Diarrhea and Gastroenteritis

Diarrhea and Gastroenteritis

Definition:

Consistency is much more important than frequency to define diarrhea…

Types

Watery, osmotic (e.g, Laxative-induced diarrhea),

secretory (eg, microscopic colitis)

Functional – mucus (typically from irritable bowel syndrome)

Inflammatory – blood +/- pus (eg, IBD as in Chron’s and UC, some invasive bacteria)

Fat (steatorrhea)

Case Approach:

Two main questions to answer are:
  1. Acute or Chronic
  2. Watery (non-bloody) or Bloody

Blood and WBCs in stool

Salmonella: contaminated poultry and eggs; more common in patients with SCD and achlorhydria
 
Campylobacter jejuni: most common cause, rarely associated with GBS
 
E. coli  O157:H7 — undercooked hamburger meat; hemolytic uremic syndrome (HUS)
 
Shigella: 2nd most common association with HUS
 
Vibrio parahaemolyticus: shellfish and cruise ships
Vibrio vulnificus: raw shellfish, h/o liver disease, iron overload and bullous skin lesions
                          * may cause invasive, life-theratening disease in immunocompromised patients or those with liver disease
 
Yersinia enterocolitica: high affinity for iron, hemochromatosis, blood transfusions; can mimic appendicitis or Chron’s disease
               tends to infect the cecum rather than distal colon
 
Clostridium difficile:  previous antibiotic use;  white and red cells in stool
Clostridium botulinum :   infected canned foods
Clostridium perfringens:  meats taht have been contaminated with spores by being unrefrigerated
 The major protozoan associated with blood in the stool is Entamoeba histolytica.

No Blood and WBCs in stool

  • Viral
  • Giardia lamblia
  • Cryptosporidiosis/ isospora: AIDS with CD4 <50-100; detected by modified acid fast stain (treat underlying AIDS, nitazoxanide which is superior to paromomycin)
  • Bacillus cereus: vomiting –  warmed or slowly re-heated fried rice
  • Staphylococcus: vomiting
Dx
  • The best initial test is for  blood and/or fecal leukocytes with methylene blue testing
  • Stool lactoferrin has greater sensitivity and specificity compared with stool leukocytes
  • The most accurate test = stool culture to determine the specific type
  • Modified acid-fast test for cryptosporidiosis because routine fecal O/P does not reliably pick up
  • ELISA stool antigen test for Giardiasis (90% sensitivity); 3 fecal O/P for Giadria has lesser sensitivity (80%) than single stool antigen test
Tx
  • supportive
  • consider antibiotics only when abdominal pain, blood in the stool, and fever
  • best initial empirical = ciprofloxacin or other fluoroquinolones +/- metronidazole
  • TMP/SMX for Isopora
  • Doxycycline for Vibrio vulnificus
  • Rifaximin for traveler’s diarrhea

Giardia lamblia

  • flagellated protozoan, often acquired during hiking/ camping activities, by drinking unpurified water from streams
  • affects small bowel (duodenum and proximal jejunum) producing upper GI symptoms such as frequent burping, bloating, distention, flatus, and loose, nonbloody, foul-smelling and fatty diarrhea (steathorrhea).
Dx:
  • duodenal aspirate/ biopsy/ immunoassay
  • stool for parasites/ eggs
  • stool ELISA
Tx-
  •   metronidazole/ Tinidazole
**Giardiasis is the only common primary infection causing chronic malabsorption.

Pseudomembranous colitis

caused by C. difficile; Gram +ve superbug whose spores are contagious (fecal-oral or from the environment)
Girotra’s triad
  1. Increasing abdominal pain/distention and diarrhea
  2. Leukocytosis > 18,000
  3. Hemodynamic instability
Tx
  • Stop the causative antibiotic (if possible)
  • No treatment if asymptomatic
  • Metronidazole for symptomatic cases
  • Vancomycin may be better in severe disease
  • Consider surgery (urgent colectomy) if complications such as toxic megacolon developed; raised LDH and in deteriorating patient

Initial evaluation of Chronic diarrhea

Fat:
  • most useful screening test is stool for fat (Sudan red stain)
  • confirm with 72-hour stool for fecal fat (gold standard for steatorrhea)
  • Steatorrhea is most prominent with pancreatic insufficiency; all require a sweat chloride (to rule out CF and Schwachman-Diamond $)
  • Serum trypsinogen may also be used
  • Screen for carbohydrate malabsorption — measure reducing substances in stool (Clinitest)
  • Breath hydrogen test
  • Protein loss — difficult to evaluate directly
  • Screen with spot stool alpha-1 anti-trypsin level

Differential Diagnoses of Chronic Diarrhea

  1. most common infectious cause = Giadiasis
  2. most common congenital cause with malabsorption = cystic fibrosis
  3. most common anomaly cause with incomplete bowel obstruction + malabsorption= malrotation
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Food Poisoning from Fish/Seafood

Food Poisoning from Fish/Seafood
Scombroid food poisoning
results from eating spoiled (decayed) fish — most commonly reported with mackerel, tuna , bluefish, mahi-mahi , bonito, sardines , anchovies , and related species of fish that were inadequately refrigerated or preserved after being caught.
most rapid onset; allergic symptoms — wheezing, flushing, rash; in severe cases – resp distress, blurred vision, tongue swelling
Tx: antihistamines (eg, DPH)
 
Ciguatera
is the most common nonbacterial foodborne illness caused by eating certain reef fish whose flesh is contaminated with toxins originally produced by dinoflagellates such as Gambierdiscus toxicus which live in tropical and subtropical waters.
Most commonly implicated fish are barracuda, red snapper, and grouper
Onset within 2-6 hours;
S/S – Neurological symptoms – paresthesias, numbness, weakness, reversal of heat and cold as well as nausea, vomiting, and abdominal cramps
Saxitoxin is the toxin found in shellfish that ingest particular dinoflagellates
The toxin affects neuronal transmission leading to symptoms of cranial nerve dysfunction and muscle weakness — high risk for respiratory failure
Tetrodotoxin is the toxin expressed by the puffer fish, a fish considered to be a delicacy in some eastern Asian countries
S/S-  perioral numbness, increasing neurologic dysfunction, and eventual respiratory arrest secondary to profound muscle weakness

Paracetamol Poisoning

Toxic dose = 150mg/kg (75mg/kg if malnourished) or 12g in adults may be fatal (10-15g ~ 20-30 tablets)
Max. Therapeutic dose = 4g/day

Acute poisoning:
1 hr = larvage + activated Charcoal
4 hr = Paracetamol level
8 hr = N-acetylcysteine (within 8 hr, effectiveness is the same, afterwards it declines); alternative – Methionine
12 hrs = Review and repeat INR q12h
24 hr = review with results (see criteria for transfer)
48 h = review (if INR normal and pt stable, possible home)

N-acetylcysteine

  • to replenish hepatic glutathione

IVI regieme

1. 150mg/kg in 200mL of 5%DW x 15min
2. 50mg/kg in 500mL of 5%DW x 4 hr
3. 100mg/kg in 1L of 5%DW x 16 hr

 

Crieteria for transfer

  • Encephalopathy or increased ICP
  • INR >2.0 at <48 hr – or >3.5 at <72h (peak at 72-96h) N.B. LFTs are NOT good markers
  • Renal impairment ( Creat > 200), consider HD if >400) * monitor urine output and daily U&Es
  • Acidosis / Blood pH <7.3
    • Lactate > 3.5 mg/dL (0.39 mmol/L) 4 hrs after early fluid resuscitation
    • Lactate > 3 mg/dL (0.33 mmol/L) after full fluid resuscitation at 12 hours
  • Systolic BP < 80mmHg

 

King’s College Hospital Criteria for Liver transplantation

Paracetamol liver failure

  • Arterial pH <7.3 24 h after ingestion

Or all of the following:

  • PT > 100s
  • Creat > 300
  • Grade III or IV encephalopathy

Non-paracetamol liver failure

  • PT > 100s

Or 3 out of 5 of the following:

  1. Drug-induced liver failure
  2. Age <10 or >40y old
  3. >1wk from 1st Jaundice to encephalopathy
  4. PT > 50s
  5. Bilirubin > 300

Benign Lymphoepithelial lesion

  • Mikulicz’s disease – bilateral parotid and lacrimal gland enlargement
  • Mikulicz’s Syndrome – secondary to another disease, such as tuberculosis, sarcoidosis, lymphoma, and Sjögren’s syndrome
  • most likely to occur in adults >50 yrs; female preponderance
  • may need biopsy to differentiate  sialadenosis (sialosis)