Infectious diarrhea

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Faizan Sheraz, M.D. [2]

Overview

See also Bacterial gastroenteritis and Gastroenteritis and Enteritis

This may be defined as diarrhea that lasts less than three and a half weeks, and is also called enteritis.

Cause/Etiology

This can nearly always be presumed to be infective, although only in a minority of cases is this formally proven. The diarrhea is usually viral in origin, and is mostly caused by Norovirus, Rotavirus, Adenovirus, or Astrovirus.

The most common organisms found are Campylobacter (from animal products), Salmonella (also often from animal foodstuffs), Cryptosporidium (ditto), and Giardia lamblia (lives in water). Shigella dysentery is less common, and usually human in origin. Cholera is rare in Western countries. It is more common in travelers and is usually related to contaminated water (its ultimate source is probably sea water). Escherichia coli is probably a very common cause of diarrhea, especially Traveler's diarrhea, but it can be difficult to detect using current technology. The types of E. coli vary from area to area and country to country. Clostridium difficile is considered the most common cause of infectious diarrhea in hospitalized patients worldwide.

Viruses, particularly rotavirus, are common in children. (Viral diarrhea is probably over-diagnosed by non-doctors). Norwalk virus can also cause these symptoms.

Toxins and food poisoning can cause diarrhea. These include staphylococcal toxin (often from milk products due to an infected wound in workers), and Bacillus cereus. Often "food poisoning" is really Salmonella infection. Diarrhea can also be caused by ingesting foods that contain indigestible material, for instance, escolar and olestra.

Parasites and worms sometimes cause diarrhea but are often accompanied by weight loss, irritability, rashes or anal itching. The most common is pinworm (mostly a nuisance rather than a severe medical illness). Other worms, such as hookworm, ascaria, and tapeworm are more medically significant and may cause weight loss, anemia, general unwellness and allergy problems. Amoebic dysentery due to Entamoeba histolytica is an important cause of bloody diarrhea in travelers and also sometimes in western countries. It requires appropriate and complete medical treatment.

Diagnosis

In more severe cases, or where it is important to find the cause of the illness, stool cultures are instituted.

Among medical inpatients, the presence of fecal leukocytes can predict a "breach in the colonic mucosa (any infectious or inflammatory condition, blood in the stool, or acute vascular insufficiency)":

• sensitivity = 28%
• specificity = 92%

Differential Diagnosis

Acute inflammatory diarrhea may be caused by different pathogens. Bellow is a table describing some of these pathogens in terms of transmission and symptoms:

Pathogen	Transmission	Clinical Manifestations
		Fever	Nausea/Vomiting	Abdominal Pain	Bloody Stool
Salmonella	Foodborne transmission, community-acquired	++	+	++	+
Shigella	Community-acquired, person-to-person	++	++	++	+
Campylobacter	Community-acquired, ingestion of undercooked poultry	++	+	++	+
E. coli (EHEC or EIEC)	Foodborne transmission, ingestion of undercooked hamburger meat	±	+	++	++
Clostridium difficile	Nosocomial spread, antibiotic use	+	±	+	+
Yersinia	Community-aquired, foodborne transmission	++	+	++	+
Entamoeba histolytica	Travel to or emigration from tropical regions	+	±	+	±
Aeromonas	Ingestion of contaminated water	++	+	++	+
Plesiomonas	Ingestion of contaminated water or undercooked shellfish, travel to tropical regions	±	++	+	+

Treatment

With mild cases of acute diarrhea, it is often reasonable to reassure a patient, ensure adequate fluid intake, and wait and see.

Parasites (worms and amoeba) should always be treated with antimicrobial drugs.

Antimotility agents

Loperamide can reduce diarrhea in patients with shigella, but not in patients with traveler's diarrhea due to enterotoxigenic E. coli.

A systematic review of randomized controlled trials found that loperamide may harm children less that 3 years old.

Antisecretory agents

A randomized controlled trial found that racecadotril, an enkephalinase inhibitor, may reduce the volume of watery diarrhea.

Immunocompetent Patients

• Bacterial

• 1. Shigella species

• Preferred regimen (1): TMP-SMZ 160/800 mg PO bid for 3 days
• Preferred regimen (2): Ofloxacin 300 mg PO bid for 3 days OR Norfloxacin 400 mg PO bid for 3 days OR Ciprofloxacin 500 mg PO bid for 3 days

• Alternative regimen (1): Nalidixic acid 1 g PO qd for 5 days
• Alternative regimen (2): Ceftriaxone 1-2 g IM/IV qd for 3 days

• Alternative regimen (3): Azithromycin 500 mg PO qd for 3 days
• Note: In immunocompromised patients increase treatment duration to 7-10 days.

• 2. Non-typhi species of Salmonella

• Preferred regimen (1): TMP-SMZ 160/800 mg PO bid for 3 days

• Preferred regimen (2): Ofloxacin 300 mg PO bid OR Norfloxacin 400 mg PO bid OR Ciprofloxacin 500 mg PO bid for 5-7 days

• Preferred regimen (3): Ceftriaxone 100 mg/kg/day IV/IM q12h for one day
• Note (1): Treatment not recommended routinely, but consider if severe or if patient is younger than 6 months old or older than 50 year old or has prostheses, valvular heart disease, severe atherosclerosis, malignancy, or uremia.
• Note (2): In immunocompromised patients increase treatment duration to 14 days or longer if relapsing.

• 3. Campylobacter species

• Preferred regimen: Erythromycin 500 mg PO bid for 5 days
• Note: Immunocompromised patients may require longer treatment.

• 4. Escherichia coli species

• 4.1. Enterotoxigenic

• Preferred regimen (1): TMP-SMZ 160/800 mg PO bid for 3 days
• Preferred regimen (2): Ofloxacin 300 mg PO bid for 3 days OR Norfloxacin 400 mg PO bid for 3 days OR Ciprofloxacin 500 mg PO bid for 3 days

• 4.2. Enteropathogenic

• Preferred regimen (1): TMP-SMZ 160/800 mg PO bid for 3 days

• Preferred regimen (2): Ofloxacin 300 mg PO bid for 3 days OR Norfloxacin 400 mg PO bid for 3 days OR Ciprofloxacin 500 mg PO bid for 3 days

• 4.3. Enteroinvasive

• Preferred regimen (1): TMP-SMZ 160/800 mg PO bid for 3 days

• Preferred regimen (2): Ofloxacin 300 mg PO bid for 3 days OR Norfloxacin 400 mg PO bid for 3 days OR Ciprofloxacin 500 mg PO bid for 3 days

• 4.4. Enteroaggregative

• Preferred regimen: Unknown
• Note: In immunocompromised patients consider Ofloxacin 300 mg PO bid for 3 days OR Norfloxacin 400 mg PO bid for 3 days OR Ciprofloxacin 500 mg PO bid for 3 days

• 4.5. Enterohemorrhagic

• Preferred regimen: Avoid antibiotics as role remains unclear.

• 5. Aeromonas/Plesiomonas

• Preferred regimen (1): TMP-SMZ 160/800 mg PO bid for 3 days

• Preferred regimen (2): Ofloxacin 300 mg PO bid for 3 days OR Norfloxacin 400 mg PO bid for 3 days OR Ciprofloxacin 500 mg PO bid for 3 days

• 6. Yersinia species

• Preferred regimen: Antibiotics are not usually required.
• Note (1): Deferoxamine therapy should be withheld.
• Note (2): For immunocompromised patients, severe infections, or associated bacteremia treat using combination therapy with Doxycycline AND either Aminoglycoside OR TMP-SMZ OR OR Fluoroquinolone

• 7. Vibrio cholerae O1 or O139

• Preferred regimen (1): Doxycycline 300 mg PO single dose
• Preferred regimen (2): Tetracycline 500 mg PO qid for 3 days
• Preferred regimen (3): TMP-SMZ 160/800 mg PO bid for 3 days
• Preferred regimen (4): Ofloxacin 300 mg PO single dose OR Norfloxacin 400 mg PO single dose OR Ciprofloxacin 500 mg PO single dose

• 8. Toxigenic Clostridium difficile

• Preferred regimen: Metronidazole 250 mg PO qid / 500 mg PO tid for 3 to 10 days
• Note: Withhold offending antibiotic if possible.

• Parasites

• 1. Giardia

• Preferred regimen: Metronidazole 250-750 mg tid for 7-10 days

• 2. Cryptosporidium species

• Preferred regimen: No treatment.

Note (1): If severe, consider Paromomycin 500 mg tid for 7 days

Note (2): For immunocompromised patients, Paromomycin 500 mg tid for 14-28 days, then bid if needed.

• 3. Isospora species

• Preferred regimen: TMP-SMZ 160/800 mg PO bid for 7 to 10 days
• Note: For immunocompromised patients, TMP-SMZ 160/800 mg PO qid for 10 days. If patient has AIDS, follow by TMP-SMZ 160/800 mg PO 3x weekly OR (Sulfadoxine 500 mg PO AND Pyrimethamine 25 mg PO) qw indefinitely.

• 4. Cyclospora species

• Preferred regimen: TMP-SMZ 160/800 mg PO bid for 7 days
• Note: For immunocompromised patients, TMP-SMZ 160/800 mg PO qid for 10 days. If patient has AIDS, follow by TMP-SMZ 160/800 mg PO 3x weekly indefinitely.

• 5. Microsporidium species

• Preferred regimen: Unknown

• 6. Entamoeba histolytica

• Preferred regimen (1): Metronidazole 750 mg PO tid for 5 to 10 days AND Diiodohydroxyquin 650 mg PO tid for 20 days
• Preferred regimen (2): Metronidazole 750 mg PO tid for 5 to 10 days AND Paromomycin 500 mg PO tid for 7 days

Prognosis

Acute infectious diarrhea usually lasts 7 days when not treated with antibiotics. It is not uncommon for diarrhea to persist. Diarrhea due to some organisms may persist for years without significant long term illness. More commonly the diarrhea slowly ameliorates but the patient becomes a carrier (harbors the infection without illness). This is often an indication for treatment, especially in food workers or institution workers.

Salmonella is the most common persistent bacterial organism in humans.

References

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