USMLE Step 3 Questions and Answers with Complete
Solutions | New Update 2025
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
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)
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
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
-GNRs: salmonella or pseudomonas, can use orals, but must cx org. first and make
sure it is sensitive (BONE bx and cx)
Cellulitis tx - ANSWER -minor infection: oral dicloxacillin or cephalexin
-severe: IV oxacillin, nafcillin or cefazolin
Solutions | New Update 2025
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
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)
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
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
-GNRs: salmonella or pseudomonas, can use orals, but must cx org. first and make
sure it is sensitive (BONE bx and cx)
Cellulitis tx - ANSWER -minor infection: oral dicloxacillin or cephalexin
-severe: IV oxacillin, nafcillin or cefazolin
