Session 6- Blood Borne Viruses- HIV and Hepatitis

Question 1

HIV life cycle

Answer 1

1- free virus
2- binding and fusion- binds to CD4 receptor
3-virus penetrates cell
4-reverse transcription RNA TO DNA
5- integration- viral DNA is combined with the cells own DNA by the integrase enzyme
6- transcription- when infected cell divides viral DNA is read and long chain proteins are made
7- assembly viral protein chains come together
8- budding- immature virus pushes out of cell membrane with it

Question 2

transmission

Answer 2

: Contact of infected bodily fluids with mucosal tissue /
blood / broken skin – sexual contact, blood transfusion, contaminated needles,
vertical transmission to fetus during delivery. Some medical procedures carry a risk
of transmission

Question 3

what happens when CD4 cell count drops

Answer 3

Once CD4 cell count drops below 350 cells/µl you begin to get more symptoms – a cold you can’t shake, athlete’s foot

Once less than 200 cells/µl – you begin to see severe infections,
AIDS defining symptoms and cancers linked with HIV/AIDS.

Question 4

diagnostic tools for HIV

Answer 4

– a) serology – detects
both antigens (viral proteins) and antibodies to HIV in the blood,

b) PCR – detects the
viral nucleic acid

c) rapid testing

Question 5

treatment of HIV

Answer 5

Every patient is treated as soon as possible with ARVs (anti-retroviral drugs)
regardless of CD4

Question 6

how do antiretroviral drugs work

Answer 6

Anti-retroviral drugs work by targeting the binding (CCR5 – entry inhibitor), the
enzymes responsible for incorporation of viral DNA into host DNA (Integrase
inhibitor), for breaking down the large proteins into smaller units (protease inhibitor)
during the maturation phase of the viral life cycle and reverse transcriptase (Nonnucleoside reverse transcriptase inhibitor (NNRTI ) – non-competitive inhibitor or
Nucleoside reverse transcriptase inhibitor (NRTI) - competitive substrate inhibitor)

Question 7

strategies to reduce prevalence of HIV

Answer 7

• Increase condom usage
• ARV treatment as prevention
• Wide-spread testing/screening
• Prevention of mother-to-child transmission
• Post-exposure prophylaxis (PEP)
• Pre-exposure prophylaxis (PrEP)
• Male circumcision
• Combine the above

Question 8

what viruses cause collateral liver damage

Answer 8

EBV- Epstein Barr Virus
CMV- cytomegalovirus
VZV- Varicella Zoster

Question 9

icteric sclera

Answer 9

white of eye turns yellow

Question 10

what kind of hepatitis does viral hepatitis cause

Answer 10

intrahepatic

Question 11

what does raised bilirubin indiacte

Answer 11

either the pre-hepatic, intrahepatic or extrahepatic

processing of this product.

Question 12

what does raised ALT AST indicate

Answer 12

If ALT (Alanine transaminase) or AST
(Aspartate aminotransferase) are elevated it tells us there is hepatocyte damage and the problem is
intrahepatic.

Question 13

ALT

AST

Answer 13

alanine transaminase

aspartate aminotrasnferase

Question 14

raised ALP indicates…

Answer 14

If ALP (Alkaline phosphatase) is elevated
there is a problem in the biliary tract- extra hepatic

Question 15

transmission if Hep B

Answer 15

Transmission is predominantly vertical (75% of cases globally) but also through
sexual contact, intravenous drug use, close household contacts (low risk) where
there is significant blood exposure and health care workers via needle stick injuries.

Question 16

symptoms of hep b

Answer 16

jaundice, fatigue, abdominal pain,

anorexia/nausea/vomiting and arthralgia (joint pain)

Question 17

HEP B serology

Answer 17

in a blood test you can detect HBsAg & HBsAb, HBeAg

& HBeAb, HBcAb (IgM followed by IgG (HBcAg is undetectable in blood))

Question 18

C diff

Answer 18

Clostridioides difficile [klos–TRID–e–OY-dees dif–uh–SEEL]

a gram-positive, anaerobic, spore-forming bacillus that is responsible for the development of antibiotic-associated diarrhoea and colitis (bowel inflammation).

Question 19

microbiology of c diff

Answer 19

C. difficile is an anaerobic bacteria. The presence of oxygen is inhibitory to its growth.
Their sensitivity to oxygen limits the conditions under which it can colonise the
human body or cause disease.
C. difficile is a minor component of the bowel microflora. Colonisation of the large
bowel is present in up to 5% of the population.

Question 20

why do patients develop c diff

Answer 20

When the balance of gut microorganisms is disrupted, C. difficile starts to dominate
and colonize the large intestine.

after use of antibiotics

Question 21

toxins of C diff

Answer 21

C. difficile produces two important types of toxins, A and B.
Toxin A is an enterotoxin that causes excessive fluid secretion, but also stimulates an
inflammatory response and has some effect on damaging cell structure.

Toxin B is a cytotoxin and damages protein synthesis and the cell structure.

Question 22

risk factors associated with Clostroidioes Difficille

Answer 22

Antibiotic exposure, older age and hospitalisation Severe illnesses, immune suppression, and gastric acid suppression

Question 23

when to suspect C diff

Answer 23

diarrhoea
who has received antibiotics within the previous 3 months, has been recently
hospitalized, and/or has an occurrence of diarrhoea within 48 hours or more after
hospitalization.

Question 24

diagnoses of CDI

Answer 24

Tests aim to identify the C. difficile bacteria and the presence of toxin.
Stool assays for C difficile include the following:
 Enzyme immunoassay (EIA): for glutamate dehydrogenase produced by C.
difficile.
 Real-time polymerase chain reaction (PCR) assay for toxin gene
 EIA for detecting toxins A and B

Question 25

treatment of CDI

Answer 25

 Mild, antibiotic-associated diarrhoea : Cessation of antibiotic(s) may be the only treatment necessary
 Mild to moderate diarrhoea or colitis: Metronidazole (oral or intravenous) or
vancomycin (oral) for 10 days
 Severe or complicated disease: Vancomycin is considered to produce faster
symptom resolution and fewer treatment failures than metronidazole;

Question 26

preventative measure against spread of c diff

Answer 26

 Isolate patients with C. difficile immediately, even if you only suspect CDI
 Wear disposable gloves and gowns when treating patients with C. difficile,
even during a short visit.
 Perform hand hygiene after removing gloves. Alcohol does NOT kill C.
difficile spores. The use of soap and water is more effective than alcoholbased hand rubs.

Question 27

metronidazole

Answer 27

oldest antibiotic used to treat CDI.
It is a broad-spectrum antibiotic used to treat anaerobic infections. Metronidazole
kills the vegetative forms of the Clostridioides bacteria but not the spores.

Question 28

vancomycin

Answer 28

Vancomycin has excellent activity against C difficile. This agent kills the organism by
inhibiting cell wall synthesis.
Oral vancomycin does not get absorbed and acts directly at the site of infection.
Vancomycin does not cross in the bowel from blood so is only effective when given
enterally. Therefore, IV vancomycin is not used here as it does not act directly on the
site of infection.

Question 29

fidaoxmicin

Answer 29

The drug is only available in an oral formulation and systemic absorption
is minimal. Fidaxomicin has bactericidal activity against C. difficile, but reduced
activity against several enteric commensal bacterial species, particularly those
thought to confer colonization resistance against C. difficile

Question 30

MRSA

Answer 30

methicillin-resistant Staphylococcus aureus

s a type of Staphylococcus aureus that is resistant to most beta-lactam
antibiotics, antistaphylococcal penicillins (e.g., methicillin, oxacillin), and
cephalosporins

Question 31

how is MRSA spread

Answer 31

h skin-to-skin contact with someone who
has an MRSA infection or has the bacteria living on their skin.
The bacteria can also spread through contact with towels, sheets, clothes, dressings
or other objects that have been used by a person infected or colonised with MRSA.
MRSA can survive for long periods on objects or surfaces, such as door handles, sinks,
floors and cleaning equipment.

Question 32

treatment of MRSA

Answer 32

doxicyclin

oral trimoxycol

Question 33

transmission of norovirus

Answer 33

s mainly faecal-oral and also thought to be respiratory. Can be spread
following ingestion of contaminated food, direct person-to-person contact or
through contact with contaminated surfaces.