Diarrhea Flashcards
What are the two preferred drugs for treatment of Campylobacter jejuni?
-
Quinolones (Ciprofloxacin)
- Inhibits DNA gyrase and/or topoisomerase IV
-
Azithromycin, erythromycin
- Binds 50S ribosomal subunit, blocking mRNA translocation
What are some potential alternatives for treatment of Campylobacter?
- Gentamicin
- Carbapenem
- Tetracycline
Among the macrolides, what differences might provide an advantage for azithromycin vs. erythromycin?
-
Erythromycin
- Pro-kinetic agent
- Risk for arrhythmias, cardiac arrest
- Drug interactions, CYP3A inhibitor
- More frequent dosing
-
Azithromycin
- Lower incidence of GI effects
- Lower incidence of cardiac effects
- Few drug interactions
- Less frequent dosing
Salmonella (non-typhi) & Shigella
What are the basic properties of these bugs?
What are the implications for drug resistance?
- Gram-negative rods
- Facultative anaerobes
- Members of the Enterobacteriaceae family
- ß-lactamase (often transmissable) has become quite common in this family
What are the approved drugs for Shigella & Salmonella?
- Ampicillin (both)
- TMP/SMX (Shigella)
- Ciprofloxacin (both)
What are the drugs used for Shigella & Salmonella?
- Ciprofloxacin
- Ceftriaxone
- Azithromycin
Why does prophylactic antibiotic therapy increase the risk for contracting Salmonella & other enteric infections?
It suppresses the normal flora
- GI normal flora is an important barrier to infection with enteric pathogens including Salmonella
What drugs are FDA-approved for C. difficile?
- Vancomycin
- Fidaxomicin
________ is a common accepted therapy for C. difficile, but is not formally FDA-approved for this use.
Metronidazole
Mutations in RNA polymerase ß (rpoB) could result in decreased sensitivity to ________.
Fidaxomicin
- Macrocyclic that blocks formation of RNA polymerase open promoter complex
Describe Metronidazole resistance in C. difficile
- Often transient
- Lost in storage
- After freeze/thaw
Which drug for C. difficile has the narrowest spectrum of antibiotic activity?
Fidaxomicin
- Primarily Clostridium only
- Some effects on Peptostreptococcus
- No effects on other gram positives or negatives
What are the possible contributors to lower recurrence of C. difficile with fidaxomicin than vancomycin?
- Less disruption of normal flora
- cidal (time-dependent) vs. static effect of vancomycin on C. difficile
- Fidaxomycin has an active metabolite OP-1118
- Fidaxomycin has post-antibiotic effect (6-10 hr)
When using oral vancomycin for treating C. difficile, which drug side effects would you expect?
Nausea, abdominal pain
- Oral vancomycin is very poorly absorbed
- Maintains high colonic concentrations
- Less likely to get systemic side effects (red man, ototoxicity, nephrotoxicity) w/ oral dosing
- IV - phlebitis
For patients unable to take oral drugs, what can be given IV for treating C. difficile?
Metronidazole
*IV vancomycin has no effect on C. diff enterocolitis
C. difficile spores germinate in the ____________ upon exposure to bile acids.
_________ facilitate C. difficile movement
C. difficile multiplies in the _____
small bowel
flagellae
colon
The most common cause of infectious diarrhea in children is _______.
Viral
True/False
Gatorade is adequate for severely ill patients
FALSE
- WHO recommends
- 3.5 g NaCl
- 2.9 g trisodium citrate or 2.5 g Na2CO3
- 1.5 g KCl
- 20 g glucose or 40 g sucrose
- 1 L of water
Constipation is a very common problem with _____ use.
opioid
afebrile
fluid overload
scleral icterus
petechial rash on LE
bilateral LE edema to ankle
E. coli O157:H7
Hemolytic Uremic Syndrome
Hemolytic Uremic Syndomre after antibiotics
Enterohemorrhagic E. coli (O157/H7)
Traveler’s diarrhea & post-infectious IBS
Enterotoxigenic E. coli
Guillain Barre Syndrome
Crohn’s Mimic
Pseudoappendicitis
Campylobacter
Pet turtles
Osteomyelitis in sickle cell/asplenic patients
Salmonella
Day care/institutions
HUS, but less common
Seizures
Reactive arthritis
Shigella
(S. dysenteriae for HUS)
Shellfish contamination
Vibrio cholerae
Most common cause of C. difficile worldwide
Cruise ships
Norovirus
Most common pediatric cause of C. difficile
Rotavirus
When should you order a stool culture?
- Severly ill
- Outbreaks
- Require hospitalization
- Immunocompromised patients (HIV)
- Patients w/ co-morbidities (IBD)
- Some employees, such as food handlers or daycare providers, may require negative stool cultures to return to work
What empiric antibiotics are used to treat Traveler’s Diarrhea?
- Moderate-severe
- Fluoroquinolone or TMP-SMX
What are the indications for empiric antibiotics?
- >8 stools/day
- Volume depletion
- Symptoms >1 wk
- Hospitalize patients
- Immunocompromised hosts
When should anti-motility agents be used?
What are some examples?
- ONLY if fever is absent & stools not bloody
- Bacterial translocation
- C. diff –> toxic megacolon
- Loperamide or diphenoxylate
What is osmotic diarrhea?
- Neither the small intestine nor the colon can maintain an osmotic gradient
- Unabsorbed ions remain in the lumen
- Retain water
- Maintain intraluminal osmolality (290 mOsm/kg)
What can cause osmotic diarrhea?
- Ingestion of poorly absorbed ions or sugars or sugar alcohols
- Mannitol, sorbitol
- Magnesium, sulfate, phosphate
- Disaccharidase deficiency will prevent absorption (lactose intolerance)
How does osmotic diarrhea present clinically compared to secretory diarrhea?
- Osmotic diarrhea disappears with fasting or cessation of the offending substance
- Electrolye absorption is not impaired in osmotic diarrhea
What are the causes of secretory diarrhea?
What is the most common cause?
- Either net secretion of anions (Cl or H2CO3) or inhibition of net Na absorption
- The most common cause is infection
- Enterotoxins
- Interact w/ receptors & modulate intestinal transport
- Block specific absorptive pathways, in addition to stimulating secretion
- Inhibit Na/H exchange in the small intestine & colon
- Peptides produced by endocrine tumors
What is the osmotic gap?
Osmotic gap = serum Osm - Est stool Osm
2 x (Na + K) ~ 290 mmol/L
small osmotic gap <50
gap >100 indicates osmotic diarrhea
What is the clinical presentation of “classic Celiac Disease”?
Diarrhea, bloating, abdominal pain & weight loss
“Atypical” Celiac Sprue
- Iron Deficiency
- Osteoporosis
- Dermatitis Herpetiformis
- IBS
- DM type 1
- Elevated LFTs
Where is folate absorbed?
Where are the fat-soluble vitamins absorbed?
Where is vitamin B12 absorbed?
- Folate & DAKE
- Duodenum & jejunum
- Vitamin B12
- Ileum
What is the non-GI presentation of Celiac Disease?
- Unexplained iron-deficiency anemia
- Folic acid or VitB12 deficiency
- Reduced serum albumin
- Unexplained elevated LFTs
- Other autoimmune disorders
- Type 1 DM
- Thyroid disfunction
- Addison disease
- Primary Biliary Cirrhosis
- Sjogren’s disease
- Autoimmune hepatitis
- Down syndrome & Turner syndrome
- Selective IgA deficiency
All newly diagnosed Celiac Disease patients should have a __________.
bone density
What are the malignant complications of Celiac Disease?
- Enteropathy Associated T-cell Lymphoma
- High-grade T-cell NHL
- 5 yr survival ~10%
- 20X more in CD
- Risk normal on GFD
What is the most clinically useful serology for CD?
What is seen on small intestinal biopsy?
- IgA Tissue Transglutaminase (tTG)
- “scalloping” or “notching” of the folds
- Small intestinal villous atrophy, intraepithelial lymphocytosis & crypt hyperplasia
What does a gluten free diet consists of?
Avoid all foods containing wheat, rye & barley gluten
Avoid malt
