Opportunistic Infections Flashcards
Secondary prophylaxis- Definition and duration in HIV
Maintenance therapy which aims to prevent relapse
Stopped when CD4>200 on ART
Organisms causing bacterial pneumonia in HIV+
S. Pneumoniae H. Influenzae S. Aureus Klebsiella Atypical bacteria
Management of candidiasis
Limited to oral cavity or vagina - topical therapy
Refractory course or esophageal involvement - fluconazole
Fluconazole drug characteristics
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
Management of PCP and complications of management
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
Cotrimoxazole drug characteristics
Indicated in PCP treatment
Used as primary prophylaxis
- indications: WHO stage 3/4, CD4
TB primary prophylaxis
6/12 isoniazid is standard regimen
Longer therapy is TST positive and if on ART
Screening for and management of cryptococcal infections
Look for cryptococcal antigen (CrAg) in all HIV + adults with CD4
MOA fluconazole
Causes the formation and accumulation of toxic sterols in the cell membrane
Amphotericin B drug characteristics
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
Clinical use of acyclovir
In immunocompetent: need to start rx early for effect-
Acyclovir drug characteristics
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
Shingles in HIV and management
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)
CMV in HIV and management
AIDS-defining if outside RES/liver - MC sites are retina, GIT, lungs and CNS
Occurs at CD4
Management of TB
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.
ART eligibility criteria
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
Patients for fast track ART
HIV + breastfeeding or pregnant : start same day or within 7/7
CD4
Initiation of ART in TB px
CD4 50 6-8/52
TBM- within 4-6/52
First line ART
Tenofovir (change to abacavir if CI, or zidovudine if both CI)
Emtricitabine (or lamovudine)
Efavirenz (CI change to nevirapine or ritonavor/lopinavir)
Definition and example of primary prophylaxis
Preventing initial infection
E.g.
Isoniazid- TB
Cotrimoxazole - toxo, PCP, bacterial pneumonia, isosporiasis, malaria
How to treat cryptococcal meningitis
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
Cotrimoxazole mechanism of action
Sequential inhibition of enzymes in the folic acid pathway
Sulfamethoxazole interferes with bacterial folic acid synthesis and growth
Trimethoprim inhibits dihydrofolic acid reduction
Principles for treating serious bacterial infections in HIV/AIDS
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
