Infectious Diseases of the GI tract Flashcards
What types of diarrhea are more likely to be upper abdominal vs lower abdominal?
Watery: Upper abdominal - affects mainly the small bowel via enterotoxins or altered absorption of villus tip
Inflammatory: Lower bowel / colon - invasion of GI mucosa and production of a cytotoxin
What are common day-care center related diarrhea precipitants? Pages 499-500 of the coursepack are all good review of diarrhea
Shigella, Rotavirus, Giardia, Cryptosporidium - all of which are fecal-oral with low inocula
Should you use antibiotics in EHEC?
No, they are not effective and may promote heolytic uremic syndrome
Should you give antibiotics for Salmonella?
Only for the enteric fever or extra-instestinal infection, otherwise they are not necessary for gastroenteritis (unless immunocompromised / high risk groups)
What three pathogens should always be included on routine cultures?
Campylobacter, Salmonella, and Shigella
What are the most common causes of non-infectious hepatitis?
Drugs / medications - i.e. Rifampin, Augmentin
Alcohol
Cholecystitis
Obstructed bile duct
What zone is at highest risk of becoming hypoxic in the liver?
The “centrilobular” zone, which is the farthest from the oxygen-rich portal triad, and the closest (radially) to the terminal hepatic vein
What is the main feature of chronic hepatitis on a cellular level which does not occur in acute?
Bridging fibrosis and necrosis + fatty changes is much more common in chronic hepatitis.
This is direct connections between the portal triad and the central veins.
What is acute hepatitis marked by on a cellular level?
- Lobular disarray - pattern of sinusoidal cords
- Ballooning and eosinophilic degeneration of hepatocytes leading to “Councilman bodies”
- Spotty necrosis
- Lymphocyte infiltration / inflammation
- Cholestasis (impairment of bile secretion)
What are the four clinical stages of viral hepatitis? What percentage of patients become jaundiced?
- Incubation
- Pre-icteric - where most of symptoms occur
- Icteric - only occurs in 20-50% of patients
- Convalescence - recovery
What are the common initial symptoms in the pre-icteric phase?
Malaise, anorexia, nausea / vomiting, dull RUQ pain, low grade fever (all before the jaundice). Can even have headache, myalgia and sore throat (nonspecific).
What usually brings viral hepatitis patients to the doctor?
Icteric phase - Jaundice or dark urine (from conjugated bilirubin showing up in the urine)
What hepatitis is a serum-sickness like syndrome associated with and what describes it?
Hep B - pre-icteric phase - arthralgias or arthritis, urticaria, fever
What color are stools in the icteric phase, and why might itching develop in severe disease?
Light - due to lack of unconjugated bilirubin
Itching may develop from bile salts accumulating in the skin
What defines fulminant viral hepatitis?
Lethargy, stupor, or coma, with widespread liver necrosis on biopsy. Asterixis (hand tremor) may result from ammonia accumulation in CNS.
It is uncommon
What labs are most elevated in viral hepatitis?
Aspartate and alanine aminotransferases (AST / ALT) 8-100 times normal
What labs are only modestly elevated in viral hepatitis, except in cholestasis patients?
- Alkaline phosphatase
- 5’ nucleotidase
- Gamma-glutamyltransferase
When is bilirubin elevated? are PT time, albumin, globulin, and hemoglobulin affected in acute disease?
Bilirubin elevated in icteric phase only
All other labs stay pretty normal throughout disease
What clinically defines an inactive carrier of HepB?
Positive HBsAg in blood, with no anti-HBsAg in blood for greater than 6 months with normal liver function tests (AST/ALT)
What percentage of people develop chronic hep B, and what is the most at-risk population?
About 10% of adults, but 90% of newborns will
What clinically defines Chronic hepatitis B?
Same as inactivate carrier stage, with HBsAg in blood, no anti-HBsAg, but abnormal liver function tests.
Often “e” antigen will be positive, along with HBV DNA and DNA polymerase (P protein).
Serum aminotransferases will vary widely over the course of the infection
What mediates the severity of Chronic hep B?
Immune tolerance = mild disease
Immune active = moderate or severe disease processes
In what percentage of Chronic hep B will there be cirrhosis and hepatocellular carcinoma?
cirrhosis - 25-30%
hepatoma - 5%
What percentage of people infected with Hep C will develop chronic disease? What clinically identifies this?
85%
Will have widely fluctuating ALT/AST levels, but not feel “sick” until very advanced stages
