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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Poisoning with Alcohol and Related Substances

Poisoning with Alcohol and Related Substances

Methanol and Ethylene glycol poisoning

1) Methanol can cause retina injury leading to blindness ( eye manifestations can happen as early as 15-20 hours post ingestion) ?  secondary to the accumulation of formic acid/ formaldehyde;

That’s why the first thing you do in suspected methanol poisoning is …

to check retinal inflammation

Methanol can be found in wood solvent, sterno, paint thinner, photocopier fluid, and cleaning solutions such as windshield washer solution

2) Ethylene glycol (coolant, anti-freeze) poisoning
toxic metabolite is Oxalic acid/ oxalate >> damage kidneys
usually has 3 distinct clinical phases-

  1. first stage- CNS effects ( first 12 hours),
  2. second stage- cardiopulmonary effects ( HTN, CCF, ARDS etc) metabolic acidosis with high anion gap and high osmolar gap and
  3. third stage- renal effects- ARF.

Tip to memorize: You see? going from top to bottom in order –  CNS -> CVS -> Renal

Initial Dx – check hypocalcemia, envelope-shaped oxalate crystals in urine

Mx

Acute management include gastric lavage and correct the metabolic acidosis.
fomepizole, an inhibitor of alcohol dehydrogenase, is now used first-line in preference to ethanol, however it cannot remove toxic substance formed already.


Haemodialysis can be done for effective and faster removal of the toxic metabolites.

Folinic acid can be used to protect against ocular toxicity of methanol whereas thiamine are administered to drive metabolism of ethlylene glycol to non-toxic metabolism.

Isopropyl alcohol ingestion and toxicity may be known only by the history, presentation with normal anion gap acidosis and specific drug level.

Alcohol

Mild withdrawal:
  • tremors, tachycardia, and anxiety;
  • Seizures may occur 6-12 hrs after the last drink
Delirium tremens (DT):
  • manifests 48-72 hrs after the last drink but can last up to 10 days
  • Mental confusion
  • autonomic hyperactivity
  • visual hallucinations
  • severe agitation
  • diaphoresis
Alcoholic hallucinosis:
  • may be confused with DT
  • starts 12-24 hours after last drink but can last days to weeks
  • Paranoid psychosis without tremors and confusion
  • Normal vital signs (no HTN and tachycardia)
  • No agitation
  • Normal appearance except for auditory (most common), visual, or tactile hallucinations
Wernicke encephalopathy:
  • Confusion, ataxia, and ophthalmoplegia (nystagmus)
Korsakoff psychosis:
  • Amnesia and confabulations
*alcohol withdrawal has a very high mortality rate (5%)
Tx
Benzodiazepines
avoid antipsychotics/neuroleptics such as haloperidol (due to risk of lower seizure threshould and prolonged QT interval)