HIV Opportunistic Infections Quiz

HIV Opportunistic Infections

HIV opportunistic infections are serious infections that occur in people with HIV.
Learning objectives include recognizing clinical manifestations, discussing treatments, summarizing indications for discontinuing treatment, and summarizing recommendations for initiating antiretroviral therapy.

Pneumocystis jiroveci Pneumonia (PCP)

Caused by P. jiroveci (formerly P. carinii).
A ubiquitous fungus found in the environment, transmitted by the airborne route.
PCP can result from reactivation or new exposure.
Risk factors include CD4 count less than 200 cells/mm³ and CD4 percentage less than 14% cells/mm³.
Clinical manifestations include progressive exertional dyspnea, fever, non-productive cough, and chest discomfort; subacute onset. Characteristic finding is hypoxia (PaO2 <70 mmHg at room air).
Mild: A-a DO2 <35 mmHg; Moderate: A-a DO2 35-<45 mmHg; Severe: A-a DO2 ≥45 mmHg.
Physical exam may reveal tachypnea, tachycardia (especially with exertion), and diffuse dry rales.
Non-specific (presumptive) diagnostic tests include chest radiograph (diffuse bilateral perihilar infiltrates, often described as ground glass and butterfly-shaped) and high-resolution chest computed tomography. More sensitive in detecting interstitial abnormalities with extensive bilateral infiltrate. Pneumatoceles or cystic lesions may develop, which could lead to pneumothorax.
Laboratory studies include 1,3-beta-D-glucan (a major component of the P. jiroveci cell wall). A level of less than 80 pg/mL makes PCP infection less likely.
Definitive diagnostic tests require demonstrating the organism. Methods include induced sputum, spontaneously expectorated sputum, bronchoscopy with bronchoalveolar lavage, transbronchial biopsy, and polymerase chain reaction (PCR).
PCP diagnosis (histopathology) can be confirmed via lung biopsy using silver stain.

PCP Treatment

Duration: 21 days for all treatment regimens.
Preferred treatment is TMP-SMX.
Moderate-to-severe PCP typically requires intravenous TMP-SMX plus corticosteroids.
Mild PCP is often treated with oral TMP-SMX.
Potential adverse reactions include rash, Stevens-Johnson syndrome, leukopenia, thrombocytopenia, and hyperkalemia.
Adjunctive corticosteroids are used for moderate-to-severe disease, typically given as early as possible within 72 hours and continued throughout the 21-day treatment duration, using prednisone or methylprednisolone.

PCP Primary Prophylaxis

Indications for initiating primary prophylaxis include CD4 count less than 200 cells/mm3 or CD4 percentage less than 14% of total lymphocyte count.
Discontinuation criteria include starting antiretroviral therapy (ART) and having a CD4 count greater than 200 cells/µL for more than 3 months.
Treatment is typically given as trimethoprim-sulfamethoxazole (TMP-SMX) 1 tablet PO daily.

Candida

Oropharyngeal and esophageal candidiasis are common infections in HIV-infected patients, most caused by Candida albicans.
Occur most frequently in patients with CD4 T lymphocyte (CD4) cell counts less than 200 cells/mm³.
Oropharyngeal candidiasis is characterized by painless, creamy white, plaque-like lesions on buccal surface, hard or soft palate, and tongue. Lesions can be easily scraped off with a tongue depressor.
Esophageal candidiasis is characterized by retrosternal burning pain or discomfort, often along with odynophagia. Endoscopy shows white plaques on the esophagus similar to those observed in oropharyngeal candidiasis.
Diagnosis is clinical for oral, and endoscopy with lab confirmation for esophageal lesions..
Treatment for oral candidiasis is fluconazole orally for 7 days, and fluconazole or itraconazole orally for 14–21 days for esophageal candidiasis.

Other Oral Lesions in HIV

Oral hairy leukoplakia is strongly associated with Epstein-Barr virus.
Recurrent oral herpes is typically caused by HSV-1, but HSV-2 can also cause lesions. Treatment includes acyclovir, valacyclovir, or famciclovir. although incidence of Kaposi's sarcoma has decreased. Treatment for Kaposi's sarcoma includes antiretroviral therapy.
Oral HPV infection can cause both benign and malignant lesions.

Disseminated MAC

M avium intracellulare is the causative agent in over 95% of cases.
MAC organisms are found in soil and water. Transmission is believed to be via inhalation or ingestion.
Usually occurs in individuals with a CD4 count less than 50 cells/µL.
Symptoms include fever, night sweats, weight loss, fatigue, diarrhea, and abdominal pain.
Physical exam may reveal hepatomegaly, splenomegaly, or central lymphadenopathy.
Laboratory findings might include anemia, increased alkaline phosphatase (often with normal bilirubin and hepatic aminotransferase levels), and increased serum lactate dehydrogenase levels.
Diagnosis includes isolation of the organism from blood, bone marrow, or lymph node.
Treatment entails daily clarithromycin and ethambutol regimens.

Cryptococcal Meningitis

Caused by Cryptococcus neoformans or, increasingly, Cryptococcus gattii.
Fungus is found in soil and commonly associated with bird droppings.
Inoculation is through inhalation.
Most common with CD4 count less than 100 cells/mm³.
Clinical Presentation: gradual onset headache, low-grade fever, photophobia, and possible neck stiffness, confusion, vomiting, obtundation, seizures, and psychosis.
Increased intracranial pressure is common, causing neurological signs and symptoms including focal neurological signs, papilledema (optic disc swelling), severe headaches, herniation, and cranial nerve deficits (II and VIII). Treatment for increased intracranial pressure aims at reducing CSF volume.
Diagnosis is via CSF examination, showing increased opening pressure, lymphocytic pleocytosis, and positive results for India ink, cryptococcal antigen, fungal culture, and serum cryptococcal antigen titer.

Toxoplasmosis

Caused by the parasite Toxoplasma gondii.
Common transmission routes include contact with infected cat feces, consumption of contaminated meat or water, and mother-to-child transmission during pregnancy.
Symptoms include lymphadenopathy together with muscle aches lasting for more than a month, generalized tonic-clonic seizures, and gradual decline in mental status.
Toxoplasmosis encephalitis on MRI typically presents as multiple ring-enhancing intracranial lesions with vasogenic edema.

Toxoplasmosis Management

All HIV patients should be tested for IgG antibody to Toxoplasma.
Patients with CD4 count less than 100 cells/mm³ and positive IgG should receive prophylaxis for Toxoplasma.
Treatment is typically pyrimethamine and leucovorin, plus sulfadiazine.

Cryptosporidiosis

Manifests as chronic intestinal infection (longer than a month), with symptoms of abdominal cramps and severe, chronic, watery diarrhea.
Most commonly occurs in HIV patients with a CD4 count less than 100 cells/mm³.
Other possible agents that cause similar infections include Cytoisospora, microsporidium, and cyclospora.
Diagnosis involves acid-fast staining of stool to detect oocysts, and polymerase chain reaction (PCR) testing.
Treatment includes nitazoxanide along with antiretroviral therapy (ART).

CMV (Cytomegalovirus) Infection

HIV-positive persons with CD4 counts less than 50 cells/mm³ are at risk for invasive CMV retinitis.
Clinical symptoms usually include floaters, scotomas (flashing lights), or visual field cuts.
Diagnosis is based on ophthalmologic examination typically showing yellow-white, fluffy, or granular retinal lesions near retinal vessels, often with associated hemorrhage. CMV PCR or antigen assays are generally not helpful in making a diagnosis.
CMV retinitis is considered sight-threatening if the lesions involve or are adjacent to the optic nerve or fovea.
Treatment involves intravitreal injections with ganciclovir or foscarnet in combination with oral valganciclovir, along with antiretroviral therapy.

IRIS (Immune Reconstitution Inflammatory Syndrome)

This process occurs due to an upregulated immune response after starting Antiretroviral Therapy (ART) and having prior infection.
Patients with IRIS may present with either a paradoxical worsening of a condition or unmasking of a previously undiagnosed infection.
Symptoms usually last for 2–3 months, though generally not life-threatening.
Antiretroviral therapy should not be stopped.

General Notes on HIV Study Material

The study material focuses on opportunistic infections prevalent in individuals with HIV/AIDS, emphasizing clinical presentation, diagnostic methods (including laboratory and imaging), and treatment approaches. Risk factors for each infection are highlighted.