265
A 65-year-old male with a history of atrial fibrillation is on long-term warfarin therapy for stroke prevention. He presents to the emergency department with complaints of bleeding gums, easy bruising, and dark stools for the past two days. He reports no recent changes in his diet but mentions starting a new antibiotic for a urinary tract infection prescribed three days ago. On further questioning, he reveals that the antibiotic is sulfamethoxazole-trimethoprim (a sulfonamide antibiotic). On examination, his vital signs are stable. Laboratory tests reveal:
Prothrombin time (PT): 35 seconds (reference: 11-14 seconds)
International Normalized Ratio (INR): 5.5 (therapeutic range: 2.0-3.0)
What is the most likely cause of this patient's symptoms?
A. Sulfonamide-induced thrombocytopenia
B. Potentiation of warfarin’s effect due to inhibition of cytochrome P450 by sulfamethoxazole
C. Vitamin K deficiency due to sulfonamide-induced malabsorption
D. Reduced warfarin clearance due to renal impairment caused by sulfonamides
A 65-year-old male with a history of atrial fibrillation is on long-term warfarin therapy for stroke prevention. He presents to the emergency department with complaints of bleeding gums, easy bruising, and dark stools for the past two days. He reports no recent changes in his diet but mentions starting a new antibiotic for a urinary tract infection prescribed three days ago. On further questioning, he reveals that the antibiotic is sulfamethoxazole-trimethoprim (a sulfonamide antibiotic). On examination, his vital signs are stable. Laboratory tests reveal:
Prothrombin time (PT): 35 seconds (reference: 11-14 seconds)
International Normalized Ratio (INR): 5.5 (therapeutic range: 2.0-3.0)
What is the most likely cause of this patient's symptoms?
A. Sulfonamide-induced thrombocytopenia
B. Potentiation of warfarin’s effect due to inhibition of cytochrome P450 by sulfamethoxazole
C. Vitamin K deficiency due to sulfonamide-induced malabsorption
D. Reduced warfarin clearance due to renal impairment caused by sulfonamides
266
A 64-year-old man comes to the office for follow-up after a recent hospitalization. Ten days ago, he was admitted
due to fever, dysuria, urinary urgency, and perinea! pain. Evaluation revealed acute prostatitis, and urine culture
was positive for Escherichia coli that was sensitive to all tested antibiotics. He received intravenous ciprofloxacin
with improvement in his symptoms and was subsequently discharged on oral ciprofloxacin. The patient has been
taking the antibiotic as prescribed, but over the past 2 days he has had recurrent fever and dysuria. He takes
diltiazem for palpitations, atorvastatin for hyperlipidemia, and an over-the-counter antacid for frequent heartburn.
Temperature is 37.3 C (99.1 F), blood pressure is 118/68 mm Hg, and pulse is 90/min. Physical examination
shows a mildly enlarged and tender prostate. Repeat urine culture grows E coli. Which of the following is the most
likely cause of this patient's recurrent symptoms?
A. Acquired antibiotic resistance
B. Decreased drug bioavailability
C. Exposure to untreated sexual partner
D. Increased renal drug clearance
E. Induction of hepatic CYP enzymes
A 64-year-old man comes to the office for follow-up after a recent hospitalization. Ten days ago, he was admitted
due to fever, dysuria, urinary urgency, and perinea! pain. Evaluation revealed acute prostatitis, and urine culture
was positive for Escherichia coli that was sensitive to all tested antibiotics. He received intravenous ciprofloxacin
with improvement in his symptoms and was subsequently discharged on oral ciprofloxacin. The patient has been
taking the antibiotic as prescribed, but over the past 2 days he has had recurrent fever and dysuria. He takes
diltiazem for palpitations, atorvastatin for hyperlipidemia, and an over-the-counter antacid for frequent heartburn.
Temperature is 37.3 C (99.1 F), blood pressure is 118/68 mm Hg, and pulse is 90/min. Physical examination
shows a mildly enlarged and tender prostate. Repeat urine culture grows E coli. Which of the following is the most
likely cause of this patient's recurrent symptoms?
A. Acquired antibiotic resistance
B. Decreased drug bioavailability
C. Exposure to untreated sexual partner
D. Increased renal drug clearance
E. Induction of hepatic CYP enzymes
267
A 76-year-old hospitalized woman is evaluated for persistent fevers. Four days ago, she was admitted to the
hospital for sepsis, for which she has received broad-spectrum empiric intravenous antibiotic therapy. Her
temperature is 38.9 C (102 F), blood pressure is 110/80 mm Hg, pulse is 98/min, and respirations are 18/min.
Cardiac examination reveals a new diastolic murmur. Multiple blood cultures drawn at different times grow
Enterococcus. Echocardiogram reveals mitral valve vegetation suggestive of endocarditis. An intravenous
antibiotic is added to the patient's treatment regimen for synergy. Several days later, she develops tinnitus and
hearing loss attributed to this antibiotic. The additional antibiotic most directly affects which of the following
processes?
A. Cell wall cross-linking
B. DNA unwinding
C. Felic acid synthesis
D. Maintenance of transmembrane potential
E. mRNA genetic code reading
F. tRNA charging
A 76-year-old hospitalized woman is evaluated for persistent fevers. Four days ago, she was admitted to the
hospital for sepsis, for which she has received broad-spectrum empiric intravenous antibiotic therapy. Her
temperature is 38.9 C (102 F), blood pressure is 110/80 mm Hg, pulse is 98/min, and respirations are 18/min.
Cardiac examination reveals a new diastolic murmur. Multiple blood cultures drawn at different times grow
Enterococcus. Echocardiogram reveals mitral valve vegetation suggestive of endocarditis. An intravenous
antibiotic is added to the patient's treatment regimen for synergy. Several days later, she develops tinnitus and
hearing loss attributed to this antibiotic. The additional antibiotic most directly affects which of the following
processes?
A. Cell wall cross-linking
B. DNA unwinding
C. Felic acid synthesis
D. Maintenance of transmembrane potential
E. mRNA genetic code reading
F. tRNA charging
268
A 65-year-old man comes to the emergency department due to fevers, chills, and confusion. He has a history of
poorly controlled diabetes mellitus with a nonhealing ulcer of the loft foot. His temperature is 38.3 C (101 F), blood
pressure is 90/60 mm Hg, pulse is 112/min, and respirations are 22/min. On examination, there is slight erythema
surrounding his left foot ulcer with foul-smelling discharge. No heart murmur is auscultated, the lungs are clear,
and the abdomen is soft and nontender. Blood cultures are obtained, and he is started on broad-spectrum
antibiotics. Twenty-four hours later, blood cultures grow 3-lactamase-producing Bacteroides species. Which of the
following is most likely to provide appropriate antimicrobial coverage for this patient?
A. Azithromycin
B. Ceftriaxone
C. Ciprofloxacin
D. Piperacillin-tazobactam
E. Vancomycin
A 65-year-old man comes to the emergency department due to fevers, chills, and confusion. He has a history of
poorly controlled diabetes mellitus with a nonhealing ulcer of the loft foot. His temperature is 38.3 C (101 F), blood
pressure is 90/60 mm Hg, pulse is 112/min, and respirations are 22/min. On examination, there is slight erythema
surrounding his left foot ulcer with foul-smelling discharge. No heart murmur is auscultated, the lungs are clear,
and the abdomen is soft and nontender. Blood cultures are obtained, and he is started on broad-spectrum
antibiotics. Twenty-four hours later, blood cultures grow 3-lactamase-producing Bacteroides species. Which of the
following is most likely to provide appropriate antimicrobial coverage for this patient?
A. Azithromycin
B. Ceftriaxone
C. Ciprofloxacin
D. Piperacillin-tazobactam
E. Vancomycin
269
A previously healthy 19-year-old college student comes to student health services 24 hours after the onset of headache,
stiff neck, and sensitivity to light. She does not recall any sick contacts. She had chickenpox at the age of 7 years. Her
most recent examination 1 year ago included PPD skin testing and showed no abnormalities. She takes a daily
multivitamin and an herbal weight-loss preparation. She received all appropriate immunizations during childhood but
has not received any since then. She does not smoke, drink alcohol, or use illicit drugs. There is no family history of
serious illness. She appears lethargic. Her temperature is 39.1°C (102.4°F), pulse is 112/min, respirations are 20/min,
and blood pressure is 100/68 mm Hg. Examination shows diffuse petechiae. Kernig and Brudzinski signs are present.
The remainder of the examination shows no abnormalities. A lumbar puncture is performed. Cerebrospinal fluid (CSF)
analysis shows numerous segmented neutrophils and a decreased glucose concentration. A Gram stain of the CSF
shows gram-negative cocci. Which of the following is the most appropriate pharmacotherapy?
(A) Ceftriaxone
(B) Clindamycin
(C) Erythromycin
(D) Metronidazole
(E) Vancomycin
A previously healthy 19-year-old college student comes to student health services 24 hours after the onset of headache,
stiff neck, and sensitivity to light. She does not recall any sick contacts. She had chickenpox at the age of 7 years. Her
most recent examination 1 year ago included PPD skin testing and showed no abnormalities. She takes a daily
multivitamin and an herbal weight-loss preparation. She received all appropriate immunizations during childhood but
has not received any since then. She does not smoke, drink alcohol, or use illicit drugs. There is no family history of
serious illness. She appears lethargic. Her temperature is 39.1°C (102.4°F), pulse is 112/min, respirations are 20/min,
and blood pressure is 100/68 mm Hg. Examination shows diffuse petechiae. Kernig and Brudzinski signs are present.
The remainder of the examination shows no abnormalities. A lumbar puncture is performed. Cerebrospinal fluid (CSF)
analysis shows numerous segmented neutrophils and a decreased glucose concentration. A Gram stain of the CSF
shows gram-negative cocci. Which of the following is the most appropriate pharmacotherapy?
(A) Ceftriaxone
(B) Clindamycin
(C) Erythromycin
(D) Metronidazole
(E) Vancomycin
270
A previously healthy 17-year-old girl comes to the emergency department because of a 5-day history of progressive lower abdominal pain, fever, and malodorous vaginal discharge. Menarche was at the age of 12 years, and her last menstrual period was 2 weeks ago. She is sexually active with one male partner and uses a combination contraceptive
patch. Her temperature is 37.8°C (100°F), pulse is 90/min, respirations are 22/min, and blood pressure is 110/70 mm Hg. Abdominal examination shows severe lower quadrant tenderness bilaterally. Pelvic examination shows a purulent cervical discharge, cervical motion tenderness, and bilateral adnexal tenderness. Her hemoglobin concentration is 10.5 g/dL, leukocyte count is 13,000/mm3, and platelet count is 345,000/mm3. A urine pregnancy test is negative. Which of the following is the most appropriate pharmacotherapy?
(A) Oral azithromycin
(B) Vaginal clindamycin
(C) Intravenous penicillin and vancomycin
(D) Intramuscular ceftriaxone and oral doxycycline
(E) Intravenous oxacillin and metronidazole
A previously healthy 17-year-old girl comes to the emergency department because of a 5-day history of progressive lower abdominal pain, fever, and malodorous vaginal discharge. Menarche was at the age of 12 years, and her last menstrual period was 2 weeks ago. She is sexually active with one male partner and uses a combination contraceptive
patch. Her temperature is 37.8°C (100°F), pulse is 90/min, respirations are 22/min, and blood pressure is 110/70 mm Hg. Abdominal examination shows severe lower quadrant tenderness bilaterally. Pelvic examination shows a purulent cervical discharge, cervical motion tenderness, and bilateral adnexal tenderness. Her hemoglobin concentration is 10.5 g/dL, leukocyte count is 13,000/mm3, and platelet count is 345,000/mm3. A urine pregnancy test is negative. Which of the following is the most appropriate pharmacotherapy?
(A) Oral azithromycin
(B) Vaginal clindamycin
(C) Intravenous penicillin and vancomycin
(D) Intramuscular ceftriaxone and oral doxycycline
(E) Intravenous oxacillin and metronidazole
271
A 25-year-old female presents to the clinic for evaluation of multiple skin changes. She reports that over the past few years, she has noticed the gradual appearance of several light-brown spots on her skin, which have progressively increased in number. She also mentions the development of a few soft, flesh-colored lumps under her skin, which are painless. Her family history is significant for a mother with similar skin changes and a father with a history of benign tumors. On physical examination, you observe several café-au-lait spots, some measuring up to 2 cm in diameter. Additionally, multiple small, soft, nodular masses are palpable under the skin, especially along her axillary and inguinal regions. No other neurological deficits are noted. What is the most likely diagnosis for this patient?
A) Tuberous sclerosis
B) Neurofibromatosis type 1 (NF1)
C) Sturge-Weber syndrome
D) Von Hippel-Lindau disease
A 25-year-old female presents to the clinic for evaluation of multiple skin changes. She reports that over the past few years, she has noticed the gradual appearance of several light-brown spots on her skin, which have progressively increased in number. She also mentions the development of a few soft, flesh-colored lumps under her skin, which are painless. Her family history is significant for a mother with similar skin changes and a father with a history of benign tumors. On physical examination, you observe several café-au-lait spots, some measuring up to 2 cm in diameter. Additionally, multiple small, soft, nodular masses are palpable under the skin, especially along her axillary and inguinal regions. No other neurological deficits are noted. What is the most likely diagnosis for this patient?
A) Tuberous sclerosis
B) Neurofibromatosis type 1 (NF1)
C) Sturge-Weber syndrome
D) Von Hippel-Lindau disease
272
A 40-year-old male presents to the clinic with a complaint of gradual, painless swelling in his left arm. The patient reports that the swelling has been present for several months and has slowly increased in size. He denies any history of trauma or changes in sensation. On physical examination, a smooth, firm, non-tender mass is palpated along the course of the left radial nerve. Neurological examination is otherwise unremarkable, with no signs of motor or sensory deficits. MRI of the left arm reveals a well-defined mass near the radial nerve with features suggestive of a benign peripheral nerve sheath tumor. The mass shows no evidence of malignancy. Which of the following is the primary treatment option for Schwannomas that are symptomatic or have risk for complications?
A) Radiation therapy
B) Chemotherapy
C) Surgical excision
D) Observation and follow-up imaging
A 40-year-old male presents to the clinic with a complaint of gradual, painless swelling in his left arm. The patient reports that the swelling has been present for several months and has slowly increased in size. He denies any history of trauma or changes in sensation. On physical examination, a smooth, firm, non-tender mass is palpated along the course of the left radial nerve. Neurological examination is otherwise unremarkable, with no signs of motor or sensory deficits. MRI of the left arm reveals a well-defined mass near the radial nerve with features suggestive of a benign peripheral nerve sheath tumor. The mass shows no evidence of malignancy. Which of the following is the primary treatment option for Schwannomas that are symptomatic or have risk for complications?
A) Radiation therapy
B) Chemotherapy
C) Surgical excision
D) Observation and follow-up imaging
273
A 5-year-old child is evaluated in the emergency department for vomiting for the past 2 days.
Three days ago, she developed a cough and fever of 39° C.
When she is febrile, there is associated diffuse abdominal pain and headache, which improve when she is given ibuprofen or acetaminophen.
Over the past 24 hours she has voided twice.
She has not had any diarrhea.
On physical examination, the girl has a heart rate of 140 beats/min, respiratory rate of 28 breaths/min, blood pressure of 95/62 mm Hg, and oxygen saturation of 93% in room air.
She appears fatigued but responds appropriately to questions.
Her mucous membranes appear slightly dry.
There are focal crackles heard in the right lower lung field, a normal cardiac rhythm with no murmur, and a soft non-tender abdomen with no guarding, rebound, organomegaly, or mass.
Her extremities are cool with a capillary refill time of 3 seconds.
The remainder of her examination findings are normal.
Of the following, the degree of this child’s dehydration is
A. no dehydration
B. mild dehydration
C. moderate dehydration
D. severe dehydration
A 5-year-old child is evaluated in the emergency department for vomiting for the past 2 days.
Three days ago, she developed a cough and fever of 39° C.
When she is febrile, there is associated diffuse abdominal pain and headache, which improve when she is given ibuprofen or acetaminophen.
Over the past 24 hours she has voided twice.
She has not had any diarrhea.
On physical examination, the girl has a heart rate of 140 beats/min, respiratory rate of 28 breaths/min, blood pressure of 95/62 mm Hg, and oxygen saturation of 93% in room air.
She appears fatigued but responds appropriately to questions.
Her mucous membranes appear slightly dry.
There are focal crackles heard in the right lower lung field, a normal cardiac rhythm with no murmur, and a soft non-tender abdomen with no guarding, rebound, organomegaly, or mass.
Her extremities are cool with a capillary refill time of 3 seconds.
The remainder of her examination findings are normal.
Of the following, the degree of this child’s dehydration is
A. no dehydration
B. mild dehydration
C. moderate dehydration
D. severe dehydration
274
A 3-month-old infant, born at term, is seen in the office for concerns about easy bruising.
She was delivered at home after an uncomplicated pregnancy.
She is exclusively breastfed.
Her parents report that as a neonate, she had some bleeding from her umbilical stump but has otherwise been well.
On physical
examination, the girl’s vital signs are normal for age.
She has bruises on her bilateral upper and lower extremities.
The remainder of her examination findings are normal.
Results of her laboratory evaluation are shown:
Laboratory Test Result
White blood cell count 6,000/µL (6.0 × 10 /L)
Hemoglobin 9.0 g/dL (90 g/L)
Platelet count 300 × 10 /µL (300 × 10 /L)
Prothrombin time 30 s
International normalized ratio 4
Activated partial thromboplastin time 40 s
Factor II 0.20 U/mL (reference range, 0.45-1.05 U/mL)
Factor V 0.60 (reference range, 0.48-1.32)
Factor VII 0.10 (reference range, 0.39-1.43)
Factor VIII 0.60 (reference range, 0.50-1.25)
Factor IX 0.19 (reference range, 0.21-1.13)
Factor X 0.18 (reference range, 0.35-1.07)
Of the following, this child’s symptoms will be MOST improved with parenteral administration of
A. aminocaproic acid
B. factor VII concentrate
C. factor VIII concentrate
D. vitamin K
A 3-month-old infant, born at term, is seen in the office for concerns about easy bruising.
She was delivered at home after an uncomplicated pregnancy.
She is exclusively breastfed.
Her parents report that as a neonate, she had some bleeding from her umbilical stump but has otherwise been well.
On physical
examination, the girl’s vital signs are normal for age.
She has bruises on her bilateral upper and lower extremities.
The remainder of her examination findings are normal.
Results of her laboratory evaluation are shown:
Laboratory Test Result
White blood cell count 6,000/µL (6.0 × 10 /L)
Hemoglobin 9.0 g/dL (90 g/L)
Platelet count 300 × 10 /µL (300 × 10 /L)
Prothrombin time 30 s
International normalized ratio 4
Activated partial thromboplastin time 40 s
Factor II 0.20 U/mL (reference range, 0.45-1.05 U/mL)
Factor V 0.60 (reference range, 0.48-1.32)
Factor VII 0.10 (reference range, 0.39-1.43)
Factor VIII 0.60 (reference range, 0.50-1.25)
Factor IX 0.19 (reference range, 0.21-1.13)
Factor X 0.18 (reference range, 0.35-1.07)
Of the following, this child’s symptoms will be MOST improved with parenteral administration of
A. aminocaproic acid
B. factor VII concentrate
C. factor VIII concentrate
D. vitamin K