©EMILLECT 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED
FIRST PUBLISH OCTOBER 2024
USMLE Step 3 Study Guide Solutions
Pseudogout associations - ANSWER✔✔-hemochromatosis, hyperparathyroidism, acromegaly,
hypothyroidism
Gout crystals - ANSWER✔✔-negatively birefringent needles
Pseudogout crystals - ANSWER✔✔-positively birefringent needles
Vasculitis associated with chronic Hep B - ANSWER✔✔-polyarteritis nodosa
Vasculitis associated with chronic Hep C - ANSWER✔✔-cryoglobulinemia
Best blood test for polyarteritis nodosa - ANSWER✔✔-There is none. Get abdominal angiography first,
then biopsy of muscle, skin, or sural nerve.
Churg-Strauss - ANSWER✔✔-vasculitis + eosinophilia + asthma
Takayasu's arteritis - ANSWER✔✔-young asian female with diminished pulses (usually preceeded by
fatigue, weight loss, arthralgia, anemia, elevated ESR)
Best test for Takayasu's - ANSWER✔✔-aortic angiography or MRA
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Bite cells on blood smear - ANSWER✔✔-G6PD
Burr/Spur cells on blood smear - ANSWER✔✔-liver disease
Acanthocytes on blood smear (looks like spur cell but with more rounded spurs) - ANSWER✔✔-liver
disease, hypothyroidism, alcoholism
Basophilic stippling on blood smear - ANSWER✔✔-lead poisoning
Schistocytes on blood smear - ANSWER✔✔-TTP-HUS, DIC, prosthetic heart valve, malignant htn, sepsis
Target cells on blood smear - ANSWER✔✔-thalassemia, other hemoglobinopathies, liver disease
5 causes of microcytic anemia - ANSWER✔✔-iron deficiency, lead poisoning, anemia of chronic disease
(but usually normocytic), thalassemia, sideroblastic anemia (can also have high MCV)
Antibody test for celiac disease - ANSWER✔✔-anti-endomysial, tissue transglutaminase (small bowel bx
is best though)
Antibiotics for MRSA - ANSWER✔✔-IV: vanc, linezolid, daptomycin, tigecycline;
if minor infection, can use oral: TMP/SMX, doxy, minocycline, or maybe clindamycin (there is inducible
resistance to clinda though)
Antibiotics for MSSA - ANSWER✔✔-Oxacillin/nafcillin, dicloxacillin (IV and oral), cefazolin (IV), cephalexin
(oral)
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Can you use cephalosporins in pt allergic to PCN? - ANSWER✔✔-yes, if the rxn is rash only; no if pt has
true anaphylaxis
Antibiotics to use for Staph with PCN allergy - ANSWER✔✔-cephalosporins if rash only; macrolides,
clindamycin, vancomycin, linezolid, daptomycin, TMP/SMX
Antibiotics for strep - ANSWER✔✔-PCN, ampicillin, amoxicillin
Antibiotics for GNRs - ANSWER✔✔-Cephalosporins: cefepime, ceftazidime
PCNs: piperacillin, ticaricillin
Monobactam: Aztreonam
Quinolones: cipro, levo, gati, moxi
Aminoglycs: gentamicin, tobramycin, amikacin
Carbapenems: imipenem, mero, erta
Limitation of ertapenem - ANSWER✔✔-does NOT cover pseudomonas
Piperacillin and ticarcillin - ANSWER✔✔-GNRs
strep
anaerobes
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Carbapenems - ANSWER✔✔-good anaerobic coverage
strep
MSSA
Tigecycline - ANSWER✔✔-MRSA
good GNR coverage
Anaerobes - ANSWER✔✔--metronidazole is BEST for abdominal anaerobes (carbapenems, piperacillin,
and ticarcillin have equal efficacy)
-cefoxitin and cefotetan are the ONLY cephalosporins
-respiratory anaerobes: clindamycin
Abx with NO anaerobic coverage - ANSWER✔✔-aminoglycs, aztreonam, fluoroquinolones,
oxacillin/nafcillin, all cephalosporins EXCEPT cefoxitin and cefotetan
Red man syndrome - ANSWER✔✔-red, flushed skin from histamine release, associated with rapid
infusion of vancomycin (so slow down the infusion rate)
Osteomyelitis - ANSWER✔✔--most common is staph: oxacillin or nafcillin IV for 4-6 wks for MSSA; vanc,
linezolid or dapto for MRSA
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