Colitis
Synonyms and keywords: Colitis, Proctocolitis, Proctitis, Enterocolitis.

# Overview
Colitis is the inflammation of the colon, that can be either acute or chronic. Colitis may be caused by microorganisms such as Chlamydia trachomatis, Neisseria gonorrhoeae, Shigella dysenteriae, HSV, allergy (food protein-induced allergic proctocolitis), drugs (NSAIDs) and radiation. Colitis may co-exist with enteritis (inflammation of the small bowel), proctitis (inflammation of the rectum) or both. The symptoms of colitis such as diarrhea especially bloody diarrhea and abdominal pain (which may be mild) are seen in all forms of colitis. Colitis may be fulminant with a rapid downhill clinical course. In addition to the diarrhea, fever, and anemia may be reported. The patient with fulminant colitis has severe abdominal pain and presents a clinical picture similar to that of septicemia, where shock is present. Treatment of colitis depends on the etiology. It may include the elimination of cows-milk protein or other food allergens from the diet, administration of antibiotics and general anti-inflammatory medications such as mesalamine or its derivatives, steroids, or one of a number of other drugs that ameliorate inflammation. The mainstay of therapy for infectious colitis is antimicrobial therapy. A common antibiotic regimen in treatment of patients with colitis is a combination of ceftriaxone and doxycycline. Supportive therapies such as correction of dehydration and anemia, and reducing the intake of carbohydrates, lactose products, soft drinks, and caffeine is often done for most patients with colitis. Irritable bowel syndrome (spastic colitis or spastic colon) has been called colitis, causing confusion despite colitis not being a feature of the disease. Immune mediated colitis is the experimental name in animal studies of ulcerative colitis.  It is a synonym of ulcerative colitis, but it should not be used as a synonym when referring to ulcerative colitis.

# Classification
There is no established classification system for colitis. However, it may be classified based on etiology, age and duration of symptom.

## Classification by etiology

## Classification by Anatomy
Colitis may co-exist with inflammation involving other parts of the gastrointestinal tract. It can be classified based on anatomy into:
- Proctitis: When it involves the rectum
- Colitis: When it involves the inflammation is limited to the colon
- Proctocolitis: When it involves the rectum and colon (usually the distal part of the colon 12cm to 15cm above the anus (sigmoid colon)
- Enterocolitis: When it involves the small intestine in addition to the colon

### Schematic of Anatomical Classification of Colitis

## Classification by Age
- Infantile (first six months of life)
- Adult

## Classification by duration of symptoms
- Acute: Less than three months.
- Chronic: Longer than three months. Often months to years.

# Differential Diagnosis
The differential diagnosis of colitis can be classified into two categories according to age group. A work up for colitis must include the following differentials:

## Differential diagnosis in Infants
- Swallowed maternal blood syndrome
- Anorectal fissure
- Necrotizing enterocolitis especially in preterm babies
- Vitamin K dependent hemorrhage
- Other coagulopathies: (hereditary such as coagulation factor deficiency or acquired such as disseminated intravascular coagulopathy)
- Intussusception
- Upper Gastrointestinal Infections
- Enteritis
- Meckel diverticulum
- Intestinal duplication cysts
- Vascular malformations
- Inflammatory bowel disease(early onset)
- Hirschsprung disease complicated by enterocolitis
- Volvulus
- Gastro-duodenal ulcers
- Gastrointestinal duplication cyst
- Liver disease with clotting factor deficiency
- Lymphonodular hyperplasia

## Differential diagnosis in Adults
- Colorectal malignancy
- Crohn's disease
- Behcet's disease
- Arteriovenous malformation
- Diverticulosis
- Enteritis
- Coagulopathy
- Systemic lupus erythematosus(SLE)
- Cytomegalovirus colitis

## Differentiating Between Different Types of Colitis
The symptoms of colitis such as diarrhea especially bloody diarrhea and abdominal pain are seen are seen in all forms of colitis. The table below differentiates among the common causes of colitis:

# Causes

## Common Causes
Common causes of proctocolitis include infectious agents such as Chlamydia trachomatis (which causes lymphogranuloma venereum), Neisseria gonorrhoeae, HSV, Shigella dysenteriae and Campylobacter species. It can also be allergic (e.g. food protein-induced proctocolitis), idiopathic (e.g. microscopic colitis), vascular (e.g. ischemic colitis), or autoimmune (e.g. inflammatory bowel disease).

## Causes by Organ System

## Causes in Alphabetical Order
- Aganglionic megacolon
- Albinism 
- Alosetron
- Alpha 1-antitrypsin deficiency
- Ampicillin Oral
- Ankylosing spondylitis
- Auranofin
- Autistic enterocolitis
- Azithromycin
- Aztreonam Injection
- Bacillary dysentery
- Bacterial gastroenteritis
- Balantidium coli
- Behcet disease
- Campylobacter jejuni
- Cap polyposis
- Cefaclor
- Cefadroxil
- Cefamandole Nafate Injection
- Cefazolin Sodium Injection
- Cefepime
- Cefepime Injection
- Cefoperazone Sodium Injection
- Cefotaxime Sodium Injection
- Cefotetan Disodium Injection
- Cefoxitin Sodium Injection
- Cefpodoxime
- Ceftazidime
- Ceftazidime Injection
- Ceftizoxime Sodium Injection
- Ceftriaxone Sodium Injection
- Cefuroxime Sodium Injection
- Cephalexin
- Cephalosporin
- Cephradine Oral
- Chemical colitis
- Chlamydia trachomatis
- Cidofovir
- Cilansetron
- Clindamycin
- Clostridium difficile 
- Co-amoxiclav
- Colitis ulcerosa
- Collagenous colitis
- Colonic ischemia
- Common variable immunodeficiency
- Corticosteroid
- Crohn's disease
- Cryptosporidiosis
- Cytomegalovirus
- Darifenacin
- Dental braces
- Desogestrel and Ethinyl Estradiol
- Dicloxacillin
- Dirithromycin
- Diversion colitis
- Diverticulosis
- Enoxacin
- Entamoeba histolytica
- Ertapenem
- Erythromycin and Sulfisoxazole
- Escherichia coli O157:H7
- EVAR
- Flucytosine
- Gerson diet
- Giardiasis
- Glycopyrrolate
- Hyoscyamine
- Idelalisib
- Imipenem and Cilastatin Sodium Injection
- Infectious colitis
- Inflammatory bowel disease
- Intestinal ischemia
- Ipilimumab
- Irritable bowel syndrome
- Ischemic colitis
- Isosporiasis
- Ixabepilone
- Lanthanum
- Levofloxacin Oral
- Lincomycin hydrochloride
- Linezolid
- Lomefloxacin
- Loracarbef
- Lymphocytic colitis
- Lysinuric protein intolerance
- Methotrexate
- Miconazole Injection
- Microscopic colitis
- Milk allergy
- Moxifloxacin
- Multiple organ dysfunction syndrome
- Nafcillin Sodium Injection
- Neisseria gonorrhoeae
- Neonatal necrotizing enterocolitis
- Nivolumab
- Norfloxacin
- Ofloxacin injection
- Oxacillin Sodium Injection
- Oxcarbazepine
- Oxybutynin
- Peginterferon alfa-2a
- Penicillin
- Pergolide
- Pigbel
- Piperacillin sodium injection
- Pramipexole
- Prednisolone
- Primary sclerosing cholangitis
- Procyclidine
- Propantheline
- Protein losing enteropathy
- Pseudoephedrine
- Pseudomembranous colitis
- Quinolone
- Radiation colitis
- Radiation proctitis
- Ramosetron
- Reserpine
- Salmonella
- Schistosoma
- Scleroderma
- Sepsis
- Shigella
- Solifenacin
- Solitary rectal ulcer syndrome
- Soy protein
- Sparfloxacin
- Strongyloides stercoralis
- Syphilis
- Tegaserod
- Toxic megacolon
- Treponema pallidum
- Typhlitis
- Ulcerative colitis
- Vasculitis
- Yersinia enterocolitica

## Life Threatening Causes
Example include toxic megacolon, ischemic colitis, infectious colitis such as  escherichia coli O157:H7 and shigella.

# Screening
There is insufficient evidence to recommend routine screening of sexual partners of patients with sexually transmitted enteric pathogens.

# Diagnosis

## History and Symptoms
- Symptoms of proctitis include anorectal pain, tenesmus, or rectal discharge.
- Symptoms of proctocolitis include fatigue, weight loss, anorectal pain, tenesmus, rectal discharge, diarrhea or abdominal cramps.

## Laboratory Findings
Laboratory findings consistent with the diagnosis of proctitis include:
- Stool examination: Detection of  blood or fecal polymorphonuclear leukocytes using gram-stained smear of any anorectal exudate from anoscopic or anal examination.
- Microbiology workup: NAAT of rectal lesions for HSV, NAAT for Neisseria gonorrhea, syphilis serology, NAAT for Chlamydia trachomatis, and NAAT for Mycoplasma genitalium in case of persistence of symptoms after receiving the recommended treatment. CMV and other opportunistic infections may be evaluated in immunosuppressed individuals as HIV/AIDS.
- An elevated erythrocyte sedimentation rate (ESR) is one typical finding in the acute exacerbation of proctocolitis.

## Other Imaging Findings

### Colonoscopy
Anoscopy or sigmoidoscopy may be helpful in the diagnosis of proctocolitis. Findings on an sigmoidoscopy suggestive of proctocolitis include inflammation of the colonic mucosa extending to 12 cm above the anus and rectal ulcers.

# Treatment

## Medical Therapy
Acute proctocolitis among individuals with receptive anal exposure is often sexually-transmitted. Empiric antibiotic treatment should be started while awaiting for the results of laboratory tests for
patients presenting with anorectal exudate on anoscopy or positive Gram-stained smear of anorectal exudate or secretions polymorphonuclear leukocytes or if anoscopy or Gram stain is not available.

### Recommended Regimen for Acute Proctitis
Ceftriaxone 500 mg IM in a single dose
plus
Doxycycline 100 mg orally 2 times/day for 7 days
- Doxycycline course is continued to 100 mg orally 2 times/day for 21 days in case of perianal or mucosal ulcers, bloody discharge, or tenesmus and a positive rectal chlamydia test.
- For individuals weighing 150 kg, 1 g of ceftriaxone is given.
- Patients presenting with mucosal or perianal ulcers or bloody diarrhea with positive NAAT for chlamydia should receive empiric therapy for Lymphogranuloma Venereum (LGV)  with a prolonged course of doxycycline 100 mg orally 2 times/day for 3 weeks.
- Patients presenting with painful perianal ulcers or mucosal ulcers on anoscopy should also receive empiric treatment for genital herpes.
- Herpes proctocolitis and LGV occur predominantly among HIV/AIDS patients; hence empiric treatment in those patients should cover genital herpes and LGV.

## Surgery
Surgical intervention is not recommended for the management of proctocolitis.

# Primary Prevention
As proctocolitis can be a sexually transmitted disease, effective measures for the primary prevention of proctocolitis include:
- Counseling on safe sex practices
- Avoiding contact with feces during sexual intercourse
- Hand washing after handing objects or materials that have been in contact with the anal area (i.e., sex toys or barriers) and after touching the anal area.

# Secondary Prevention
Effective measures for the secondary prevention of proctocolitis include:
- Abstinence from sexual activity until the patient and their partners are successfully treated (i.e., completion of a 7-day regimen and resolution of symptoms)
- Sexual partners with individuals treated for chlamydia or gonorrhea <60 days before the onset of  symptoms should receive evaluation and empiric treatment of the causative infection
- Testing for other sexually-transmitted diseases
- In case of proctocolitis caused by chlamydia or Neisseria gonorrhea, retesting for the causative organism is recommended 3 months after completion of treatment.