GI Infections

Lin Cao

Ahmed Samy

Acute Diarrhea

Presentation 

  • ≥3 BMs/day or abnormally loose stools
  • Vast majority of infectious diarrhea cases are acute with more persistent diarrhea, consider additional workup for noninfectious etiologies as well
  • Can be watery or inflammatory (bloody stools, signs of sepsis, severe abdominal pain)
  • History: food hx (particularly undercooked meats or unpasteurized dairy), occupational exposures, recent travel, pet and animal exposures, immunocompromised

Evaluation 

  • Exam: volume status, abdominal pain
  • Labs: CBC for leukocytosis/eosinophilia, BMP for electrolyte abnormalities, BCx if c/f systemic illness, consider GIPP or stool testing if severe illness or immunocompromise

Management 

  • Most cases are self-limited and resolve with just supportive care
  • Antimotility agents: bismuth subsalicylate, loperamide
    • Avoid antimotility agents with C. diff and inflammatory diarrhea
  • Avoid abx with Shigella and EHEC (can precipitate HUS), Salmonella (prolongs carrier time)
  • Antibiotics only indicated with severe illness or certain immunocompromised hosts:
    • Cipro 500mg bid
    • Levofloxacin 500mg qd 3-5 days
    • Azithro 500mg qd 3 days

C. Diff (see GI section)

Other GI Infections

Less commonly infectious than acute diarrheal illnesses

Whipple disease (T. whipplei)

  • Constellation of arthralgias (can be the first symptom to appear), weight loss, chronic intermittent diarrhea, abdominal pain
  • Dx: upper endoscopy with biopsy with PAS and PCR testing for T. whipplei, can sometimes also do testing from synovial fluid/lymph nodes/etc
  • Tx: CTX 2g IV daily or PCN 2 MU IV q4h x 2 wks followed by Bactrim 1 DS tablet bid x 1 yr

Small intestinal bacterial overgrowth (SIBO)

  • Presents with bloating, abdominal discomfort, watery diarrhea
  • More commonly seen in pts with intestinal motility disorders, chronic pancreatitis, post-surgical changes (adhesions/strictures/blind loops)
  • Immunocompromised pts: consider CMV, MAC, TB, fungal etiologies, cryptosporidium
  • Tx: Rifaximin 1650mg qdaily for 14 days

H. pylori (see GI section)

Acute cholangitis (see GI section)

Viral Hepatitis (A-E)

  • Also consider HSV (especially in pregnancy), VZV, EBV, CMV though less common and usually seen more in immunocompromised pts
  • Evaluation
    • HAV, HBV, HCV IgG with PCR, HDV, HEV, EBV Qt, CMV Qt, HSV Qt, VZV IgM/IgG
    • LFTs: elevated AST/ALT (ALT>AST generally) that often precedes elevation of bilirubin
    • Can present on a spectrum of severity ranging from elevated LFTs to acute liver failure; get hepatology involved early for evaluation and monitoring

Hepatitis A

  • Presentation: self-limited, N/V, fever, malaise, abdominal pain, jaundice, dark urine
  • Transmission: Fecal oral transmission
  • Tx: supportive care, vaccine available

Hepatitis B

  • Transmission: perinatal, sexual contact, parenteral
  • Acute:
    • Presentation: Most pts have subclinical hepatitis but can present with serum sickness-like syndrome, anorexia, nausea, jaundice, RUQ pain, elevated LFTs
    • Tx: Generally supportive care unless severe illness, then generally treat with tenofovir/entecavir
    • HBV is less likely to become chronic than HCV
  • Chronic:
    • Presentation: Generally asymptomatic but can progress to cirrhosis and HCC
    • Extrahepatic manifestations 2/2 circulating immune complexes: polyarteritis nodosa, membranous nephropathy, aplastic anemia
    • Tx: entecavir/tenofovir, involve GI/ID, based on development of cirrhosis, ALT, HBV DNA level, immunosuppressed status.
    • Vaccine available

Hepatitis C 

  • Transmission: parenteral, blood transfusion (prior to 1992), sexual, perinatal transmission
    • USPSTF recommends screening in all adults 18-79
  • Acute Presentation
    • Generally asymptomatic but may have jaundice, nausea, dark urine, RUQ pain, elevated LFTs
    • Majority of hep C cases progress to chronic infection
  • Chronic Presentation:
    • Nonspecific nausea, diarrhea, abdominal pain, anorexia, weakness but can progress to cirrhosis and HCC, LFTs not always elevated
    • Extrahepatic manifestations directly related to viral infection: essential mixed cryoglobulinemia, membranoproliferative glomerulonephritis, thyroiditis, porphyria cutanea tarda, lichen planus, etc.
  • Tx: antivirals targeted to HCV genotype, however, there are pangenotypic regimens. Recheck viral load after 12 wks

Hepatitis D

  • Requires HBV for infection, consider screening with HBV

Hepatitis E

  • Presentation: self-limited acute infection with jaundice, malaise, anorexia, N/V, ab pain
  • Transmission: Fecal oral transmission Significantly higher mortality in pregnant individuals
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