Internal Medicine_Infectious Diseases_17 Flashcards
HIV
In what instances should a patient be screened for HIV?
Oral candidiasis
Oral hairy leukoplakia
Pneumocystis jirovecii (PCP)
Cryptococcal meningitis
CMV retinitis
STIs (syphilis, gonorrhea, chlamydia, HSV, trichomonas)
Disseminated TB
What is the most common opportunistic eye infection in patients with AIDS?
Cytomegalovirus (CMV) retinitis, typically seen in patients with CD4 counts <50 cells/μL.
What are the clinical features of CMV retinitis?
Blurred vision, floaters, or painless vision loss.
Fundoscopy: Retinal hemorrhages and yellow-white, fluffy lesions (“pizza-pie” appearance).
Progressive symptoms: Can lead to blindness without treatment.
How is CMV retinitis diagnosed?
Slit lamp or fundoscopy: Retinal findings of necrosis, hemorrhage, and exudates.
CMV DNA PCR: Confirms systemic CMV infection in blood or aqueous humor.
What is the first-line treatment for CMV retinitis?
Oral valganciclovir for mild disease.
Intravitreal ganciclovir or foscarnet injections for sight-threatening lesions (near macula or optic nerve).
What is foscarnet, and when is it indicated for CMV retinitis?
Foscarnet is a pyrophosphate analog that inhibits viral DNA polymerase.
Indications:
CMV retinitis resistant to ganciclovir.
Patients intolerant to ganciclovir (e.g., severe neutropenia).
What are the side effects of foscarnet?
Nephrotoxicity: Monitor creatinine and electrolytes.
Electrolyte imbalances: Hypocalcemia, hypomagnesemia, and hypokalemia.
Seizures: Due to electrolyte disturbances.
What is ganciclovir, and how does it treat CMV retinitis?
Ganciclovir is a guanosine analog that inhibits viral DNA polymerase after being phosphorylated by CMV UL97 kinase.
It prevents viral replication and reduces retinal inflammation.
How does CMV develop resistance to ganciclovir?
UL97 gene mutation: Reduces ganciclovir phosphorylation, preventing its activation.
UL54 gene mutation: Alters viral DNA polymerase, reducing binding of ganciclovir.
What is the mechanism of action of valganciclovir?
Prodrug of ganciclovir with higher oral bioavailability.
Converts to ganciclovir in the body, where it inhibits viral DNA polymerase after activation by UL97 kinase.
What are the complications of untreated CMV retinitis?
Blindness: Due to progressive retinal necrosis.
Contralateral eye involvement: Without systemic treatment.
CNS involvement: CMV encephalitis or ventriculitis.
What is immune reconstitution inflammatory syndrome (IRIS), and how does it relate to CMV retinitis?
IRIS is a paradoxical worsening of symptoms due to the immune system recovering after starting antiretroviral therapy (ART). In CMV retinitis, IRIS can cause retinal detachment or severe inflammation.
How is CMV retinitis managed in patients with advanced HIV?
Treat CMV first: Valganciclovir or intravitreal therapy.
Initiate ART after 2 weeks to avoid IRIS.
Regular ophthalmologic follow-up to monitor for complications.
Why is regular screening important for CMV retinitis in AIDS patients?
Early detection prevents blindness.
Fundoscopic exams are recommended for HIV patients with CD4 counts <50 cells/μL.
What should be the differential when considering PML in an HIV patient?
PML in HIV:
Associated with untreated HIV/AIDS and low CD4 counts.
Cognitive decline with white matter changes
(PML: White matter lesions, no enhancement, JC virus)
Often a result of stopping or not initiating ART.
Differentiation:
CNS Lymphoma: Enhancing lesions, EBV-positive.
Toxoplasmosis: Ring-enhancing lesions, mass effect.
