Opportunistic Infections

Question 1

Secondary prophylaxis- Definition and duration in HIV

Answer 1

Maintenance therapy which aims to prevent relapse

Stopped when CD4>200 on ART

Question 2

Organisms causing bacterial pneumonia in HIV+

Answer 2

S. Pneumoniae
H. Influenzae
S. Aureus
Klebsiella
Atypical bacteria

Question 3

Management of candidiasis

Answer 3

Limited to oral cavity or vagina - topical therapy

Refractory course or esophageal involvement - fluconazole

Question 4

Fluconazole drug characteristics

Answer 4

Excellent oral bioavailability
Long half life
Penetrates CSF well
Renally excreted
Weak CYT p450 inhibitor
Active against yeasts- crypto and candida
Well tolerated - can lead to skin rash and hepatitis rarely

Question 5

Management of PCP and complications of management

Answer 5

High dose cotrimoxazole for 21/7 - risks associated: high risk of severe hypersensitivity reaction (SJS/TEN, hepatitis); Prolonged use –> BM suppression
Adjunctive corticosteroids- indicated in all hypoxia patients

Question 6

Cotrimoxazole drug characteristics

Answer 6

Indicated in PCP treatment
Used as primary prophylaxis
- indications: WHO stage 3/4, CD4

Question 7

TB primary prophylaxis

Answer 7

6/12 isoniazid is standard regimen

Longer therapy is TST positive and if on ART

Question 8

Screening for and management of cryptococcal infections

Answer 8

Look for cryptococcal antigen (CrAg) in all HIV + adults with CD4

Question 9

MOA fluconazole

Answer 9

Causes the formation and accumulation of toxic sterols in the cell membrane

Question 10

Amphotericin B drug characteristics

Answer 10

MOA: causes leak of intracellular proteins and cations
Drug of choice: invasive fungal infections- most active, little resistance, broad spectrum
Toxicity: nephrotoxic - dose-related,reversible, causes major loss of K and Mg
Route: slow IV - associated with fevers and rigors, managed with paracetamol or corticosteroids; prolonged use less to anemia and LOW

Question 11

Clinical use of acyclovir

Answer 11

In immunocompetent: need to start rx early for effect-

Question 12

Acyclovir drug characteristics

Answer 12

MOA: purine nucleoside analogue –> inhibits herpes DNA polymerase
Very well tolerated
Active against HSV and VZV (need higher doses)
PK: poor oral bioavailability, short plasma half life but long intracellular , excreted via kidneys
Resistance: uncommon, more often in immunocompromised, associated with extent of exposure

Question 13

Shingles in HIV and management

Answer 13

Very common with moderate immunosuppression (CD4 around 350)
Tends to have longer duration, affect >1 dermatome and cause more severe pain with increased risk of post-herpetic neuralgia
Management: high dose acyclovir, pain mx, PHN rx with analgesia and adjuvant (eg amitriptyline)

Question 14

CMV in HIV and management

Answer 14

AIDS-defining if outside RES/liver - MC sites are retina, GIT, lungs and CNS
Occurs at CD4

Question 15

Management of TB

Answer 15

Intensive phase:
- 2/12
- rifampicin, isoniazid, ethambutol, pyrazinamide
Continuation phase:
- 4/12
- rifampicin, isoniazid
Main complication: isoniazid causes peripheral neuropathy - treat with prophylactic pyridine in high risk px.

Question 16

ART eligibility criteria

Answer 16

WHO 3 or 4
All types of TB
Women who are pregnant, breastfeeding or within 1 year postpartum regardless of CD4 or feeding choice
Children >5, adolescents or adults with CD4

Question 17

Patients for fast track ART

Answer 17

HIV + breastfeeding or pregnant : start same day or within 7/7
CD4

Question 18

Initiation of ART in TB px

Answer 18

CD4 50 6-8/52

TBM- within 4-6/52

Question 19

First line ART

Answer 19

Tenofovir (change to abacavir if CI, or zidovudine if both CI)
Emtricitabine (or lamovudine)
Efavirenz (CI change to nevirapine or ritonavor/lopinavir)

Question 20

Definition and example of primary prophylaxis

Answer 20

Preventing initial infection
E.g.
Isoniazid- TB
Cotrimoxazole - toxo, PCP, bacterial pneumonia, isosporiasis, malaria

Question 21

How to treat cryptococcal meningitis

Answer 21

Amphotericin B 1mg/kg/day PLUS fluconazole 800mg/day for 2/52
Then fluconazole 400mg for 2/12
Then fluconazole 200mg for at least 12/12 and CD4>200

Question 22

Cotrimoxazole mechanism of action

Answer 22

Sequential inhibition of enzymes in the folic acid pathway
Sulfamethoxazole interferes with bacterial folic acid synthesis and growth
Trimethoprim inhibits dihydrofolic acid reduction

Question 23

Principles for treating serious bacterial infections in HIV/AIDS

Answer 23

Prompt appropriate empirical antibiotics
Reasonable to use broader spectrum
Duration - standard for pneumonia, prolongs for non-typhoid salmonella bacteremia
Opportunistic organisms can present acutely, mimicking bacterial infections