Diarrhea - GI Flashcards
Acute Diarrhea
- Abrupt onset of 3 or more loose stools per day
- Lasting 14 days or fewer
- Infectious, malabsorption, enteropathy
- Usually self-limited
- Most common complication - dehydration
- Gastric involvement is RARE (gastroenteritis)
- Chronic Diarrhea: Lasts more than 14 days
Pathophysiology
- Reversal of normal net absorptive state of water and electrolytes (Absorption>Secretion)
- Osmotic force in lumen (non-absorptive sugar ingestion)
- Goes away with stopping offending ingestion
- High stool ion gap (Total Osm - [(Na+K)x2])
- Active secretory state in the enterocytes (enterotoxin-induced)
- Bacterial infection most common - enterotoxins and inflammation
- Doesn’t go away with fasting
- Normal stool ion gap
Epidemiology
- Viral most common in young children
- Rotovirus and adenovirus in < 5 yrs
- Yersinia enterocolitis < 1 yr
- Aeromonas also common in young children
History
- Clinical presentation and course are organism specific
- Flatulence, foul smelling stools that float – fat malabsorption – Giardia lamblia
- Stool characteristics many times help determine the source
Small Bowel stool characteristics
- watery appearance
- large volume
- increased frequency
- may have blood but not a lot
- pH <5/hpf
- serum wbc normal
large bowel stool characteristics
- mucoid and/or grossly bloody appearance
- small volume
- highly increased freq
- commonly grossly bloody
- pH >5.5
- WBC >10/hpf
- serum WBCs possible leukocytosis, bandemia
Organisms in small bowel
Viral
-Rotavirus, Adenovirus, Calcivirus, Astrovirus, Norovirus
Enterotoxigenic bacteria
-E coli, Klebsiella, Clostridium perfringens, Cholera species, Vibrio species
Parasites
-Giardia species, Cryptosporidium species
Organisms in large bowel
Invasive bacteria
-E Coli (enteroinvasive, enterohemorrhagic)
Shigella, Salmonella, Campylobacter, Yersinia, Aeromonas, Plesiomonas
Toxic bacteria
-Clostridium difficile
Parasites
-Entamoeba organisms
Food History
- Ingestion of raw or contaminated food is a common cause of infectious diarrhea.
- Organisms that cause food poisoning include the following:
- Dairy food -Campylobacter and Salmonella species
- Eggs -Salmonella species
- Meats -C perfringens and Aeromonas, Campylobacter, and Salmonella species
- Ground beef - Enterohemorrhagic E coli
- Poultry -Campylobacter species
- Pork -C perfringens, Y enterocolitica
- Seafood - Astrovirus and Aeromonas, -Plesiomonas, and Vibrio species
- Oysters - Calicivirus and Plesiomonas and Vibrio species
- Vegetables -Aeromonas species and C perfringens
Water Exposure
- Water is a major reservoir for many organisms that cause diarrhea.
- Swimming pools - Shigella species
- Aeromonas organisms are associated with exposure to the marine environment
- Giardia, Cryptosporidium, and Entamoeba organisms are resistant to water chlorination
Travel
- Camping - Giardia
- Traveler’s Diarrhea - Enterotoxigenic E coli #1
- Consider Rotavirus and Shigella, Salmonella, and Campylobacter organisms worldwide
- Africa - highest risk
- Central and South America and Eastern European countries also relatively high risk
- CDC Website for specific countries/organisms
Pet Exposure
- Young dogs/cats - Campylobacter
- Turtles - Salmonella
Medical Conditions
- C difficile - Hospitalization, antibiotic administration
- Plesiomonas species - Liver diseases or malignancy
- Salmonella species - Intestinal dysmotility, malnutrition, achlorhydria, hemolytic anemia (especially sickle cell disease), immunosuppression, malaria
- Giardia species -Agammaglobulinemia, chronic pancreatitis, achlorhydria, cystic fibrosis
Non-infectious Causes
Drug-induced
-Antibiotic-associated, laxatives, antacids that contain magnesium, opiate withdrawal, other drugs
Food allergies or intolerances
-Cow’s milk protein allergy, soy protein allergy, multiple food allergies, olestra, methylxanthines (caffeine, theobromine, theophylline)
Disorders of digestive/absorptive processes
-Glucose-galactose malabsorption, sucrase-isomaltase deficiency, late-onset (adult-type) hypolactasia, resulting in lactose intolerance
- Chemotherapy or radiation-induced enteritis
- Surgical conditions
- Acute appendicitis, intussusception
Vitamin deficiencies
-Niacin or folate deficiency
Vitamin toxicity
- Vitamin C, Niacin, vitamin B3
- Ingestion of heavy metals or toxins (eg, copper, tin, zinc)
- Ingestion of plants (eg, hyacinths, daffodils, azalea, mistletoe, Amanita species mushrooms)
Exam
Dehydration
- Principal cause of morbidity and mortality
- Assess every for signs, symptoms, and severity
- Failure to thrive and malnutrition
- Reduced muscle and fat mass or peripheral edema may be clues to the presence of carbohydrate, fat, and/or protein malabsorption
- Giardia organisms can cause intermittent diarrhea and fat malabsorption
- Abdominal pain
- Nonspecific, nonfocal, and usually does not increase with palpation
- If focal abdominal pain worsened by palpation, rebound tenderness, or guarding, BEWARE - complication or other non-infectious diagnosis
- Borborygmi - Significant increases in peristaltic activity can cause an audible and/or palpable increase in bowel activity
- Skin: Perianal erythema or skin breakdown, Secondary bile acid malabsorption can result in a severe diaper dermatitis that is often characterized as a “burn”
Labs
- Stool pH level <5.5 or reducing substances = carbohydrate intolerance, usually viral/transient
- Stool WBCs, predominantly neutrophils
- Likely enteroinvasive infection of the large bowel
- Rules out enterotoxigenic E coli, Vibrio species, and viruses
- Leukocytes in exudates found in stool for highly suggests colitis
- Infectious, allergic, or part of inflammatory bowel disease (Crohn disease, ulcerative colitis)
- If clinical colitis or WBCs
- Culture stool for Salmonella, Shigella, and -Campylobacter organisms and Y enterocolitica
- Episodes of diarrhea characterized by colitis and/or blood with or without antibiotic use - look for C. difficile
- Bloody diarrhea + ground beef ingestion - enterohemorrhagic E. coli
- E coli O157:H7 is the most common, but not only, cause of Hemolytic Uremic Syndrome
- Raw seafood ingestion or foreign travel - look for Vibrio and Plesiomonas species
- Stool rotavirus antigen : False-negative rate 50%, False-positive more likely with blood
- Stool ova and parasites exam done every 2-3 days
- CBC - Shigella organisms cause a marked bandemia with a variable total white blood cell count
- Low serum Albumin + high fecal alpha1-antitrypsin levels : Protein-losing enteropathy from extensive inflammation in enteroinvasive intestinal infections (eg, Salmonella species, enteroinvasive E coli)
Management
-Prevention and treatment of dehydration is key to management
-Oral rehydration solutions (Pedialyte, packets, home made) begun within 4-6 hours ideal
-No/minimal dehydration - replace losses
10 kg -120-140 mL per diarrhea stool or vomiting episode
-Mild to moderate dehydration: Rehydration therapy - Oral rehydration solution (50-100 mL/kg over 3-4 h), + Replacement of losses
-Severe dehydration
-Rehydration therapy - IV LR or NS (20 mL/kg until perfusion and mental status improve), followed by 100 mL/kg oral rehydration solution over 4 hours or 5% dextrose (half normal saline) intravenously at twice maintenance fluid rates
+ Replacement of losses
-If unable to drink, administer through nasogastric tube or intravenously administer 5% dextrose (one fourth normal saline) with 20 mEq/L potassium chloride
-Resume feeding ASAP
-Continue breastfeeding throughout
-Resume prediarrhea diet
-Occasionally need 4-5 days lactose free
-Antimotility agents not recommended in infectious diarrhea
When to Work Up
- Profuse diarrhea with dehydration
- Grossly bloody stools
- High fever
- Persistent symptoms without improvement >48 hrs
- Recent antibiotic therapy
- Associated severe abdominal pain
- Esp in older patients, >70 years
- Immune compromise
- New community outbreak of illness
Enteric Fever
- Salmonella typhi
- Insidious onset of malaise, fever, abdominal pain, and bradycardia
- Diarrhea and rash (rose spots) appear after 1 week of symptoms.
- Bacteria may have disseminated at that time, and treatment is required to prevent systemic complications such as hepatitis, myocarditis, cholecystitis, or GI bleeding
Hemolytic Uremic Syndrome
- Caused by damage to vascular endothelial cells by verotoxin (released by enterohemorrhagic E coli and by Shigella organisms)
- Thrombocytopenia, microangiopathic hemolytic anemia, and acute renal failure
- Symptoms usually develop one week after onset of diarrhea, when the organism may be absent
Reiter Syndrome
- RS can complicate acute infections
- Characterized by arthritis, urethritis, conjunctivitis, and mucocutaneous lesions
- Individuals with RS usually do not demonstrate all features
Tx
Not necessary to treat except in those marked with **
- Aeromonas species: Use cefixime and most third-generation and fourth-generation cephalosporins
- Campylobacter species: Erythromycin shortens illness duration and shedding
- C difficile: Discontinue potential causative antibiotics. If antibiotics cannot be stopped or this does not result in resolution, use oral metronidazole or vancomycin
- C perfringens: Do not treat with antibiotics
- E coli: Trimethoprim-sulfamethoxazole (TMP-SMX) should be administered if moderate or severe diarrhea is noted, Antibiotic treatment may increase likelihood of hemolytic-uremic syndrome (HUS), Parenteral second-generation or third-generation cephalosporin is indicated for systemic complications
- **G lamblia: Metronidazole or nitazoxanide can be used
- Salmonella species: Treatment prolongs carrier state, is associated with relapse, and is not indicated for nontyphoid-uncomplicated diarrhea. , Treat infants younger than 3 months and high-risk patients (eg, immunocompromised, sickle cell disease), TMP-SMX 1st line; Cefotaxime, ceftriaxone for invasive disease
- **Shigella species: Treatment shortens illness duration and shedding but does not prevent complications, TMP-SMX 1st line; Cefixime, cefotaxime, ceftriaxone for invasive disease
- **V cholerae: Treat infected individuals and contacts., Doxycycline 1st line; erythromycin 2nd line
- Yersinia species: TMP-SMX, cefixime, ceftriaxone, or cefotaxime , Treatment does not shorten disease duration; reserve for complicated cases.
