USMLE Step 3 Study Guide
Pseudogout associations (Ans - hemochromatosis, hyperparathyroidism, acromegaly, hypothyroidism
Gout crystals (Ans - negatively birefringent needles
Pseudogout crystals (Ans - positively birefringent needles
Vasculitis associated with chronic Hep B (Ans - polyarteritis nodosa
Vasculitis associated with chronic Hep C (Ans - cryoglobulinemia
Best blood test for polyarteritis nodosa (Ans - There is none. Get abdominal angiography first, then biopsy of muscle, skin, or sural nerve.
Churg-Strauss (Ans - vasculitis + eosinophilia + asthma
Takayasu's arteritis (Ans - young asian female with diminished pulses (usually proceeded by fatigue, weight loss, arthralgia, anemia, elevated ESR)
Best test for Takayasu's (Ans - aortic angiography or MRA
Bite cells on blood smear (Ans - G6PD 1 / 4
Burr/Spur cells on blood smear (Ans - liver disease
Acanthocytes on blood smear (looks like spur cell but with more rounded spurs) (Ans - liver disease, hypothyroidism, alcoholism
Basophilic stippling on blood smear (Ans - lead poisoning
Schistocytes on blood smear (Ans - TTP-HUS, DIC, prosthetic heart valve, malignant htn, sepsis
Target cells on blood smear (Ans - thalassemia, other hemoglobinopathies, liver disease
- causes of microcytic anemia
(Ans - iron deficiency, lead poisoning, anemia of chronic disease (but usually normocytic), thalassemia, sideroblastic anemia (can also have high MCV)
Antibody test for celiac disease (Ans - anti-endomysia, tissue transglutaminase (small bowel bx is best though)
Antibiotics for MRSA
(Ans - 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 (Ans - Oxacillin/nafcillin, dicloxacillin (IV and oral), cefazolin (IV), cephalexin (oral)
- / 4
Can you use cephalosporins in pt allergic to PCN?(Ans - yes, if the rxn is rash only; no if pt has true anaphylaxis
Antibiotics to use for Staph with PCN allergy (Ans - cephalosporins if rash only; macrolides, clindamycin, vancomycin, linezolid, daptomycin, TMP/SMX
Antibiotics for strep (Ans - PCN, ampicillin, amoxicillin
Antibiotics for GNRs
(Ans - Cephalosporins: cefepime, ceftazidime
PCNs: piperacillin, ticarcillin
Monobactam: Aztreonam
Quinolones: cipro, levo, gati, moxi
Aminoglycs: gentamicin, tobramycin, amikacin
Carbapenems: imipenem, mero, erta
Limitation of ertapenem (Ans - does NOT cover pseudomonas
Piperacillin and ticarcillin (Ans
- GNRs
strep anaerobes
Carbapenems (Ans – good anaerobic coverage strep MSSA
- / 4
Tigecycline (Ans – MRSA good GNR coverage
Anaerobes (Ans – -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 (Ans - aminoglycs, aztreonam, fluoroquinolones, oxacillin/nafcillin, all cephalosporins EXCEPT cefoxitin and cefotetan
Red man syndrome (Ans - red, flushed skin from histamine release, associated with rapid infusion of vancomycin (so slow down the infusion rate)
Osteomyelitis (Ans –
-most common is staph: oxacillin or nafcillin IV for 4-6 wks for MSSA; vanc,
linezolid or dapto for MRSA
-GNRs: salmonella or pseudomonas, can use orals, but must cx org. first
and make sure it is sensitive (BONE bx and cx)
Cellulitis tx (Ans –
-minor infection: oral dicloxacillin or cephalexin
-severe: IV oxacillin, nafcillin or cefazolin
-PCN allergy: if rash, then cephalosporin; if anaphylaxis, then vanc,
linezolid, dapto (macrolides or clinda for minor infection)
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