Colon infections, also known as colitis, can occur for a variety of reasons. The colon, or large intestine, is responsible for absorbing water and forming stool as food passes through the digestive system. An infection develops when bacteria, viruses, or parasites invade the lining of the colon, leading to inflammation and discomfort. Colon infections are relatively common, though some causes are more serious than others. Being aware of the risk factors and common causes of colitis can help prevent uncomfortable colon infections.
What is a colon infection?
A colon infection, or colitis, refers to inflammation of the inner lining of the colon, or large intestine. This part of the digestive system is responsible for absorbing water and nutrients from food to form stool as it passes through. When the colon becomes inflamed, its ability to function properly is impaired, leading to symptoms like diarrhea, abdominal pain and cramping, blood or mucus in the stool, fatigue, and fever or chills.
Colon infections may be acute and temporary, often caused by a bacterial or viral infection that runs its course in a few days. However, some colon infections can become chronic or recur periodically. These may be caused by underlying conditions like Crohn’s disease or ulcerative colitis. Colon infections should be diagnosed by a doctor, as some causes like C. difficile can be life-threatening.
Common causes of colon infections
Bacterial infections
Some of the most common causes of colon infections are related to bacterial imbalances or overgrowth in the gut. Potential culprits include:
- Salmonella – This bacteria is typically transmitted by contaminated food or water. It usually causes acute symptoms like diarrhea, fever, and abdominal cramps within 12-72 hours of exposure.
- Campylobacter – Also typically foodborne, Campylobacter infection can lead to symptoms similar to salmonella within 2-5 days.
- Shigella – Shigella spreads through contact with an infected person’s feces. It may lead to bloody diarrhea, fever, and cramps starting 1-3 days after exposure.
- E. coli – While most E. coli strains are harmless, some like E. coli O157:H7 can cause severe stomach cramps and bloody diarrhea.
- Clostridium difficile (C. diff) – Usually occurs after antibiotic use disrupts normal gut bacteria. Can cause watery diarrhea, abdominal pain, fever, and nausea.
Viral infections
Viruses that can lead to colon inflammation and infection include:
- Norovirus – Highly contagious virus often called the “stomach flu.” Causes acute nausea, vomiting, diarrhea, and abdominal pain.
- Rotavirus – Leading cause of infectious diarrhea in infants and young children. Spread through contaminated surfaces.
- Cytomegalovirus – A common herpesvirus that may cause colon inflammation in those with weakened immune systems.
- Enteroviruses – Group of viruses that can cause viral meningitis and less commonly, diarrhea and colon infection.
Parasitic infections
Protozoa and intestinal parasites that may infect the colon include:
- Giardia – Single-celled parasite spread through contaminated food/water. Can cause greasy stools, gas, nausea, fatigue.
- Cryptosporidium – Also transmitted through contaminated water sources. Causes watery diarrhea and cramps.
- Entamoeba histolytica – Can lead to amebic colitis with bloody diarrhea, abdominal pain.
- Blastocystis hominis – Controversial parasite that may cause diarrhea, constipation, cramping.
Inflammatory bowel diseases
Chronic conditions like Crohn’s disease and ulcerative colitis involve ongoing colon inflammation. Symptoms may flare up and subside but can’t be fully cured. Causes involve a malfunctioning immune response against harmless gut bacteria.
Diverticulitis
Infection of small pouches or sacs called diverticula that can form in the colon walls. Often has no symptoms but may cause abdominal pain, fever, chills, nausea.
Ischemic colitis
Inflammation and injury to the colon resulting from inadequate blood supply. Most often occurs in the elderly and those with vascular disease. Symptoms include pain, rectal bleeding, diarrhea.
Risk factors
Certain factors can increase susceptibility to colon infections:
- Recent antibiotic use – Antibiotics kill off beneficial bacteria in the gut, allowing “bad” bacteria to proliferate.
- Immune deficiency – Those with weakened immune systems are more prone to bacterial/viral infections.
- Poor diet – Diets high in processed foods and low in fiber alter gut microbiome balance.
- Dehydration – Inadequate fluid intake allows stool to become hard, dry, and difficult to pass.
- Intestinal obstruction – Blockages prevent proper waste elimination, causing bacterial buildup.
- Abdominal surgery – Invasive procedures on the colon/rectum may introduce bacteria.
- Inflammatory bowel diseases – Crohn’s and colitis involve chronic colon inflammation.
Other potential factors include older age, frequent use of antacids, laxative abuse, family history, and stress. Those with risk factors should be attentive to any colon infection symptoms and seek medical care promptly.
Symptoms
Signs and symptoms of a colon infection may include:
- Diarrhea – loose, watery, or bloody stool
- Cramps and abdominal pain
- Constipation – difficulty passing hard, dry stool
- Bloating or gas
- Mucus or blood in stool
- Tenesmus – sensation of incomplete evacuation
- Nausea and vomiting
- Loss of appetite
- Fatigue and weakness
- Fever and chills
Symptoms may be acute and last a few days, or chronic and recur frequently. Pain, bleeding, high fever, dehydration, or inability to pass stool are signs to seek urgent medical attention.
Diagnosis
To diagnose a colon infection, doctors use:
- Medical history – discussing symptoms, duration, risk factors, and prior GI issues.
- Physical exam – checking for pain, tenderness, swelling of the abdomen.
- Stool sample testing – identifying bacterial, viral, or parasitic causes.
- Blood tests – signs of infection include high white blood cell count.
- Colonoscopy – visual examination of the colon lining for inflammation.
- CT scan – detailed images revealing obstruction, tissue damage, or abscesses.
- Biopsy – taking a tissue sample to test for Crohn’s, colitis, cancer.
Identifying the specific cause of colon infection guides appropriate treatment.
Treatment
Treatment options for colon infections include:
- Antibiotics -used for bacterial infections like salmonella, campylobacter, C. difficile.
- Anti-parasitic medication – prescribed for giardia, amebiasis, or other parasites.
- Over-the-counter anti-diarrheals – helps control acute symptoms of infectious colitis.
- IV fluids and electrolytes – counteracts dehydration and electrolyte imbalance.
- Bland diet -BRAT diet of bananas, rice, applesauce, toast recommended during infection.
- Surgery – for perforation, abscess, or severe inflammatory bowel disease complications.
Most acute bacterial and viral colon infections resolve with conservative treatment in a few days. Seek prompt medical attention for severe dehydration, toxicity, high fever, or bloody stool.
Prevention
To help prevent colon infections:
- Wash hands thoroughly with soap and water, especially before eating and after using the bathroom.
- Avoid exposure to feces during sex.
- Drink purified/bottled water when traveling.
- Cook meats thoroughly and avoid unpasteurized dairy.
- Wash all fruits and vegetables thoroughly.
- Avoid food/water that may be contaminated.
- Take probiotics to promote healthy gut flora.
- Stay hydrated and eat a fiber-rich diet.
- Avoid unnecessary antibiotics when possible.
Getting recommended screenings like colonoscopies after age 50 can help detect any problematic colon issues early. Seek medical attention for any ongoing digestive problems or colon infection symptoms.
When to see a doctor
Consult a doctor promptly if you experience:
- Diarrhea lasting over 3 days
- Intense or worsening abdominal pain
- High fever over 101°F (38°C)
- Blood or pus in stool
- Dehydration symptoms like dizziness, confusion, rapid heart rate
- Inability to pass stool or gas
- Recent antibiotic use with new diarrhea
- Recent travel to high-risk areas
- Weakened immune system
- Weight loss and malnutrition
Prompt medication can help treat infectious causes early and prevent complications. Seek emergency care for symptoms like vomiting blood, severe pain, high fever with shaking chills, or fainting.
Complications
Potential complications of colon infections if left untreated include:
- Dehydration and electrolyte imbalances from fluid loss
- Malnutrition due to poor nutrient absorption
- Low blood pressure
- Rectal bleeding
- Anemia
- Perforated colon
- Sepsis
- Toxic megacolon – severely inflamed and expanded colon
- Colon cancer
Those with chronic conditions like ulcerative colitis are also at increased risk of colon cancer over time if inflammation is not properly controlled.
Conclusion
Colon infections can arise from a variety of bacterial, viral, or parasitic causes. Symptoms may be acute, sporadic, or chronic depending on the underlying condition. Diagnosis through stool tests, endoscopy, and medical imaging can identify the source of inflammation. Most infectious causes can be effectively treated with antibiotics, hydration, and a bland diet. However, prompt medical treatment is important to avoid complications like dehydration, bleeding, perforation, or sepsis. Preventive measures like handwashing, safer food handling, and regular colon cancer screening can reduce the risks of developing uncomfortable colon infections.