Author:
Isam F.Nasr
Description
Bowel movements characterized as frequent (>3/d), loose, and watery owing to an infectious or toxin exposure
Etiology
- Viruses:
- Invasive bacteria:
- Campylobacter:
- Contaminated food or water, wilderness water, birds, and animals
- Most common bacterial diarrhea
- Gross or occult blood is found in 60-90%
- Salmonella:
- Contaminated water, eggs, poultry, or dairy products
- Typhoid fever (Salmonella typhi) characterized by unremitting fever, abdominal pain, rose spots, splenomegaly, and bradycardia
- Shigella:
- Vibrio parahaemolyticus:
- Raw and undercooked seafood
- Yersinia:
- Contaminated food (pork), water, and milk
- May present as mesenteric adenitis or mimic appendicitis
- Bacterial toxin:
- Escherichia coli:
- Major cause of traveler's diarrhea
- Ingestion of food or water contaminated by feces
- Staphylococcus aureus:
- Most common toxin-related disease
- Symptoms 1-6 hr after ingesting food
- Bacillus cereus:
- Classic source - fried rice left on steam tables
- Symptoms within 1-36 hr
- Clostridium difficile:
- Antibiotic-associated enteritis linked to pseudomembranous colitis
- Incubation period within 10 d of exposure or initiation of antibiotics
- Aeromonas hydrophila:
- Aquatic sources primarily
- Affects children <3 yr of age
- Fecal leukocytes absent
- Cholera:
- Caused by enterotoxin produced by Vibrio cholerae
- Profuse watery stools with mucus (classic appearance of rice-water stools)
- Protozoa:
- Giardia lamblia:
- Most common cause of parasite gastroenteritis in North America
- High-risk groups: Travelers, children in day-care centers, institutionalized people, homosexual men, and campers who drink untreated mountain water
- Cryptosporidium parvum:
- Commonly carried in patients with AIDS
- Entamoeba histolytica (entamebiasis):
- 5-10% extraintestinal manifestations (hepatic amebic abscess)
Pediatric Considerations |
- Most are viral in origin and self-limited
- Rotavirus accounts for 50%
- Shigella: Infections associated with seizures
- Focus evaluation on state of hydration
|
Gastroenteritis
Signs and Symptoms
History
- Loose, watery bowel movements
- Bloody stools with mucus
- Abdominal pain and cramps, tenesmus, flatulence
- Fever, headache, myalgias
- Nausea, vomiting
- Dehydration, lethargy, and stupor
Physical Exam
- Dry mucous membranes
- Abdominal tenderness
- Perianal inflammation, fissure, fistula
Essential Workup
- Digital rectal exam to determine presence of gross or occult blood
- Fecal leukocyte determination:
- Present with invasive bacteria
- Absent in protozoal infections, viral, toxin-induced food poisoning
Diagnostic Tests & Interpretation
Lab
- CBC - indications:
- Significant blood loss
- Systemic toxicity
- Electrolytes, glucose, BUN, creatinine - indications:
- Stool culture - indications:
- Presence of fecal leukocytes
- Historical markers: Immunocompromised, travel, homosexual
- Public health: Food hand ler, day-care or health care worker, institutionalized
- Blood cultures - indications:
- Suspected bacteremia or systemic infections
- Ill patients requiring admission
- Immunocompromised
- Elderly patients and infants
Imaging
Abdominal radiographs:
- No value unless obstruction or toxic megacolon suspected
Differential Diagnosis
- Ulcerative colitis
- Crohn disease
- Mesenteric ischemia
- Diverticulitis, anal fissures, hemorrhoids
- Irritable bowel syndrome
- Milk and food allergies
- Malrotation with midgut volvulus
- Meckel diverticulum
- Intussusception
- Appendicitis
- Drugs and toxins:
- Mannitol
- Sorbitol
- Phenolphthalein
- Magnesium-containing antacids
- Quinidine
- Colchicine
- Mushrooms
- Mercury poisoning
Prehospital
- Difficult IV access with severe dehydration
- Avoid exposure to contaminated clothes or body substances
Initial Stabilization/Therapy
- ABCs
- IV fluid with 0.9% normal saline (NS) resuscitation for severely dehydrated
ED Treatment/Procedures
- Oral fluids for mild dehydration (Gatorade/Pedialyte)
- IV fluids for:
- Hypotension, nausea and vomiting, obtundation, metabolic acidosis, significant hypernatremia or hyponatremia
- 0.9% NS bolus: 500 mL-1 L (peds: 20 mL/kg) for resuscitation, then 0.9% NS or D5W 0.45% NS (peds: D5W 0.25% NS) to maintain adequate urine output
- Bismuth subsalicylate (Pepto-Bismol):
- Antisecretory agent
- Effective clinical relief without adverse effects
- Kaolin-pectin (Kaopectate):
- Reduces fluidity of stools
- Does not influence course of disease
- Antimotility drugs: Diphenoxylate (Lomotil), loperamide (Imodium), paregoric, codeine:
- Appropriate in noninfectious diarrhea
- Initial use of sparse amounts to control symptoms in infectious diarrhea
- Avoid prolonged use in infectious diarrhea—may increase duration of fever, diarrhea, and bacteremia and may precipitate toxic megacolon
- Antibiotics for infectious pathogens:
Medication
- Ampicillin: 500 mg (peds: 20 mg/kg/24 hr) PO or IV q6h
- TMP-SMX (Bactrim DS): 1 tab (peds: 8-10 mg TMP/40-50 mg SMX/kg/24 hr) PO b.i.d or 8-20 TMP/kg/24 hr IV q 6-12h
- Ceftriaxone: 1 g (peds: 50-75 mg/kg/12 hr) IM or IV q12h
- Ciprofloxacin (quinolone): 500 mg PO or 400 mg IV q12h (>18 yr)
- Doxycycline: 100 mg PO or 100 mg IV q12h
- Erythromycin: 500 mg (peds: 40-50 mg/kg/24 hr) PO q.i.d
- Iodoquinol: 650 mg (peds: 30-40 mg/kg/24 hr not to exceed 2 g daily) PO t.i.d
- Metronidazole: 250 mg (peds: 35 mg/kg/24 hr) PO t.i.d (>8 yr)
- Tetracycline: 500 mg PO or IV q6h
- Vancomycin: 125-500 mg (peds: 40 mg/kg/24 hr) PO q6h
Disposition
Admission Criteria
- Hypotension, unresponsive to IV fluids
- Significant bleeding
- Signs of sepsis or toxicity
- Intractable vomiting or abdominal pain
- Severe electrolyte imbalance or metabolic acidosis
- Altered mental status
- Children with >10-15% dehydration
Discharge Criteria
- Mild cases requiring oral hydration
- Dehydration responsive to IV fluids
Issues for Referral
Cases of prolonged diarrhea may be referred to a gastroenterologist for further workup
Follow-up Recommendations
Since diarrhea is self-limiting, follow-up is optional