsible for most C. perfringens-associated food poisoning and non-foodborne diarrheal disease. According to CDC epidemiology surveillance data for foodborne disease outbreaks, C. perfringens accounts for 5% of outbreaks, 10% of illnesses, and 4% of hospitalizations.[4] The annual median outbreak size was 24, with a median outbreak-associated disease of close to 1,200. Data shows a slightly higher prevalence in males (65%), with the majority of cases presenting between 20 and 49 years of age. The most common vehicle for transmission is undercooked beef, followed by poultry. Outbreaks occurred throughout the year, with the highest prevalence in November and December.[3] The pathogen ranks within the top five most common etiologies for foodborne disease outbreaks in the US and has an even higher prevalence worldwide.[5]

Type C has been associated with endemic enteritis necroticans in post-World War II Germany from 1944 to 1949 and in the Highlands of Papua New Guinea, named Darmbrand and Pigbel, respectively.[6] It is hypothesized that severe malnutrition increases susceptibility to type C infection. From the 1960s to 1970s, Pigbel was identified as the most common cause of death in children over 1-year-old.[7] A vaccination campaign in the 1980s helped to reduce the incidence, but the disease continues to cause significant morbidity and mortality.[8]

Pathophysiology

Pathophysiology from C. perfringens is through toxin-mediated tissue necrosis. Most toxins are pore-forming, causing an influx of solute and water, leading to cellular swelling and cell death. A hallmark of C. perfringens infection is the production of histotoxic gas through glucose fermentation.[9]

Toxins produced by C. perfringens

• CPA is an enzyme that can break down phosphatidylcholine and sphingomyelin on the cell membrane, inhibit both migration and maturation of neutrophils, and activate arachidonic acid metabolism leading to vasoconstriction and platelet aggregation.[10]. Consequently, this toxin creates a micro-environment with poor tissue circulation and impairment of the innate immune response.[11]
• CPB is a pore-forming toxin known to bind endothelial cells and have neurotoxic properties through the release of substance P. Furthermore. The toxin has been shown to play a critical role in the pathogenesis of necrotizing enterocolitis.[12]
• CPE is a pore-forming toxin that binds to claudin receptors on the cell surface, forming a hexamer complex that allows an influx of calcium. This toxin is the major culprit causing food poisoning and non-foodborne diarrhea. Calcium influx is dose-dependent and leads to activation of calpain and, ultimately, cell death.[2]
• ETX is associated with hemorrhagic enteritis and enterotoxaemia in sheep. The toxin is activated by enteric proteases and increases intestinal permeability by disrupting tight junctions and the lamina propria. It causes perivascular edema with rapid cellular swelling and is found to accumulate in the kidney and brain, but the mechanism has remained elusive.[13]
• ITX is a binary toxin produced as two distinct proteins, Ia and Ib. Ib binds to a cell surface receptor and associates with Ia. The complex is then endocytosed. Ia will pass to the cytosol through a membrane channel created by Ib and then depolymerize the actin cytoskeleton via ADP-ribosylation.[14]
• NetB is a pore-forming toxin identified in avian necrotic enteritis that has been shown to have a 38% sequence similarity with CPB. Its discovery created the type G classification but has not been linked to human pathogenicity.[15]
• Perfringolysin O (PFO) is a pore-forming toxin shown to have synergistic effects with CPA and has been implicated in the pathogenesis of gas gangrene.[16] It is known to target red blood cells and cause coagulative necrosis. Furthermore, this toxin shares homology with other pore-forming toxins found in Streptococcus, Bacillus, and Listeria.[17]

Histopathology

Microscopy and gram staining will reveal gram-positive bacillus.

History and Physical

In food poisoning and non-foodborne diarrheal disease, a history and physical can help to identify the causative agent and help to create a differential. The onset of symptoms is typically 8 to 16 hours after consuming raw or undercooked meat or poultry. The patient often has diffuse abdominal pain, profuse watery, non-bloody diarrhea, and vomiting.

Rarely will these patients present with abdominal sepsis that may manifest with hypotension, tachycardia, and abnormal thermal homeostasis. In addition to hemodynamic instability, there will likely be signs of abdominal distention with tenderness, a rigid hypertympanic abdomen, and altered mental status. These signs are indicative of a medical and surgical emergency.

Clostridial myonecrosis (gas gangrene) typically occurs after an injury (traumatic) but can develop spontaneously in patients with ischemic vascular disease or diabetes (non-traumatic). The patients present with cellulitis at the site of infection, fever, and chills. The wound has edema, tenderness, and bullae that can have a discharge with a musty odor. Symptoms are disproportionately dominant compared to signs. Infection of the deeper tissues results in necrosis of subcutaneous fat, muscle, or nerves. Symptoms can rapidly progress to septic shock, disseminated intravascular coagulation, and acute respiratory distress syndrome, which is associated with high mortality.[18][19]

Evaluation

In suspected C. perfringens infections, stool studies should be performed, which include stool culture and ELISA testing for CPA toxin. Stool studies will often also include WBCs, ova, and parasites to help rule out other etiologies. In more severe clostridial infections, imaging will be warranted to help identify the affected tissue.

An outbreak of foodborne disease is defined as the “occurrence of two or more cases of a similar illness from ingestion of a common food.”[3] Outbreak data, including the number of illnesses, hospitalizations, and mortality, should be reported to the local public health department and the Centers for Disease Control and Prevention.

Infection is confirmed in the following cases:

• Positive stool culture (i.e., growth of at least 10colony-forming units [CFU] C. perfringens/g)

C. perfringens can be confirmed as the source of an outbreak when either of these is positive:

• Stool cultures are positive from at least two affected individuals
• Enterotoxin is detected in stool from at least two affected individuals
• The culture of the suspect food grows at least 10 CFU C. perfringens/g

In cases of clostridial myonecrosis, imaging such as an X-ray or computerized tomography (CT) scan of the affected area should be obtained in addition to blood tests, which include:

• Complete blood count
• Metabolic panel
• Blood culture
• Creatine kinase levels
• Arterial blood gases
• Lactic acid

Treatment / Management

Since most C. perfringens-associated acute diarrheal disease is self-limiting, only supportive care is needed to maintain a euvolemic state. Antibiotics are generally not indicated.

The exception is clostridial sepsis, which is a medical emergency. Clostridial sepsis often presents in septic shock with possible intravascular hemolysis due to CPA-mediated destruction of red blood cells. In this situation, early antibiotic treatment with penicillin G and clindamycin, tetracycline, or metronidazole in combination with surgical debridement of necrotic tissue may help to prevent death.[20][21] These patients will likely be refractory to medical therapy unless source control is achieved.(B3)

A suspicion of clostridial myonecrosis warrants a surgical consultation. Consultation should not be delayed waiting for laboratory or imaging results. Broad-spectrum antibiotics should be promptly administered. In addition, hyperbaric oxygen is shown to improve outcomes in cases of severe infection.[18]

Differential Diagnosis

Acute infectious diarrhea

• Norovirus
• Salmonella
• Campylobacter
• Staphylococcus aureus
• Escherichia coli producing Shiga toxin

Abdominal sepsis

• Appendicitis
• Infectious colitis
• Ischemic colitis
• Perforated peptic ulcer
• Pancreatitis

Clostridial cellulitis/myonecrosis

• Escherichia coli
• Klebsiella
• Streptococcus pyogenes
• Staphylococcus aureus
• Anaerobic bacteria: Bacteroides and Peptostreptococcus

Prognosis

The majority of cases of food poisoning and non-foodborne diarrheal disease are self-limiting. Those who are hospitalized need fluid resuscitation and an advancing diet when tolerated. Generally, the prognosis is good. On the other hand, clostridial myonecrosis and sepsis are medical emergencies with a guarded prognosis. Early recognition and treatment, including surgical debridement, are vital. Even with appropriate treatment, the mortality rate is 20 to 30%, while the mortality rate is 100% without treatment.[18]

Complications

Most cases of food poisoning and non-foodborne diarrheal disease have minimal to no complications if volume status is adequately managed. However, the bloodstream infection can result in toxin-mediated intravascular hemolysis and septic shock.

A beta toxin produced by type C strains can cause hemorrhagic necrosis of the jejunum, also known as enteritis necroticans or pigbel. It usually occurs in resource-limited countries (particularly Papua New Guinea) following pork consumption or has been associated with the consumption of pork chitterlings in resource-rich settings. In addition, the simultaneous ingestion of sweet potatoes may often potentiate it. Sweet potatoes contain trypsin inhibitors that prevent the intestinal degradation of the toxin. Symptoms of pigbel abdominal distention, pain, and dilated thickened bowel loops with segmental necrosis.[22]

Clostridial myonecrosis may require extensive debridement, amputation, and complications of severe sepsis, including shock, encephalopathy, acute respiratory distress syndrome, and death.