Infectious Diseases

Question 1

TB risk factors

Answer 1

• HIV
• immunosuppression
• overcrowed living
• ethnic minorities
• malnutrition
• IVDU
• chronic lung disease

Question 2

TB pulmonary presentation

Answer 2

• constitutional symptoms (weight loss, night sweats, fatigue, fever and chills)
• lymphadenopathy
• Cough ± haemoptysis
• SOB
• chest pain

Question 3

Extra-pulmonary symptoms of TB

Answer 3

Neuro: meningisms
Opthalmology: blurred vision, red eyes
GU: dysuria, haematuria
GI: abdo pain, abdo mass
rheum: arthritis
osteo: osteomyelitis

Question 4

How is TB diagnosed

Answer 4

• Sputum sample alcohol and acid fast bacilli (AAFB)
• Rapid PCR - immediate confirmation of species and early implication of rifampicin sensitivity
• Nucleic acid amplification tests (NAAT) rapid diagnosis of mycobacterium complex

Question 5

What is the management of TB

Answer 5

Rifampicin 6/12 *red urine, CI OC*
Isoniazid 6/12 *perupheral neuropathy*
Pyrazinamide 2/12 *liver toxicity*
Ethambutol 2/12 *optic neuritis*

Contact screening

• mantoux test or interferon gamma release assay
• if +ve -> CXR
• if -ve 3/12 prophylaxis

Question 6

what is multi-drug resistant TB

Answer 6

TB that is resistant to at least izoniazid and rifampicin normally due to poor compliance or incomplete courses

Question 7

how is multi-drug resistant TB managed

Answer 7

combo of 5-8 drugs for up to 2 years

Question 8

HIV transmission

Answer 8

• sexual
• vertical
  
  • untreated risk 25-40%
  • treated risk <1%
  • C-section if mother has detectable viral load at birth
• needles
• blood products

Question 9

HIV pathology

Answer 9

*RNA retrovirus*

1. virus becomes part of host cell
2. transcriptase enzyme transcripts RNA-> DNA
3. Integrase integrates virus DNA into hosts
4. host cells produces/releases virons (cleaved by protease)
5. Virons infect any cells with CD4 receptor by binding with GP120 glycoprotein
6. CD4 receptor cells now release virons
7. infection progressed, CD4 cells destroyed, reduced host immune system

Question 10

Which cells have CD4 receptors?

Answer 10

T cells, macrophages, monocytes, neurons

Question 11

How is HIV diagnosed?

Answer 11

• serology for antibodies and antigens at 4 weeks (2-3 weeks where tests will be -ve because no Ab response yet)
• P24 antigen
• IgG and IgM

Question 12

HIV monitoring

Answer 12

CD4 normal range 450-1600

Viral Load = quantity of virus in serum
Undetectable VL = Untransmittable disease

Question 13

HIV Management

Answer 13

2 NRTI + NNRTI OR PI

NRTI (nucleoside reverse transcriptase inhib)- zidovudine, abacavir

NNRTI (non-NRTI)- nevirapine, etravirine

PI (protease inhib)- indinavir, lopinavir

Question 14

HIV prophylaxis

Answer 14

PrEP - pre exposure prophylaxis

• Truvada
• daily or when needed 12 hours before sex

PEP - post exposure prophylaxis

• Truvada
• given to pt after high risk exposure for 4 weeks
• follow up test

Question 15

What is truvada

Answer 15

tenofovir and emtricitabine

Question 16

When does a person have AIDS

Answer 16

when their CD4 count is less than 200 or presence of an aids defining condition

Question 17

AIDS defining conditions

Answer 17

Resp: TB, PCP

Gastro: persistent cryptosporidiosis

opthal: CMV retinitis

Malig: Kaposis sarcoma, non-hodgkins lymphoma, cervical cancer

Neuro

• cerebral toxoplasmosis
• primary cerebral lymphoma
• crytococcal meningitis
• progressive multifocus leucoencephalopathy

Question 18

AIDS management

Answer 18

Co-trimazole - PCP, toxoplasma, bacterial infection

pentamidine - PCP

azithromycin - Mycobacterium Avium Intracellulare

ganciclovir - CMV

Question 19

Hepatitis transmission

Answer 19

B- vertical, sexual, blood, needles

D- blood and body fluids

C- blood and body fluids

A - faeco-oral

E- faeco-oral (water)

Question 20

Hep B presentation

Answer 20

fever
malaise
upper abdo discomfort
jaundice

can be asymp then cirrhosis and liver failure

Question 21

Hep C presentation

Answer 21

85% asymptomatic/mild symptoms forllowing infection (develop chronic HCV: also asymptomatic or nonspecifc - malaise, fatigue, RUQ pain)

15% malaise, nausea, RUQ pain, jaundice (more likely to clear disease)

Question 22

Presentatio of Hep A

Answer 22

anorexia, nausea, jaundice

Question 23

presentation of hep E

Answer 23

abdo pain, jaundice, fever, fatigue

Question 24

Diagnosis of hep C

Answer 24

enzyme immunoassay -> immunoblot assay

if +ve confirmed by HCV RNA test by PCR

Question 25

Hep C monitoring

Answer 25

Baseline liver fibrosis assessment

• all patients- no need for biopsy

Every 6/12 ATP (alpha fetoprotein - HCC marker) and liver USS

• patient with evidence of advanced fibrosis or cirrhosis

OGD

• pt with evidence of portal HTN
• screening for varices

Question 26

Hep C management

Answer 26

• Direct acting antiviral drugs (DAA)
• fixed dose combined tablets for 8-16 weeks
• Aim - undetectable HCV RNA in blood 12 weeks post treatment finishing
• if unsuccessful
  
  • vosevi OD 12 weeks if no decompensated cirrhosis
  • epclusa + RBV 24 weeks if decompensated cirrhosis

Question 27

What methods are used to prevent vertical transmission of HIV in birth

Answer 27

1) C section
2) bottle feed
3) zidovudine

Question 28

SE of vidozudine

Answer 28

haemolytic anaemia

Question 29

How do you prevent HIV transmission?

Answer 29

Prep: Truvida either daily or 12 hours before

Pep: Truvida 4 weeks

Question 30

Malaria investigations

Answer 30

Thick (how much parasite) and thin (which parasite) blood films

Antigen detection test

Rapid diagnostic tests - dipstick based, only for P falciparum and P Vivax

Question 31

why is p. falciparum worse

Answer 31

sticks to blood vessels (doesnt just infect RBC) so falsely low viral load (survives longer because not broken down by spleen)

can cause vascular ischaemia -> encephalopathy

Question 32

Complications of severe malaria

Answer 32

Haemolytic Anaemia

Cerebral Malaria

AKI

Hypoglycaemia

DIC