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USMLE STEP3 Exam Questions
Step3 (Page 16 )

Updated On: 15-Feb-2026
Page 16 of 162
PDF with 804 Questions

A 48-year-old woman complaining of dysuria is diagnosed with a UTI by urinalysis. Urine culture and sensitivities reveal that the causative organism belongs to the genus Klebsiella and is resistant to multiple antibiotics. Based upon the results available, you decide to begin therapy with gentamicin. Which of the following irreversible complications is also associated with gentamicin use?

  1. vestibular dysfunction
  2. cardiomyopathy
  3. optic nerve dysfunction
  4. myelodysplastic disease
  5. cerebellar degeneration

Answer(s): A

Explanation:

Aminoglycosides such as gentamicin accumulate in the proximal tubular cells of the kidney, resulting in a defect in renal concentrating ability and reduced glomerular filtration after several days. This renal impairment is almost always reversible. Of all the aminoglycosides, gentamicin and tobramycin are the most nephrotoxic. Aminoglycosides may also cause ototoxicity in the form of irreversible auditory or vestibular damage. There is a direct relationship between aminoglycoside dosage and the risk for development of ototoxicity, so doses should be adjusted according to a patient's baseline renal function. Complicated UTIs involve metabolic or hormonal abnormalities such as those seen in M or during pregnancy; the presence of foreign bodies such as calculi, tumors, or catheters; the presence of strictures causing turbulent urine flow or vesicoureteral reflux; incomplete voiding such as that seen in neurogenic bladder, prostate hyperplasia or cancer; and, the presence of unusual infecting microorganisms. A history of recurrent UTI does not in itself lead to the classification of subsequent infections as complicated. Due to anatomic differences in urethral length between males and females, any UTI in a male is considered complicated. A history of recent surgery does not correlate with development of a complicated UTI unless the surgical procedure resulted in the creation of some anatomic abnormality which increased the risk of infection; examples of such abnormalities include adhesions or strictures. Apostvoid residual volume greater than 50100 mL suggests abnormal bladder emptying, which would predispose an individual to development of UTIs.



A 48-year-old woman complaining of dysuria is diagnosed with a UTI by urinalysis. Urine culture and sensitivities reveal that the causative organism belongs to the genus Klebsiella and is resistant to multiple antibiotics. Based upon the results available, you decide to begin therapy with gentamicin.

Which of the following would lead to the classification of this patient's infection as "complicated?"

  1. a history of recurrent UTIs
  2. a diagnosis of type II DM
  3. the patient's gender
  4. a history of undergoing a laparoscopic appendectomy 1 month ago
  5. a postvoid residual volume of 25 cc

Answer(s): B

Explanation:

Aminoglycosides such as gentamicin accumulate in the proximal tubular cells of the kidney, resulting in a defect in renal concentrating ability and reduced glomerular filtration after several days. This renal impairment is almost always reversible. Of all the aminoglycosides, gentamicin and tobramycin are the most nephrotoxic. Aminoglycosides may also cause ototoxicity in the form of irreversible auditory or vestibular damage. There is a direct relationship between aminoglycoside dosage and the risk for development of ototoxicity, so doses should be adjusted according to a patient's baseline renal function. Complicated UTIs involve metabolic or hormonal abnormalities such as those seen in M or during pregnancy; the presence of foreign bodies such as calculi, tumors, or catheters; the presence of strictures causing turbulent urine flow or vesicoureteral reflux; incomplete voiding such as that seen in neurogenic bladder, prostate hyperplasia or cancer; and, the presence of unusual infecting microorganisms. A history of recurrent UTI does not in itself lead to the classification of subsequent infections as complicated. Due to anatomic differences in urethral length between males and females, any UTI in a male is considered complicated. A history of recent surgery does not correlate with development of a complicated UTI unless the surgical procedure resulted in the creation of some anatomic abnormality which increased the risk of infection; examples of such abnormalities include adhesions or strictures. Apostvoid residual volume greater than 50100 mL suggests abnormal bladder emptying, which would predispose an individual to development of UTIs.



A 53-year-old fisherman develops pain and swelling of the right hand 8 hours after suffering a fish hook injury to the finger. On physical examination, the patient's temperature is 102.8°F and the patient ap pears septic. The patient's hand and a Gram stain of material aspirated from a bulla are shown in Figures below.



What is the most likely etiology of this bacteremia?

  1. Staphylococcus aureus cellulitis
  2. group A, beta-hemolytic Streptococcus sepsis
  3. Pasteurella multocida cellulitis
  4. Vibrio vulnificus sepsis
  5. Eikenella corrodens cellulitis

Answer(s): D

Explanation:

V. vulnificus is associated with sepsis in patients with liver disease who eat raw oysters or those with salt water contamination of wounds, like those caused by fish hooks. P. multocida is a cause of cellulitis caused by exposure to cat saliva as a result of a bite or a clawing injury. E. corrodens is associated with cellulitis caused by a human bite. Staphylococcus and Streptococcus are the most common causes of cellulitis. The Gram stain shows gram-negative, commashaped organisms typical for vibrios. Close attention should be paid to the wound site in the setting of a V. vulnificus infection. The wound site must be thoroughly cleaned and any necrotic tissue debrided. If necessary, fasciotomy or limb amputation should be performed. Antibiotic therapy should begin immediately as well. Use of a combination of doxycycline and a thirdgeneration cephalosporin such as ceftazidime is considered first-line. Quinolones may be considered as alternative therapy in the case of drug allergy or contraindication. A combination regimen using TMP-SMZ and an aminoglycoside is indicated for treatment in children since doxycycline and quinolones are contraindicated.



A 53-year-old fisherman develops pain and swelling of the right hand 8 hours after suffering a fish hook injury to the finger. On physical examination, the patient's temperature is 102.8°F and the patient ap pears septic. The patient's hand and a Gram stain of material aspirated from a bulla are shown in Figures below.



After appropriate wound care and debridement of necrotic tissue as necessary, which antibiotics should be started in this patient?

  1. levofloxacin
  2. vancomycin
  3. doxycycline and ceftazidime
  4. nafcillin and gentamicin
  5. trimethoprim-sulfamethoxazole(TMP-SMZ)

Answer(s): C

Explanation:

V. vulnificus is associated with sepsis in patients with liver disease who eat raw oysters or those with salt water contamination of wounds, like those caused by fish hooks. P. multocida is a cause of cellulitis caused by exposure to cat saliva as a result of a bite or a clawing injury. E. corrodens is associated with cellulitis caused by a human bite. Staphylococcus and Streptococcus are the most common causes of cellulitis. The Gram stain shows gram-negative, commashaped organisms typical for vibrios. Close attention should be paid to the wound site in the setting of a V. vulnificus infection. The wound site must be thoroughly cleaned and any necrotic tissue debrided. If necessary, fasciotomy or limb amputation should be performed. Antibiotic therapy should begin immediately as well. Use of a combination of doxycycline and a thirdgeneration cephalosporin such as ceftazidime is considered first-line. Quinolones may be considered as alternative therapy in the case of drug allergy or contraindication. A combination regimen using TMP-SMZ and an aminoglycoside is indicated for treatment in children since doxycycline and quinolones are contraindicated.



You receive a call from the nurse at a nursing home for a 70-year-old patient of yours who was febrile overnight and had blood cultures, CXR, and urinalysis ordered by the housestaff. The patient was started empirically on a fluoroquinolone orally. The nurse informs you that the CXR and urinalysis were normal but the blood culture grew out Enterococcus faecalis. The patient has been on oral fluoroquinolone for 36 hours and patient is still febrile but appears stable. Which of the following is most appropriate?

  1. Continue the oral quinolone and add an intravenous first-generation cephalosporin.
  2. Discontinue the oral quinolone and start treatment with an intravenous secondgeneration cephalosporin.
  3. Discontinue the quinolone and start treatment with an intravenous thirdgeneration cephalosporin.
  4. Discontinue the quinolone and start treatment with intravenous ampicillin and an aminoglycoside.
  5. Continue the quinolone, but change from oral to IV route of administration.

Answer(s): D

Explanation:

No cephalosporin is appropriate for the treatment of E. faecalis. This organism is occasionally sensitive to fluoroquinolones, but this choice is unreliable. The combination of ampicillin and an aminoglycoside is synergistic for susceptible E






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