Infectious Colitis

What is Infectious Colitis?

When harmful bacteria, viruses, or parasites invade the colon, it can result in a type of diarrhea linked with inflammation. This is often the reason behind most cases of sudden-onset diarrhea. These people usually have symptoms such as loose stools that can look pus-filled, bloody, or mucus-like, as well as fever, an urgent need to empty the bowels, and abdominal pain.

Diarrhea can be caused by a variety of bacteria including things like C. jejuni, Salmonella, Shigella, E. coli, Yersinia enterocolitia, C. diff, and Mycobacterium tuberculosis. It can also come from viruses including Norovirus, Rotavirus, Adenovirus, and Cytomegalovirus. Some parasites can cause this infection too, like Entamoeba histolytica, which is a single-celled parasite which can invade the lining of the colon.

When we talk about infections spread through sexual contact that can affect the rectum, they may also need to be taken into account. These may be more common in people with HIV or men who have sex with men, and can include bacteria like Neisseria gonorrhoeae, Chlamydia trachomatis, as well as the Herpes simplex virus (HSV), and Treponema pallidum.

People with these infections can have symptoms that could be mistaken for inflammatory bowel disease, including rectal pain, an urgent need to empty their bowels, bloody mucus discharge, and a feeling of urgency. To diagnose this condition, it’s important to take a detailed medical history and identify specific risk factors. Laboratory tests on stool samples and a test, called an endoscopy, which allows doctors to examine the inside of your body, are usually key in making the diagnosis.

However, stool tests may only help to diagnose less than half of the people suffering from bacterial-caused inflammation of the colon, and endoscopies usually only show changes that don’t point directly to a specific disorder. Because of this, it’s important to evaluate and diagnose the cause of the colon inflammation, while ruling out causes that are not infection-related.

This topic discusses the strategies currently being used to diagnose and manage colon infections, how to suspect that this might be the problem based on symptoms, and how to use these investigative methods to come to a final diagnosis. Aspects like causes, prevalence, how disease develops, symptoms, evaluation, ruling out other conditions, complications, and management of patients with colon infections, will also be discussed.

What Causes Infectious Colitis?

Infectious colitis is an infection in the colon, which can be caused by three types of organisms.

1. Bacterial infections: This can be caused by bacteria like C. jejuni, Salmonella, Shigella, and different types of E. coli. Other causes could be Yersinia enterocolitica, C. diff, and Mycobacterium tuberculosis.

2. Viral infections: Viruses such as Norovirus, Rotavirus, Adenovirus, and Cytomegalovirus (CMV) can also cause colitis.

3. Parasitic infections: Parasites like Entamoeba histolytica (which causes an infection known as amoebic colitis) can lead to colitis.

In patients with HIV infection or men who have sex with men, sexually transmitted infections can cause colitis as well. Responsible infections include Neisseria gonorrhoeae, Chlamydia trachomatis, Herpes simplex 1 and 2, and Treponema pallidum (which causes syphilis).

Traveler’s diarrhea is often the result of a specific type of E. coli. It’s also important to note that some E. coli infections are related to ingesting undercooked beef or contaminated milk or vegetables.

Strains of E. coli known as enterotoxigenic E. coli and enteroaggregative E. coli can cause watery diarrhea while strains like enterohemorrhagic E. coli lead to bloody diarrhea.

Enteropathogenic E. coli and enteroinvasive E. coli do not produce toxins. The former is known to cause outbreaks, especially in children under 2 years old. The latter, however, causes a short-term type of colitis and has been connected to outbreaks in developing countries. A notable outbreak happened in Nottingham, England in 2014, showing that it can be a concern even in developed countries.

Children in daycare centers, older people in nursing homes, and individuals with weakened immune systems are especially susceptible to these infections. In most cases, these infections are spread through contact with feces, through animals, and by consuming contaminated food or water. Large outbreaks of diseases can occur when food and water get contaminated with harmful bacteria.

Risk Factors and Frequency for Infectious Colitis

Bacterial colitis makes up nearly half of all acute diarrhea cases. The most common bacterial trigger worldwide is C. jejuni, which affect 25 to 30 out of every 100,000 individuals. In the United States, Salmonella infection is estimated to cause 1.2 million cases of non-typhoid-related illness each year.

Shigellosis is a global concern with approximately 165 million cases reported annually, however death rates have reduced over the last three decades, thanks to better diagnostics and treatment. In the United States, the annual case estimate is around 500,000, with a mortality count of 38 to 45 individuals.

Yersinia enterocolitica colitis is usually seen in young children during winter months. It’s estimated to affect 1 in 100,000 people in the United States each year.

In terms of hospital-acquired infection, C.diff infection in the United States increased significantly from 4.5 cases in 2001 to 8.2 cases in 2010, per 1,000 hospital discharges. As of 2011, there were about 500,000 cases with 83,000 recurrences and 29,300 deaths.

Mycobacterium tuberculosis is responsible for 12.8% of all extrapulmonary tuberculosis cases. The disease rate in developing countries mirrors the corresponding AIDS epidemic distribution. Increases in tuberculosis cases in developed countries are also tied to immigration, worsening social conditions, cutbacks in public health services, and rising numbers of immunocompromised individuals.

Amebiasis is recognized as the second deadliest protozoan infection, following diseases like malaria, Chagas disease, and leishmaniasis.

The likelihood of CMV infection in patients with colitis varies from 21% to 34%. For patients suffering from severe ulcerative colitis, up to 25% may experience CMV reactivation, especially those requiring surgical removal of the colon due to severe colitis.

• In a recent study on infectious proctitis, chlamydia was found to affect 23% of HIV-positive and 22% of HIV-negative men.
• Gonorrhea affected 13% of HIV-positive men versus 11% of HIV-negative men.
• For HSV-1, the numbers were 14% versus 6%, while HSV-2 was present in 22% versus 12% of the participants.
• There was a noted 8% instance of lymphogranuloma venereum in HIV-positive men versus 0.7% in HIV-negative men.
• Mixed infections were seen in 18% of HIV-positive men versus 9% of HIV-negative men.
• About 32% of the cases of proctitis caused by HSV had external anal ulcerations.

Signs and Symptoms of Infectious Colitis

Getting a comprehensive medical history and identifying possible exposure risks can help significantly in diagnosing intestinal infections. It’s worth noting that people with conditions that affect their immune system, such as sickle cell anemia, certain types of blood disorders, or those on treatments that suppress the immune system like corticosteroids, chemotherapy for cancer, or those with AIDS are more likely to be infected by the Salmonella bacteria. These patients may experience nonspecific symptoms like diarrhea, fever, a feeling of needing to urgently empty their bowel, and abdominal pain.

C. diff infection tends to be more common in people who have inflammatory bowel diseases like ulcerative colitis. Any antibiotic could potentially trigger the infection, but frequently implicated antibiotics include:

• Cephalosporins
• Clindamycin
• Carbapenems
• Trimethoprim
• Sulfonamides
• Fluoroquinolone
• Penicillin combinations

Patients with Mycobacterial tuberculosis might experience abdominal pain, pass bloody stools, fever, feel tired, and look pale. Patients with a history of pulmonary tuberculosis treatment are more likely to be affected. Abdominal tenderness in the right lower abdomen is a common sign, given that this is a commonly affected area in intestinal tuberculosis.

Viral colitis, triggered by various viruses such as Norovirus, Rotavirus, and Adenovirus, is most often seen in infants and young children. Symptoms are nausea, vomiting, watery diarrhea, and abdominal pain. Infections caused by the CMV virus can cause symptoms, particularly in patients with healthy immune systems. These symptoms can include diarrhea, abdominal pain, fever, fatigue, rectal bleeding, and weight loss. The most frequent symptoms, however, are bloody stools and diarrhea. Oftentimes, it’s quite challenging to distinguish between ulcerative colitis and CMV colitis based on clinical presentation.

Amoebic colitis usually shows symptoms like diarrhea, mucus-filled stools, bloody stools, a feeling of needing to urgently empty their bowel, and a bloated abdomen. This type of colitis is often traced back to contaminated water supplies and poor sanitation, often associated with international travel to areas where the disease is common. Transmission of the amoebas causing the disease usually occurs through the fecal-oral route.

Colitis associated with sexually transmitted infections leads to symptoms like pain in the anal region, along with a pus-filled, mucus-filled, or bloody discharge, and a feeling of urgency to empty the bowels. Getting the patient’s sexual history is crucial in such cases.

Testing for Infectious Colitis

The process of diagnosing colitis, an inflammation of the inner lining of the colon, relies on a mixture of physical examinations, lab tests, endoscopy, and biopsy. Usually, endoscopy and biopsy are used after an initial examination and consideration of the patient’s overall health.

As infections can often cause colitis and mimic other bowel diseases, the initial examination usually involves microbiological tests and cultures to identify any bacterial or parasitic infections. A number of standard lab tests may also be carried out, including blood tests and tests to determine levels of various proteins and electrolytes. A type of test called a polymerase chain reaction (PCR)-based molecular test can be used to identify specific bacterial infections from stool samples. More in-depth examinations may include abdominal and pelvis CT scans, colonoscopy, tissue biopsies, and fecal cultures. These can all help distinguish between infectious and non-infectious causes of colitis and inform treatment options.

The use of multidetector CT scans of the abdomen has recently been employed to differentiate between inflammatory bowel disease and acute colitis resulting from bacterial infection. Five signs are used in this process.

When diagnosing Mycobacterium tuberculosis colitis, a type of colitis caused by a specific form of bacteria, the focus is on physical symptoms, clinical evaluation, and additional lab tests. Certain changes in blood count can be indicative, as well other signs such as fibrotic changes or old scars detected via chest X-ray. Abdominal and pelvis CT scans can show specific changes in the colonic wall, and a colonoscopy may reveal widespread ulceration throughout the colon. Certain skin tests and PCR testing can also provide valuable clues towards a diagnosis.

For CMV colitis, a type of colitis caused by a particular kind of virus, as well as Amoebic Colitis, which is caused by a parasite, specific clinical findings and lab tests, along with endoscopy and specialized testing, are employed for diagnosis confirmation.

In cases where sexually transmitted infections could be causing colitis, laboratory tests can be used to detect specific types of bacteria or viruses. The appearance of lesions under the microscope as well as certain test results can aid in the identification of the disease causing the infection.

Treatment Options for Infectious Colitis

Certain types of infectious colitis, a condition causing inflammation of the large intestine, don’t always require antibiotics. For example, mild-to-moderate C. jejuni or Salmonella infections often clear up on their own without specific treatment. However, antibiotics may be needed in patients with high fever and severe symptoms, or those who have conditions like AIDS, cancer, or are elderly.

In the case of C. diff, a bacterium that can cause symptoms ranging from diarrhea to life-threatening inflammation of the colon, the recommended treatment varies depending on the severity of the illness.

For E. coli, particularly in children, antibiotics are usually not recommended. This is due to the risk of certain strains of E. coli releasing harmful toxins when killed by antibiotics, which may increase the risk of severe complications.

Mycobacterium Tuberculosis, a bacterium responsible for tuberculosis, is becoming increasingly resistant to commonly used drugs. As such, patients with this type of infection are typically prescribed an extended course of several different medications.

With CMV colitis, most patients with a healthy immune system don’t need antiviral treatment. However, treatment may be recommended for men over the age of 55 who have severe illness and conditions that weaken the immune system.

E. histolytica, a parasite causing amoebiasis which leads to stomach pain and loose stools, requires treatment even if the patient does not have symptoms. A combination of medications is typically used to first treat the acute symptoms and then eradicate the parasite from the body.

For gonorrhea, a sexually transmitted infection, treatment usually involves a combination of antibiotics due to the increasing resistance of the bacteria to certain drugs.

Lymphogranuloma venereum, a sexually transmitted infection caused by certain types of chlamydia, is typically treated with a course of antibiotics.

Herpes simplex virus (HSV) can cause painful sores on the mouth or genitals. Treatment usually involves antiviral medications, and possibly pain management strategies.

Syphilis, another sexually transmitted infection, is usually treated with a specific type of penicillin, with alternative treatment options available for those who are allergic. Ensuring the infection is completely cleared and notifying partners is also an important part of the treatment process.

What else can Infectious Colitis be?

When diagnosing infectious colitis, it’s necessary to consider and rule out a range of other health conditions that can present with similar symptoms such as:

• Inflammatory bowel disease
• Colorectal cancer
• Diverticulitis
• Ischemic colitis (insufficient blood flow to the colon)
• Irritable bowel disease
• Drug-induced colitis
• Radiation-associated colitis
• Colitis due to immune deficiency disorders
• Graft-versus-host disease (immune rejection in transplants)
• Acute appendicitis or ileocecal mass

In particular, when diagnosing acute appendicitis or ileocecal mass (a mass in the lower part of the small intestine and the beginning of the large intestine), the doctor needs to consider:

• Yersinia enterocolitica infection
• Crohn’s disease
• Amoebic colitis (a parasitic infection)
• Ulcerative colitis
• Colorectal cancer involving the cecum (the first part of the large intestine)

What to expect with Infectious Colitis

Infections of the colon (colitis) typically last for around a week, but in severe cases, it can drag on for several weeks. If not treated, the disease can last so long that it might be mistaken for a condition known as ulcerative colitis.

Possible Complications When Diagnosed with Infectious Colitis

Infectious colitis can give rise to several complications, which include:

• Bowel rupture
• Extreme colon enlargement, known as toxic megacolon, seen with certain infections
• Formation of false membranes in the colon (typically with C. diff infection)
• Colitis resulting in bleeding (linked to certain E. coli strains)
• Blood-related and kidney-related issues (linked to E. coli, C. jejuni, Shigella)
• Symptoms similar to Irritable Bowel Syndrome and digestion difficulties post infection
• Guillain-Barre syndrome, a condition causing muscle weakness (seen with C. jejuni and Cytomegalovirus colitis)
• Brain inflammation and seizures (Shigella)
• Joint inflammation (Shigella, C. jejuni, Yersinia enterocolitica colitis)
• Pancreas and gallbladder inflammation, meningitis, joint infection (C. jejuni)
• Septic shock and death (Shigella, C. diff)
• Elevated pancreatic enzymes without pancreas inflammation (Salmonella)
• Kidney failure, shock (C. diff)
• Low blood sugar, low blood sodium levels (Shigella)
• Skin condition called Erythema nodosum (Yersinia enterocolitica)

For patients suffering from CMV colitis on top of inflammatory bowel disease, complications can include severe bleeding, an abnormally enlarged colon, severe colitis, or colon rupture. These severe complications may lead to increased risk of death.

Preventing Infectious Colitis

It’s crucial for patients to understand the importance of taking their antibiotics as prescribed, as this helps to fight infection and promote healing. Patients should also be aware of any changes in their symptoms or any signs that their condition could be getting worse. This understanding allows patients to take an active role in their wellbeing, alerting their doctors promptly if anything seems amiss.