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Colon infection

Dr. Rajalakshmi VK (AIIMS)MBBS

June 01, 2020

January 07, 2021

Colon infection
Colon infection

Colon infections are quite common and they are characterized by inflammation of the inner lining of the colon. Viral or bacterial infections, including sexually transmitted diseases, and overuse of antibiotics are among the causes of colon infections.

Medically, colon infections are known as infectious colitis. This is different from ulcerative colitis, which is also marked by inflammation of the colon and/or rectum. However, in ulcerative colitis, the condition is usually chronic (lifelong) and the cause is non-infectious.

Infectious colitis is usually contracted by eating poorly cooked, unhygienic food or contaminated water. E. Coli infection, Shigellosis, Clostridium difficile infection, Salmonella infection are some common causes of infectious colitis. There is also antibiotic-associated colitis: overuse of antibiotics can disturb the gut flora and cause the growth of C. difficile.

Symptoms vary widely from pain in the abdomen to aches and joint pain, fever, fatigue, diarrhoea (sometimes bloody), and depression. It depends on what the underlying issue is and the severity of the infection.

Diagnosis usually involves imaging tests, lab tests including blood tests and analysis of symptoms. Treatment depends on the underlying cause and can range from general, symptomatic therapy to more intensive intravenous therapy. Surgery may be required in cases involving ischemic colitis.

Difference between colon infection and ulcerative colitis

Both colon infection and ulcerative colitis are marked by inflammation of the colon or large intestine. However, they are different in the following ways:

  • While colon infections can happen to anyone, ulcerative colitis tends to run in families and is sometimes associated with autoimmune disorders.
  • According to a write-up in the Inflammatory Bowel Diseases: A Clinician’s Guide, another key difference between ulcerative and infectious colitis is that there tends to be patchy inflammation of the inner lining of the colon in infectious colitis compared with continuous inflammation in ulcerative colitis.
  • Infectious colitis is caused by a pathogen. As such the treatment for it also involves appropriate antibiotic or antiviral course. In mild cases, the patient's body may be able to fight the infection on its own. Ulcerative colitis, on the other hand, tends to require lifelong management including dietary restrictions.

Colon infection symptoms

The symptoms of colon infections start off as generalized gastritis symptoms and common flu signs as well. Often they recover after this point, but in some cases more severe symptoms manifest. Here is a list of possible symptoms:

A range of underlying conditions can lead to colitis and symptoms will vary depending on these.

Colon infection causes

Colitis is an umbrella term that refers to inflammation of the colon. The colon lies at the end of the gastrointestinal (GI) tract in the large intestine and absorbs water and remaining nutrients from food, and changes the remaining liquid material into a solid state before moving it to the rectum. Given the colon’s large surface area, the likelihood of infections is always there. Here is a look at some pathogens that cause infectious colitis:

  • Bacteria: These are the bacteria commonly associated with infection of the colon or large intestines:

    • Salmonella: Salmonella is a type of bacteria that is naturally present in the gut. However, if it makes its way into the body through undercooked meat or unpasteurized milk, it can cause a bacterial infection. Treatment usually involves fluid replacement and rest. In some cases, the infection can be severe, and a rash across the body can break out—this will require hospitalization.
    • E. Coli: Escherichia coli infection also occurs when food is poorly prepared or if hands are not washed properly before eating. In severe cases, the infection can lead to kidney disease, dehydration, decreased urine output. The infection usually lasts for five to 10 days and in milder cases, home care is sufficient to clear it. However, if the diarrhoea is severe, intravenous (IV) drips may be required to maintain fluid levels. (Read more: What is fluid therapy?)
    • Clostridium difficile: C. difficile (C. diff for short) is naturally present in healthy guts, but can cause an infection if the good bacteria balancing it out is reduced. C. diff is usually spread through the fecal oral route, either through indirect contact or through contaminated food. It is a hardy bacteria that is immune to common disinfectants as well. Those who take lots of general antibiotics, are older, and those with compromised immune systems are more likely to get C. diff. Abdominal cramps are a common symptom, and in some cases, bloody stools are also present.
    • Treatment involves specific antibiotics and the outcome is often good. The infection usually clears up after 10 days. Severe complications involve kidney infection, bowel perforation and toxic megacolon.
    • Shigella: Shigellosis is a common infection in children in the Indian subcontinent. The Shigella bacteria produces symptoms like fever, diarrhoea, drowsiness, loss of appetite, vomiting and a constant feeling that you need to defecate. Symptoms tend to be milder in grown-ups.
    • Campylobacter: Campylobacter jejuni is a known cause of acute infectious-type colitis or acute self-limited colitis (ASLC).
    • Yersinia enterocolitica
    • Mycobacterium tuberculosis
  • Virus:
    • Norovirus
    • Rotavirus
    • Adenovirus
    • Cytomegalovirus
  • Parasites:
    • Entamoeba histolytica: A protozoan that can enter the mucosal lining of the colon and cause inflammation.
  • Sexually transmitted infection: An infection in the rectum can affect the colon too. Some STD-causing pathogens that have been known to cause colon infection, too, are:
    • HIV
    • Neisseria gonorrhoeae
    • Chlamydia trachomatis
    • Herpes simplex virus
    • Treponema pallidum

Ischemic colitis

Ischaemic colitis occurs when blood flow to the large intestine is cut off or impeded, resulting in inflammation of the colon. Narrowed arteries usually cause this to happen, but complications from certain infections can precipitate this also. For example, septic shock and haemorrhagic shock can cause ischaemic colitis. Signs include severe abdominal pain, bright red stool and diarrhoea.

In most cases, home care is sufficient and the disease is cleared without complication. In more severe cases, antibiotics and/or surgery is required to get read of any dead tissue. Gangrene can be caused in severe cases.

Other types of colitis

Allergic colitis, which more commonly affects infants, is triggered in response to a milk allergy and causes symptoms of regular gastric distress. Drug-induced colitis is caused by NSAIDs (painkillers like ibuprofen), or by extensive use of antibiotics as well.
Microscopic colitis gets its name from the fact that the inflamed colonic tissue needs to be examined under a microscope to reach a diagnosis. There are two types of inflammation; collagenous colitis in which the layer of collagen protein in the colon becomes thicker, lymphocytic colitis in which there is a substantial increase in white blood cells in the colon.
Incontinence, dehydration and watery diarrhoea are common symptoms. Certain bacteria and viruses can cause the disease, but autoimmune diseases such as rheumatoid arthritis, celiac disease and psoriasis are common underlying causes. Smoking and regular consumption of certain NSAIDs have also been linked to elevated risk. (Read more: How to quit smoking).

The disease usually resolves on its own but sometimes medication such as steroids, antidiarrheal and anti-inflammatory drugs are required.

You might also be interested in digestive disorders and food allergies.

Colon infection prevention

Colon infections, also known as acute infectious-type colitis or acute self-limited colitis (ASLC), can be prevented to a large degree by improving personal hygiene and food preparation habits. In the case of infectious colitis, these steps can be taken:

  • Thoroughly washing hands before eating or cooking 
  • Washing produce or meat before using it for cooking
  • Drinking clean water and pasteurized milk 
  • Separating raw meats from other foods
  • Keeping utensils clean 
  • Ensuring meat and eggs are cooked thoroughly before eating 
  • Not cooking if you are sick yourself, even if you have gastric symptoms
  • For some people, certain foods trigger allergic reactions that may lead to colitis. It is best to avoid these foods to prevent symptoms from flaring up. Caffeine, raw fruits and vegetables and alcohol are generally not advised for those who suffer from colon infection since they have the tendency to increase stool output. 
  • Giving up smoking also reduces the likelihood of colon infections.
  • It is also recommended to eat smaller, more frequent meals rather than heavy meals to give the colon more time to process the food.
  • Tackling underlying conditions is also important: though most cases of infectious colitis clear up within 10-14 days, it is important to take proper treatment. and there will be many preventive measures for this as well. Regular exercise and balanced meals are the best preventive steps you can take for your overall health. (Read more: Healthy recipes)
  • Practising safe sex, including safe anal sex.

Colon infection diagnosis

If gastric distress is persistent, or if there is a sudden onset of severe symptoms, you must go to the doctor. Since symptoms are generalized most of the time, a slew of diagnostic methods and approaches will be required.

  • For starters, the doctor will take a full medical history, including recent travel history and recent history of eating out. He or she may ask if an event or certain food group triggered symptoms.
  • Next, a physical exam will be conducted: inflammation in the colon region would help localize the issue to the area and can suggest a bunch of causes all the way from bloating to a hernia. The doctor can check for distention, pain, and listen for sounds using a stethoscope as well.
  • Lab tests, blood tests, blood cultures, stool test, imaging tests, biopsy, endoscopy or colonoscopy are some diagnostic options that may be used, depending on the situation.
    Blood tests can check for raised levels of white blood cells which would suggest some sort of infection or check for anaemia. Low levels of protein and albumin would also suggest severe infection. Stool tests can also be conducted to further analyse the spread of infection or malabsorption in the gut. 
    Methods that use probes such as endoscopy or colonoscopy may be required since they give a detailed look at the workings of the inner tract and can be used to spot growths or blockages.

Colon infection treatment

In most cases of colon infection, the aim of treatment is to stabilize fluid levels and alleviate symptoms. This gives the body some time and respite as it works to gradually clear the infection. 

Treatment will be dictated by the underlying condition. Infectious colitis will require treatment with antibiotics (if the infection is caused by bacteria) or antivirals, as the case demands—some of these medicines may be delivered with IV fluids. Some infections, like Salmonella, do not usually require antibiotics and resolve slowly on their own. C. Diff, on the other hand, does require antibacterial medicine as the strain of bacteria involved is more resilient against the body’s natural defences. 

Many gastric infections cause severe diarrhoea and nausea which can lead to dehydration. Those with more severe infections may need to be admitted to hospital to ensure that their vitals are within reasonable levels—some may require oral rehydration salts.

Anti-diarrhea and antiemetic may be needed in some cases as well.

In a few cases, especially those involving tissue death and gangrene, surgery may be required to remove the affected tissue to prevent the spread of further infection. 

Broadly speaking, colon infections usually clear up over time and require symptomatic treatment to alleviate pain and to maintain vitals.


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