ID 1

Question 1

1. P.E. is a 56-year-old man who comes to the clinic
   with a 3-day history of fever, chills, pleuritic chest
   pain, malaise, and productive cough. In the clinic,
   his temperature is 102.1°F (38.9°C) (all other vital
   signs are normal). His chest radiograph reveals
   consolidation in the right lower lobe. His white
   blood cell count (WBC) is 14,400 cells/mm3
   , but
   all other laboratory values are normal. He is given
   a diagnosis of community-acquired pneumonia
   (CAP). He has not received any antibiotics in 5
   years and has no chronic disease states. Which is
   the best empiric therapy for P.E.?
   A. Doxycycline 100 mg orally twice daily.
   B. Cefuroxime axetil 250 mg orally twice daily.
   C. Levofloxacin 750 mg orally daily.
   D. Trimethoprim/sulfamethoxazole double strength
   orally twice daily.

Answer 1

1. Answer: A
   The patient has CAP that does not require hospitaliza-
   tion (PSI score is 56, class II, which is low risk). Because
   he has not received any antibiotics in the past 3 months
   and has no comorbidities, he is at low risk of DRSP.
   Therefore, the drug of choice is either a macrolide or
   doxycycline (Answer A is correct). Cefuroxime is not
   recommended for the treatment of CAP (Answer B is
   incorrect). Fluoroquinolones are recommended only if
   the patient has had recent antibiotics or has comorbid-
   ities (Answer C is incorrect). Trimethoprim/sulfame-
   thoxazole is not used for CAP (Answer D is incorrect)

Question 2

2. H.W. is a 38-year-old woman who presents with a
   fever, malaise, dry cough, nasal congestion, and
   severe headaches. Her symptoms began suddenly
   3 days ago, and she has been in bed since then. She
   reports no other illness in her family, but several
   people have recently called in sick at work. It is
   influenza season. Which is best for H.W.?
   A. Azithromycin 500 mg, followed by 250 mg
   daily orally for 4 more days.
   B. Amoxicillin/clavulanic acid 875 mg orally
   twice daily for 5 days.
   C. Oseltamivir 75 mg twice daily orally for 5
   days.
   D. Symptomatic treatment only.

Answer 2

2. Answer: D
   The symptoms of this patient (high temperature, mal-
   aise, dry cough, nasal congestion, and severe head-
   aches) are most consistent with influenza; therefore, an
   antibacterial agent would not affect recovery (Answers
   A and B are incorrect). Oseltamivir should be initiated
   within 48 hours of symptom onset, so because this
   patient is more than 3 days out from symptom onset,
   oseltamivir will not affect recovery (Answer C is incor-
   rect). Because of the viral etiology and time since symp-
   tom onset, symptomatic treatment is all that is indicated
   (Answer D is correct).

Question 3

3. A study is designed to assess the risk of pneumo-
   coccal pneumonia in older adults 10 years or more
   after receiving their last pneumococcal vaccina-
   tion, compared with older adults who have never
   received any pneumococcal vaccinations. Which
   study design is best?
   A. Case series.
   B. Case-control study.
   C. Prospective cohort study.
   D. Randomized controlled trial.

Answer 3

3. Answer: B
   A case-control study would be the most appropri-
   ate study design because it is the most ethical, cost-
   effective, timely method (Answer B is correct). A stron-
   ger study design—for instance, a prospective cohort
   study or a randomized controlled trial—has many dis-
   advantages if used to answer this question. In a pro-
   spective cohort study, too many patients would need
   to be observed because of the low incidence of con-
   firmed pneumococcal pneumonia. This study would
   be too costly and take too long to complete (Answer
   C is incorrect). Randomized controlled trials also have
   many disadvantages in this situation. First, patients
   would need to be vaccinated and then observed for at
   least 10 years. Second, too many patients would need to
   be observed because of the low incidence of confirmed
   pneumococcal pneumonia. Third, it would be unethical
   to randomly assign half of the patients to no vaccina-
   tion. This study would therefore be too costly, uneth-
   ical, and time-consuming (Answer D is incorrect).
   A case series would evaluate only a few patients given
   a diagnosis of pneumococcal pneumonia 10 years or
   more after vaccination. It would not provide compar-
   ative data, nor would it provide a strong study design
   (Answer A is incorrect).

Question 4

4. A.B. is a 63-year-old woman who presents to the
   emergency department with left leg pain and ery-
   thema. The pain and erythema have worsened over
   the past 24 hours. The left leg is significantly swol-
   len with a large area of erythema and large bullae
   extending from the thigh to the upper leg. There
   is crepitus within the soft tissue. A.B. is found to
   have rapidly progressing necrotizing fasciitis. A.B.
   has normal renal function and no known drug
   allergies. Which is the best empiric therapy for
   A.B.?
   A. Vancomycin 15 mg/kg intravenously every 12
   hours.
   B. Piperacillin/tazobactam 4.5 g intravenously
   every 8 hours.
   C. Vancomycin 15 mg/kg intravenously every
   12 hours plus meropenem 1 g intravenously
   every 8 hours plus clindamycin 900 mg intra-
   venously every 8 hours.
   D. Linezolid 600 mg intravenously every 12
   hours plus ceftriaxone 1 g intravenously every
   24 hours plus azithromycin 500 mg intrave-
   nously daily.

Answer 4

4. Answer: C
   Although necrotizing fasciitis can be caused by
   Streptococcus only, it is often a mixed infection that
   includes gram-positive, gram-negative, and anaero-
   bic bacteria. Therefore, in addition to urgent surgi-
   cal debridement, it must be treated empirically with
   broad-spectrum antibiotics. It is recommended that one
   of those antibiotics have activity against P. aeruginosa.
   Clindamycin therapy is also recommended initially
   to decrease the production of toxin by Streptococcus.
   Because vancomycin alone has no activity against
   gram-negative organisms and does not decrease toxin
   production, it is not the best empiric agent (Answer A is
   incorrect). Moreover, piperacillin/tazobactam alone has
   no activity against MRSA and does not decrease toxin
   production (Answer B is incorrect). Although there are
   some data that azithromycin may also decrease toxin
   production and that linezolid has MRSA activity, ceftri-
   axone has no activity against P. aeruginosa (Answer D
   is incorrect). The best empiric option is vancomycin plus
   meropenem plus clindamycin (Answer C is correct).

Question 5

5. N.R. is a 28-year-old woman who presents to the
   clinic with a 2-day history of dysuria, frequency,
   and urgency. She has no significant medical his-
   tory, and the only drug she takes is an oral con-
   traceptive. Which is the best empiric therapy for
   N.R.?
   A. Nitrofurantoin extended release (ER) 100 mg
   orally twice daily for 3 days.
   B. Ciprofloxacin 500 mg orally twice daily for
   7 days.
   C. Trimethoprim/sulfamethoxazole double strength
   orally twice daily for 3 days.
   D. Cephalexin 500 mg orally four times daily for
   3 days.

Answer 5

5. Answer: C
   Although nitrofurantoin is a recommended first-
   line agent, the therapy duration is too short for its
   use (Answer A is incorrect). Because this patient
   has no contraindications to the use of trimethoprim/
   sulfamethoxazole or nitrofurantoin, and trimethoprim/
   sulfamethoxazole resistance rates are not mentioned as
   being high, fluoroquinolones would not be considered
   appropriate as first-line therapy in this particular case
   (Answer B is incorrect). In addition, 7 days of therapy
   is not necessary. The best choice for this patient is tri-
   methoprim/sulfamethoxazole double strength twice
   daily orally for 3 days. The patient should be counseled
   about the potential interaction between antibiotics and
   oral contraceptives (Answer C is correct). β-Lactams
   are not as effective as trimethoprim/sulfamethoxazole,
   and data are limited on their use for 3 days (Answer D
   is incorrect).

Question 6

6. B.Y. is an 85-year-old woman who is bedridden and
   lives in a nursing home. She is chronically cathe-
   terized, and her urinary catheter was last changed
   3 weeks ago. Today, her urine is cloudy, and a uri-
   nalysis reveals many bacteria. B.Y. is not noticing
   any symptoms. A urine culture is obtained. Which
   option is best for B.Y.?
   A. No antibiotic therapy because she is chron-
   ically catheterized and has no symptoms.
   B. No antibiotic therapy, but the catheter should
   be changed.
   C. Ciprofloxacin 500 mg orally twice daily for
   7 days and change the catheter.
   D. Ciprofloxacin 500 mg orally twice daily for
   14–21 days without a change in catheter.

Answer 6

6. Answer: A
   For the asymptomatic patient who is bedridden and
   chronically catheterized, with cloudy urine and bac-
   teria revealed by urinalysis, no therapy is indicated
   (Answer A is correct). All patients with chronic urinary
   catheters will be bacteriuric. Because this patient is
   asymptomatic, the catheter does not need to be replaced
   (Answer B is incorrect). If she were symptomatic, cath-
   eter replacement might be indicated. Antibiotics are not
   indicated; however, a 7-day course would be appropri-
   ate if treatment were instituted (Answer C and D are
   incorrect). A long course of treatment only increases
   the risk of acquiring resistant organisms.

Question 7

7. V.E. is a 44-year-old man who presents to the
   emergency department with a warm, erythema-
   tous, and painful right lower extremity. There is
   no raised border at the edge of the infection. Three
   days ago, he scratched his leg on a barbed wire
   fence on his property (no puncture wound associ-
   ated with the fence). His temperature has been as
   high as 101.8°F (38°C) with chills. Doppler studies
   of his lower extremity are negative. Blood cultures
   are negative. Which is the best empiric therapy
   for V.E.?
   A. Cefazolin 1 g intravenously every 8 hours.
   B. Penicillin G 2 million units intravenously
   every 4 hours.
   C. Piperacillin/tazobactam 3.375 g intravenously
   every 6 hours.
   D. Apixaban 10 mg orally twice daily for 7 days,
   followed by 5 mg orally twice daily.

Answer 7

7. Answer: A
   Because cellulitis (which the patient appears to have)
   is usually caused by Streptococcus or Staphylococcus,
   cefazolin is the drug of choice (vancomycin could be
   initiated empirically if MRSA were a concern in this
   patient) (Answer A is correct). Although penicillin is
   the treatment of choice for erysipelas, the patient prob-
   ably has acute cellulitis (there is no raised border at
   the edge of the infection, which indicates erysipelas)
   (Answer B is incorrect). Although piperacillin/tazo-
   bactam has activity against both Streptococcus and
   Staphylococcus, this treatment is too broad spectrum
   for an acute cellulitis (Answer C is incorrect). Because
   Doppler studies are negative, the likelihood of a deep
   venous thrombosis is low (Answer D is incorrect).

Question 8

8. R.K. is a 36-year-old woman who presents to the
   emergency department with a severe headache and
   neck stiffness. Her temperature is 99.5°F (37.5°C).
   After a negative computed tomographic scan of
   the head, a lumbar puncture reveals the following:
   glucose 54 mg/dL (peripheral, 104 mg/dL), protein
   88 mg/dL, and WBC 220 cells/mm3
   (100% lym-
   phocytes). The Gram stain reveals no organisms.
   Which option is best for R.K.?
   A. This is aseptic meningitis, and no antibiotics
   are necessary.
   B. Administer ceftriaxone 2 g intravenously
   every 12 hours until the cerebrospinal fluid
   (CSF) cultures are negative for bacteria.
   C. Administer ceftriaxone 2 g intravenously
   every 12 hours and vancomycin 15 mg/kg
   intravenously every 12 hours until the CSF
   cultures are negative for bacteria.
   D. Administer acyclovir 500 mg intravenously
   every 8 hours until the CSF culture results are
   negative for bacteria

Answer 8

8. Answer: C
   Even if a patient is believed to have aseptic meningi-
   tis after analysis of the CSF, antibiotics must be given
   until CSF cultures are negative (Answer A is incorrect).
   In empiric therapy for bacterial meningitis in adults
   (i.e., when the CSF Gram stain is negative), ceftriax-
   one should be used in combination with vancomycin
   (Answer B is incorrect). The vancomycin is necessary
   for activity against resistant S. pneumoniae (Answer
   C is correct). Although the symptoms and CSF results
   are similar to what is expected for herpes simplex
   encephalitis, the use of acyclovir alone in this patient
   is inappropriate. Antibacterials must be used as well.
   Viral meningitis is generally caused by coxsackievirus,
   echovirus, and enterovirus, which are not treated with
   acyclovir (Answer D is incorrect).

Question 9

9.. L.G. is a 49-year-old woman with a history of
mitral valve prolapse. She presents to her physi-
cian’s office with malaise and a low-grade fever.
Her physician notes that her murmur is louder
than usual and orders blood cultures and an echo-
cardiogram. A large vegetation is observed on
L.G.’s mitral valve, and her blood cultures are
growing Enterococcus faecalis (susceptible to all
antibiotics). Which is the best therapy for L.G.?
A. Penicillin G plus gentamicin for 2 weeks.
B. Vancomycin plus ceftriaxone for 2 weeks.
C. Ampicillin plus ceftriaxone for 4–6 weeks.
D. Cefazolin plus gentamicin for 4–6 weeks.

Answer 9

9. Answer: C
   Enterococcal endocarditis should be treated for 4–6
   weeks. The 2-week treatment regimen is indicated only
   for streptococcal endocarditis (Answer A is incorrect).
   There is also no indication that the patient is penicil-
   lin allergic; thus, vancomycin should not be used as
   first-line treatment (Answer B is incorrect). Ampicillin
   plus ceftriaxone for 4–6 weeks is a regimen of choice
   for penicillin-susceptible enterococcal endocarditis
   (Answer C is correct). Cefazolin has no activity against
   Enterococcus; therefore, the regimen with cefazolin is
   inappropriate (Answer D is incorrect).

Question 10

10. N.L. is a 28-year-old woman with no significant
    medical history. She reports to the emergency
    department with fever and severe right lower
    quadrant abdominal pain. The pain had been dull
    for the past few days, but it suddenly became
    severe during the past 8 hours. Her temperature is 103.5°F (39.7°C), and she has rebound tenderness
    on abdominal examination. She is taken to surgery
    immediately, where a perforated appendix is
    diagnosed and repaired. Which is the best follow-up
    antibiotic regimen?
    A. Vancomycin 1000 mg intravenously every
    12 hours plus metronidazole 500 mg intrave-
    nously every 8 hours.
    B. Cefazolin 1 g intravenously every 8 hours plus
    ciprofloxacin 400 mg intravenously every 12
    hours.
    C. Ceftriaxone 1 g intravenously every 24 hours
    plus metronidazole 500 mg intravenously
    every 8 hours.
    D. No antibiotics needed after surgical repair of
    a perforated appendix.

Answer 10

10. Answer: C
    A perforated appendix requires antibiotics after surgery
    for an intra-abdominal infection (Answer D is incor-
    rect). The combination of vancomycin and metronida-
    zole does not have adequate activity against aerobic,
    gram-negative organisms (e.g., E. coli) (Answer A is
    incorrect). The combination of cefazolin and ciproflox-
    acin does not have adequate activity against anaerobic
    organisms (e.g., B. fragilis group) (Answer B is incor-
    rect). Ceftriaxone plus metronidazole is a good choice
    for intra-abdominal infections, although it has limited
    activity against Enterococcus (Answer C is correct).

Question 11

11. O.R. is a 73-year-old man who presents to the
    emergency department with a 3-day history of
    fever, chills, frequency, urgency, and perineal
    pain. A urinalysis reveals many bacteria. A rectal
    examination reveals a swollen, tender prostate. He
    is given a diagnosis of acute bacterial prostatitis.
    Which is the best regimen for this patient?
    A. Amoxicillin/clavulanate 875 orally twice daily
    for 7 days.
    B. Trimethoprim/sulfamethoxazole double strength
    orally twice daily for 14 days.
    C. Cefprozil 500 mg orally twice daily for 21
    days.
    D. Ciprofloxacin 500 mg orally twice daily for
    28 days.

Answer 11

11. Answer: D
    β-Lactam antibiotics are not recommended first-line
    agents for patients with acute bacterial prostatitis.
    Therefore, amoxicillin/clavulanate and cefprozil are
    not the best options in this patient (Answers A and C
    are incorrect). Although trimethoprim/sulfamethoxaz-
    ole is an appropriate antibiotic, 14 days of treatment
    is too short for prostatitis. Treatment duration should
    be 4 weeks (Answer B is incorrect). Fluoroquinolones
    are an appropriate antibiotic class for prostatitis, and
    the 28-day duration is also appropriate (Answer D is
    correct).

Question 12

12. J.M. is a 72-year-old woman with a history of atrial
    fibrillation, hypertension, a right total hip replace-
    ment 8 months earlier, and Crohn disease. She has
    no drug allergies. She presents to the hospital with
    increasing pain in her prosthetic hip over the past
    month. There is concern about hip osteomyelitis.
    Bone cultures are growing methicillin-sensitive
    Staphylococcus aureus. J.M. has normal renal
    function and no known drug allergies. Which is
    the best antibiotic regimen for this patient?
    A. Vancomycin 1000 mg intravenously every 12
    hours plus rifampin 300 mg orally twice daily
    for 2 weeks.
    B. Cefazolin 2 g intravenously every 8 hours
    plus rifampin 300 mg orally twice daily for
    6 weeks followed by long-term oral antibiotics.
    C. Nafcillin 1 g intravenously every 4 hours for
    6 weeks.
    D. Daptomycin 6 mg/kg intravenously daily for
    6 weeks followed by long-term oral antibiotics.

Answer 12

12. Answer: B
    Because the organism causing the infection is known
    to be MSSA, using vancomycin or daptomycin is
    unnecessary. They both can potentially cause serious
    toxicities, and daptomycin is expensive (Answers A
    and D are incorrect). Both nafcillin and cefazolin are
    appropriate choices for MSSA osteomyelitis; however,
    because this infection involves a prosthetic joint rifam-
    pin must be combined with the primary antibiotic, and this combination must continue for 2–6 weeks (Answer
    C is incorrect). This must be followed with 3 months of
    appropriate oral antibiotics. (Answer B is correct).

Question 13

13. B.K. is a 58-year-old woman (height 66 inches,
    weight 82 kg) who is scheduled to undergo a total
    knee replacement tomorrow. She has no significant
    medical history and no drug allergies. Which is the
    best surgical prophylaxis regimen for this patient?
    A. Cefazolin 2 g within 1 hour of the incision and
    no doses postoperatively.
    B. Cefazolin 2 g within 4 hours of the incision
    and three doses every 8 hours postoperatively.
    C. Cefazolin 1 g within 1 hour of the incision and
    three doses every 8 hours postoperatively.
    D. Cefazolin 1 g within 4 hours of the incision
    and no doses postoperatively.

Answer 13

13. Answer: A
    For any orthopedic surgical procedures in which pros-
    thetic materials will be implanted, surgical prophylaxis
    is necessary. The preferred agent is cefazolin, although
    vancomycin may be used in patients with allergies. The
    recommended dosage of cefazolin is at least 2 g (3 g
    for those weighing more than 120 kg) (Answers C and
    D are incorrect). Antibiotics must be present in the tis-
    sues at the time of incision, and it is best to adminis-
    ter the agent within 1 hour of the incision (Answer A
    is correct). Because orthopedic procedures tend to be
    shorter procedures, redosing is probably unnecessary.
    Administering antibiotics beyond surgical closure is
    unnecessary (Answer B is incorrect).

Question 14

Patient Case
1. R.L. is a 68-year-old man who presents to the emergency department with coughing and shortness of
breath. His symptoms, which began 4 days ago, have worsened during the past 24 hours. He is coughing up
yellow-green sputum, and he has chills, with a temperature of 102.4°F (39°C). His medical history includes
coronary artery disease with a myocardial infarction 5 years ago, congestive heart failure, hypertension, and
osteoarthritis. He rarely drinks alcohol and has not smoked since his myocardial infarction. He lives at home
with his wife. His medications on admission include lisinopril 10 mg/day, hydrochlorothiazide 25 mg/day,
and acetaminophen 650 mg four times/day. On physical examination, he is alert and oriented, with the following
vital signs: temperature 101.8°F (38°C), heart rate 100 beats/minute, respiratory rate 32 breaths/minute,
and blood pressure 142/94 mm Hg. His laboratory results are normal except for blood urea nitrogen (BUN)
32 mg/dL (serum creatinine [SCr] 1.23 mg/dL). A chest radiograph reveals infiltrates in the right lower lobe.
A sputum specimen is not available. If R.L. were hospitalized, which would be the best empiric therapy for him?
A. Ampicillin/sulbactam 1.5 g intravenously every 6 hours.
B. Piperacillin/tazobactam 4.5 g intravenously every 6 hours plus gentamicin 180 mg intravenously every
12 hours.
C. Ceftriaxone 1 g intravenously every 24 hours plus azithromycin 500 mg intravenously every 24 hours.
D. Doxycycline 100 mg intravenously every 12 hours.

Answer 14

1. Answer: C
   Although ampicillin/sulbactam has good activity
   against H. influenzae, Moraxella catarrhalis, and S.
   pneumoniae (but not drug-resistant S. pneumoniae
   [DRSP]), it has no activity against atypical organisms
   (L. pneumophila, Mycoplasma pneumoniae,
   Chlamydia pneumoniae). Current recommendations
   are to include a macrolide with a β-lactam antibiotic for
   hospitalized patients with CAP (Answer A is incorrect).
   Piperacillin/tazobactam has good activity against H.
   influenzae, M. catarrhalis, and S. pneumoniae (but not
   DRSP) and, with gentamicin, is excellent for pneumonia
   caused by most gram-negative organisms. However,
   this increased activity is not necessary for CAP, and the
   combination has no activity against atypical organisms
   (Answer B is incorrect). Ceftriaxone plus azithromycin
   is the best initial choice. It has excellent activity
   against atypical organisms (because of azithromycin),
   H. influenzae, M. catarrhalis, and S. pneumoniae (even
   intermediate DRSP) (Answer C is correct). Although
   doxycycline has activity against atypical organisms and
   most of the typical organisms that cause CAP, it is not
   recommended as monotherapy in hospitalized patients.
   In addition, its activity against S. pneumoniae may be
   limited (if the patient lives in an area with extensive
   DRSP). Doxycycline would not be the best initial choice
   (Answer D is incorrect).

Question 15

Patient Case
2. B.P. is a 66-year-old woman who underwent a two-vessel coronary artery bypass graft 8 days ago and has
been on a ventilator in the surgical intensive care unit since then. Her temperature is now rising and her chest
radiograph reveals a new infiltrate in the right lower lobe. Her medical history includes coronary artery disease
with a myocardial infarction 2 years ago, COPD, and hypertension. All antipseudomonal antibiotics in
the institution are active against at least 90% of strains. B.P. has no known drug allergies. Which is the best
empiric therapy for B.P.?
A. Ceftriaxone 1 g intravenously every 24 hours plus gentamicin 7 mg/kg intravenously every 24 hours plus
linezolid 600 mg intravenously every 12 hours.
B. Piperacillin/tazobactam 4.5 g intravenously every 6 hours.
C. Levofloxacin 750 mg intravenously every 24 hours plus linezolid 600 mg intravenously every 12 hours.
D. Cefepime 2 g intravenously every 8 hours plus tobramycin 7 mg/kg intravenously every 24 hours plus
vancomycin 15 mg/kg intravenously every 12 hours.

Answer 15

2. Answer: D
   Ceftriaxone plus gentamicin plus linezolid is not good
   empiric therapy because ceftriaxone has no activity
   against P. aeruginosa. Because the patient has been in a
   hospital for 5 days or more (8 days at this point), she is at
   increased risk of MDR organisms, specifically P. aeruginosa
   and MRSA (Answer A is incorrect). Although
   piperacillin/tazobactam has good activity against most
   common causes of nosocomial pneumonia (including
   P. aeruginosa), the most recent guidelines recommend
   two antibiotics with activity against P. aeruginosa for
   patients with risk factors for MDR organisms She also
   needs an antibiotic with MRSA activity (Answer B is
   incorrect). Levofloxacin has activity against P. aeruginosa,
   but two drugs should be used (Answer C is incorrect).
   Cefepime plus tobramycin plus vancomycin is the
   best empiric therapy because it includes two antibiotics
   with activity against P. aeruginosa and another agent
   for MRSA (Answer D is correct).

Question 16

Patient Case
3. S.C. is a 46-year-old woman who presents to the clinic with purulent nasal discharge, nasal and facial congestion,
headaches, fever, and dental pain. Her symptoms began about 10 days ago, improved after about 4 days,
and then worsened again a few days later. Which is the best empiric therapy for S.C.?
A. Cefpodoxime proxetil 200 mg orally twice daily.
B. Clindamycin 300 mg orally four times daily.
C. Amoxicillin/clavulanate 875 mg/125 mg orally twice daily.
D. No antibiotic therapy needed.

Answer 16

3. Answer: C
   This patient has symptoms suggestive of bacterial sinusitis,
   including two major symptoms and a few minor
   symptoms. That the symptoms improved and then
   worsened suggests a bacterial sinusitis that followed a
   viral infection (Answer D is incorrect). Although the
   combination of cefpodoxime and clindamycin is an
   option for sinusitis in penicillin-allergic patients, it is
   not recommended to give either of these alone for treatment
   (Answers A and B are incorrect). The best option
   is amoxicillin/clavulanate, which has activity against
   organisms commonly seen in bacterial sinusitis and is
   considered a first-line agent (Answer C is correct).

Question 17

Patient Case
4. G.N. is a 62-year-old woman who presents to the emergency department with a 3-day history of urinary frequency
and dysuria. During the past 24 hours, she has had nausea, vomiting, and flank pain. G.N. has a history
of type 2 diabetes, which is poorly controlled, with some diabetes-related complications. G.N. also has
hypertension and a history of several episodes of deep venous thrombosis. Her medications include glyburide
5 mg orally daily, enalapril 10 mg orally twice daily, warfarin 3 mg orally daily, and metoclopramide 10 mg
orally four times daily. On physical examination, she is alert and oriented, with the following vital signs:
temperature 102.8°F (39°C), heart rate 120 beats/minute, respiratory rate 16 breaths/minute, supine blood
pressure 140/75 mm Hg, and standing blood pressure 110/60 mm Hg. Her laboratory values are within normal
limits except for elevated international normalized ratio 2.7, BUN 26 mg/dL, SCr 1.88 mg/dL, and WBC
12,000 cells/mm3 (78 polymorphonuclear leukocytes, 7 band neutrophils, 10 lymphocytes, and 5 monocytes).
Her urinalysis reveals turbidity, 2+ glucose, pH 7.0, protein 100 mg/dL, 50–100 WBCs, positive nitrites, 3–5
red blood cells, and many bacteria and positive for casts. Which is the best empiric therapy for G.N.?
A. Trimethoprim/sulfamethoxazole double strength orally twice daily for 7 days. Monitor INR carefully.
B. Ciprofloxacin 400 mg intravenously twice daily and then 500 mg orally twice daily for a total of 7 days.
Monitor INR carefully.
C. Gentamicin 140 mg intravenously every 24 hours for 3 days.
D. Tigecycline 100 mg once, then 50 mg intravenously every 12 hours and then doxycycline 100 mg orally
twice daily for a total of 10 days.

Answer 17

4. Answer: B
   Although the treatment duration is correct for this
   patient’s diagnosis (7 days), oral trimethoprim/sulfamethoxazole
   is inappropriate for complicated pyelonephritis.
   It will also interact with warfarin, increasing the
   risk of bleeding. (Answer A is incorrect). Ciprofloxacin
   400 mg intravenously twice daily and then 500 mg
   orally twice daily for 7 days is an appropriate choice
   and duration (7–14 days) for this complicated pyelonephritis
   (it may also interact with warfarin but to a
   lesser extent than trimethoprim/sulfamethoxazole). It
   would be expected to have activity against the common
   organisms causing complicated pyelonephritis (Answer
   B is correct). Gentamicin for 3 days is too short a treatment
   duration (Answer C is incorrect). Tigecycline,
   followed by doxycycline, is not recommended for complicated
   pyelonephritis (although tigecycline is found
   unchanged in the urine) (Answer D is incorrect).

Question 18

Patient Case
5. G.N. returns to the clinic in 6 months with no urinary symptoms, but her chief concern is now an ulcer on her
right foot. She recently returned from a vacation in Florida and thinks she might have stepped on something
while walking barefoot on the beach. Her foot is not sore but is red and swollen around the deep ulcer. Her
medications are the same as in Patient Case 4. Vital signs are stable, and there is nothing significant on physical
examination except for the right foot ulcer. Laboratory values are within normal limits (SCr 0.86 mg/dL).
Which is the best empiric therapy for G.N.?
A. Nafcillin 2 g intravenously every 6 hours for 6–12 weeks.
B. Tobramycin 120 mg intravenously every 12 hours plus levofloxacin 750 mg intravenously every 24 hours
for 1–2 weeks.
C. Ampicillin/sulbactam 3 g intravenously every 6 hours for 2–3 weeks.
D. Below-the-knee amputation followed by ceftriaxone 1 g intravenously every 24 hours for 1 week.

Answer 18

5. Answer: C
   Nafcillin has excellent activity against gram-positive
   organisms, but it would miss the gram-negative organisms
   and anaerobes often involved in moderate to
   severe diabetic foot infections (Answer A is incorrect).
   Tobramycin and levofloxacin would be good against
   aerobic organisms, but levofloxacin has only limited
   activity against anaerobes. Tobramycin may also not
   be a good choice for a patient with diabetes mellitus
   with long-term complications (because of the increased
   risk of nephrotoxicity) (Answer B is incorrect).
   β-Lactamase inhibitor combinations are good agents
   because they have activity against the organisms that
   are often involved. At this time, a regimen active against P. aeruginosa is probably not necessary.
   Treatment duration may need to be extended if the bone
   is involved (Answer C is correct). Aggressive antibiotic
   treatment often prevents the need for an amputation
   (Answer D is incorrect).

Question 19

Patient Case
6. W.A. is a 55-year-old man who is admitted with weight loss, malaise, and severe back pain and spasms that
have progressed during the past 2 months. He has also experienced loss of sensation in his lower extremities.
Four months before this admission, he had surgery for a fractured tibia, followed by an infection treated with
unknown antibiotics. W.A. has hypertension and a history of diverticulitis. On physical examination, he is
alert and oriented, with the following vital signs: temperature 99.4°F (37.4°C), heart rate 88 beats/minute,
respiratory rate 14 breaths/minute, and blood pressure 130/85 mm Hg. His laboratory values are within normal
limits, except for WBC 14,300 cells/mm3, erythrocyte sedimentation rate 89 mm/hour, and C-reactive
protein 12 mg/dL. Magnetic resonance imaging reveals bony destruction of lumbar vertebrae 1 and 2, which
is confirmed by a bone scan. A computed tomography–guided bone biopsy reveals gram-positive cocci in
clusters. Which is the best therapy for W.A.?
A. Vancomycin 15 mg/kg intravenously every 12 hours for 6 weeks.
B. Nafcillin 2 g intravenously every 6 hours for 2 weeks.
C. Levofloxacin 750 mg orally every 24 hours for 6 weeks.
D. Ampicillin/sulbactam 3 g intravenously every 6 hours for 2 weeks.

Answer 19

6. Answer: A
   Because sensitivities of the gram-positive organism are
   still unknown, vancomycin is the best choice. In addition,
   the therapy duration for osteomyelitis is 4–6 weeks
   (Answer A is correct). Therefore, the 2-week duration
   with nafcillin is too short (Answer B is incorrect).
   Although levofloxacin is advantageous because it can be
   given orally, it will probably not achieve adequate bone
   concentrations to eradicate S. aureus (the most likely
   organism) (Answer C is incorrect). Ampicillin/sulbactam
   is effective against S. aureus (except for MRSA); its
   broad spectrum of activity is not necessary in this situation,
   and the duration is too short (Answer D is incorrect).

Question 20

Patient Case
7. D.M. is a 21-year-old university student who presents to the emergency department with the worst headache
of his life. During the past few days, he has felt slightly ill but has been able to go to class regularly and eat and
drink adequately. This morning, he awoke with a terrible headache and pain whenever he moved his neck. He
has no significant medical history and takes no medications. He cannot remember the last time he received a
vaccination. On physical examination, he is in extreme pain (10/10) with the following vital signs: temperature
102.4°F (39.1°C), heart rate 110 beats/minute, respiratory rate 18 breaths/minute, and blood pressure
130/75 mm Hg. His laboratory values are within normal limits, except for WBC 22,500 cells/mm3 (82 polymorphonuclear
leukocytes, 11 band neutrophils, 5 lymphocytes, and 2 monocytes). A computed tomography
scan of the head is normal, so a lumbar puncture is performed with the following results: glucose 44 mg/dL
(peripheral, 110), protein 220 mg/dL, and WBC 800 cells/mm3 (85% neutrophils, 15% lymphocytes). Which
is the best empiric therapy for D.M.?
A. Penicillin G 4 million units intravenously every 4 hours.
B. Ceftriaxone 2 g intravenously every 12 hours.
C. Ceftriaxone 2 g intravenously every 12 hours plus dexamethasone 10 mg intravenously every 6 hours.
D. Ceftriaxone 2 g intravenously every 12 hours plus vancomycin 1000 mg intravenously every 8 hours plus
dexamethasone 10 mg intravenously every 6 hours.

Answer 20

7. Answer: D
   From his presentation and laboratory values, this
   patient has bacterial meningitis. Penicillin is effective
   against N. meningitidis and S. pneumoniae; however,
   some strains are resistant, and until culture results are
   received, it is unwise to use this agent alone (Answer A
   is incorrect). Ceftriaxone alone is effective for meningococcal
   and pneumococcal meningitis; however,
   vancomycin should be started empirically with ceftriaxone
   in case the patient has a highly penicillin-resistant
   S. pneumoniae (Answers B and C are incorrect).
   Ceftriaxone is the appropriate empiric antibiotic therapy
   in this situation and vancomycin is generally used
   empirically because of its activity against highly penicillin-
   resistant S. pneumoniae (Answer D is correct).
   The vancomycin can be discontinued when highly penicillin-
   resistant pneumococcal meningitis is ruled out.

Question 21

Patient Case
8. D.M.’s CSF cultures grew N. meningitidis. Which is the best recommendation for meningitis prophylaxis?
A. The health care providers in close contact with D.M. should receive rifampin 600 mg orally every
12 hours for four doses.
B. Everyone in D.M.’s dormitory and in all of his classes should receive rifampin 600 mg orally every
24 hours for 4 days.
C. Everyone in the emergency department at the time of D.M.’s presentation should receive the meningococcal
conjugate vaccine.
D. Everyone in the emergency department at the time of D.M.’s presentation should receive rifampin
600 mg orally every 12 hours for four doses.

Answer 21

8. Answer: A
   Only people in close contact to a patient with meningococcal
   meningitis need prophylaxis (primarily those
   who live closely with the patient and those who are
   exposed to oral secretions) (Answer B and D are incorrect).
   The correct regimen is rifampin 600 mg every 12
   hours for four doses (Answer A is correct). Although
   the vaccine is a good idea for those at future risk of
   acquiring this infection (e.g., college students living in
   dormitories), its use during an outbreak is very limited
   (Answer C is incorrect).

Question 22

9. T.S. is a 48-year-old man who presents to the emergency department with fever, chills, nausea and vomiting,
   anorexia, lymphangitis in his right hand, and lower back pain. He has no significant medical history except
   for kidney stones 4 years ago. He has no known drug allergies. He is homeless and was a person with substance
   use disorder (intravenous heroin) for the past year but quit 2 weeks ago. On physical examination, he
   is alert and oriented, with the following vital signs: temperature 100.8°F (38°C), heart rate 114 beats/minute,
   respiratory rate 12 breaths/minute, and blood pressure 127/78 mm Hg. He has a faint systolic ejection murmur,
   and his right hand is erythematous and swollen. His laboratory values are all within normal limits. He had an
   HIV test 1 year ago, which was negative. One blood culture was obtained in the emergency department that
   later grew MSSA. Two more cultures were obtained 24 hours after the first culture and are now both growing
   gram-positive cocci in clusters. A transesophageal echocardiogram reveals vegetation on the mitral valve.
   Which is the best therapeutic regimen for T.S.?
   A. Nafcillin therapy for 7–10 days.
   B. Nafcillin plus rifampin plus gentamicin therapy for 6 weeks or longer.
   C. Nafcillin plus gentamicin therapy for 2 weeks of both antibiotics.
   D. Nafcillin therapy for 6 weeks.

Answer 22

9. Answer: D
   A treatment duration of 7-10 days is too short for S.
   aureus endocarditis in the mitral position (Answer A
   is incorrect). Only streptococcal endocarditis can be
   treated for 2 weeks. Although nafcillin intravenously
   plus rifampin plus gentamicin therapy for 6 weeks or
   longer is an appropriate duration for MSSA, the rifampin
   and gentamicin need not be added in patients with
   native valve endocarditis (Answer B is incorrect).
   Nafcillin intravenously plus gentamicin intravenously
   for 2 weeks is too short for S. aureus endocarditis
   (Answer C is incorrect). Nafcillin intravenously for 6
   weeks is the recommended treatment for MSSA endocarditis
   (Answer D is correct).

Question 23

Patient Case
10. Six months after treatment of his endocarditis, T.S. is visiting his dentist for a tooth extraction. Which antibiotic
is best for prophylaxis?
A. Tooth extractions do not warrant endocarditis prophylaxis.
B. Administer amoxicillin 2 g 1 hour before the extraction.
C. Administer amoxicillin 3 g 1 hour before the extraction and 1.5 g 6 hours for four doses after the extraction.
D. T.S. is not at increased risk of endocarditis and does not need prophylactic antibiotics.

Answer 23

10. Answer: B
    This patient is at increased risk of endocarditis because
    of his history of the disease (Answer D is incorrect).
    Tooth extractions warrant prophylaxis for those at risk
    (Answer A is incorrect) Amoxicillin 2 g, 1 hour before
    the tooth extraction, is the current recommended dose
    (Answer B is correct). The 2-g dose is adequate for protection,
    and a follow-up dose is not needed. Amoxicillin
    3 g 1 hour before the extraction and 1.5 g 6 hours for
    four doses after the extraction is the older recommended
    dose. A follow-up dose is not needed (Answer
    C is incorrect).

Question 24

Patient Case
11. R.K. is a 72-year-old man who presents to the emergency department with a 2-day history of redness and
swelling of his upper right extremity. He scraped his arm while clearing some brush in his yard. Although
the scratch was initially healing, the area around the injury has become red and warm to the touch over the
past few days, and the redness appears to be spreading. His medical history includes gastroesophageal reflux
disease, hypertension, hyperlipidemia, and osteoarthritis. R.K. is taking pantoprazole 40 mg orally daily, lisinopril
20 mg orally daily, atorvastatin 40 mg orally daily, and acetaminophen 500 mg orally as needed. R.K.
has no known drug allergies. R.K. is hospitalized and sent home after a few days with a prescription for oral
clindamycin for his cellulitis. Two weeks after completing therapy for his cellulitis, R.K. has watery diarrhea.
R.K. goes to the emergency department, and his C. difficile toxin is positive. His WBC is 24,500 cells/mm3,
albumin is 2.8 g/dL, and SCr is 1.74 mg/dL (normally around 0.90 mg/dL). Which is the best therapeutic
regimen for R.K.?
A. Metronidazole 500 mg orally three times daily for 7 days.
B. Vancomycin 125 mg orally four times daily for 10 days.
C. Fidaxomicin 200 mg orally twice daily for 14 days.
D. Rifaximin 400 mg orally twice daily for 7 days.

Answer 24

11. Answer: B
    This patient is having a severe episode of C. difficile
    diarrhea, as demonstrated by his low albumin, high
    WBC, and elevated SCr. Therefore, metronidazole is
    not the optimal choice (and the duration is too short)
    (Answer A is incorrect). Fidaxomicin and rifaximin are
    not first-line agents (Answers C and D are incorrect).
    Fidaxomicin could be used first line in patients who are
    at high risk of recurrence, but the duration of 14 days is
    too long. The best therapy for this patient is vancomycin
    for 10 days (Answer B is correct).

Question 25

Patient Case
12. You are a pharmacist who works closely with the surgery department to optimize therapy for patients undergoing
surgical procedures at your institution. The surgeons provide you with principles of surgical prophylaxis
that they believe are appropriate. Which is the best practice for optimizing surgical prophylaxis?
A. Antibiotics should be redosed for extended surgical procedures; redose if the surgery lasts longer than
4 hours or involves considerable blood loss.
B. All patients should be given antibiotics for 24 hours after the procedure; this will optimize prophylaxis.
C. Preoperative antibiotics can be given up to 4 hours before the incision; this will make giving the antibiotics
logistically easier.
D. Vancomycin is the antibiotic of choice for surgical wound prophylaxis because of its long half-life and
activity against MRSA.

Answer 25

12. Answer: A
    Redosing antibiotics for surgical prophylaxis is very
    important, especially for antibiotics with short halflives,
    for extended surgical procedures, or for when
    there is extensive blood loss (Answer A is correct).
    Antibiotics given beyond the surgical procedure are generally
    unnecessary and only increase the potential for
    adverse drug reactions and resistant bacteria (Answer
    B is incorrect). Although preoperative antibiotics given up to 4 hours before the incision may improve the logistics
    of administering surgical prophylaxis, study results
    show that antibiotics must be given as close to the time
    of the incision as possible (definitely within 2 hours)
    (Answer C is incorrect). Vancomycin should not be
    used routinely for surgical prophylaxis. The Centers for
    Disease Control and Prevention does not recommend
    the use of vancomycin for “routine surgical prophylaxis
    other than in a patient with life-threatening allergy to
    β-lactam antibiotics.”(Answer D is incorrect).