Diarrhea Flashcards
Secretory diarrhea and fasting
A 24-;48 hour fast does not stop secretory diarrhea, except in fatty acid-and bile acid-related diarrheas
osmotic gap in osmotic diarrhea
> 50
If an osmotic diarrhea persists despite a 24-hour fast
suspect surreptitious ingestion of a Mg-containing antacid. Most laxatives, including castor oil, cause an osmotic diarrhea
Stool osmolality that is greater than serum osmolality
indicates an improper stool collection procedure
AB in invasive diarrhea
TMP/SMX
Quinolones
AB for Campylobacter
erythromycin
AB for amebiasis
metronidazole
AB for E. coli O157:H7 infection (EHEC).
is treated only symptomatically. Antibiotics are contraindicated
If you suspect E coli O157:H7
specifically ask for MacConkey-sorbitol agar for the stool culture media. If you suspect Clostridium difficile, also add C. difficile toxin assay.
Treat travelers’ diarrhea with antibiotics if
Treat travelers’ diarrhea with antibiotics if the patient is febrile (TMP/SMX, ciprofloxacin, doxycycline, bismuth subsalicylate); otherwise, usually treat by replacing fluid and with antimotility drugs (e.g., diphenoxylate + atropine [Lomotil)
the most common cause of invasive diarrhea
Campylobacter
suspect this bacteria especially in patients with sickle cell or achlorhydria
Salmonella
usually ingested from undercooked/raw poultry or unpasteurized milk, but may also be obtained from drinking water from mountain streams, foreign travel, or contact with infected dogs and cats.
Campvlobacter jejuni
Symptoms of Campylobacter
Symptoms of Campylobacter enteritis include abdominal cramping and diarrhea that is often bloody. Symptoms last 5-7 days, but may be shortened by taking erythromycin
What is the first and most critical laboratory test to do in an acute diarrhea workup?
fecal WBC
A stool culture in a patient with common “travelers’ diarrhea” will usually show what?
normal flora
Which diarrheal organism is Guillain Barre most commonly linked to?
Campylobacter
especially associated with ingestion of raw eggs or contaminated icc cream
Salmonella
The larger the dose of Salmonella, the worse the disease.
Salmonellosis consists of
fever, abdominal cramps. and diarrhea-often bloody,
do we treat salmonella diarrhea with AB?
most of the time you do not treat Salmonella diarrhea with antibiotics
a major reservoir for EHEC
Dairy cattle
and the disease is linked to eating undercooked beef and unpasteurized milk or apple juice.
These patients more commonly experience nausea and vomiting, compared to other bacterial colitides
EHEC
which diarrhea organism can cause HUS
EHEC
HUS associated with E coli O157:H7 (EHEC)presents with what triad of symptoms?
HUS classically has the triad of kidney failure, thrombocytopenia with purpura, and hemolytic anemia
correlation between pseudomembranous diarrhea and AB
This usually presents in about a week after starting antibiotics.
but it may start up to 6-8 weeks after antibiotics are stopped!
the best test for Clostridium difficile:
Because the organism is carried in 20% of healthy persons, the best test for disease is finding the toxin in the feces using the
C. difficile toxin assay
when to consider C.difficile
Consider C. difficile anytime diarrhea occurs > 6 days after initiation of antibiotics.
Also suspect C. difficile infection in patients on antibiotics in whom unexplained leukocytosis (WBC > 15,000) develops.
Diagnosis of C. difficile:
First, do a fecal leukocyte (very sensitive). If fecal leukocyte is positive, do an EIA (best) or toxin assay (good, just a long wait).
If the patient with AIDS has diarrhea and weight loss without fever. suspect
Cryptosporidia (usual cause), E. histolytica, Giardia, Isospora, Strongyloides, and AIDS enteropathy
If the patient with AIDS has diarrhea and weight loss with fever. suspect
Mycobacterium, Campylobacter, Salmonella, Crvptococcus, Histoplasma, and CMV .
A CD4 count < 200. especially if accompanied by weight loss, points to which etiology of diarrhea in AIDS?
points to an infectious etiology rather than AIDS enteropathy
Diabetic diarrhea may be caused by:
- use of dietetic foods rich in sorbitol (erroneously labeled “sugarless”)
- visceral autonomic neuropathy (especially suspect this in the incontinent diabetic patient),
- malabsorption (less common) due to sprue (present in 5% of diabetics), pancreatic insufficiency, or bacterial overgrowth (treat with metronidazoleor arnoxicillin-clavulanate)
where most of the secretory carsinoids are located?
About 75% of the secreting, symptomatic carcinoids are in the ileum,
Diagnosis of carsinoids(secretory)
Diagnosis: check 24-hour urine for 5-hydroxyindoleacetic acid (5-HIAA)-a breakdown product of 5-hydroxytryptamine. Normal is < 10 mg/24 hr; with carcinoid, patient has > 25 mg/24 hr.
What is the best way to diagnose giardial infection?
II is best diagnosed with an enzyme-linked immunosorbent assay for Giardia antigen. This is both sensitive (92%) and specific (99%), and becomes negative after successful therapy (i.e., this is an antigen test, not an antibody test). The classic series of 3 stool specimens is only 60-80% sensitive
What are the symptoms of a secreting carcinoid?
The symptornatic carcinoids [Know] secrete various vasoactive mediators, including 5..hydroxytryptophan, 5-hydroxytryptamine. and histamine, which cause paroxysmal flushing; crampy, explosive diarrhea; and sometimes tachycardia and hypotension. The flushing is often bright red with well defined borders and can be on the whole body-including hands and soles.
What are the 3 stages used in the workup of chronic diarrhea?
Stage I: Stool O&P & fecal leukocytes x 3.
Stage 2.:Imrnunoabsorbent assay for giardiasis.
Stage 3: EGD and colonoscopy.
