CD4 Markers & Buzzwords
A silver stain from bronchoscopy show "crushed ping pong balls."
Pneumocystis Pneumonia (PCP)
A patient with HIV and a CD4 count below 50 has a new seizure, confusion, and arm weakness. MRI shows multiple ring-enhancing lesions with surrounding edema.
Cerebral toxoplasmosis
What is the first line drug treatment for PCP and how many days should they be on this?
TMP-SMX (Bactrim) for 21 days
Fungi that grow as yeast in the body and as mold in the environment are called what?
dimorphic
An India ink stain of CSF shows yeast with a "clear halo". This infection typically appears below this CD4 count.
Cryptococcal meningitis, CD4 < 100
About 2/3 of children have antibodies to this organism by age 2-4, so nearly everyone has been exposed.
Pneumocystis jirovecii
Disseminated MAC requires at least two drugs: one for this antibiotic class plus this anti-TB drug.
Macrolide (clarithromycin or azithromycin) plus ethambutol
MAC = macrolide + ethambutol
What endemic fungus is found in the Ohio and Mississippi River valleys?
Histoplasma
Rank these from highest to lowest CD4 threshold: toxoplasmosis, PCP, cryptococcal disease.
1. PCP < 200
2. Cryptococcus < 100
3. Toxoplasmosis < 50
A patient with HIV has purple, elliptical lesions on the skin and roof of the mouth. They don't itch or hurt, and biopsy shows spindle cells.
Kaposi Sarcoma (HHV-8)
Toxoplasmosis is treated with pyrimethamine and sulfadiazine plus this third drug.
Leucovorin (folinic acid)
Pyrimethamine + Sulfadiazine block folate synthesis, so folinic acid (derivative of folic acid) can help rescue the patient's bone marrow
What is the drug of choice for invasive Aspergillus?
Voriconazole
A patient's CD4 count just dropped to 150. Name the two opportunistic conditions whose risk threshold they've now crossed.
PCP and Kaposi Sarcoma (< 200)
A patient starts treatment for cryptococcal meningitis. The team waits 4-6 weeks to start ART to prevent this complication.
IRIS (Immune reconstitution inflammatory syndrome)
Induction therapy for cryptococcal meningitis pairs these two drugs for 2 weeks. One of them is never used alone because resistance develops quickly.
Amphotericin B + Flucytosine
1. induction: "clear it quickly" amphotericin B + flucytosine
2. consolidation: "finish clearing it" fluconazole
3. maintenance: "prevent relapse" fluconazole
Which cell wall component do echinocandins blocks?
beta-glucan
Ground-glass infiltrates plus an elevated fungal serum marker point to PCP. Name the marker.
Beta-D-glucan
A patient with HIV has a CD4 count of 40, fever, night sweats, weight loss, and an enlarged liver and spleen. A blood culture grows an acid-fast organism. Name the disease and explain why the liver, spleen, and bone marrow are involved.
Disseminated MAC, which spreads through the blood to the reticuloendothelial organs.
Low-dose TMP-SMX prophylaxis for PCP also protects against this second infection, which dapsone alone doesn't cover. Name the infection and at what CD4 level can the drug be stopped.
Toxoplasmosis, can be stopped once CD4 stays above 200 for 3 months.
In disseminated histoplasmosis, antigen is best detected in which fluid?
Urine