Introduction

Pseudomembranous (Soo-dough-mem-bruh-nus) colitis (PMC) is an inflammatory condition of the colon, or large intestine, which is an organ of the digestive system. PMC is characterised by the increased presence of yellowish-white plaques that form pseudomembranes on the inner lining of the colon (mucosa).²

The colon has a key role in food digestion, waste removal and maintaining the body’s fluid and electrolyte balance. Upon consuming food, it travels into the oesophagus and enters the stomach, where it is broken down and passed onto the small intestine. Here, there is a continued breakdown of food and the absorption of vitamins and nutrients. The remainder of what is broken down, which is mainly in a liquid form, enters the colon and is processed by colonic bacteria to break down and convert the material into waste, which is excreted from the body.¹

PMC often manifests as severe inflammation of the colon due to excessive usage of antibiotics or a bacterial infection caused by Clostridioides difficile (C. difficile).³ One of the most common outcomes of a C. difficile infection is diarrhoea.

Clostridioides difficile infection

Clostridioides difficile (C. difficile), formerly Clostridium difficile, is a bacterial infection most commonly known to affect individuals who take certain antibiotics.⁴ Common symptoms of a C. difficile infection include diarrhoea, an increased temperature, stomach pain and loss of appetite.⁵ It causes infectious diarrhoea and pseudomembranous colitis and is highly prevalent amongst hospitalised patients of the elderly population or those with weakened immune systems.⁶

Getting a C. difficile infection

The microbiome (i.e., community of trillions of bacteria and other microorganisms) is present in the body to ensure that everything is functioning properly. Most bacteria in the microbiome are beneficial or harmless and aid in the absorption of dietary foods and nutrients. However, some bacteria are not as friendly and may disrupt the balance of the microbiome in the body. This is seen in the instance of when a person takes antibiotics, which kills the “good” bacteria and grants other bacteria the ‘opportunity’ to rapidly outgrow them.⁷ Bacteria including C. difficile is an opportunistic pathogen.

When C. difficile numbers increase in the microbiome and overtake those of beneficial bacteria, they release harmful toxins that inflame the lining of the colon and cause a variety of symptoms ranging from mild to severe.⁷

Risk factors for C. difficile infection

The risk factors for C. difficile infection (CDI) include the following:

• Increased age: individuals aged over 65 years old are more susceptible to developing a C. difficile infection⁶
• Antibiotic treatment: disruption of the gut flora due to intake of antibiotics allowing for the growth of C. difficile and can cause antibiotic-associated diarrhoea⁸
• Prolonged hospitalisation: despite discrepancies in data, individuals who remain in the hospital setting for an extended period of time are at high risk of developing CDI⁹
• Immunosuppressive therapy: individuals undergoing certain medical treatments such as chemotherapy are at risk of developing CDI because the treatment has the ability to suppress the body’s natural ability to defend against C. difficile¹⁰

While almost all antibacterial antibiotics are capable of eliciting CDI, some antibiotics are more commonly associated with pseudomembranous colitis:¹¹

• Clindamycin
• Cephalosporins
• Fluoroquinolones

Other causes of pseudomembranous colitis

Besides antibiotic usage, there are several other ways a person can develop pseudomembranous colitis, mainly through colon disorders such as inflammatory bowel disease and Behcet’s disease, amongst others.³

Inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic inflammatory condition of the gastrointestinal (GI) tract that encompasses ulcerative colitis and Crohn’s disease.¹² 

• Ulcerative colitis: causes inflammation in the lining of the colon
• Crohn’s disease: can affect any part of the GI tract, but most commonly affects the ileum (end of the small intestine) and the colon

IBD patients are given antibiotics and treatments that alter the composition of the intestine, favouring overgrowth of C. difficile and causing inflammation that damages the colon lining and allows for the formation of pseudomembranes.

Behcet’s disease

Behcet’s disease is a rare autoimmune disorder that causes inflammation in blood vessels and is characterised by the presence of ulcers in the mouth and genitals.¹³

Symptoms of pseudomembranous colitis

Symptoms of pseudomembranous colitis may occur within a day or two of starting an antibiotic treatment or several months after finishing the antibiotic treatment:¹⁴

• Watery diarrhoea
• Abdominal pain
• Fever
• Nausea

Complications of pseudomembranous colitis

• Dehydration: severe diarrhoeal episodes can cause loss of bodily fluids and electrolytes that are needed for the proper functioning of the body. This may cause blood pressure to drop to low, and often critical, levels
• Toxic megacolon: refers to a condition where the colon (large intestine) is abnormally dilated due to inflammation and an inability of the body to remove gas and stools.¹⁴ If left untreated, the colon may rupture and cause infections
• Bowel perforation: characterised by a hole in the colon due to damage to the inner lining of the colon, and often occurs after toxic megacolon. A perforated colon may leak bacteria and other harmful substances from the intestine into the abdominal region, leading to a life-threatening condition called peritonitis¹⁴
• Death: C. difficile infections can be fatal if left untreated

FAQ’s

Is pseudomembranous colitis contagious?

There are some types of colitis that are contagious and other types which are not.

Contagious colitis types can be spread from person to person, primarily through the faecal-oral route (e.g., eating food or drinking water that is contaminated). Other types of colitis can be transmitted by touching contaminated items such as clothing or toothbrushes and then touching your face without washing your hands first.

What antibiotics are most commonly associated with pseudomembranous colitis?

Most antibiotics can cause pseudomembranous colitis. However, there are some antibiotics that are more likely to bring about this inflammatory intestinal condition than others, including clindamycin, fluoroquinolones (e.g., ciprofloxacin) penicillins (e.g., amoxicillin and ampicillin).

What is an important risk factor associated with Pseudomembranous Colitis?

The most common risk factor associated with pseudomembranous colitis is C. difficile infection, which as mentioned earlier has a significant side effect of potentially causing diarrhoea.

What does Pseudomembranous Colitis look like?

Pseudomembranous colitis typically appears as thick yellow-white plaques on the inner lining of the colon. They are composed of inflammatory cells and cellular debris that may resemble a membrane covering the colon regions that may be up to two centimetres in diameter.² Pseudomembranes may be scattered in the colonic area, or in severe cases, cover a larger area as one mass.

How to prevent the spreading of a C. difficile infection?

If you or someone you know has CDI, do remain at home until the diarrhoea stops.⁵ Wash your hands with soap and water and use disinfectant.

Summary

Pseudomembranous colitis (PMC) is primarily an antibiotic-associated condition that causes inflammation of the inner lining of the colon, or large intestine. PMC often occurs after exposure to antibiotic treatment, depleting the numbers of beneficial bacteria in the intestine and allowing the rapid overgrowth of C. difficile instead. Risk factors for pseudomembranous colitis include increasing age (>65 years old), a weakened immune system, prolonged hospitalisation, and consuming certain antibiotics such as cephalosporins or fluoroquinolones which are indicated in the development of pseudomembranous colitis, and sometimes taking other medications or undergoing medical treatments like chemotherapy that kill the repertoire of healthy bacteria in the intestine. Symptoms often associated with PMC are infectious diarrhoea (many watery or loose stools per day), abdominal pain and fever. Complications of PMC include dehydration due to loss of bodily fluids, toxic megacolon and perforation of the colon. Death is also possible.