Think Like the Test Maker

USMLE Step 1
Pass/Fail
Course

Rahul Damania, MD
Integrated Microbiology |
Renal

USMLE Step 1
 Renal Renal Microbiology

26 yo M presents with burning on urination. The patient has had increased

tendency to void over the past few days. He denies any abdominal pain. He
is sexually active with his boyfriend. The patient is afebrile. There is no
CVA tenderness on exam. Genital exam shows an uncircumcised penis
NBME STYLE with no active discharge or lesions. UA is notable for LE & Nitrite . ⊕ ⊕
Which of the following is the most likely causative organism?
QUESTION A. Candida albicans
B. HSV
C. E. Coli
D. S. saphrophyticus

Viva. “14 Difference between Male Urethra and Female Urethra (with Pictures).” Viva Differences, 21 Dec. 2020,
https://vivadifferences.com/male-urethra-vs-female-urethra/.

A 19 yo F presents with dysuria, urinary urgency, and incontinence. She is

sexually active. She is noted to have a UA consistent with a UTI. The
organism on culture is noted to be gram , catalase , urease & ⊕ ⊕ ⊕
novobiocin resistant. Which of the following additional laboratory
NBME STYLE characteristics may be present in this patient?
QUESTION ⊕
A. Gram stain for safranin pink
B. Coagulase ⊖
C. Growth in X & Y agar
D. Bacitracin resistant
E. Optochin sensitive

USMLE Step 1 Pass/Fail Course Gastroenterology: Renal Microbiology

 Renal Renal Microbiology

A 38 yo M presents with urinary urgency and frequency. He has a history of

obesity, dyslipidemia, elevated Hb A1c, and hypertension. He is noted to
⊕ ⊕ ⊕
have a UA: LE, nitrites, 3 glucosuria. Chart review reveals a similar
presentation 4 months prior. Which of the diabetic medication may be
likely contra-indicated in this patient?
USMLE STYLE
→
Sodium-glucose co-transporter 2 inhibitors -gliflozin
QUESTIONS ⬆ glucosuria:
UTIs
Vulvovaginal candidiasis
Weight loss
⬇ ⬇
Use with caution in renal insufficiency ( efficacy with GFR).

USMLE Step 1 Pass/Fail Course Gastroenterology: Renal Microbiology

 Renal Renal Microbiology

A 50 yo M presents after cystoscopy. He has been complaining of using

the bathroom multiple times a day and burning with urination. He denies
hematuria. Exam is notable for 100.4. A UA is notable for nitrites , LE ,⊖ ⊕
& many WBCs. What would urine culture most likely show?
USMLE STYLE ⊕
Gm cocci in chains + Ɣ hemolysis on blood agar. + PYR + growth ⊕
QUESTIONS in bile & 6.5% NaCl → What is the likely organism?
Enterococcus
Part of intestinal flora & seen after cystoscopy, nosocomial, or
BPH.

A 55 yo M presents with a skin rash. He was noted to also have decreased

urine output over the last few days. He was recently treated for PNA with
amoxicillin as an outpatient. The patient is afebrile. He has a diffuse,
erythematous rash on his trunk. Labs show Cr elevation. UA is notable for
few WBCs and on microscopy cells with characteristic dumbbell shaped,
NBME STYLE
bi-lobed nuclei. Urine cx is negative. Which of the following areas of the
QUESTION urinary tract is likely affected?
A. Afferent arteriole
B. Proximal convoluted tubule
C. Renal papillae
D. Renal interstitium

USMLE Step 1 Pass/Fail Course Gastroenterology: Renal Microbiology

Renal Renal Microbiology

USMLE Step 1 Pass/Fail Course Gastroenterology: Renal Microbiology

 Renal Renal Microbiology

Kumar V, Fausto N, Abbas A: Robbins and Cotran Pathologic Basis of Disease, 7th ed, Philadelphia, Saunders, 2004, p 1003, Fig.
20-45.

A 68 yo F presents with agitation. She is a nursing home resident and was

brought in today as she was “yelling at care takers.” Her temperature is
100.4. On exam, she is agitated and not oriented to place. Her serum
sodium is 133 (L). What is the likely diagnosis?
USMLE STYLE
Acute delirium
QUESTIONS Urinary tract infections are frequent cause of delirium in elderly
patients
What is the likely mechanism?
Acute phase cytokines & TLR activation CNS changes. →

USMLE Step 1 Pass/Fail Course Gastroenterology: Renal Microbiology

 Renal Renal Microbiology

A 4 yo F presents with abdominal pain and vomiting. She is noted to be

mildly febrile over the last few days. She has recently been potty trained.
Upon hx review she is noted to have a few abnormal UAs warranting
treatment with antibiotics. Renal ultrasound shows cortical atrophy of
bilateral kidneys and dilated renal calyces. There is no evidence of stones.
Which of the following pathophysiological mechanisms most likely
NBME STYLE
explains this patient’s symptomatology?
QUESTIONS A. Vesicoureteral reflux
B. Fecal translocation to urethra
C. AR Polycystic kidney
D. Renal dysplasia
E. Posterior urethral valve

A 60 yo M is admitted to the ICU for septic shock. On initial presentation, a

CVL, radial arterial line, and indwelling urinary catheter were placed. On day
6 of admission, the patient is noted to have fever and altered mental
status. After complete evaluation, he is noted to have a UA positive for
nitrites & leukocyte esterase. What is the likely intervention which may have
USMLE STYLE
prevented this complication?
QUESTION Prompt removal of the urinary catheter after stabilization of patient
Also, use sterile technique when inserting the catheter.
What organism is likely to be found on urine cx?
Pseudomonas aeruginosa
⊕
Oxidase , non-lactose-fermenting, gram rod. ⊖
A patient presents with fever and dysuria. The patient is admitted as she
has intractable nausea and vomiting. On exam, moderate bilateral CVA
tenderness is noted. A urine culture grows gram negative rods that
demonstrate green hue on EMB agar. What is the likely pathophysiological
NBME STYLE
mechanism explaining this patient’s symptomatology?
QUESTION A. LPS
B. K1 capsular polysaccharide
C. P-fimbriae
D. Heat stable enterotoxin

USMLE Step 1 Pass/Fail Course Gastroenterology: Renal Microbiology

 Renal Renal Microbiology

A 24 yo F presents for prenatal care. The patient is 12 weeks gestation by

⊖
LMP. Screening UA is performed and is notable for a Gm organism (>
100,000 CFU/mL). The patient is asymptomatic. Would this patient warrant
treatment?
USMLE STYLE
Yes
QUESTION Treatment reduces:
UTI progression
Pre-term birth
Low birth weight.

USMLE Step 1 Pass/Fail Course Gastroenterology: Renal Microbiology

 Renal Renal Microbiology

A patient presents with flank pain. The patient is afebrile. An ultrasound of

the abdomen is notable for cortical dilation. UA is positive for LE. A gram
negative bacili is isolated on urine culture. When plated, the bacteria
catalyzes a reaction from NH2 to ammonia. What is the likely diagnosis?
A Struvite Stone 2/2 Proteus Mirabilis or Klebsiella UTI
MICROBIOLOGY What is the composition of these stones?
INTEGRATION Ammonium, Magnesium, Phosphate
Relate to Urease + organisms.

USMLE Step 1 Pass/Fail Course Gastroenterology: Renal Microbiology

Renal Renal Microbiology

Kern WF, Silva FG, Laszik ZG, et al [eds]: Atlas of Renal Pathology, Philadelphia, Saun- ders, 1999,
pp 129, 149

USMLE Step 1 Pass/Fail Course Gastroenterology: Renal Microbiology

 Renal Renal Microbiology

An experimental study is looking at key UA changes between pathologies.

Analysis is performed using direct microscopic visualization of urine
specimen in diseased patients. Which of the following changes on lab
evaluation would most specifically differentiate pyelonephritis from
cystitis?
NBME STYLE
A. 10 WBCs / hpf on urine microscopy
QUESTIONS B. Leukocytosis in blood
C. Increased TNF-ɑ in blood
D. Increased CRP in blood
E. WBC casts on urine microscopy

USMLE Step 1 Pass/Fail Course Gastroenterology: Renal Microbiology

 Renal Renal Microbiology

A 46 yo M presents with hematuria. He states that at the end of his stream

he is noted to have a red hue of urine. He has had no pain during these
episodes. He was recently in Egypt for business. Social history is notable
for 2 packs of cigarettes over the past 15 years. UA is suspicious of an
infectious etiology. Which of the following animals is most likely
NBME STYLE associated with this acute presentation?
A. Bat
QUESTIONS
B. Dog
C. Snail
D. Fish
E. Beaver

Murray PR, Rosenthal KS, Pfaller MA: Medical Microbiology, 7th ed, Philadelphia, Saunders Elsevier, 2013, p 803, Fig. 84-13.

A patient with a history of smoking presents with non-painful hematuria.

Cystoscopy is notable for a sessile mass at the dome of the bladder. Which
of the following microscopic changes would be most suggestive of a
NBME STYLE malignant tumor?
A. Balloon-cells and transitional epithelium
QUESTION
B. Decreased nuclear to cytoplasm fraction
C. Atypical mitosis
D. Involvement of lamina propria and muscularis propria

USMLE Step 1 Pass/Fail Course Gastroenterology: Renal Microbiology

 Renal Renal Microbiology

A child presents to the physician with acute onset lower abdominal pain.
Over the last few days he has had fever and sore throat. He was sent home
from school yesterday due to ‘pink-eye.’ VS is notable for tachycardia. He
USMLE STYLE has suprapubic tenderness. When obtaining a UA specimen, the child notes
clots from urethra. What is the likely diagnosis?
QUESTIONS
→
Hemorrhagic cystitis What is the likely organism?
Adenovirus (DNA virus, non-enveloped, linear).

King TS: Elsevier’s Integrated Pathology, 2007, St. Louis, Mosby Elsevier, p 292, Fig. 12-1

USMLE Step 1 Pass/Fail Course Gastroenterology: Renal Microbiology

 Renal Renal Microbiology

USMLE STYLE
QUESTIONS

USMLE Step 1 Pass/Fail Course Gastroenterology: Renal Microbiology