GI Infections

Definitions

• "Diarrhea"
  • Increase in water content, volume or frequency of stools.
  • Typically ≥3 stools/day (defined epidemiologically)
• "Infectious Diarrhea"
  • Diarrhea due to infectious etiology.
  • Often accompanied by nausea, vomiting, abdo cramps. 
• "Acute Diarrhea"
  • ≤14 days
• "Chronic Diarrhea"
  • >14 days (Sometimes >30)

Food-Related Diarrheal Illnesses

• 
• Questions on history:
  • Characterize Symptoms:
    • Onset
      • abrupt? gradual? duration?)
    • Stool Characteristics
      • Watery, bloody, mucous, purulent, greasy etc..
    • Frequency of BM + quanity of stool
    • Dysenteric symptoms
      • fever, tenesmus (feeling need to passing stools, despite empty colon), blood and/or pus in stool
    • Volume Status
      • Thirst, tachycardia, orthostasis, decreased urination, lethargy, skin turgor
    • Associated Sx:
      • Nausea, vomiting, abdo pain, cramps, headache, myalgias, sensorium
  • Epidemiological Risk Factors
    • Travel to developing area
    • Day care
    • Unsafe foods (raw meats, eggs, shellfish, unpasteurized milk)
      • Swimming in or drinking untreated fresh surface water (lake/stream)
    • Sick contacts
    • Medications (antibiotics, antacids, anti-motility agents)
    • Medical Conditions (AIDS, immunosuppression)
    • Receptive anal intercourse

Clostridium Difficile

Source: "A woman with community-acquired Clostridium difficile infection" by Christopher Kandel, et al (2012) CMAJ

Source: Orange book

source: NEJM+ Knowledge

Click here for 2010 guidelines. 

• Risk Factors
  • Antibiotic use in last 3 months (most modifiable)
    • Clindamycin
    • Fluoroquinolones
    • Broad-spectrum penicillins
    • Cephalosporins
  • PPIs
  • Previous abdo sugery
  • Age ≥65
  • IBD
  • Recent hospital stays
• Symptoms:
  • ACUTE non-bloody watery diarrhea (occasionally bloody).
  • Lower abdominal pain
• Clinical Features:
  • Fever, High WBC count
• Complications:
  • Fulminant colitis (2-3%)
  • Toxic megacolon (triad: colon dilation ≥ 6cm on KUB, colonic atony, systemic toxicity)
  • Bowel Perforation
• Diagnosis:
  • Stool PCR -many false negatives of colonization
  • (OR toxin assay EIA detects toxin B or A, fast, more specific)

• Treatment
  • Stop offending abx (or shorten course)
  • Stop anti-motility agents
  • Determine if Severe or Non-Severe

    • Severe Vs. Non-Severe C.diff infection ANY of the following:     1. Leukocytosis WBC ≥ 15,000 /uL   2. Creat 1.5x patient's baseline   For Severe, differentiate by: Complicated Vs. Uncomplicated ANY of following  1. Hypotension   2. Shock   3. Ileus   4. Megacolon

  • If NON-SEVERE (mild-to-mod)
    • Metronidazole 500mg po q8h  x10-14d
      • (new evidence, but not in guidelines, to start with OR Vancomycin 125mg PO q6h)
        • (NEJM paper: equal cure rates, MTZ less well tolerated)
    • Treat for 10-14d 
  • If SEVERE:
    • Vancomycin 125mg po q6h  x 10-14d (+/- Metronidazole)
  • If SEVERE + COMPLICATED
    • Vancomycin 500mg QID PO/NG + metronidazole 500mg IV q8h
    • (If Ileus, add PR vanco)
  • If worsening  (ileus, rising WBC, rising lactate, shock, toxic megacolon, peritonitis)
    • Abdo CT
    • Urgent SURGERY CONSULT (subtotal colectomy (?diverting loop ileostomy or colonic lavage)
    • Consider PR vanco
  • NOTES
    • if cannot discontinue offending abx... continue C.diff therapy until ≥7d abx stopped. 
    • Stools may continue to be C.diff positive (do not retreat unless symptoms)
  • Recurrence:
    • 15-30% risk (usually in 2w of stopping abx therapy)
    • 1st Recurrence: Same as initial episode
    • 2nd Recurrence: Vancomycin PO pulse + taper.
      •  Consider ID, consider fecal transplant (NEJM 2013, JAMA 2016), or fidaxomicin 200mg BID x10d. 
  • Probiotics Saccharomyces boulardii - reduce recurrence risk. (avoid in immunosuppression).
    • Studies controversial.  
    • Most antibiotics not helpful (Lancet 2013)
  • 
• Monitor Treatment
  • Watch complications:   Ileus, Peritonitis
  • Typically diarrhea x3-4 days resolves by day 7.
  • Do not re-test stool (toxin persists for up to 6 weeks (40%))
• Prevent Spread
  • Contact precautions!!
  • Two factors in prevention:
    • 1. Limiting Transmission
    • 2. Minimizing abx exposure 
  • Hand hygeine important!
    • Use Soap & Water.  C. diff spores are resistant to EtOH-based hand sanitizers.
    • All eqiupment wash with hypochloride-based solution.
• Future Research:
  • Fidaxomicin vs. vancomycin --> similar cure rates.
    • Fidaxomicin had lower recurrence than vanco.
  • Monoclonal antibodies to C.diff toxin A and B reduce recurrence.
  • Rifaximin (minimally-absorbed macrolide) - given for two weeks after course of vanco decreased recurrence.
  • Fecal transplant - Observational studies --> effective to prevent recurrence.
    • No standardized regimens and no RCTs.

Liver Abscesses / Cholangitis

• Sources:
    1. Biliary tract infection
    2. Portal vein bacteremia  (Appendicitis, diverticulitis, IBD)
    3. Direct extension (perfed duodenal ulcer, perfed gall bladder, or perinephrin/pancreatic/subphrenic abscess).
    4. Skin (Penetrating wounds, surgical)
    5. Bactermia (any cause, via hepatic artery and multiple abscesses)
    6. Unidentified (25% of cases)
   
• Organisms:
  • 1. Gram negatives + (Enterococcus) + anaerobes.!!!! (MOST COMMON)
  • 2. Skin organisms (S. aureus, GAS)
  • 3. Bacteremia (S.aureus, Strep angionus?, Klebsiella, Odd things)
• Organisms (approach #2)
  • By site of primary infection
    • Peritonitis
      • Usually polymicrobial
        • Anaerobes (Bacteroides, Fusobacterium Peptostreptococcus, Actinomyces, and microaerophilic streptococci (S. milleri)
        • Gram-negatives (K. pneumoniae - esp the K1 serotype)
    • Candida (if immunocompromised)
    • Amoebic liver abscess 
• Treat with Amox-Clav for 3-4-6 weeks (esp longer if cannot drain abscesses)
  • If allergic to amox clav then treat with Cipro-flagyl (ignore Enterococcus).