Infectious Disease Compendium

AIDS

Diagnosis

What infection patients get with AIDS depends on their CD4 counts. For HIV therapy (i.e. HAART) go to HIV.

Risks

HIV infection, a sexually transmitted disease. Keeping the viral load suppressed and then, hopefully, the CD4 counts up, offers the best hope for prevention if AIDS related opportunistic infection.

Microbiology

While any number of organisms can infect the AIDS patients, what are below are the more common infections.

All CD4 counts: any other sexually transmitted disease: Syphilis, Neisseria, Herpes, Lymphogranuloma venereum and they can occur in any of the three or more sexually active orifices.

CD4 counts > 500: normal, not at risk for opportunistic infections.

CD4 counts > 250: increased risk of bacteremic Streptococcus pneumoniae and Haemophilus. These organisms in the blood for no other reason should result in an HIV test.

CD4 counts > 200: Varicella Zoster i.e. shingles.

CD4 counts 200: Thrush and Pneumocystis.

CD4 counts >100: Cryptococcus neoformans, Toxoplasma, reactivation of Coccidioides immitis, Histoplasmosis, Mycobacterium tuberculosis, Penicillium. Diarrhea from Cyclosporidia, Cryptosporidia, Isospora.

3% of HIV patients with CD < 100 will be CRAG positive, a high enough rate to warrant screening (PubMed).

CD4 counts > 50: Bacillary angiomatosis, KS, M. avium-intracellulari, Cytomegalovirus.

CD4 counts > 10: lymphoma, PML.

As part of IRIS, HIV patient can get a CD8 encephalitis (PubMed) that is treated with steroids.

Medistainal lymphadenopathy in a patient in ART is likely malignancy (PubMed)

Empiric Therapy

It depends in the infecting organism.

Prophylaxis

There is both primary and secondary prophylaxis for all the above (2014 Guidelines).

- Pneumocystis carinii prophylaxis (CD4 200/ml): trimethoprim/sulfamethoxazole 160/800 mg q.d. OR dapsone 100 mg q.d. OR Aerosolized pentamidine 300 mg every month OR atovaquone 1500 mg q.d.

- MAC prophylaxis (CD4 50/ml): azithromycin 1200 mg each week OR clarithromycin 500 mg b.i.d. OR rifabutin 300 mg q.d.

- Toxoplasma gondii prophylaxis (CD4 100/ml): pyrimethamine 50 mg each week with leucovorin 25 mg each week (if patient ion trimethoprim/sulfamethoxisole for PJP, then they are on adequate toxoplasmosis prevention).

- Cytomegalovirus prophylaxis (CD4 50/ml): ganciclovir 1000 mg t.i.d OR valganciclovir (dose for prevention not known, ? 900 mg q.d., OR ganciclovir implant. Primary prevention usually not done due to toxicities and interaction with HAART. Active CMV in HIV patients also increases mortality in some populations; whether to treat with more than HAART if no invasice disease is uncertain (PubMed).

- Tuberculosis prophylaxis: isoniazid 300 mg q.d. OR rifampin/pyrazinamide 600/1500 mg q.d. If TST (what we called in the old days a PPD, but the PC term is tuberculin skin test) is positive (and remember 5 mm is positive in the HIV patient) and there is no evidence of active TB.

-Fungal infection prophylaxis: (CD4 50/ml) fluconazole 200 mg q.d. OR itraconazole (remember it requires stomach acid for absorption) 200 mg q.d.

-Herpes simplex virus prophylaxis: acyclovir 400 mg b.i.d.

-Vaccinate against the following: Hepatitis A, B, pneumococcal infection, H. influenza b, Meningococcus. However, expect the response to be of shorter duration (PubMed). Influenza vaccine annually. In sexually active check a VDRL every six months.

- Cervical SCC (CD4 20-500/ml) Pap smear twice in first year, then annually.

- Anal SCC: Annual Pap smear. And never pass up the opportunity to remind people of the evils of tobacco and the benefits of condoms.

Pearls

Generally speaking, if the CD4 remains greater than 200 and the viral load remains undetectable for a 3 months primary prophylaxis can be discontinued and secondary prophylaxis can be discontinued if CD4 remains greater than 200 and the viral load remains undetectable for at least 6 months. Watch for the Immune

Reconstitution Syndrome: occurs in 20-30% of patients one to 6 months after starting HAART. As the immune system returns patients can get a marked inflammatory response to any of the OI's above. The OI's tend to be atypical and often localized eg: Cytomegalovirus retinitis and focal M. avium-intracellulari infections.

At least with mycobacterial IRIS, infixamab was of benefit (PubMed) and didnot adversely affect the HIV treatment.

HIV is now a chronic illness that will be managed in part by primary care providers; the guidelines are here.

Rants

Everyone lies about sex, drugs and rock and roll. I mean, really, who ever liked Frank Zappa? So I think the major risk factor for HIV is being human.