Chapter 25: ID IV: Opportunistic Infections

Question 1

Opportunistic Infections (OI): background, what patient/ disease state is at risk?

Answer 1

Immunocompromised patients are at higher risk for opportunistic infections (OIs), caused by various pathogens such as bacteria, fungi, viruses, and protozoa, due to their weakened immune response. Factors contributing to immunocompromise include:
- diseases that destroy key components of immune response: like HIV with low CD4+ T lymphocyte counts (<200 aka AIDs)
- prolonged systemic steroid use ( +14 days) at a prednisone dose or equivalant of >20mg/day or >2mg/kg/day
- Asplenia
- use of immunosuppressants for autoimmune conditions or transplant, and cancer chemotherapy (particularly with severe neutropenia (ANC < 500).

Question 2

Primary Prophalaxis OI

Common OIs requiring primary ppx include:

Answer 2

• Pneumocystis pneumonia (PCP or PJP)
• Toxoplasmosis gondii encephalitis
• Mycobacterium avium complex (MAC)
  .
  Note: Candida infections in the mouth/esophagus (e.g., thrush) are a higher risk in immunocompromised states, but prophylaxis
  is not usually recommended!

Question 3

OIs Primary PPX Regimens in HIV

OIs Primary PPX Regimens in HIV: Cavets, what will the future slide tell us/ indicate for us?

Answer 3

• In the following slides; the CD4 count at which a patient with HIV becomes at risk for the infection and the primary ppx regimen is used to prevent the infection.
• Selection for alternative agents (for ppx) depends on patient specific factors (ie. allergies or G6PD deficency) for example atovaquone, dapsone, and pentamidine are options for PJP ppx in a setting of sulfa allergies and atovaquone and pentamidine are options in the setting of G6PD deficency!
• Leucovorine is added to all pyrimethamine-containing regimen as a rescue therapy to reduce risk of myelosuppresion!

Question 4

OIs Primary PPX Regimens in HIV

Pneumocystis pneumonia (PCP or PJP): Criteria for starting, Primary PPX regimen (preferred/ alternative), criteria for discontinuing

Answer 4

1. Criteria for starting
   CD4 < 200 or AIDs
2. Primary PPX regimen (preferred/ alternative)
   Preferred: SMX/TMP DS or SS Daily
   Alternative:
   Dapsone
   Dapsone + Pyrimethamine + Leucovorin
   Atovaquone
   Atovaquone + Pyrimethamine + Leucovorin
3. Criteria for discontinuing
   CD4 > 200 for > 3 months on ART

Question 5

OIs Primary PPX Regimens in HIV

Toxoplasma Gondii Encephalitis: Criteria for starting, Primary PPX regimen (preferred/ alternative), criteria for discontinuing

Answer 5

1. Criteria for starting
   Toxoplasma IgG POSITIVE or CD4 < 100
2. Primary PPX regimen (preferred/ alternative)
   Preferred: SMX/TMP DS Daily
   Alternative:
   Dapsone + Pyrimethamine + Leucovorin
   Atovaquone
   Atovaquone + Pyrimethamine + Leucovorin
3. Criteria for discontinuing
   CD4 > 200 for > 3 months on ART

Question 6

OIs Primary PPX Regimens in HIV

Mycobacterium Avium Complex (MAC): Criteria for starting, Primary PPX regimen (preferred/ alternative), criteria for discontinuing

Answer 6

1. Criteria for starting
   Initiate if not taking ART and CD4 < 50 (not recc if ART is started immediately!)
2. Primary PPX regimen (preferred/ alternative)
   Preferred: Azithromycin 1200 mg Weekly
   Alternative:
   Clarithromycin 500 BID
3. Criteria for discontinuing
   Taking fully suppresive ART

Question 7

TREATMENT and Secondary PPX

The table below highlights recommended medications for treating select OIs. After initial treatment, secondary prophylaxis is often prescribed to prevent recurrence, especially in patients at continued risk. For HIV patients with thrush, systemic treatment is preferred over localized agents like clotrimazole, miconazole, or nystatin, even for mild cases.

Question 8

OI Treatment

Candidiasis (thrush): preferred/ alternative regimen, what to use for secondary ppx?

Answer 8

1. Preferred: Fluconazole
2. Alternative: Itraconazole (oropharyngeal); voriconazole (esophageal)
3. Secondary ppx? NOT RECOMMEDED

Question 9

OI Treatment

Crytococcal meningitis: preferred/ alternative regimen, what to use for secondary ppx?

Answer 9

1. Preferred: Amp B (deoxycholate or lipid formulation) + Flucytosine
2. Alternative: Fluconazole + Flucytosine
3. Secondary ppx? Low dose Fluconazole

Question 10

OI Treatment

Cytomegalovirus (CMV): preferred/ alternative regimen, what to use for secondary ppx?

Answer 10

1. Preferred: Valgancyclovir or Ganciclovir
2. Alternative: If toxicities occur or resistant? use: Foscarnet or Cidofovir
3. Secondary ppx? N/A

Question 11

OI Treatment

Mycobacterium avium complex (MAC): preferred/ alternative regimen, what to use for secondary ppx?

Answer 11

1. Preferred: Azithro or Clarithro + ethambutol
2. Alternative: add a 3rd or 4th agent: rifabutin, streptomycin, moxifloxacin or levofloxacin
3. Secondary ppx? Same as TX regimen

Question 12

OI Treatment

PJP/PCP: preferred/ alternative regimen, what to use for secondary ppx?

Answer 12

1. Preferred: Bactrim High Dose
2. Alternative: Atovaquone or Pentamidine IV
3. Secondary ppx? Same as primary PPX

Question 13

OI Treatment

Toxoplasmosis gondii encep: What increases the risk of getting it?, preferred/ alternative regimen, what to use for secondary ppx?

Answer 13

1. Risk: uncooked meat/ raw meat, contact with cat poop/litter
2. Preferred: Pyrimethamine + leucovorin + sulfadiazine
3. Alternative: Bactrim or Atovaquone
4. Secondary ppx? Same as TX but reduced dose