MCAT & USMLE Gunner Review: High yield topics in medicine that you should know for the MCAT, USMLE STEP 1, USMLE STEP 2, and USMLE STEP 3 exams by Elijah Gold

Author:Elijah Gold [Gold, Elijah]
Language: eng
Format: epub
Published: 2016-10-10T17:00:00+00:00

IMMUNOLOGY & INFECTIOUS DISEASES

● Infectious mononucleosis: systemic viral infection, “atypical lymphocytes”, elevated LFTs.

● Tx of scabies—>topical 5% permethrin cream or lindane

● Tx of Tinea infxns: antifungal for 2-4 weeks.

● Pancreatitis with necrosis>30%--> IV abx with meropenem or imipenem

● FUO: >38.3 C for > 3 weeks; most common cause is connective tissue disorder, followed by infectious disease.

● AIDS: CD4 count and HIV load checked every 3-4 months.

● Oseltamivir/zanamivir (neuraminidase inhibitors) appropriate for influenza in low-risk patients if started <48 hours from onset

○ Amantadine (interferes with M2 ion channel protein) and rimantadine no longer recommended.

● ITP: Platelets<50k

● Salmonella osteomyelitis= sickle cell anemia (order hemoglobin electrophoresis)

● Pentamidine: prophylaxis of PCP in immunocompromised and tx of Trypanosoma brucei gambiense parasite

○ Metabolic SE: hyperkalemia/hypokalemia, hypocalcemia, hypoglycemia/hyperglycemia.

○ Always check finger stick glucose.

● Rosacea: facial erythema, telangiectasias, papules and pustules.

○ Topical metronidazole +/- oral abx (tetracycline, doxycycline, minocycline, & erythromycin).

○ Secondary Ocular sx: blepharitis, keratitis, conjunctivitis, chalazion (granulomatous inflammation of meibomian gland), and episcleritis.

● Endophthalmitis: associated with corneal ulcers and ocular infxns by Pseudomonas, Yersinia, and Mycobacterium.

● Imipenem (and other beta-lactamases including fluoroquinolones) associated with increased risk of seizures.

● PCP:

○ CD4<200

○ Dx with fiberoptic bronchoscopy with BAL

○ Tx: TMP-SMX; if refractory then: IV pentamidine

○ Adjunct tx with steroid if: alveolar/arterial O2 gradient>35 mmHg OR PaO2<70 mmHg.

○ Can show vertical nystagmus in awake patient.

● Rabies: skunks, foxes, and bats in U.S; prodrome of fever and pharyngitis, followed by neurologic symptoms (drooling, dysphagia, incoordination, lethargy)

○ No tx exists; universally fatal

○ Tx: Rabies immunoglobulin first 10 days and 4 vaccines in first 14 days. If previously vaccinated, then 2 vaccines (active immunization) on day 0 and 2, without need for IgG.

○ Milwaukee protocol: ketamine, midazolam, and amantadine.

● Tuberculosis:

○ If health care worker at risk, check PPD; if negative→repeat in 3 months; if positive→monotherapy with isoniazid (INH).

○ IFN gamma release assay can differentiate between active TB or prior BCG vaccination

○ If latent TB→tx is isoniazid (INH) for 9 months

● Cat bite: give IV ampicillin/sulbactam, then follow up with oral amoxicillin/clavulanate for 3-5 days to cover pasteurella multocida; infxn rate is ~50%.

● Hemolytic uremic syndrome (HUS): kids <2 yr old; abdominal pain with diarrhea (bloody) and progresses to acute renal failure.

● TTP: Pentad of thrombocytopenia, microangiopathic hemolytic anemia, fluctuating neurological signs, renal failure, and fever. Can be confused with HUS, but is different because of more neurological symptoms.

● Henoch-Schonlein purpura: abdominal pain, arthralgias, skin lesions (erythema in extremities that progresses to papules), and renal involvement.

● Sporotrichosis: dimorphic fungus sporothrix schenckii; from soil; starts as papule that ulcerates and follows lymph nodes locally. Tx: itraconazole for 3-6m

● Blastomycosis: fungus blastomyces dermatitis via inhalation and starts as pulmonary infection.

● Actinomycosis: gram + organism; humans are only reservoir and causes cervicofacial disease; due to bad oral hygiene or trauma with subsequent mass growing into multiple abscesses, fistulas, and draining sinus tracts.

● Coccidioidomycosis: airborne dimorphic fungus coccidioides immitis; chest pain, fever, cough (+/- hemoptysis) followed by Erythema nodosum as delayed hypersensitivity rxn.

● Progressive multifocal leukoencephalopathy (PML): classic MRI finding of multiple demyelinating non-enhancing lesions with no mass effect.

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