EM Boards Survival Guide: Infectious Diseases 1

Author: Alex Koyfman, MD (@EMHighAK) // Edited by: Brit Long, MD (@long_brit)

With Inservice exam coming up, this week we bring you Infectious Disease. Many questions can delve into details, and we highlight some of the must-know items. Many of these below will be summarized in some great artwork, courtesy of Dr. Katy Hanson (Hanson’s Anatomy).

Boards Must-Knows:

1) HIV/AIDS: High-yield area from head to toe. Know CD4 cut-offs and illnesses to expect. CD4 < 50 + visual issue: CMV retinitis; treat with ganciclovir. Oral thrush: consider HIV/AIDS, dysphagia/odynophagia, treat with nystatin or clotrimazole, if not improving then consider esophagitis (Candida, HSV, CMV). AIDS + diarrheal illness: Cryptosporidium, Isospora. AIDS + meningitis: Cryptococcus; high-opening pressure; India ink; treat with amphotericin B + flucytosine; still cover for more common bugs. AIDS + ring-enhancing lesions on CT: Toxoplasma; treat with pyrimethamine + sulfadiazine. MCC pneumonia in HIV/AIDS pt: Strep pneumoniae; MCC opportunistic infection: PJP; CD4 < 200, know classic X-ray, elevated LDH, treat with TMP-SMX, know when to give steroids. Respiratory complaint: don’t forget to consider TB. MC cancer in AIDS pt: Kaposi’s; identify skin lesions. Know common medications and their side effects (e.g. indinavir and kidney stones; pentamidine and hypo/hyperglycemia; etc.)

2) HIV post-exposure prophylaxis: Know high-/low-risk exposures and sources e.g. bloody, hollow bore needle, deep puncture in patient with high viral load = very high risk. Start medications within 1 hour; effective up to 72 hours.

3) Diarrheal bugs: Exam loves this, particularly associations (some examples follow, recommend making a chart with treatments). Traveler’s diarrhea: ETEC. Contaminated meat/poultry: C. perfringens. Reheated fried rice: B. cereus. Contaminated water/shellfish: V. cholera. Reversal of hot/cold sensation + paresthesias: Ciguatera. Metallic/peppery taste + itchy rash: Scombroid. Invasive diarrhea: SSCYE – salmonella, shigella, campylobacter, C diff, yersinia, EHEC.

4) Botulism: Descending paralysis. Three flavors: canned food, infant, injection drug use. Respiratory failure kills. Treat with immunoglobulin.

5) Dengue: Aedes mosquito, PAIN!, supportive care.

6) Chagas: Reduviid bug, heart failure / megaesophagus / megacolon, treat with nifurtimox or benznidazole.

7) Leptospirosis: Hiker/triathlete, conjunctival suffusion, acute febrile illness with potential to progress to multiorgan failure.

8) Mucormycosis: Nose and/or throat findings, immunocompromised/diabetes, amphotericin B, to OR with ENT.

9) Blastomycosis / Coccidioidomycosis / Histoplasmosis: Pneumonia not responding to antibiotics. Know regions for each.

10) Influenza: Febrile illness +/- GI symptoms. Consider flu mimics. Secondary bacterial pneumonia (Staph, Strep). Antiviral for high-risk populations (yes, controversial).