Microbiology of the Liver Flashcards
what is the most common reason for liver transplantation?
viral hepatitis
Out of the all the different types of hepatitis:
- which ones are acute?
- which ones are chronic?
- which ones are faeco-oral route?
- which ones are sex/permucous transmission?
- which ones have immunisations?
1) A+E (think acute - go to a&e)
2) C,B,D
3) a+e (when your in a&e you hav a shit time)
4) C, B,D
5) A, B, D
How is Hep A diagnosed in acute and past infection setting ?
EIA -enzyme immune-assay to detect for an antigen.
What is the treatment for Hep A?
Acute - EIA detects IgM for Hep A virus
Past infection = EIA detects IgG
No treatment - do LFTs to ensure liver is healing.
How is Hep B diagnosed?
Treatment for Hep B?
Blood test for HBV surface antigens: HBsAg
1 - interferon
2 - Lamivudine (inhibits reverse transcriptase)
How (when) is Hep C diagnosed?
Treatment for Hep C?
Antibody test for HCV works 4 weeks after infection
1 - Interferon
2 - Ribavirin - RNA synthesis inhibitor
Pathophysiology of Hep B and C
Chronic perisistent hepatitis (asymptomatic)
Chronic active hepatitis
Cirrhosis
HCC
- Do children always develop chronic infections after Hep B infection?
- Do adults always develop chronic infection after a Hep B infection?
90% of the time, yes
Only 5% of the time
- What are the common and uncommon causes of viral hepatitis?
- In what groups are the ‘uncommon’ sources of infection actually more common than the ‘common’ sources of infection?
Common Hepatitis A (HAV) Hepatitis B (HBV) Hepatitis C (HCV) Hepatitis D (HDV) Hepatitis E (HEV)
Uncommon Adenovirus Cytomegalovirus (CMV) Epstein-Barr virus (EBV) Herpes simplex virus (HSV)
In the immunosuppressed.
• Which are the enteral hepatitis-causing viruses? Enteral = in the gut,
so HAV and HEV are the enteral pathogens. These cause the acute, self-limiting infections.
• Which of the common viruses resembles a plant virus?
HDV
• What are the signs and symptoms of someone with an acute viral hepatitis?
o Main three to remember are: 1. Jaundice 2. Fever 3. RUQ pain o Others include loss of appetite, nausea, vomiting, dark urine, pale stools, hepatomegaly, joint pain
• In what body fluids is Hep B the highest?
o Highest in blood
o Intermediate in semen, vaginal fluid and saliva
What is the first line diagnostic technique for Hep B?
Why is this unique?
Serology for the surface polypeptide that Hep B makes in massive amounts. HBsAg
This is unique because all the other Hepatitides are diagnosed using PCR.
• What is the e antigen? HBeAg
The hepatitis antigen that suggests an active and replicating HBV infection if you find lots of it on a blood test. This implies high infectivity.
• How does HBV replicate?
- DNA gets inside nucleus
- Covalently closed circular DNA, cccDNA, is formed (i.e. the DNA becomes a ring)
- This DNA is transcribed so that new particles can be made
• Is cccDNA present in people who don’t have an active Hep B infection?
- theoreticallly how can you get rid of cccDNA?
Yes, the cccDNA can hide in the hepatocytes without causing an active infection. Hence why people can develop a chronic HepB years after intial infection in periods of immunosuppression. Theoretically the only way to get rid of this cccDNA is to have a liver transplant.
• If you acquire Hep B early, are you more or less likely to develop chronic HepB?
o If you’re young, you’re more likely to develop chronicity
o If you’re old, you’re more likely to clear the virus
• What serological markers are present during a typical course of HBV infection?
Post infection:
At 1 month:
At 2 months:
At 3 months:
At 6 months:
1 month: HBsAg (hep B surface antigen appears)
2 months: HBeAg (e antigen) tells you that virus is replicating quickly + pt is very infectious.
Anti- HBc (antibody against HBV core present all the wat through from 2 months onwards - start off as IgM and end up as IgG - keep for life)
3 months: anti-HBe antibodies appear against HBeAg and antigen disappears.
6 months: anti-HBs antibodies appear and HBsAg disappears.
As antibodies appear the corresponding antigens disappear.
what does the HBV vaccination involve?
Injection of the HBsAg so that your body makes anti-HBs, which will protect you from a later infection.
• How does the serology compare of someone who has had HBV in the past versus someone who has been immunised to HBV in the past?
o They both have anti-HBs antibodies
o Only the person who has been infected with actual HBV in the past will have the IgG antibodies against the HBV core protein (Anti-HBc)
Relevance if raised:
1) HBV surface antigen: HBsAg
2) HBV core antibody (IgM type) Anti-HBc IgM
3) HBV core antibody (IgG type) Anti-HBc
4) HBV e antigen: HBeAg
5) HBV e antibody: Anti-HBe
6) HBV surface antibody: Anti-HBs
1) means you’re infected (acute or chronic )
2) had a recent infection
3) infection in the past
4) infected and have a high viral load - very infectious
5) been infected in the past
6) infected in the past or immunised
• What would be an ideal therapy for HBV infection for the future?
A cccDNA antiviral
• How do you define chronic hep B?
On-going infection (so you have HbsAg) for >6 months
HEPATITIS A
1) is there a vaccine?
3) what is the treatment?
4) why does it pose an infection control risk?
5) Why can you never get Hep A twice?
1) yes
3) merely supportive (check LFTs and clotting)
4) HAV is found in stool of infected patient.
5) IgG response is lifelong.
